xK/xC.c

/*
 * xC.c: a terminal-based IRC client
 *
 * Copyright (c) 2015 - 2022, Přemysl Eric Janouch <p@janouch.name>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */

// A table of all attributes we use for output
#define ATTR_TABLE(XX)                                                  \
	XX( PROMPT,      prompt,      Terminal attrs for the prompt       ) \
	XX( RESET,       reset,       String to reset terminal attributes ) \
	XX( DATE_CHANGE, date_change, Terminal attrs for date change      ) \
	XX( READ_MARKER, read_marker, Terminal attrs for the read marker  ) \
	XX( WARNING,     warning,     Terminal attrs for warnings         ) \
	XX( ERROR,       error,       Terminal attrs for errors           ) \
	XX( EXTERNAL,    external,    Terminal attrs for external lines   ) \
	XX( TIMESTAMP,   timestamp,   Terminal attrs for timestamps       ) \
	XX( HIGHLIGHT,   highlight,   Terminal attrs for highlights       ) \
	XX( ACTION,      action,      Terminal attrs for user actions     ) \
	XX( USERHOST,    userhost,    Terminal attrs for user@host        ) \
	XX( JOIN,        join,        Terminal attrs for joins            ) \
	XX( PART,        part,        Terminal attrs for parts            )

enum
{
#define XX(x, y, z) ATTR_ ## x,
	ATTR_TABLE (XX)
#undef XX
	ATTR_COUNT
};

// User data for logger functions to enable formatted logging
#define print_fatal_data    ((void *) ATTR_ERROR)
#define print_error_data    ((void *) ATTR_ERROR)
#define print_warning_data  ((void *) ATTR_WARNING)

#include "config.h"
#define PROGRAM_NAME "xC"

#include "common.c"
#include "xD-replies.c"
#include "xC-proto.c"

#include <math.h>
#include <langinfo.h>
#include <locale.h>
#include <pwd.h>
#include <sys/utsname.h>
#include <wchar.h>

#include <termios.h>
#include <sys/ioctl.h>

#include <curses.h>
#include <term.h>

// Literally cancer
#undef lines
#undef columns

#include <ffi.h>

#ifdef HAVE_LUA
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#endif // HAVE_LUA

// --- Terminal information ----------------------------------------------------

static struct
{
	bool initialized;                   ///< Terminal is available
	bool stdout_is_tty;                 ///< `stdout' is a terminal
	bool stderr_is_tty;                 ///< `stderr' is a terminal

	struct termios termios;             ///< Terminal attributes
	char *color_set_fg[256];            ///< Codes to set the foreground colour
	char *color_set_bg[256];            ///< Codes to set the background colour

	int lines;                          ///< Number of lines
	int columns;                        ///< Number of columns
}
g_terminal;

static void
update_screen_size (void)
{
#ifdef TIOCGWINSZ
	if (!g_terminal.stdout_is_tty)
		return;

	struct winsize size;
	if (!ioctl (STDOUT_FILENO, TIOCGWINSZ, (char *) &size))
	{
		char *row = getenv ("LINES");
		char *col = getenv ("COLUMNS");
		unsigned long tmp;
		g_terminal.lines =
			(row && xstrtoul (&tmp, row, 10)) ? tmp : size.ws_row;
		g_terminal.columns =
			(col && xstrtoul (&tmp, col, 10)) ? tmp : size.ws_col;
	}
#endif // TIOCGWINSZ
}

static bool
init_terminal (void)
{
	int tty_fd = -1;
	if ((g_terminal.stderr_is_tty = isatty (STDERR_FILENO)))
		tty_fd = STDERR_FILENO;
	if ((g_terminal.stdout_is_tty = isatty (STDOUT_FILENO)))
		tty_fd = STDOUT_FILENO;

	int err;
	if (tty_fd == -1 || setupterm (NULL, tty_fd, &err) == ERR)
		return false;

	// Make sure all terminal features used by us are supported
	if (!set_a_foreground || !set_a_background
	 || !enter_bold_mode || !exit_attribute_mode
	 || tcgetattr (tty_fd, &g_terminal.termios))
	{
		del_curterm (cur_term);
		return false;
	}

	// Make sure newlines are output correctly
	g_terminal.termios.c_oflag |= ONLCR;
	(void) tcsetattr (tty_fd, TCSADRAIN, &g_terminal.termios);

	g_terminal.lines   = tigetnum ("lines");
	g_terminal.columns = tigetnum ("cols");
	update_screen_size ();

	int max = MIN (256, max_colors);
	for (int i = 0; i < max; i++)
	{
		g_terminal.color_set_fg[i] = xstrdup (tparm (set_a_foreground,
			i, 0, 0, 0, 0, 0, 0, 0, 0));
		g_terminal.color_set_bg[i] = xstrdup (tparm (set_a_background,
			i, 0, 0, 0, 0, 0, 0, 0, 0));
	}
	return g_terminal.initialized = true;
}

static void
free_terminal (void)
{
	if (!g_terminal.initialized)
		return;

	for (int i = 0; i < 256; i++)
	{
		free (g_terminal.color_set_fg[i]);
		free (g_terminal.color_set_bg[i]);
	}
	del_curterm (cur_term);
}

// --- User interface ----------------------------------------------------------

// I'm not sure which one of these backends is worse: whether it's GNU Readline
// or BSD Editline.  They both have their own annoying problems.  We use lots
// of hacks to get the results we want and need.
//
// The abstraction is a necessary evil.  It's still not 100%, though.

/// Some arbitrary limit for the history
#define HISTORY_LIMIT 10000

/// Characters that separate words
#define WORD_BREAKING_CHARS " \f\n\r\t\v"

struct input
{
	struct input_vtable *vtable;        ///< Virtual methods
	void (*add_functions) (void *);     ///< Define functions for binding
	void *user_data;                    ///< User data for callbacks
};

typedef void *input_buffer_t;           ///< Pointer alias for input buffers

/// Named function that can be bound to a sequence of characters
typedef bool (*input_fn) (int count, int key, void *user_data);

// A little bit better than tons of forwarder functions in our case
#define CALL(self, name)        ((self)->vtable->name ((self)))
#define CALL_(self, name, ...)  ((self)->vtable->name ((self), __VA_ARGS__))

struct input_vtable
{
	/// Start the interface under the given program name
	void (*start) (void *input, const char *program_name);
	/// Stop the interface
	void (*stop) (void *input);
	/// Prepare or unprepare terminal for our needs
	void (*prepare) (void *input, bool enabled);
	/// Destroy the object
	void (*destroy) (void *input);

	/// Hide the prompt if shown
	void (*hide) (void *input);
	/// Show the prompt if hidden
	void (*show) (void *input);
	/// Retrieve current prompt string
	const char *(*get_prompt) (void *input);
	/// Change the prompt string; takes ownership
	void (*set_prompt) (void *input, char *prompt);
	/// Ring the terminal bell
	void (*ding) (void *input);

	/// Create a new input buffer
	input_buffer_t (*buffer_new) (void *input);
	/// Destroy an input buffer
	void (*buffer_destroy) (void *input, input_buffer_t buffer);
	/// Switch to a different input buffer
	void (*buffer_switch) (void *input, input_buffer_t buffer);

	/// Register a function that can be bound to character sequences
	void (*register_fn) (void *input,
		const char *name, const char *help, input_fn fn, void *user_data);
	/// Bind an arbitrary sequence of characters to the given named function
	void (*bind) (void *input, const char *seq, const char *fn);
	/// Bind Ctrl+key to the given named function
	void (*bind_control) (void *input, char key, const char *fn);
	/// Bind Alt+key to the given named function
	void (*bind_meta) (void *input, char key, const char *fn);

	/// Get the current line input and position within
	char *(*get_line) (void *input, int *position);
	/// Clear the current line input
	void (*clear_line) (void *input);
	/// Insert text at current position
	bool (*insert) (void *input, const char *text);

	/// Handle terminal resize
	void (*on_tty_resized) (void *input);
	/// Handle terminal input
	void (*on_tty_readable) (void *input);
};

#define INPUT_VTABLE(XX)                                                       \
	XX (start) XX (stop) XX (prepare) XX (destroy)                             \
	XX (hide) XX (show) XX (get_prompt) XX (set_prompt) XX (ding)              \
	XX (buffer_new) XX (buffer_destroy) XX (buffer_switch)                     \
	XX (register_fn) XX (bind) XX (bind_control) XX (bind_meta)                \
	XX (get_line) XX (clear_line) XX (insert)                                  \
	XX (on_tty_resized) XX (on_tty_readable)

// ~~~ GNU Readline ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#ifdef HAVE_READLINE

#include <readline/readline.h>
#include <readline/history.h>

#define INPUT_START_IGNORE  RL_PROMPT_START_IGNORE
#define INPUT_END_IGNORE    RL_PROMPT_END_IGNORE

struct input_rl_fn
{
	ffi_closure closure;                ///< Closure

	LIST_HEADER (struct input_rl_fn)
	input_fn callback;                  ///< Real callback
	void *user_data;                    ///< Real callback user data
};

struct input_rl_buffer
{
	HISTORY_STATE *history;             ///< Saved history state
	char *saved_line;                   ///< Saved line content
	int saved_point;                    ///< Saved cursor position
	int saved_mark;                     ///< Saved mark
};

struct input_rl
{
	struct input super;                 ///< Parent class

	bool active;                        ///< Interface has been started
	char *prompt;                       ///< The prompt we use
	int prompt_shown;                   ///< Whether the prompt is shown now

	char *saved_line;                   ///< Saved line content
	int saved_point;                    ///< Saved cursor position
	int saved_mark;                     ///< Saved mark

	struct input_rl_fn *fns;            ///< Named functions
	struct input_rl_buffer *current;    ///< Current input buffer
};

static void
input_rl_ding (void *input)
{
	(void) input;
	rl_ding ();
}

static const char *
input_rl_get_prompt (void *input)
{
	struct input_rl *self = input;
	return self->prompt;
}

static void
input_rl_set_prompt (void *input, char *prompt)
{
	struct input_rl *self = input;
	cstr_set (&self->prompt, prompt);

	if (!self->active || self->prompt_shown <= 0)
		return;

	// First reset the prompt to work around a bug in readline
	rl_set_prompt ("");
	rl_redisplay ();

	rl_set_prompt (self->prompt);
	rl_redisplay ();
}

static void
input_rl_clear_line (void *input)
{
	(void) input;
	rl_replace_line ("", false);
	rl_redisplay ();
}

static void
input_rl__erase (struct input_rl *self)
{
	rl_set_prompt ("");
	input_rl_clear_line (self);
}

static bool
input_rl_insert (void *input, const char *s)
{
	struct input_rl *self = input;
	rl_insert_text (s);
	if (self->prompt_shown > 0)
		rl_redisplay ();

	// GNU Readline, contrary to Editline, doesn't care about validity
	return true;
}

static char *
input_rl_get_line (void *input, int *position)
{
	(void) input;
	if (position) *position = rl_point;
	return rl_copy_text (0, rl_end);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_rl_bind (void *input, const char *seq, const char *function_name)
{
	(void) input;
	rl_bind_keyseq (seq, rl_named_function (function_name));
}

static void
input_rl_bind_meta (void *input, char key, const char *function_name)
{
	// This one seems to actually work
	char keyseq[] = { '\\', 'e', key, 0 };
	input_rl_bind (input, keyseq, function_name);
#if 0
	// While this one only fucks up UTF-8
	// Tested with urxvt and xterm, on Debian Jessie/Arch, default settings
	// \M-<key> behaves exactly the same
	rl_bind_key (META (key), rl_named_function (function_name));
#endif
}

static void
input_rl_bind_control (void *input, char key, const char *function_name)
{
	char keyseq[] = { '\\', 'C', '-', key, 0 };
	input_rl_bind (input, keyseq, function_name);
}

static void
input_rl__forward (ffi_cif *cif, void *ret, void **args, void *user_data)
{
	(void) cif;

	struct input_rl_fn *data = user_data;
	if (!data->callback
		(*(int *) args[0], UNMETA (*(int *) args[1]), data->user_data))
		rl_ding ();
	*(int *) ret = 0;
}

static void
input_rl_register_fn (void *input,
	const char *name, const char *help, input_fn callback, void *user_data)
{
	struct input_rl *self = input;
	(void) help;

	void *bound_fn = NULL;
	struct input_rl_fn *data = ffi_closure_alloc (sizeof *data, &bound_fn);
	hard_assert (data);

	static ffi_cif cif;
	static ffi_type *args[2] = { &ffi_type_sint, &ffi_type_sint };
	hard_assert (ffi_prep_cif
		(&cif, FFI_DEFAULT_ABI, 2, &ffi_type_sint, args) == FFI_OK);

	data->prev = data->next = NULL;
	data->callback = callback;
	data->user_data = user_data;
	hard_assert (ffi_prep_closure_loc (&data->closure,
		&cif, input_rl__forward, data, bound_fn) == FFI_OK);

	rl_add_defun (name, (rl_command_func_t *) bound_fn, -1);
	LIST_PREPEND (self->fns, data);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int app_readline_init (void);
static void on_readline_input (char *line);
static char **app_readline_completion (const char *text, int start, int end);

static void
input_rl_start (void *input, const char *program_name)
{
	struct input_rl *self = input;
	using_history ();
	// This can cause memory leaks, or maybe even a segfault.  Funny, eh?
	stifle_history (HISTORY_LIMIT);

	const char *slash = strrchr (program_name, '/');
	rl_readline_name = slash ? ++slash : program_name;
	rl_startup_hook = app_readline_init;
	rl_catch_sigwinch = false;
	rl_change_environment = false;

	rl_basic_word_break_characters = WORD_BREAKING_CHARS;
	rl_completer_word_break_characters = NULL;
	rl_attempted_completion_function = app_readline_completion;

	// We shouldn't produce any duplicates that the library would help us
	// autofilter, and we don't generally want alphabetic ordering at all
	rl_sort_completion_matches = false;

	hard_assert (self->prompt != NULL);
	// The inputrc is read before any callbacks are called, so we need to
	// register all functions that our user may want to map up front
	self->super.add_functions (self->super.user_data);
	rl_callback_handler_install (self->prompt, on_readline_input);

	self->prompt_shown = 1;
	self->active = true;
}

static void
input_rl_stop (void *input)
{
	struct input_rl *self = input;
	if (self->prompt_shown > 0)
		input_rl__erase (self);

	// This is okay as long as we're not called from within readline
	rl_callback_handler_remove ();
	self->active = false;
	self->prompt_shown = false;
}

static void
input_rl_prepare (void *input, bool enabled)
{
	(void) input;
	if (enabled)
		rl_prep_terminal (true);
	else
		rl_deprep_terminal ();
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// The following part shows you why it's not a good idea to use
// GNU Readline for this kind of software.  Or for anything else, really.

static void
input_rl__save_buffer (struct input_rl *self, struct input_rl_buffer *buffer)
{
	(void) self;

	buffer->history = history_get_history_state ();
	buffer->saved_line = rl_copy_text (0, rl_end);
	buffer->saved_point = rl_point;
	buffer->saved_mark = rl_mark;

	rl_replace_line ("", true);
	if (self->prompt_shown > 0)
		rl_redisplay ();
}

static void
input_rl__restore_buffer (struct input_rl *self, struct input_rl_buffer *buffer)
{
	if (buffer->history)
	{
		// history_get_history_state() just allocates a new HISTORY_STATE
		// and fills it with its current internal data.  We don't need that
		// shell anymore after reviving it.
		history_set_history_state (buffer->history);
		free (buffer->history);
		buffer->history = NULL;
	}
	else
	{
		// This should get us a clean history while keeping the flags.
		// Note that we've either saved the previous history entries, or we've
		// cleared them altogether, so there should be nothing to leak.
		HISTORY_STATE *state = history_get_history_state ();
		state->offset = state->length = state->size = 0;
		state->entries = NULL;
		history_set_history_state (state);
		free (state);
	}

	if (buffer->saved_line)
	{
		rl_replace_line (buffer->saved_line, true);
		rl_point = buffer->saved_point;
		rl_mark = buffer->saved_mark;
		cstr_set (&buffer->saved_line, NULL);

		if (self->prompt_shown > 0)
			rl_redisplay ();
	}
}

static void
input_rl_buffer_switch (void *input, input_buffer_t input_buffer)
{
	struct input_rl *self = input;
	struct input_rl_buffer *buffer = input_buffer;
	// There could possibly be occurences of the current undo list in some
	// history entry.  We either need to free the undo list, or move it
	// somewhere else to load back later, as the buffer we're switching to
	// has its own history state.
	rl_free_undo_list ();

	// Save this buffer's history so that it's independent for each buffer
	if (self->current)
		input_rl__save_buffer (self, self->current);
	else
		// Just throw it away; there should always be an active buffer however
#if RL_READLINE_VERSION >= 0x0603
		rl_clear_history ();
#else // RL_READLINE_VERSION < 0x0603
		// At least something... this may leak undo entries
		clear_history ();
#endif // RL_READLINE_VERSION < 0x0603

	input_rl__restore_buffer (self, buffer);
	self->current = buffer;
}

static void
input_rl__buffer_destroy_wo_history (struct input_rl_buffer *self)
{
	free (self->history);
	free (self->saved_line);
	free (self);
}

static void
input_rl_buffer_destroy (void *input, input_buffer_t input_buffer)
{
	(void) input;
	struct input_rl_buffer *buffer = input_buffer;

	// rl_clear_history, being the only way I know of to get rid of the complete
	// history including attached data, is a pretty recent addition.  *sigh*
#if RL_READLINE_VERSION >= 0x0603
	if (buffer->history)
	{
		// See input_rl_buffer_switch() for why we need to do this BS
		rl_free_undo_list ();

		// This is probably the only way we can free the history fully
		HISTORY_STATE *state = history_get_history_state ();

		history_set_history_state (buffer->history);
		rl_clear_history ();
		// rl_clear_history just removes history entries,
		// we have to reclaim memory for their actual container ourselves
		free (buffer->history->entries);
		free (buffer->history);
		buffer->history = NULL;

		history_set_history_state (state);
		free (state);
	}
#endif // RL_READLINE_VERSION

	input_rl__buffer_destroy_wo_history (buffer);
}

static input_buffer_t
input_rl_buffer_new (void *input)
{
	(void) input;
	struct input_rl_buffer *self = xcalloc (1, sizeof *self);
	return self;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Since {save,restore}_buffer() store history, we can't use them here like we
// do with libedit, because then buffer_destroy() can free memory that's still
// being used by readline.  This situation is bound to happen on quit.

static void
input_rl__save (struct input_rl *self)
{
	hard_assert (!self->saved_line);

	self->saved_point = rl_point;
	self->saved_mark = rl_mark;
	self->saved_line = rl_copy_text (0, rl_end);
}

static void
input_rl__restore (struct input_rl *self)
{
	hard_assert (self->saved_line);

	rl_set_prompt (self->prompt);
	rl_replace_line (self->saved_line, false);
	rl_point = self->saved_point;
	rl_mark = self->saved_mark;
	cstr_set (&self->saved_line, NULL);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_rl_hide (void *input)
{
	struct input_rl *self = input;
	if (!self->active || self->prompt_shown-- < 1)
		return;

	input_rl__save (self);
	input_rl__erase (self);
}

static void
input_rl_show (void *input)
{
	struct input_rl *self = input;
	if (!self->active || ++self->prompt_shown < 1)
		return;

	input_rl__restore (self);
	rl_redisplay ();
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_rl_on_tty_resized (void *input)
{
	(void) input;
	// This fucks up big time on terminals with automatic wrapping such as
	// rxvt-unicode or newer VTE when the current line overflows, however we
	// can't do much about that
	rl_resize_terminal ();
}

static void
input_rl_on_tty_readable (void *input)
{
	(void) input;
	rl_callback_read_char ();
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_rl_destroy (void *input)
{
	struct input_rl *self = input;
	free (self->saved_line);
	LIST_FOR_EACH (struct input_rl_fn, iter, self->fns)
		ffi_closure_free (iter);
	free (self->prompt);
	free (self);
}

#define XX(a) .a = input_rl_ ## a,
static struct input_vtable input_rl_vtable = { INPUT_VTABLE (XX) };
#undef XX

static struct input *
input_rl_new (void)
{
	struct input_rl *self = xcalloc (1, sizeof *self);
	self->super.vtable = &input_rl_vtable;
	return &self->super;
}

#define input_new input_rl_new
#endif // HAVE_READLINE

// ~~~ BSD Editline ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

#ifdef HAVE_EDITLINE

#include <histedit.h>

#define INPUT_START_IGNORE  '\x01'
#define INPUT_END_IGNORE    '\x01'

struct input_el_fn
{
	ffi_closure closure;                ///< Closure

	LIST_HEADER (struct input_el_fn)
	input_fn callback;                  ///< Real callback
	void *user_data;                    ///< Real callback user data

	wchar_t *name;                      ///< Function name
	wchar_t *help;                      ///< Function help
};

struct input_el_buffer
{
	HistoryW *history;                  ///< The history object
	wchar_t *saved_line;                ///< Saved line content
	int saved_len;                      ///< Length of the saved line
	int saved_point;                    ///< Saved cursor position
};

struct input_el
{
	struct input super;                 ///< Parent class
	EditLine *editline;                 ///< The EditLine object

	bool active;                        ///< Are we a thing?
	char *prompt;                       ///< The prompt we use
	int prompt_shown;                   ///< Whether the prompt is shown now

	struct input_el_fn *fns;            ///< Named functions
	struct input_el_buffer *current;    ///< Current input buffer
};

static void app_editline_init (struct input_el *self);

static void
input_el__redisplay (void *input)
{
	// See rl_redisplay(), however NetBSD editline's map.c v1.54 breaks VREPRINT
	// so we bind redisplay somewhere else in app_editline_init()
	struct input_el *self = input;
	wchar_t x[] = { L'q' & 31, 0 };
	el_wpush (self->editline, x);

	// We have to do this or it gets stuck and nothing is done
	int dummy_count = 0;
	(void) el_wgets (self->editline, &dummy_count);
}

static char *
input_el__make_prompt (EditLine *editline)
{
	struct input_el *self = NULL;
	el_get (editline, EL_CLIENTDATA, &self);
	if (!self->prompt)
		return "";
	return self->prompt;
}

static char *
input_el__make_empty_prompt (EditLine *editline)
{
	(void) editline;
	return "";
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_ding (void *input)
{
	// XXX: this isn't probably very portable;
	//   we could use "bell" from terminfo but that creates a dependency
	(void) input;
	write (STDOUT_FILENO, "\a", 1);
}

static const char *
input_el_get_prompt (void *input)
{
	struct input_el *self = input;
	return self->prompt;
}

static void
input_el_set_prompt (void *input, char *prompt)
{
	struct input_el *self = input;
	cstr_set (&self->prompt, prompt);

	if (self->prompt_shown > 0)
		input_el__redisplay (self);
}

static void
input_el_clear_line (void *input)
{
	struct input_el *self = input;
	const LineInfoW *info = el_wline (self->editline);
	int len = info->lastchar - info->buffer;
	int point = info->cursor - info->buffer;
	el_cursor (self->editline, len - point);
	el_wdeletestr (self->editline, len);
	input_el__redisplay (self);
}

static void
input_el__erase (struct input_el *self)
{
	el_set (self->editline, EL_PROMPT, input_el__make_empty_prompt);
	input_el_clear_line (self);
}

static bool
input_el_insert (void *input, const char *s)
{
	struct input_el *self = input;
	bool success = !*s || !el_insertstr (self->editline, s);
	if (self->prompt_shown > 0)
		input_el__redisplay (self);
	return success;
}

static char *
input_el_get_line (void *input, int *position)
{
	struct input_el *self = input;
	const LineInfo *info = el_line (self->editline);
	int point = info->cursor - info->buffer;
	if (position) *position = point;
	return xstrndup (info->buffer, info->lastchar - info->buffer);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_bind (void *input, const char *seq, const char *function_name)
{
	struct input_el *self = input;
	el_set (self->editline, EL_BIND, seq, function_name, NULL);
}

static void
input_el_bind_meta (void *input, char key, const char *function_name)
{
	char keyseq[] = { 'M', '-', key, 0 };
	input_el_bind (input, keyseq, function_name);
}

static void
input_el_bind_control (void *input, char key, const char *function_name)
{
	char keyseq[] = { '^', key, 0 };
	input_el_bind (input, keyseq, function_name);
}

static void
input_el__forward (ffi_cif *cif, void *ret, void **args, void *user_data)
{
	(void) cif;

	struct input_el_fn *data = user_data;
	*(unsigned char *) ret = data->callback
		(1, *(int *) args[1], data->user_data) ? CC_NORM : CC_ERROR;
}

static wchar_t *
ascii_to_wide (const char *ascii)
{
	size_t len = strlen (ascii) + 1;
	wchar_t *wide = xcalloc (sizeof *wide, len);
	while (len--)
		hard_assert ((wide[len] = (unsigned char) ascii[len]) < 0x80);
	return wide;
}

static void
input_el_register_fn (void *input,
	const char *name, const char *help, input_fn callback, void *user_data)
{
	void *bound_fn = NULL;
	struct input_el_fn *data = ffi_closure_alloc (sizeof *data, &bound_fn);
	hard_assert (data);

	static ffi_cif cif;
	static ffi_type *args[2] = { &ffi_type_pointer, &ffi_type_sint };
	hard_assert (ffi_prep_cif
		(&cif, FFI_DEFAULT_ABI, 2, &ffi_type_uchar, args) == FFI_OK);

	data->user_data = user_data;
	data->callback = callback;
	data->name = ascii_to_wide (name);
	data->help = ascii_to_wide (help);
	hard_assert (ffi_prep_closure_loc (&data->closure,
		&cif, input_el__forward, data, bound_fn) == FFI_OK);

	struct input_el *self = input;
	el_wset (self->editline, EL_ADDFN, data->name, data->help, bound_fn);
	LIST_PREPEND (self->fns, data);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_start (void *input, const char *program_name)
{
	struct input_el *self = input;
	self->editline = el_init (program_name, stdin, stdout, stderr);
	el_set (self->editline, EL_CLIENTDATA, self);
	el_set (self->editline, EL_PROMPT_ESC,
		input_el__make_prompt, INPUT_START_IGNORE);
	el_set (self->editline, EL_SIGNAL, false);
	el_set (self->editline, EL_UNBUFFERED, true);
	el_set (self->editline, EL_EDITOR, "emacs");

	app_editline_init (self);

	self->prompt_shown = 1;
	self->active = true;
}

static void
input_el_stop (void *input)
{
	struct input_el *self = input;
	if (self->prompt_shown > 0)
		input_el__erase (self);

	el_end (self->editline);
	self->editline = NULL;
	self->active = false;
	self->prompt_shown = false;
}

static void
input_el_prepare (void *input, bool enabled)
{
	struct input_el *self = input;
	el_set (self->editline, EL_PREP_TERM, enabled);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el__save_buffer (struct input_el *self, struct input_el_buffer *buffer)
{
	const LineInfoW *info = el_wline (self->editline);
	int len = info->lastchar - info->buffer;
	int point = info->cursor - info->buffer;

	wchar_t *line = calloc (sizeof *info->buffer, len + 1);
	memcpy (line, info->buffer, sizeof *info->buffer * len);
	el_cursor (self->editline, len - point);
	el_wdeletestr (self->editline, len);

	buffer->saved_line = line;
	buffer->saved_point = point;
	buffer->saved_len = len;
}

static void
input_el__save (struct input_el *self)
{
	if (self->current)
		input_el__save_buffer (self, self->current);
}

static void
input_el__restore_buffer (struct input_el *self, struct input_el_buffer *buffer)
{
	if (buffer->saved_line)
	{
		el_winsertstr (self->editline, buffer->saved_line);
		el_cursor (self->editline,
			-(buffer->saved_len - buffer->saved_point));
		free (buffer->saved_line);
		buffer->saved_line = NULL;
	}
}

static void
input_el__restore (struct input_el *self)
{
	if (self->current)
		input_el__restore_buffer (self, self->current);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Editline keeping its own history position (look for "eventno" there).
// This is the only sane way of resetting it.
static void
input_el__start_over (struct input_el *self)
{
	wchar_t x[] = { L'c' & 31, 0 };
	el_wpush (self->editline, x);

	int dummy_count = 0;
	(void) el_wgets (self->editline, &dummy_count);
}

static void
input_el_buffer_switch (void *input, input_buffer_t input_buffer)
{
	struct input_el *self = input;
	struct input_el_buffer *buffer = input_buffer;
	if (!self->active)
		return;

	if (self->current)
		input_el__save_buffer (self, self->current);

	self->current = buffer;
	el_wset (self->editline, EL_HIST, history, buffer->history);
	input_el__start_over (self);
	input_el__restore_buffer (self, buffer);
}

static void
input_el_buffer_destroy (void *input, input_buffer_t input_buffer)
{
	struct input_el *self = input;
	struct input_el_buffer *buffer = input_buffer;
	if (self->active && self->current == buffer)
	{
		el_wset (self->editline, EL_HIST, history, NULL);
		self->current = NULL;
	}

	history_wend (buffer->history);
	free (buffer->saved_line);
	free (buffer);
}

static input_buffer_t
input_el_buffer_new (void *input)
{
	(void) input;
	struct input_el_buffer *self = xcalloc (1, sizeof *self);
	self->history = history_winit ();

	HistEventW ev;
	history_w (self->history, &ev, H_SETSIZE, HISTORY_LIMIT);
	return self;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_hide (void *input)
{
	struct input_el *self = input;
	if (!self->active || self->prompt_shown-- < 1)
		return;

	input_el__save (self);
	input_el__erase (self);
}

static void
input_el_show (void *input)
{
	struct input_el *self = input;
	if (!self->active || ++self->prompt_shown < 1)
		return;

	input_el__restore (self);
	el_set (self->editline,
		EL_PROMPT_ESC, input_el__make_prompt, INPUT_START_IGNORE);
	input_el__redisplay (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_on_tty_resized (void *input)
{
	struct input_el *self = input;
	el_resize (self->editline);
}

static void
input_el_on_tty_readable (void *input)
{
	// We bind the return key to process it how we need to
	struct input_el *self = input;

	// el_gets() with EL_UNBUFFERED doesn't work with UTF-8,
	// we must use the wide-character interface
	int count = 0;
	const wchar_t *buf = el_wgets (self->editline, &count);
	if (!buf || count-- <= 0)
		return;

	if (count == 0 && buf[0] == ('D' - 0x40) /* hardcoded VEOF in el_wgets() */)
	{
		el_deletestr (self->editline, 1);
		input_el__redisplay (self);
		input_el_ding (self);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
input_el_destroy (void *input)
{
	struct input_el *self = input;
	LIST_FOR_EACH (struct input_el_fn, iter, self->fns)
	{
		free (iter->name);
		free (iter->help);
		ffi_closure_free (iter);
	}
	free (self->prompt);
	free (self);
}

#define XX(a) .a = input_el_ ## a,
static struct input_vtable input_el_vtable = { INPUT_VTABLE (XX) };
#undef XX

static struct input *
input_el_new (void)
{
	struct input_el *self = xcalloc (1, sizeof *self);
	self->super.vtable = &input_el_vtable;
	return &self->super;
}

#define input_new input_el_new
#endif // HAVE_EDITLINE

// --- Application data --------------------------------------------------------

// All text stored in our data structures is encoded in UTF-8.  Or at least
// should be--our only ways of retrieving strings are: via the command line
// (converted from locale, no room for errors), via the configuration file
// (restrictive ASCII grammar for bare words and an internal check for strings),
// and via plugins (meticulously validated).
//
// The only exception is IRC identifiers.

// ~~~ Scripting support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// We need a few reference countable objects with support for both strong
// and weak references (mainly used for scripted plugins).
//
// Beware that if you don't own the object, you will most probably want
// to keep the weak reference link so that you can get rid of it later.
// Also note that you have to make sure the user_data don't leak resources.
//
// Having a callback is more versatile than just nulling out a pointer.

/// Callback just before a reference counted object is destroyed
typedef void (*destroy_cb_fn) (void *object, void *user_data);

struct weak_ref_link
{
	LIST_HEADER (struct weak_ref_link)

	destroy_cb_fn on_destroy;           ///< Called when object is destroyed
	void *user_data;                    ///< User data
};

static struct weak_ref_link *
weak_ref (struct weak_ref_link **list, destroy_cb_fn cb, void *user_data)
{
	struct weak_ref_link *link = xcalloc (1, sizeof *link);
	link->on_destroy = cb;
	link->user_data = user_data;
	LIST_PREPEND (*list, link);
	return link;
}

static void
weak_unref (struct weak_ref_link **list, struct weak_ref_link **link)
{
	if (*link)
		LIST_UNLINK (*list, *link);
	free (*link);
	*link = NULL;
}

#define REF_COUNTABLE_HEADER                                                   \
	size_t ref_count;                   /**< Reference count                */ \
	struct weak_ref_link *weak_refs;    /**< To remove any weak references  */

#define REF_COUNTABLE_METHODS(name)                                            \
	static struct name *                                                       \
	name ## _ref (struct name *self)                                           \
	{                                                                          \
		self->ref_count++;                                                     \
		return self;                                                           \
	}                                                                          \
																			   \
	static void                                                                \
	name ## _unref (struct name *self)                                         \
	{                                                                          \
		if (--self->ref_count)                                                 \
			return;                                                            \
		LIST_FOR_EACH (struct weak_ref_link, iter, self->weak_refs)            \
		{                                                                      \
			iter->on_destroy (self, iter->user_data);                          \
			free (iter);                                                       \
		}                                                                      \
		name ## _destroy (self);                                               \
	}                                                                          \
																			   \
	static struct weak_ref_link *                                              \
	name ## _weak_ref (struct name *self, destroy_cb_fn cb, void *user_data)   \
	{ return weak_ref (&self->weak_refs, cb, user_data); }                     \
																			   \
	static void                                                                \
	name ## _weak_unref (struct name *self, struct weak_ref_link **link)       \
	{ weak_unref (&self->weak_refs, link); }

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Simple introspection framework to simplify exporting stuff to Lua, since
// there is a lot of it.  While not fully automated, at least we have control
// over which fields are exported.

enum ispect_type
{
	ISPECT_BOOL, ISPECT_INT, ISPECT_UINT, ISPECT_SIZE, ISPECT_STRING,

	ISPECT_STR,                         ///< "struct str"
	ISPECT_STR_MAP,                     ///< "struct str_map"
	ISPECT_REF                          ///< Weakly referenced object
};

struct ispect_field
{
	const char *name;                   ///< Name of the field
	size_t offset;                      ///< Offset in the structure
	enum ispect_type type;              ///< Type of the field

	enum ispect_type subtype;           ///< STR_MAP subtype
	struct ispect_field *fields;        ///< REF target fields
	bool is_list;                       ///< REF target is a list
};

#define ISPECT(object, field, type)                                            \
	{ #field, offsetof (struct object, field), ISPECT_##type, 0, NULL, false },
#define ISPECT_REF(object, field, is_list, ref_type)                           \
	{ #field, offsetof (struct object, field), ISPECT_REF, 0,                  \
	  g_##ref_type##_ispect, is_list },
#define ISPECT_MAP(object, field, subtype)                                     \
	{ #field, offsetof (struct object, field), ISPECT_STR_MAP,                 \
	  ISPECT_##subtype, NULL, false },
#define ISPECT_MAP_REF(object, field, is_list, ref_type)                       \
	{ #field, offsetof (struct object, field), ISPECT_STR_MAP,                 \
	  ISPECT_REF, g_##ref_type##_ispect, is_list },

// ~~~ Chat ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

struct user_channel
{
	LIST_HEADER (struct user_channel)

	struct channel *channel;            ///< Reference to channel
};

static struct user_channel *
user_channel_new (struct channel *channel)
{
	struct user_channel *self = xcalloc (1, sizeof *self);
	self->channel = channel;
	return self;
}

static void
user_channel_destroy (struct user_channel *self)
{
	// The "channel" reference is weak and this object should get
	// destroyed whenever the user stops being in the channel.
	free (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// We keep references to user information in channels and buffers,
// and weak references in the name lookup table.

struct user
{
	REF_COUNTABLE_HEADER

	char *nickname;                     ///< Literal nickname
	bool away;                          ///< User is away

	struct user_channel *channels;      ///< Channels the user is on (with us)
};

static struct ispect_field g_user_ispect[] =
{
	ISPECT( user, nickname, STRING )
	ISPECT( user, away,     BOOL   )
	{}
};

static struct user *
user_new (char *nickname)
{
	struct user *self = xcalloc (1, sizeof *self);
	self->ref_count = 1;
	self->nickname = nickname;
	return self;
}

static void
user_destroy (struct user *self)
{
	free (self->nickname);
	LIST_FOR_EACH (struct user_channel, iter, self->channels)
		user_channel_destroy (iter);
	free (self);
}

REF_COUNTABLE_METHODS (user)

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct channel_user
{
	LIST_HEADER (struct channel_user)

	struct user *user;                  ///< Reference to user
	char *prefixes;                     ///< Ordered @+... characters
};

static struct channel_user *
channel_user_new (struct user *user, const char *prefixes)
{
	struct channel_user *self = xcalloc (1, sizeof *self);
	self->user = user;
	self->prefixes = xstrdup (prefixes);
	return self;
}

static void
channel_user_destroy (struct channel_user *self)
{
	user_unref (self->user);
	free (self->prefixes);
	free (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// We keep references to channels in their buffers,
// and weak references in their users and the name lookup table.

struct channel
{
	REF_COUNTABLE_HEADER

	struct server *s;                   ///< Server

	char *name;                         ///< Channel name
	char *topic;                        ///< Channel topic

	// XXX: write something like an ordered set of characters object?
	struct str no_param_modes;          ///< No parameter channel modes
	struct str_map param_modes;         ///< Parametrized channel modes

	struct channel_user *users;         ///< Channel users
	struct strv names_buf;              ///< Buffer for RPL_NAMREPLY
	size_t users_len;                   ///< User count

	bool left_manually;                 ///< Don't rejoin on reconnect
	bool show_names_after_who;          ///< RPL_ENDOFWHO delays RPL_ENDOFNAMES
};

static struct ispect_field g_channel_ispect[] =
{
	ISPECT( channel, name,           STRING  )
	ISPECT( channel, topic,          STRING  )
	ISPECT( channel, no_param_modes, STR     )
	ISPECT_MAP( channel, param_modes, STRING )
	ISPECT( channel, users_len,      SIZE    )
	ISPECT( channel, left_manually,  BOOL    )
	{}
};

static struct channel *
channel_new (struct server *s, char *name)
{
	struct channel *self = xcalloc (1, sizeof *self);
	self->ref_count = 1;
	self->s = s;
	self->name = name;
	self->no_param_modes = str_make ();
	self->param_modes = str_map_make (free);
	self->names_buf = strv_make ();
	return self;
}

static void
channel_destroy (struct channel *self)
{
	free (self->name);
	free (self->topic);
	str_free (&self->no_param_modes);
	str_map_free (&self->param_modes);
	// Owner has to make sure we have no users by now
	hard_assert (!self->users && !self->users_len);
	strv_free (&self->names_buf);
	free (self);
}

REF_COUNTABLE_METHODS (channel)

// ~~~ Buffers ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

enum formatter_item_type
{
	FORMATTER_ITEM_END,                 ///< Sentinel value for arrays
	FORMATTER_ITEM_TEXT,                ///< Text
	FORMATTER_ITEM_ATTR,                ///< Formatting attributes
	FORMATTER_ITEM_FG_COLOR,            ///< Foreground colour
	FORMATTER_ITEM_BG_COLOR,            ///< Background colour
	FORMATTER_ITEM_SIMPLE,              ///< Toggle IRC formatting
	FORMATTER_ITEM_IGNORE_ATTR          ///< Un/set attribute ignoration
};

enum
{
	TEXT_BOLD        = 1 << 0,
	TEXT_ITALIC      = 1 << 1,
	TEXT_UNDERLINE   = 1 << 2,
	TEXT_INVERSE     = 1 << 3,
	TEXT_BLINK       = 1 << 4,
	TEXT_CROSSED_OUT = 1 << 5,
	TEXT_MONOSPACE   = 1 << 6
};

struct formatter_item
{
	enum formatter_item_type type : 16; ///< Type of this item
	int attribute                 : 16; ///< Attribute ID or a TEXT_* mask
	int color;                          ///< Colour ([256 << 16] | 16)
	char *text;                         ///< String
};

static void
formatter_item_free (struct formatter_item *self)
{
	free (self->text);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct formatter
{
	struct app_context *ctx;            ///< Application context
	struct server *s;                   ///< Server

	struct formatter_item *items;       ///< Items
	size_t items_len;                   ///< Items used
	size_t items_alloc;                 ///< Items allocated
};

static struct formatter
formatter_make (struct app_context *ctx, struct server *s)
{
	struct formatter self = { .ctx = ctx, .s = s };
	self.items = xcalloc (sizeof *self.items, (self.items_alloc = 16));
	return self;
}

static void
formatter_free (struct formatter *self)
{
	for (size_t i = 0; i < self->items_len; i++)
		formatter_item_free (&self->items[i]);
	free (self->items);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

enum buffer_line_flags
{
	BUFFER_LINE_SKIP_FILE   = 1 << 0,   ///< Don't log this to file
	BUFFER_LINE_UNIMPORTANT = 1 << 1,   ///< Joins, parts, similar spam
	BUFFER_LINE_HIGHLIGHT   = 1 << 2,   ///< The user was highlighted by this
};

// NOTE: This sequence must match up with xC-proto, only one lower.
enum buffer_line_rendition
{
	BUFFER_LINE_BARE,                   ///< Unadorned
	BUFFER_LINE_INDENT,                 ///< Just indent the line
	BUFFER_LINE_STATUS,                 ///< Status message
	BUFFER_LINE_ERROR,                  ///< Error message
	BUFFER_LINE_JOIN,                   ///< Join arrow
	BUFFER_LINE_PART,                   ///< Part arrow
	BUFFER_LINE_ACTION,                 ///< Highlighted asterisk
};

struct buffer_line
{
	LIST_HEADER (struct buffer_line)

	unsigned flags;                     ///< Functional flags
	enum buffer_line_rendition r;       ///< What the line should look like
	time_t when;                        ///< Time of the event
	struct formatter_item items[];      ///< Line data
};

/// Create a new buffer line stealing all data from the provided formatter
struct buffer_line *
buffer_line_new (struct formatter *f)
{
	// We make space for one more item that gets initialized to all zeros,
	// meaning FORMATTER_ITEM_END (because it's the first value in the enum)
	size_t items_size = f->items_len * sizeof *f->items;
	struct buffer_line *self =
		xcalloc (1, sizeof *self + items_size + sizeof *self->items);
	memcpy (self->items, f->items, items_size);

	// We've stolen pointers from the formatter, let's destroy it altogether
	free (f->items);
	memset (f, 0, sizeof *f);
	return self;
}

static void
buffer_line_destroy (struct buffer_line *self)
{
	for (struct formatter_item *iter = self->items; iter->type; iter++)
		formatter_item_free (iter);
	free (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

enum buffer_type
{
	BUFFER_GLOBAL,                      ///< Global information
	BUFFER_SERVER,                      ///< Server-related messages
	BUFFER_CHANNEL,                     ///< Channels
	BUFFER_PM                           ///< Private messages (query)
};

struct buffer
{
	LIST_HEADER (struct buffer)
	REF_COUNTABLE_HEADER

	enum buffer_type type;              ///< Type of the buffer
	char *name;                         ///< The name of the buffer

	struct input *input;                ///< API for "input_data"
	input_buffer_t input_data;          ///< User interface data

	// Buffer contents:

	struct buffer_line *lines;          ///< All lines in this buffer
	struct buffer_line *lines_tail;     ///< The tail of buffer lines
	unsigned lines_count;               ///< How many lines we have

	unsigned new_messages_count;        ///< # messages since last left
	unsigned new_unimportant_count;     ///< How much of that is unimportant
	bool highlighted;                   ///< We've been highlighted
	bool hide_unimportant;              ///< Hide unimportant messages

	FILE *log_file;                     ///< Log file

	// Origin information:

	struct server *server;              ///< Reference to server
	struct channel *channel;            ///< Reference to channel
	struct user *user;                  ///< Reference to user
};

static struct ispect_field g_server_ispect[];
static struct ispect_field g_buffer_ispect[] =
{
	ISPECT( buffer, name,                  STRING )
	ISPECT( buffer, new_messages_count,    UINT   )
	ISPECT( buffer, new_unimportant_count, UINT   )
	ISPECT( buffer, highlighted,           BOOL   )
	ISPECT( buffer, hide_unimportant,      BOOL   )
	ISPECT_REF( buffer, server,  false, server    )
	ISPECT_REF( buffer, channel, false, channel   )
	ISPECT_REF( buffer, user,    false, user      )
	{}
};

static struct buffer *
buffer_new (struct input *input, enum buffer_type type, char *name)
{
	struct buffer *self = xcalloc (1, sizeof *self);
	self->ref_count = 1;
	self->input = input;
	self->input_data = CALL (input, buffer_new);
	self->type = type;
	self->name = name;
	return self;
}

static void
buffer_destroy (struct buffer *self)
{
	free (self->name);
	if (self->input_data)
	{
#ifdef HAVE_READLINE
		// FIXME: can't really free "history" contents from here, as we cannot
		//   be sure that the user interface pointer is valid and usable
		input_rl__buffer_destroy_wo_history (self->input_data);
#else // ! HAVE_READLINE
		CALL_ (self->input, buffer_destroy, self->input_data);
#endif // ! HAVE_READLINE
	}
	LIST_FOR_EACH (struct buffer_line, iter, self->lines)
		buffer_line_destroy (iter);
	if (self->log_file)
		(void) fclose (self->log_file);
	if (self->user)
		user_unref (self->user);
	if (self->channel)
		channel_unref (self->channel);
	free (self);
}

REF_COUNTABLE_METHODS (buffer)
#define buffer_ref do_not_use_dangerous

// ~~~ Relay ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

struct client
{
	LIST_HEADER (struct client)
	struct app_context *ctx;            ///< Application context

	// TODO: Convert this all to TLS, and only TLS, with required client cert.
	//   That means replacing plumbing functions with the /other/ set from xD.

	int socket_fd;                      ///< The TCP socket
	struct str read_buffer;             ///< Unprocessed input
	struct str write_buffer;            ///< Output yet to be sent out

	uint32_t event_seq;                 ///< Outgoing message counter
	bool initialized;                   ///< Initial sync took place

	struct poller_fd socket_event;      ///< The socket can be read/written to
};

static struct client *
client_new (void)
{
	struct client *self = xcalloc (1, sizeof *self);
	self->socket_fd = -1;
	self->read_buffer = str_make ();
	self->write_buffer = str_make ();
	return self;
}

static void
client_destroy (struct client *self)
{
	if (!soft_assert (self->socket_fd == -1))
		xclose (self->socket_fd);

	str_free (&self->read_buffer);
	str_free (&self->write_buffer);
	free (self);
}

static void client_kill (struct client *c);
static bool client_process_buffer (struct client *c);

// ~~~ Server ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// The only real purpose of this is to abstract away TLS
struct transport
{
	/// Initialize the transport
	bool (*init) (struct server *s, const char *hostname, struct error **e);
	/// Destroy the user data pointer
	void (*cleanup) (struct server *s);

	/// The underlying socket may have become readable, update `read_buffer'
	enum socket_io_result (*try_read) (struct server *s);
	/// The underlying socket may have become writeable, flush `write_buffer'
	enum socket_io_result (*try_write) (struct server *s);
	/// Return event mask to use in the poller
	int (*get_poll_events) (struct server *s);

	/// Called just before closing the connection from our side
	void (*in_before_shutdown) (struct server *s);
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

enum server_state
{
	IRC_DISCONNECTED,                   ///< Not connected
	IRC_CONNECTING,                     ///< Connecting to the server
	IRC_CONNECTED,                      ///< Trying to register
	IRC_REGISTERED,                     ///< We can chat now
	IRC_CLOSING,                        ///< Flushing output before shutdown
	IRC_HALF_CLOSED                     ///< Connection shutdown from our side
};

/// Convert an IRC identifier character to lower-case
typedef int (*irc_tolower_fn) (int);

/// Key conversion function for hashmap lookups
typedef size_t (*irc_strxfrm_fn) (char *, const char *, size_t);

struct server
{
	REF_COUNTABLE_HEADER
	struct app_context *ctx;            ///< Application context

	char *name;                         ///< Server identifier
	struct buffer *buffer;              ///< The buffer for this server
	struct config_item *config;         ///< Configuration root

	// Connection:

	enum server_state state;            ///< Connection state
	struct connector *connector;        ///< Connection establisher
	struct socks_connector *socks_conn; ///< SOCKS connection establisher
	unsigned reconnect_attempt;         ///< Number of reconnect attempt
	bool manual_disconnect;             ///< Don't reconnect after disconnect

	int socket;                         ///< Socket FD of the server
	struct str read_buffer;             ///< Input yet to be processed
	struct str write_buffer;            ///< Outut yet to be be sent out
	struct poller_fd socket_event;      ///< We can read from the socket

	struct transport *transport;        ///< Transport method
	void *transport_data;               ///< Transport data

	// Events:

	struct poller_timer ping_tmr;       ///< We should send a ping
	struct poller_timer timeout_tmr;    ///< Connection seems to be dead
	struct poller_timer reconnect_tmr;  ///< We should reconnect now
	struct poller_timer autojoin_tmr;   ///< Re/join channels as appropriate

	// IRC:

	// TODO: an output queue to prevent excess floods (this will be needed
	//   especially for away status polling)

	bool rehashing;                     ///< Rehashing IRC identifiers

	struct str_map irc_users;           ///< IRC user data
	struct str_map irc_channels;        ///< IRC channel data
	struct str_map irc_buffer_map;      ///< Maps IRC identifiers to buffers

	struct user *irc_user;              ///< Our own user
	int nick_counter;                   ///< Iterates "nicks" when registering
	struct str irc_user_mode;           ///< Our current user modes
	char *irc_user_host;                ///< Our current user@host
	bool autoaway_active;               ///< Autoaway is currently active

	struct strv cap_ls_buf;             ///< Buffer for IRCv3.2 CAP LS
	bool cap_echo_message;              ///< Whether the server echoes messages
	bool cap_away_notify;               ///< Whether we get AWAY notifications
	bool cap_sasl;                      ///< Whether SASL is available

	// Server-specific information (from RPL_ISUPPORT):

	irc_tolower_fn irc_tolower;         ///< Server tolower()
	irc_strxfrm_fn irc_strxfrm;         ///< Server strxfrm()

	char *irc_chantypes;                ///< Channel types (name prefixes)
	char *irc_idchan_prefixes;          ///< Prefixes for "safe channels"
	char *irc_statusmsg;                ///< Prefixes for channel targets

	char irc_extban_prefix;             ///< EXTBAN prefix or \0
	char *irc_extban_types;             ///< EXTBAN types

	char *irc_chanmodes_list;           ///< Channel modes for lists
	char *irc_chanmodes_param_always;   ///< Channel modes with mandatory param
	char *irc_chanmodes_param_when_set; ///< Channel modes with param when set
	char *irc_chanmodes_param_never;    ///< Channel modes without param

	char *irc_chanuser_prefixes;        ///< Channel user prefixes
	char *irc_chanuser_modes;           ///< Channel user modes

	unsigned irc_max_modes;             ///< Max parametrized modes per command
};

static struct ispect_field g_server_ispect[] =
{
	ISPECT( server, name,              STRING )
	ISPECT( server, state,             INT    )
	ISPECT( server, reconnect_attempt, UINT   )
	ISPECT( server, manual_disconnect, BOOL   )
	ISPECT( server, irc_user_host,     STRING )
	ISPECT( server, autoaway_active,   BOOL   )
	ISPECT( server, cap_echo_message,  BOOL   )
	ISPECT_REF( server, buffer, false, buffer )

	// TODO: either rename the underlying field or fix the plugins
	{ "user",      offsetof (struct server, irc_user),
	  ISPECT_REF, 0, g_user_ispect, false },
	{ "user_mode", offsetof (struct server, irc_user_mode),
	  ISPECT_STR, 0, NULL, false },

	{}
};

static void on_irc_timeout (void *user_data);
static void on_irc_ping_timeout (void *user_data);
static void on_irc_autojoin_timeout (void *user_data);
static void irc_initiate_connect (struct server *s);

static void
server_init_specifics (struct server *self)
{
	// Defaults as per the RPL_ISUPPORT drafts, or RFC 1459

	self->irc_tolower                   = irc_tolower;
	self->irc_strxfrm                   = irc_strxfrm;

	self->irc_chantypes                 = xstrdup ("#&");
	self->irc_idchan_prefixes           = xstrdup ("");
	self->irc_statusmsg                 = xstrdup ("");

	self->irc_extban_prefix             = 0;
	self->irc_extban_types              = xstrdup ("");

	self->irc_chanmodes_list            = xstrdup ("b");
	self->irc_chanmodes_param_always    = xstrdup ("k");
	self->irc_chanmodes_param_when_set  = xstrdup ("l");
	self->irc_chanmodes_param_never     = xstrdup ("imnpst");

	self->irc_chanuser_prefixes         = xstrdup ("@+");
	self->irc_chanuser_modes            = xstrdup ("ov");

	self->irc_max_modes                 = 3;
}

static void
server_free_specifics (struct server *self)
{
	free (self->irc_chantypes);
	free (self->irc_idchan_prefixes);
	free (self->irc_statusmsg);

	free (self->irc_extban_types);

	free (self->irc_chanmodes_list);
	free (self->irc_chanmodes_param_always);
	free (self->irc_chanmodes_param_when_set);
	free (self->irc_chanmodes_param_never);

	free (self->irc_chanuser_prefixes);
	free (self->irc_chanuser_modes);
}

static struct server *
server_new (struct poller *poller)
{
	struct server *self = xcalloc (1, sizeof *self);
	self->ref_count = 1;

	self->socket = -1;
	self->read_buffer = str_make ();
	self->write_buffer = str_make ();
	self->state = IRC_DISCONNECTED;

	self->timeout_tmr = poller_timer_make (poller);
	self->timeout_tmr.dispatcher = on_irc_timeout;
	self->timeout_tmr.user_data = self;

	self->ping_tmr = poller_timer_make (poller);
	self->ping_tmr.dispatcher = on_irc_ping_timeout;
	self->ping_tmr.user_data = self;

	self->reconnect_tmr = poller_timer_make (poller);
	self->reconnect_tmr.dispatcher = (poller_timer_fn) irc_initiate_connect;
	self->reconnect_tmr.user_data = self;

	self->autojoin_tmr = poller_timer_make (poller);
	self->autojoin_tmr.dispatcher = on_irc_autojoin_timeout;
	self->autojoin_tmr.user_data = self;

	self->irc_users = str_map_make (NULL);
	self->irc_users.key_xfrm = irc_strxfrm;
	self->irc_channels = str_map_make (NULL);
	self->irc_channels.key_xfrm = irc_strxfrm;
	self->irc_buffer_map = str_map_make (NULL);
	self->irc_buffer_map.key_xfrm = irc_strxfrm;

	self->irc_user_mode = str_make ();

	self->cap_ls_buf = strv_make ();
	server_init_specifics (self);
	return self;
}

static void
server_destroy (struct server *self)
{
	free (self->name);

	if (self->connector)
	{
		connector_free (self->connector);
		free (self->connector);
	}
	if (self->socks_conn)
	{
		socks_connector_free (self->socks_conn);
		free (self->socks_conn);
	}

	if (self->transport
	 && self->transport->cleanup)
		self->transport->cleanup (self);

	if (self->socket != -1)
	{
		poller_fd_reset (&self->socket_event);
		xclose (self->socket);
	}
	str_free (&self->read_buffer);
	str_free (&self->write_buffer);

	poller_timer_reset (&self->ping_tmr);
	poller_timer_reset (&self->timeout_tmr);
	poller_timer_reset (&self->reconnect_tmr);
	poller_timer_reset (&self->autojoin_tmr);

	str_map_free (&self->irc_users);
	str_map_free (&self->irc_channels);
	str_map_free (&self->irc_buffer_map);

	if (self->irc_user)
		user_unref (self->irc_user);
	str_free (&self->irc_user_mode);
	free (self->irc_user_host);

	strv_free (&self->cap_ls_buf);
	server_free_specifics (self);
	free (self);
}

REF_COUNTABLE_METHODS (server)
#define server_ref do_not_use_dangerous

// ~~~ Scripting ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

struct plugin
{
	LIST_HEADER (struct plugin)

	char *name;                         ///< Name of the plugin
	struct plugin_vtable *vtable;       ///< Methods
};

struct plugin_vtable
{
	/// Collect garbage
	void (*gc) (struct plugin *self);
	/// Unregister and free the plugin including all relevant resources
	void (*free) (struct plugin *self);
};

static void
plugin_destroy (struct plugin *self)
{
	self->vtable->free (self);
	free (self->name);
	free (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// This is a bit ugly since insertion is O(n) and the need to get rid of the
// specific type because of list macros, however I don't currently posses any
// strictly better, ordered data structure

struct hook
{
	LIST_HEADER (struct hook)
	int priority;                       ///< The lesser the sooner
};

static struct hook *
hook_insert (struct hook *list, struct hook *item)
{
	// Corner cases: list is empty or we precede everything
	if (!list || item->priority < list->priority)
	{
		LIST_PREPEND (list, item);
		return list;
	}

	// Otherwise fast-forward to the last entry that precedes us
	struct hook *before = list;
	while (before->next && before->next->priority < item->priority)
		before = before->next;

	// And link ourselves in between it and its successor
	if ((item->next = before->next))
		item->next->prev = item;
	before->next = item;
	item->prev = before;
	return list;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct input_hook
{
	struct hook super;                  ///< Common hook fields

	/// Takes over the ownership of "input", returns either NULL if input
	/// was thrown away, or a possibly modified version of it
	char *(*filter) (struct input_hook *self,
		struct buffer *buffer, char *input);
};

struct irc_hook
{
	struct hook super;                  ///< Common hook fields

	/// Takes over the ownership of "message", returns either NULL if message
	/// was thrown away, or a possibly modified version of it
	char *(*filter) (struct irc_hook *self,
		struct server *server, char *message);
};

struct prompt_hook
{
	struct hook super;                  ///< Common hook fields

	/// Returns what the prompt should look like right now based on other state
	char *(*make) (struct prompt_hook *self);
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct completion_word
{
	size_t start;                       ///< Offset to start of word
	size_t end;                         ///< Offset to end of word
};

struct completion
{
	char *line;                         ///< The line which is being completed

	struct completion_word *words;      ///< Word locations
	size_t words_len;                   ///< Number of words
	size_t words_alloc;                 ///< Number of words allocated

	size_t location;                    ///< Which word is being completed
};

struct completion_hook
{
	struct hook super;                  ///< Common hook fields

	/// Tries to add possible completions of "word" to "output"
	void (*complete) (struct completion_hook *self,
		struct completion *data, const char *word, struct strv *output);
};

// ~~~ Main context ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

struct app_context
{
	char *attrs_defaults[ATTR_COUNT];   ///< Default terminal attributes

	// Configuration:

	struct config config;               ///< Program configuration
	char *attrs[ATTR_COUNT];            ///< Terminal attributes
	bool isolate_buffers;               ///< Isolate global/server buffers
	bool beep_on_highlight;             ///< Beep on highlight
	bool logging;                       ///< Logging to file enabled
	bool show_all_prefixes;             ///< Show all prefixes before nicks
	bool word_wrapping;                 ///< Enable simple word wrapping

	struct str_map servers;             ///< Our servers

	// Relay:

	int relay_fd;                       ///< Listening socket FD
	struct client *clients;             ///< Our relay clients

	/// A single message buffer to prepare all outcoming messages within
	struct relay_event_message relay_message;

	// Events:

	struct poller_fd tty_event;         ///< Terminal input event
	struct poller_fd signal_event;      ///< Signal FD event
	struct poller_fd relay_event;       ///< New relay connection available

	struct poller_timer flush_timer;    ///< Flush all open files (e.g. logs)
	struct poller_timer date_chg_tmr;   ///< Print a date change
	struct poller_timer autoaway_tmr;   ///< Autoaway timer

	struct poller poller;               ///< Manages polled descriptors
	bool quitting;                      ///< User requested quitting
	bool polling;                       ///< The event loop is running

	// Buffers:

	struct buffer *buffers;             ///< All our buffers in order
	struct buffer *buffers_tail;        ///< The tail of our buffers

	struct buffer *global_buffer;       ///< The global buffer
	struct buffer *current_buffer;      ///< The current buffer
	struct buffer *last_buffer;         ///< Last used buffer

	struct str_map buffers_by_name;     ///< Buffers by name

	unsigned backlog_limit;             ///< Limit for buffer lines
	time_t last_displayed_msg_time;     ///< Time of last displayed message

	// Terminal:

	iconv_t term_to_utf8;               ///< Terminal encoding to UTF-8
	iconv_t term_from_utf8;             ///< UTF-8 to terminal encoding

	struct input *input;                ///< User interface

	struct poller_idle prompt_event;    ///< Deferred prompt refresh
	struct poller_idle input_event;     ///< Pending input event
	struct strv pending_input;          ///< Pending input lines

	int *nick_palette;                  ///< A 256-colour palette for nicknames
	size_t nick_palette_len;            ///< Number of entries in nick_palette

	bool awaiting_formatting_escape;    ///< Awaiting an IRC formatting escape
	bool in_bracketed_paste;            ///< User is pasting some content
	struct str input_buffer;            ///< Buffered pasted content

	bool running_pager;                 ///< Running a pager for buffer history
	bool running_editor;                ///< Running editor for the input
	char *editor_filename;              ///< The file being edited by user
	int terminal_suspended;             ///< Terminal suspension level

	// Plugins:

	struct plugin *plugins;             ///< Loaded plugins
	struct hook *input_hooks;           ///< Input hooks
	struct hook *irc_hooks;             ///< IRC hooks
	struct hook *prompt_hooks;          ///< Prompt hooks
	struct hook *completion_hooks;      ///< Autocomplete hooks
}
*g_ctx;

static struct ispect_field g_ctx_ispect[] =
{
	ISPECT_MAP_REF( app_context, servers,    false, server )
	ISPECT_REF( app_context, buffers,        true,  buffer )
	ISPECT_REF( app_context, global_buffer,  false, buffer )
	ISPECT_REF( app_context, current_buffer, false, buffer )
	{}
};

static int *
filter_color_cube_for_acceptable_nick_colors (size_t *len)
{
	// This is a pure function and we don't use threads, static storage is fine
	static int table[6 * 6 * 6];
	size_t len_counter = 0;
	for (int x = 0; x < (int) N_ELEMENTS (table); x++)
	{
		int r =  x / 36;
		int g = (x / 6) % 6;
		int b = (x % 6);

		// The first step is 95/255, the rest are 40/255,
		// as an approximation we can double the first step
		double linear_R = pow ((r + !!r) / 6., 2.2);
		double linear_G = pow ((g + !!g) / 6., 2.2);
		double linear_B = pow ((b + !!b) / 6., 2.2);

		// Use the relative luminance of colours within the cube to filter
		// colours that look okay-ish on terminals with both black and white
		// backgrounds (use the test-nick-colors script to calibrate)
		double Y = 0.2126 * linear_R + 0.7152 * linear_G + 0.0722 * linear_B;
		if (Y >= .25 && Y <= .4)
			table[len_counter++] = 16 + x;
	}
	*len = len_counter;
	return table;
}

static bool
app_iconv_open (iconv_t *target, const char *to, const char *from)
{
	if (ICONV_ACCEPTS_TRANSLIT)
	{
		char *to_real = xstrdup_printf ("%s//TRANSLIT", to);
		*target = iconv_open (to_real, from);
		free (to_real);
	}
	else
		*target = iconv_open (to, from);
	return *target != (iconv_t) -1;
}

static void
app_context_init (struct app_context *self)
{
	memset (self, 0, sizeof *self);

	self->config = config_make ();
	poller_init (&self->poller);

	self->relay_fd = -1;

	self->servers = str_map_make ((str_map_free_fn) server_unref);
	self->servers.key_xfrm = tolower_ascii_strxfrm;

	self->buffers_by_name = str_map_make (NULL);
	self->buffers_by_name.key_xfrm = tolower_ascii_strxfrm;

	// So that we don't lose the logo shortly after startup
	self->backlog_limit = 1000;
	self->last_displayed_msg_time = time (NULL);

	char *native = nl_langinfo (CODESET);
	if (!app_iconv_open (&self->term_from_utf8, native, "UTF-8")
	 || !app_iconv_open (&self->term_to_utf8, "UTF-8", native))
		exit_fatal ("creating the UTF-8 conversion object failed: %s",
			strerror (errno));

	self->input = input_new ();
	self->input->user_data = self;
	self->pending_input = strv_make ();
	self->input_buffer = str_make ();

	self->nick_palette =
		filter_color_cube_for_acceptable_nick_colors (&self->nick_palette_len);
}

static void
app_context_relay_stop (struct app_context *self)
{
	if (self->relay_fd != -1)
	{
		poller_fd_reset (&self->relay_event);
		xclose (self->relay_fd);
		self->relay_fd = -1;
	}
}

static void
app_context_free (struct app_context *self)
{
	// Plugins can try to use of the other fields when destroyed
	LIST_FOR_EACH (struct plugin, iter, self->plugins)
		plugin_destroy (iter);

	config_free (&self->config);
	for (size_t i = 0; i < ATTR_COUNT; i++)
	{
		free (self->attrs_defaults[i]);
		free (self->attrs[i]);
	}

	LIST_FOR_EACH (struct buffer, iter, self->buffers)
	{
#ifdef HAVE_READLINE
		// We can use the user interface here; see buffer_destroy()
		CALL_ (self->input, buffer_destroy, iter->input_data);
		iter->input_data = NULL;
#endif // HAVE_READLINE
		buffer_unref (iter);
	}
	str_map_free (&self->buffers_by_name);

	app_context_relay_stop (self);
	LIST_FOR_EACH (struct client, c, self->clients)
		client_kill (c);
	relay_event_message_free (&self->relay_message);

	str_map_free (&self->servers);
	poller_free (&self->poller);

	iconv_close (self->term_from_utf8);
	iconv_close (self->term_to_utf8);

	CALL (self->input, destroy);
	strv_free (&self->pending_input);
	str_free (&self->input_buffer);

	free (self->editor_filename);
}

static void
refresh_prompt (struct app_context *ctx)
{
	// XXX: the need for this conditional could probably be resolved
	//   by some clever reordering
	if (ctx->prompt_event.poller)
		poller_idle_set (&ctx->prompt_event);
}

// --- Configuration -----------------------------------------------------------

static void
on_config_debug_mode_change (struct config_item *item)
{
	g_debug_mode = item->value.boolean;
}

static void
on_config_show_all_prefixes_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	ctx->show_all_prefixes = item->value.boolean;
	refresh_prompt (ctx);
}

static void on_config_relay_bind_change (struct config_item *item);
static void on_config_backlog_limit_change (struct config_item *item);
static void on_config_attribute_change (struct config_item *item);
static void on_config_logging_change (struct config_item *item);

#define TRIVIAL_BOOLEAN_ON_CHANGE(name)                                        \
	static void                                                                \
	on_config_ ## name ## _change (struct config_item *item)                   \
	{                                                                          \
		struct app_context *ctx = item->user_data;                             \
		ctx->name = item->value.boolean;                                       \
	}

TRIVIAL_BOOLEAN_ON_CHANGE (isolate_buffers)
TRIVIAL_BOOLEAN_ON_CHANGE (beep_on_highlight)
TRIVIAL_BOOLEAN_ON_CHANGE (word_wrapping)

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool
config_validate_nonjunk_string
	(const struct config_item *item, struct error **e)
{
	if (item->type == CONFIG_ITEM_NULL)
		return true;

	hard_assert (config_item_type_is_string (item->type));
	for (size_t i = 0; i < item->value.string.len; i++)
	{
		// Not even a tabulator
		unsigned char c = item->value.string.str[i];
		if (iscntrl_ascii (c))
		{
			error_set (e, "control characters are not allowed");
			return false;
		}
	}
	return true;
}

static bool
config_validate_addresses
	(const struct config_item *item, struct error **e)
{
	if (item->type == CONFIG_ITEM_NULL)
		return true;
	if (!config_validate_nonjunk_string (item, e))
		return false;

	// Comma-separated list of "host[:port]" pairs
	regex_t re;
	int err = regcomp (&re, "^([^/:,]+(:[^/:,]+)?)?"
		"(,([^/:,]+(:[^/:,]+)?)?)*$", REG_EXTENDED | REG_NOSUB);
	hard_assert (!err);

	bool result = !regexec (&re, item->value.string.str, 0, NULL, 0);
	if (!result)
		error_set (e, "invalid address list string");

	regfree (&re);
	return result;
}

static bool
config_validate_nonnegative
	(const struct config_item *item, struct error **e)
{
	if (item->type == CONFIG_ITEM_NULL)
		return true;

	hard_assert (item->type == CONFIG_ITEM_INTEGER);
	if (item->value.integer >= 0)
		return true;

	error_set (e, "must be non-negative");
	return false;
}

static struct config_schema g_config_server[] =
{
	{ .name      = "nicks",
	  .comment   = "IRC nickname",
	  .type      = CONFIG_ITEM_STRING_ARRAY,
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "username",
	  .comment   = "IRC user name",
	  .type      = CONFIG_ITEM_STRING,
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "realname",
	  .comment   = "IRC real name/e-mail",
	  .type      = CONFIG_ITEM_STRING,
	  .validate  = config_validate_nonjunk_string },

	{ .name      = "addresses",
	  .comment   = "Addresses of the IRC network (e.g. \"irc.net:6667\")",
	  .type      = CONFIG_ITEM_STRING_ARRAY,
	  .validate  = config_validate_addresses },
	{ .name      = "password",
	  .comment   = "Password to connect to the server, if any",
	  .type      = CONFIG_ITEM_STRING,
	  .validate  = config_validate_nonjunk_string },
	// XXX: if we add support for new capabilities, the value stays unchanged
	{ .name      = "capabilities",
	  .comment   = "Capabilities to use if supported by server",
	  .type      = CONFIG_ITEM_STRING_ARRAY,
	  .validate  = config_validate_nonjunk_string,
	  .default_  = "\"multi-prefix,invite-notify,server-time,echo-message,"
		"message-tags,away-notify,cap-notify,chghost\"" },

	{ .name      = "tls",
	  .comment   = "Whether to use TLS",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off" },
	{ .name      = "tls_cert",
	  .comment   = "Client TLS certificate (PEM)",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "tls_verify",
	  .comment   = "Whether to verify certificates",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on" },
	{ .name      = "tls_ca_file",
	  .comment   = "OpenSSL CA bundle file",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "tls_ca_path",
	  .comment   = "OpenSSL CA bundle path",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "tls_ciphers",
	  .comment   = "OpenSSL cipher preference list",
	  .type      = CONFIG_ITEM_STRING,
	  .default_  = "\"DEFAULT:!MEDIUM:!LOW\"" },

	{ .name      = "autoconnect",
	  .comment   = "Connect automatically on startup",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on" },
	{ .name      = "autojoin",
	  .comment   = "Channels to join on start (e.g. \"#abc,#def key,#ghi\")",
	  .type      = CONFIG_ITEM_STRING_ARRAY,
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "command",
	  .comment   = "Command to execute after a successful connect",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "command_delay",
	  .comment   = "Delay between executing \"command\" and joining channels",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "0" },
	{ .name      = "reconnect",
	  .comment   = "Whether to reconnect on error",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on" },
	{ .name      = "reconnect_delay",
	  .comment   = "Time between reconnecting",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "5" },

	{ .name      = "socks_host",
	  .comment   = "Address of a SOCKS 4a/5 proxy",
	  .type      = CONFIG_ITEM_STRING,
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "socks_port",
	  .comment   = "SOCKS port number",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "1080" },
	{ .name      = "socks_username",
	  .comment   = "SOCKS auth. username",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "socks_password",
	  .comment   = "SOCKS auth. password",
	  .type      = CONFIG_ITEM_STRING },
	{}
};

static struct config_schema g_config_general[] =
{
	{ .name      = "autosave",
	  .comment   = "Save configuration automatically after each change",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on" },
	{ .name      = "debug_mode",
	  .comment   = "Produce some debugging output",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off",
	  .on_change = on_config_debug_mode_change },
	{ .name      = "logging",
	  .comment   = "Log buffer contents to file",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off",
	  .on_change = on_config_logging_change },
	{ .name      = "plugin_autoload",
	  .comment   = "Plugins to automatically load on start",
	  .type      = CONFIG_ITEM_STRING_ARRAY,
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "relay_bind",
	  .comment   = "Address to bind to for a user interface relay point",
	  .type      = CONFIG_ITEM_STRING,
	  .validate  = config_validate_nonjunk_string,
	  .on_change = on_config_relay_bind_change },

	// Buffer history:
	{ .name      = "backlog_limit",
	  .comment   = "Maximum number of lines stored in the backlog",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "1000",
	  .on_change = on_config_backlog_limit_change },
	{ .name      = "pager",
	  .comment   = "Shell command to page buffer history (args: name [path])",
	  .type      = CONFIG_ITEM_STRING,
	  .default_  = "`name=$(echo \"$1\" | sed 's/[%?:.]/\\\\&/g'); "
		"prompt='?f%F:'$name'. ?db- page %db?L of %D. .(?eEND:?PB%PB\\%..)'; "
		"LESSSECURE=1 less +Gb -Ps\"$prompt\" \"${2:--R}\"`" },
	{ .name      = "pager_strip_formatting",
	  .comment   = "Strip terminal formatting from pager input",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off" },

	// Output adjustments:
	{ .name      = "beep_on_highlight",
	  .comment   = "Ring the bell when highlighted or on a new invisible PM",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on",
	  .on_change = on_config_beep_on_highlight_change },
	{ .name      = "date_change_line",
	  .comment   = "Input to strftime(3) for the date change line",
	  .type      = CONFIG_ITEM_STRING,
	  .default_  = "\"%F\"" },
	{ .name      = "isolate_buffers",
	  .comment   = "Don't leak messages from the server and global buffers",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off",
	  .on_change = on_config_isolate_buffers_change },
	{ .name      = "read_marker_char",
	  .comment   = "The character to use for the read marker line",
	  .type      = CONFIG_ITEM_STRING,
	  .default_  = "\"-\"",
	  .validate  = config_validate_nonjunk_string },
	{ .name      = "show_all_prefixes",
	  .comment   = "Show all prefixes in front of nicknames",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "off",
	  .on_change = on_config_show_all_prefixes_change },
	{ .name      = "word_wrapping",
	  .comment   = "Enable simple word wrapping in buffers",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on",
	  .on_change = on_config_word_wrapping_change },

	// User input:
	{ .name      = "editor",
	  .comment   = "VIM: \"vim +%Bgo %F\", Emacs: \"emacs -nw +%L:%C %F\", "
		"nano/micro/kakoune: \"nano/micro/kak +%L:%C %F\"",
	  .type      = CONFIG_ITEM_STRING },
	{ .name      = "process_pasted_text",
	  .comment   = "Normalize newlines and quote the command prefix in pastes",
	  .type      = CONFIG_ITEM_BOOLEAN,
	  .default_  = "on" },

	// Pan-server configuration:
	{ .name      = "autoaway_message",
	  .comment   = "Automated away message",
	  .type      = CONFIG_ITEM_STRING,
	  .default_  = "\"I'm not here right now\"" },
	{ .name      = "autoaway_delay",
	  .comment   = "Delay from the last keypress in seconds",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "1800" },
	{ .name      = "reconnect_delay_growing",
	  .comment   = "Growth factor for the reconnect delay",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "2" },
	{ .name      = "reconnect_delay_max",
	  .comment   = "Maximum reconnect delay in seconds",
	  .type      = CONFIG_ITEM_INTEGER,
	  .validate  = config_validate_nonnegative,
	  .default_  = "600" },
	{}
};

static struct config_schema g_config_attributes[] =
{
#define XX(x, y, z) { .name = #y, .comment = #z, .type = CONFIG_ITEM_STRING, \
	.on_change = on_config_attribute_change },
	ATTR_TABLE (XX)
#undef XX
	{}
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
load_config_general (struct config_item *subtree, void *user_data)
{
	config_schema_apply_to_object (g_config_general, subtree, user_data);
}

static void
load_config_attributes (struct config_item *subtree, void *user_data)
{
	config_schema_apply_to_object (g_config_attributes, subtree, user_data);
}

static void
register_config_modules (struct app_context *ctx)
{
	struct config *config = &ctx->config;
	// The servers are loaded later when we can create buffers for them
	config_register_module (config, "servers",    NULL, NULL);
	config_register_module (config, "aliases",    NULL, NULL);
	config_register_module (config, "plugins",    NULL, NULL);
	config_register_module (config, "general",    load_config_general,    ctx);
	config_register_module (config, "attributes", load_config_attributes, ctx);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static const char *
get_config_string (struct config_item *root, const char *key)
{
	struct config_item *item = config_item_get (root, key, NULL);
	hard_assert (item);
	if (item->type == CONFIG_ITEM_NULL)
		return NULL;
	hard_assert (config_item_type_is_string (item->type));
	return item->value.string.str;
}

static bool
set_config_string
	(struct config_item *root, const char *key, const char *value)
{
	struct config_item *item = config_item_get (root, key, NULL);
	hard_assert (item);

	struct config_item *new_ = config_item_string_from_cstr (value);
	struct error *e = NULL;
	if (config_item_set_from (item, new_, &e))
		return true;

	config_item_destroy (new_);
	print_error ("couldn't set `%s' in configuration: %s", key, e->message);
	error_free (e);
	return false;
}

static int64_t
get_config_integer (struct config_item *root, const char *key)
{
	struct config_item *item = config_item_get (root, key, NULL);
	hard_assert (item && item->type == CONFIG_ITEM_INTEGER);
	return item->value.integer;
}

static bool
get_config_boolean (struct config_item *root, const char *key)
{
	struct config_item *item = config_item_get (root, key, NULL);
	hard_assert (item && item->type == CONFIG_ITEM_BOOLEAN);
	return item->value.boolean;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static struct str_map *
get_servers_config (struct app_context *ctx)
{
	return &config_item_get (ctx->config.root, "servers", NULL)->value.object;
}

static struct str_map *
get_aliases_config (struct app_context *ctx)
{
	return &config_item_get (ctx->config.root, "aliases", NULL)->value.object;
}

static struct str_map *
get_plugins_config (struct app_context *ctx)
{
	return &config_item_get (ctx->config.root, "plugins", NULL)->value.object;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
serialize_configuration (struct config_item *root, struct str *output)
{
	str_append (output,
		"# " PROGRAM_NAME " " PROGRAM_VERSION " configuration file\n"
		"#\n"
		"# Relative paths are searched for in ${XDG_CONFIG_HOME:-~/.config}\n"
		"# /" PROGRAM_NAME " as well as in $XDG_CONFIG_DIRS/" PROGRAM_NAME "\n"
		"#\n"
		"# Everything is in UTF-8.  Any custom comments will be overwritten.\n"
		"\n");

	config_item_write (root, true, output);
}

// --- Relay plumbing ----------------------------------------------------------

static void
client_kill (struct client *c)
{
	struct app_context *ctx = c->ctx;
	poller_fd_reset (&c->socket_event);
	xclose (c->socket_fd);
	c->socket_fd = -1;

	LIST_UNLINK (ctx->clients, c);
	client_destroy (c);
}

static bool
client_try_read (struct client *c)
{
	struct str *buf = &c->read_buffer;
	ssize_t n_read;

	while ((n_read = read (c->socket_fd, buf->str + buf->len,
		buf->alloc - buf->len - 1 /* null byte */)) > 0)
	{
		buf->len += n_read;
		if (!client_process_buffer (c))
			break;
		str_reserve (buf, 512);
	}

	if (n_read < 0)
	{
		if (errno == EAGAIN || errno == EINTR)
			return true;

		print_debug ("%s: %s: %s", __func__, "read", strerror (errno));
	}

	client_kill (c);
	return false;
}

static bool
client_try_write (struct client *c)
{
	struct str *buf = &c->write_buffer;
	ssize_t n_written;

	while (buf->len)
	{
		n_written = write (c->socket_fd, buf->str, buf->len);
		if (n_written >= 0)
		{
			str_remove_slice (buf, 0, n_written);
			continue;
		}
		if (errno == EAGAIN || errno == EINTR)
			return true;

		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
		client_kill (c);
		return false;
	}
	return true;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
client_update_poller (struct client *c, const struct pollfd *pfd)
{
	int new_events = POLLIN;
	if (c->write_buffer.len)
		new_events |= POLLOUT;

	hard_assert (new_events != 0);
	if (!pfd || pfd->events != new_events)
		poller_fd_set (&c->socket_event, new_events);
}

static void
on_client_ready (const struct pollfd *pfd, void *user_data)
{
	struct client *c = user_data;
	if (client_try_read (c) && client_try_write (c))
		client_update_poller (c, pfd);
}

static bool
relay_try_fetch_client (struct app_context *ctx, int listen_fd)
{
	// XXX: `struct sockaddr_storage' is not the most portable thing
	struct sockaddr_storage peer;
	socklen_t peer_len = sizeof peer;

	int fd = accept (listen_fd, (struct sockaddr *) &peer, &peer_len);
	if (fd == -1)
	{
		if (errno == EAGAIN || errno == EWOULDBLOCK)
			return false;
		if (errno == EINTR)
			return true;

		if (accept_error_is_transient (errno))
			print_warning ("%s: %s", "accept", strerror (errno));
		else
			// TODO: Rather dispose of the listening socket.
			print_fatal ("%s: %s", "accept", strerror (errno));
		return true;
	}

	hard_assert (peer_len <= sizeof peer);
	set_blocking (fd, false);
	set_cloexec (fd);

	// We already buffer our output, so reduce latencies.
	int yes = 1;
	soft_assert (setsockopt (fd, IPPROTO_TCP, TCP_NODELAY,
		&yes, sizeof yes) != -1);

	struct client *c = client_new ();
	c->ctx = ctx;
	c->socket_fd = fd;
	LIST_PREPEND (ctx->clients, c);

	c->socket_event = poller_fd_make (&c->ctx->poller, c->socket_fd);
	c->socket_event.dispatcher = (poller_fd_fn) on_client_ready;
	c->socket_event.user_data = c;

	client_update_poller (c, NULL);
	return true;
}

static void
on_relay_client_available (const struct pollfd *pfd, void *user_data)
{
	struct app_context *ctx = user_data;
	while (relay_try_fetch_client (ctx, pfd->fd))
		;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
relay_listen (struct addrinfo *ai, struct error **e)
{
	int fd = socket (ai->ai_family, ai->ai_socktype, ai->ai_protocol);
	if (fd == -1)
	{
		error_set (e, "socket: %s", strerror (errno));
		return -1;
	}

	set_cloexec (fd);

	int yes = 1;
	soft_assert (setsockopt (fd, SOL_SOCKET, SO_KEEPALIVE,
		&yes, sizeof yes) != -1);
	soft_assert (setsockopt (fd, SOL_SOCKET, SO_REUSEADDR,
		&yes, sizeof yes) != -1);

	if (bind (fd, ai->ai_addr, ai->ai_addrlen))
		error_set (e, "bind: %s", strerror (errno));
	else if (listen (fd, 16 /* arbitrary number */))
		error_set (e, "listen: %s", strerror (errno));
	else
		return fd;

	xclose (fd);
	return -1;
}

static int
relay_listen_with_context (struct addrinfo *ai, struct error **e)
{
	char *address = gai_reconstruct_address (ai);
	print_debug ("binding to `%s'", address);

	struct error *error = NULL;
	int fd = relay_listen (ai, &error);
	if (fd == -1)
	{
		error_set (e, "binding to `%s' failed: %s", address, error->message);
		error_free (error);
	}
	free (address);
	return fd;
}

static bool
relay_start (struct app_context *ctx, char *address, struct error **e)
{
	const char *port = NULL, *host = tokenize_host_port (address, &port);
	if (!port || !*port)
		return error_set (e, "missing port");

	struct addrinfo hints = {}, *result = NULL;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_PASSIVE;

	int err = getaddrinfo (*host ? host : NULL, port, &hints, &result);
	if (err)
	{
		return error_set (e, "failed to resolve `%s', port `%s': %s: %s",
			host, port, "getaddrinfo", gai_strerror (err));
	}

	// Just try the first one, disregarding IPv4/IPv6 ordering.
	int fd = relay_listen_with_context (result, e);
	freeaddrinfo (result);
	if (fd == -1)
		return false;

	set_blocking (fd, false);

	struct poller_fd *event = &ctx->relay_event;
	*event = poller_fd_make (&ctx->poller, fd);
	event->dispatcher = (poller_fd_fn) on_relay_client_available;
	event->user_data = ctx;

	ctx->relay_fd = fd;
	poller_fd_set (event, POLLIN);
	return true;
}

static void
on_config_relay_bind_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	char *value = item->value.string.str;
	app_context_relay_stop (ctx);
	if (!value)
		return;

	struct error *e = NULL;
	char *address = xstrdup (value);
	if (!relay_start (ctx, address, &e))
	{
		// TODO: Try to make sure this finds its way to the global buffer.
		print_error ("%s: %s", item->schema->name, e->message);
		error_free (e);
	}
	free (address);
}

// --- Relay output ------------------------------------------------------------

static void
relay_send (struct client *c)
{
	struct relay_event_message *m = &c->ctx->relay_message;
	m->event_seq = c->event_seq++;

	// TODO: Also don't try sending anything if half-closed.
	if (!c->initialized || c->socket_fd == -1)
		return;

	// liberty has msg_{reader,writer} already, but they use 8-byte lengths.
	size_t frame_len_pos = c->write_buffer.len, frame_len = 0;
	str_pack_u32 (&c->write_buffer, 0);
	if (!relay_event_message_serialize (m, &c->write_buffer)
	 || (frame_len = c->write_buffer.len - frame_len_pos - 4) > UINT32_MAX)
	{
		print_error ("serialization failed, killing client");
		client_kill (c);
		return;
	}

	uint32_t len = htonl (frame_len);
	memcpy (c->write_buffer.str + frame_len_pos, &len, sizeof len);
	client_update_poller (c, NULL);
}

static void
relay_broadcast (struct app_context *ctx)
{
	LIST_FOR_EACH (struct client, c, ctx->clients)
		relay_send (c);
}

static struct relay_event_message *
relay_prepare (struct app_context *ctx)
{
	struct relay_event_message *m = &ctx->relay_message;
	relay_event_message_free (m);
	memset (m, 0, sizeof *m);
	return m;
}

static void
relay_prepare_ping (struct app_context *ctx)
{
	relay_prepare (ctx)->data.event = RELAY_EVENT_PING;
}

static void
relay_prepare_buffer_update (struct app_context *ctx, struct buffer *buffer)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_update *e = &m->data.buffer_update;
	e->event = RELAY_EVENT_BUFFER_UPDATE;
	e->buffer_name = str_from_cstr (buffer->name);
}

static void
relay_prepare_buffer_rename (struct app_context *ctx, struct buffer *buffer,
	const char *new_name)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_rename *e = &m->data.buffer_rename;
	e->event = RELAY_EVENT_BUFFER_RENAME;
	e->buffer_name = str_from_cstr (buffer->name);
	e->new = str_from_cstr (new_name);
}

static void
relay_prepare_buffer_remove (struct app_context *ctx, struct buffer *buffer)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_remove *e = &m->data.buffer_remove;
	e->event = RELAY_EVENT_BUFFER_REMOVE;
	e->buffer_name = str_from_cstr (buffer->name);
}

static void
relay_prepare_buffer_activate (struct app_context *ctx, struct buffer *buffer)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_activate *e = &m->data.buffer_activate;
	e->event = RELAY_EVENT_BUFFER_ACTIVATE;
	e->buffer_name = str_from_cstr (buffer->name);
}

static void
relay_prepare_buffer_line (struct app_context *ctx, struct buffer *buffer,
	struct buffer_line *line)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_line *e = &m->data.buffer_line;
	e->event = RELAY_EVENT_BUFFER_LINE;
	e->buffer_name = str_from_cstr (buffer->name);
	e->is_unimportant = !!(line->flags & BUFFER_LINE_UNIMPORTANT);
	e->is_highlight = !!(line->flags & BUFFER_LINE_HIGHLIGHT);
	e->rendition = 1 + line->r;
	e->when = line->when * 1000;

	size_t len = 0;
	for (size_t i = 0; line->items[i].type; i++)
		len++;

	// XXX: This way helps xP's JSON conversion, but is super annoying for us.
	union relay_item_data *p = e->items = xcalloc (len * 6, sizeof *e->items);
	for (struct formatter_item *i = line->items; len--; i++)
	{
		// XXX: See attr_printer_decode_color(), this is a footgun.
		int16_t c16  = i->color;
		int16_t c256 = i->color >> 16;
		switch (i->type)
		{
		case FORMATTER_ITEM_TEXT:
			p->text.text = str_from_cstr (i->text);
			(p++)->kind = RELAY_ITEM_TEXT;
			break;
		case FORMATTER_ITEM_ATTR:
			// For future consideration.
			(p++)->kind = RELAY_ITEM_RESET;
			break;
		case FORMATTER_ITEM_FG_COLOR:
			p->fg_color.color = c256 <= 0 ? c16 : c256;
			(p++)->kind = RELAY_ITEM_FG_COLOR;
			break;
		case FORMATTER_ITEM_BG_COLOR:
			p->bg_color.color = c256 <= 0 ? c16 : c256;
			(p++)->kind = RELAY_ITEM_BG_COLOR;
			break;
		case FORMATTER_ITEM_SIMPLE:
			if (i->attribute & TEXT_BOLD)
				(p++)->kind = RELAY_ITEM_FLIP_BOLD;
			if (i->attribute & TEXT_ITALIC)
				(p++)->kind = RELAY_ITEM_FLIP_ITALIC;
			if (i->attribute & TEXT_UNDERLINE)
				(p++)->kind = RELAY_ITEM_FLIP_UNDERLINE;
			if (i->attribute & TEXT_INVERSE)
				(p++)->kind = RELAY_ITEM_FLIP_INVERSE;
			if (i->attribute & TEXT_CROSSED_OUT)
				(p++)->kind = RELAY_ITEM_FLIP_CROSSED_OUT;
			if (i->attribute & TEXT_MONOSPACE)
				(p++)->kind = RELAY_ITEM_FLIP_MONOSPACE;
			break;
		default:
			break;
		}
	}

	e->items_len = p - e->items;
}

static void
relay_prepare_buffer_clear (struct app_context *ctx,
	struct buffer *buffer)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_buffer_clear *e = &m->data.buffer_clear;
	e->event = RELAY_EVENT_BUFFER_CLEAR;
	e->buffer_name = str_from_cstr (buffer->name);
}

static void
relay_prepare_error (struct app_context *ctx, uint32_t seq, const char *message)
{
	struct relay_event_message *m = relay_prepare (ctx);
	struct relay_event_data_error *e = &m->data.error;
	e->event = RELAY_EVENT_ERROR;
	e->command_seq = seq;
	e->error = str_from_cstr (message);
}

// --- Terminal output ---------------------------------------------------------

/// Default colour pair
#define COLOR_DEFAULT -1

/// Bright versions of the basic colour set
#define COLOR_BRIGHT(x) (COLOR_ ## x + 8)

/// Builds a colour pair for 256-colour terminals with a 16-colour backup value
#define COLOR_256(name, c256) \
	(((COLOR_ ## name) & 0xFFFF) | (((c256) & 0xFFFF) << 16))

typedef int (*terminal_printer_fn) (int);

static int
putchar_stderr (int c)
{
	return fputc (c, stderr);
}

static terminal_printer_fn
get_attribute_printer (FILE *stream)
{
	if (stream == stdout && g_terminal.stdout_is_tty)
		return putchar;
	if (stream == stderr && g_terminal.stderr_is_tty)
		return putchar_stderr;
	return NULL;
}

static void
vprint_attributed (struct app_context *ctx,
	FILE *stream, intptr_t attribute, const char *fmt, va_list ap)
{
	terminal_printer_fn printer = get_attribute_printer (stream);
	if (!attribute)
		printer = NULL;

	if (printer)
		tputs (ctx->attrs[attribute], 1, printer);

	vfprintf (stream, fmt, ap);

	if (printer)
		tputs (ctx->attrs[ATTR_RESET], 1, printer);
}

static void
print_attributed (struct app_context *ctx,
	FILE *stream, intptr_t attribute, const char *fmt, ...)
{
	va_list ap;
	va_start (ap, fmt);
	vprint_attributed (ctx, stream, attribute, fmt, ap);
	va_end (ap);
}

static void
log_message_attributed (void *user_data, const char *quote, const char *fmt,
	va_list ap)
{
	FILE *stream = stderr;
	struct app_context *ctx = g_ctx;

	CALL (ctx->input, hide);

	print_attributed (ctx, stream, (intptr_t) user_data, "%s", quote);
	vprint_attributed (ctx, stream, (intptr_t) user_data, fmt, ap);
	fputs ("\n", stream);

	CALL (ctx->input, show);
}

static ssize_t
attr_by_name (const char *name)
{
	static const char *table[ATTR_COUNT] =
	{
#define XX(x, y, z) [ATTR_ ## x] = #y,
		ATTR_TABLE (XX)
#undef XX
	};

	for (size_t i = 0; i < N_ELEMENTS (table); i++)
		if (!strcmp (name, table[i]))
			return i;
	return -1;
}

static void
on_config_attribute_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	ssize_t id = attr_by_name (item->schema->name);
	if (id != -1)
	{
		cstr_set (&ctx->attrs[id], xstrdup (item->type == CONFIG_ITEM_NULL
			? ctx->attrs_defaults[id]
			: item->value.string.str));
	}
}

static void
init_colors (struct app_context *ctx)
{
	bool have_ti = init_terminal ();
	char **defaults = ctx->attrs_defaults;

#define INIT_ATTR(id, ti) defaults[ATTR_ ## id] = xstrdup (have_ti ? (ti) : "")

	INIT_ATTR (PROMPT,      enter_bold_mode);
	INIT_ATTR (RESET,       exit_attribute_mode);
	INIT_ATTR (DATE_CHANGE, enter_bold_mode);
	INIT_ATTR (READ_MARKER, g_terminal.color_set_fg[COLOR_MAGENTA]);
	INIT_ATTR (WARNING,     g_terminal.color_set_fg[COLOR_YELLOW]);
	INIT_ATTR (ERROR,       g_terminal.color_set_fg[COLOR_RED]);

	INIT_ATTR (EXTERNAL,    g_terminal.color_set_fg[COLOR_WHITE]);
	INIT_ATTR (TIMESTAMP,   g_terminal.color_set_fg[COLOR_WHITE]);
	INIT_ATTR (ACTION,      g_terminal.color_set_fg[COLOR_RED]);
	INIT_ATTR (USERHOST,    g_terminal.color_set_fg[COLOR_CYAN]);
	INIT_ATTR (JOIN,        g_terminal.color_set_fg[COLOR_GREEN]);
	INIT_ATTR (PART,        g_terminal.color_set_fg[COLOR_RED]);

	char *highlight = have_ti ? xstrdup_printf ("%s%s%s",
		g_terminal.color_set_fg[COLOR_YELLOW],
		g_terminal.color_set_bg[COLOR_MAGENTA],
		enter_bold_mode) : NULL;
	INIT_ATTR (HIGHLIGHT, highlight);
	free (highlight);

#undef INIT_ATTR

	// This prevents formatters from obtaining an attribute printer function
	if (!have_ti)
	{
		g_terminal.stdout_is_tty = false;
		g_terminal.stderr_is_tty = false;
	}

	g_log_message_real = log_message_attributed;

	// Apply the default values so that we start with any formatting at all
	config_schema_call_changed
		(config_item_get (ctx->config.root, "attributes", NULL));
}

// ~~~ Attribute printer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// A little tool that tries to make the most of the terminal's capabilities
// to set up text attributes.  It mostly targets just terminal emulators as that
// is what people are using these days.  At least no stupid ncurses limits us
// with colour pairs.

struct attr_printer
{
	char **attrs;                       ///< Named attributes
	FILE *stream;                       ///< Output stream
	bool dirty;                         ///< Attributes are set
};

#define ATTR_PRINTER_INIT(ctx, stream) { ctx->attrs, stream, true }

static void
attr_printer_filtered_puts (FILE *stream, const char *attr)
{
	for (; *attr; attr++)
	{
		// sgr/set_attributes and sgr0/exit_attribute_mode like to enable or
		// disable the ACS with SO/SI (e.g. for TERM=screen), however `less -R`
		// does not skip over these characters and it screws up word wrapping
		if (*attr == 14 /* SO */ || *attr == 15 /* SI */)
			continue;

		// Trivially skip delay sequences intended to be processed by tputs()
		const char *end = NULL;
		if (attr[0] == '$' && attr[1] == '<' && (end = strchr (attr, '>')))
			attr = end;
		else
			fputc (*attr, stream);
	}
}

static void
attr_printer_tputs (struct attr_printer *self, const char *attr)
{
	terminal_printer_fn printer = get_attribute_printer (self->stream);
	if (printer)
		tputs (attr, 1, printer);
	else
		// We shouldn't really do this but we need it to output formatting
		// to the pager--it should be SGR-only
		attr_printer_filtered_puts (self->stream, attr);
}

static void
attr_printer_reset (struct attr_printer *self)
{
	if (self->dirty)
		attr_printer_tputs (self, self->attrs[ATTR_RESET]);

	self->dirty = false;
}

static void
attr_printer_apply_named (struct attr_printer *self, int attribute)
{
	attr_printer_reset (self);
	if (attribute != ATTR_RESET)
	{
		attr_printer_tputs (self, self->attrs[attribute]);
		self->dirty = true;
	}
}

// NOTE: commonly terminals have:
//   8 colours (worst, bright fg often with BOLD, bg sometimes with BLINK)
//   16 colours (okayish, we have the full basic range guaranteed)
//   88 colours (the same plus a 4^3 RGB cube and a few shades of grey)
//   256 colours (best, like above but with a larger cube and more grey)

/// Interpolate from the 256-colour palette to the 88-colour one
static int
attr_printer_256_to_88 (int color)
{
	// These colours are the same everywhere
	if (color < 16)
		return color;

	// 24 -> 8 extra shades of grey
	if (color >= 232)
		return 80 + (color - 232) / 3;

	// 6 * 6 * 6 cube -> 4 * 4 * 4 cube
	int x[6] = { 0, 1, 1, 2, 2, 3 };
	int index = color - 16;
	return 16 +
		( x[ index / 36      ] << 8
		| x[(index /  6) % 6 ] << 4
		| x[(index %  6)     ] );
}

static int
attr_printer_decode_color (int color, bool *is_bright)
{
	int16_t c16  = color;        hard_assert (c16  < 16);
	int16_t c256 = color >> 16;  hard_assert (c256 < 256);

	*is_bright = false;
	switch (max_colors)
	{
	case 8:
		if (c16 >= 8)
		{
			c16 -= 8;
			*is_bright = true;
		}
		// Fall-through
	case 16:
		return c16;

	case 88:
		return c256 <= 0 ? c16 : attr_printer_256_to_88 (c256);
	case 256:
		return c256 <= 0 ? c16 : c256;

	default:
		// Unsupported palette
		return -1;
	}
}

static void
attr_printer_apply (struct attr_printer *self,
	int text_attrs, int wanted_fg, int wanted_bg)
{
	bool fg_is_bright;
	int fg = attr_printer_decode_color (wanted_fg, &fg_is_bright);
	bool bg_is_bright;
	int bg = attr_printer_decode_color (wanted_bg, &bg_is_bright);

	bool have_inverse = !!(text_attrs & TEXT_INVERSE);
	if (have_inverse)
	{
		bool tmp = fg_is_bright;
		fg_is_bright = bg_is_bright;
		bg_is_bright = tmp;
	}

	// In 8 colour mode, some terminals don't support bright backgrounds.
	// However, we can make use of the fact that the brightness change caused
	// by the bold attribute is retained when inverting the colours.
	// This has the downside of making the text bold when it's not supposed
	// to be, and we still can't make both colours bright, so it's more of
	// an interesting hack rather than anything else.
	if (!fg_is_bright && bg_is_bright && have_inverse)
		text_attrs |= TEXT_BOLD;
	else if (!fg_is_bright && bg_is_bright
		&& !have_inverse && fg >= 0 && bg >= 0)
	{
		// As long as none of the colours is the default, we can swap them
		int tmp = fg; fg = bg; bg = tmp;
		text_attrs |= TEXT_BOLD | TEXT_INVERSE;
	}
	else
	{
		// This often works, however...
		if (fg_is_bright) text_attrs |= TEXT_BOLD;
		// this turns out to be annoying if implemented "correctly"
		if (bg_is_bright) text_attrs |= TEXT_BLINK;
	}

	attr_printer_reset (self);

	// TEXT_MONOSPACE is unimplemented, for obvious reasons
	if (text_attrs)
		attr_printer_tputs (self, tparm (set_attributes,
			0,   // standout
			text_attrs & TEXT_UNDERLINE,
			text_attrs & TEXT_INVERSE,
			text_attrs & TEXT_BLINK,
			0,   // dim
			text_attrs & TEXT_BOLD,
			0,   // blank
			0,   // protect
			0)); // acs
	if ((text_attrs & TEXT_ITALIC) && enter_italics_mode)
		attr_printer_tputs (self, enter_italics_mode);

	char *smxx = NULL;
	if ((text_attrs & TEXT_CROSSED_OUT)
	 && (smxx = tigetstr ("smxx")) && smxx != (char *) -1)
		attr_printer_tputs (self, smxx);

	if (fg >= 0)
		attr_printer_tputs (self, g_terminal.color_set_fg[fg]);
	if (bg >= 0)
		attr_printer_tputs (self, g_terminal.color_set_bg[bg]);

	self->dirty = true;
}

// --- Helpers -----------------------------------------------------------------

static int
irc_server_strcmp (struct server *s, const char *a, const char *b)
{
	int x;
	while (*a || *b)
		if ((x = s->irc_tolower (*a++) - s->irc_tolower (*b++)))
			return x;
	return 0;
}

static int
irc_server_strncmp (struct server *s, const char *a, const char *b, size_t n)
{
	int x;
	while (n-- && (*a || *b))
		if ((x = s->irc_tolower (*a++) - s->irc_tolower (*b++)))
			return x;
	return 0;
}

static char *
irc_cut_nickname (const char *prefix)
{
	return cstr_cut_until (prefix, "!@");
}

static const char *
irc_find_userhost (const char *prefix)
{
	const char *p = strchr (prefix, '!');
	return p ? p + 1 : NULL;
}

static bool
irc_is_this_us (struct server *s, const char *prefix)
{
	// This shouldn't be called before successfully registering.
	// Better safe than sorry, though.
	if (!s->irc_user)
		return false;

	char *nick = irc_cut_nickname (prefix);
	bool result = !irc_server_strcmp (s, nick, s->irc_user->nickname);
	free (nick);
	return result;
}

static bool
irc_is_channel (struct server *s, const char *ident)
{
	return *ident
		&& (!!strchr (s->irc_chantypes,       *ident) ||
			!!strchr (s->irc_idchan_prefixes, *ident));
}

// Message targets can be prefixed by a character filtering their targets
static const char *
irc_skip_statusmsg (struct server *s, const char *target)
{
	return target + (*target && strchr (s->irc_statusmsg, *target));
}

static bool
irc_is_extban (struct server *s, const char *target)
{
	// Some servers have a prefix, and some support negation
	if (s->irc_extban_prefix && *target++ != s->irc_extban_prefix)
		return false;
	if (*target == '~')
		target++;

	// XXX: we don't know if it's supposed to have an argument, or not
	return *target && strchr (s->irc_extban_types, *target++)
		&& strchr (":\0", *target);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// As of 2020, everything should be in UTF-8.  And if it's not, we'll decode it
// as ISO Latin 1.  This function should not be called on the whole message.
static char *
irc_to_utf8 (const char *text)
{
	if (!text)
		return NULL;

	// XXX: the validation may be unnecessarily harsh, could do with a lenient
	//   first pass, then replace any errors with the replacement character
	size_t len = strlen (text) + 1;
	if (utf8_validate (text, len))
		return xstrdup (text);

	// Windows 1252 redefines several silly C1 control characters as glyphs
	static const char c1[32][4] =
	{
		"\xe2\x82\xac", "\xc2\x81",     "\xe2\x80\x9a", "\xc6\x92",
		"\xe2\x80\x9e", "\xe2\x80\xa6", "\xe2\x80\xa0", "\xe2\x80\xa1",
		"\xcb\x86",     "\xe2\x80\xb0", "\xc5\xa0",     "\xe2\x80\xb9",
		"\xc5\x92",     "\xc2\x8d",     "\xc5\xbd",     "\xc2\x8f",
		"\xc2\x90",     "\xe2\x80\x98", "\xe2\x80\x99", "\xe2\x80\x9c",
		"\xe2\x80\x9d", "\xe2\x80\xa2", "\xe2\x80\x93", "\xe2\x80\x94",
		"\xcb\x9c",     "\xe2\x84\xa2", "\xc5\xa1",     "\xe2\x80\xba",
		"\xc5\x93",     "\xc2\x9d",     "\xc5\xbe",     "\xc5\xb8",
	};

	struct str s = str_make ();
	for (const char *p = text; *p; p++)
	{
		int c = *(unsigned char *) p;
		if (c < 0x80)
			str_append_c (&s, c);
		else if (c < 0xA0)
			str_append (&s, c1[c & 0x1f]);
		else
			str_append_data (&s,
				(char[]) {0xc0 | (c >> 6), 0x80 | (c & 0x3f)}, 2);
	}
	return str_steal (&s);
}

// --- Output formatter --------------------------------------------------------

// This complicated piece of code makes attributed text formatting simple.
// We use a printf-inspired syntax to push attributes and text to the object,
// then flush it either to a terminal, or a log file with formatting stripped.
//
// Format strings use a #-quoted notation, to differentiate from printf:
//   #s inserts a string (expected to be in UTF-8)
//   #d inserts a signed integer
//   #l inserts a locale-encoded string
//
//   #S inserts a string from the server with unknown encoding
//   #m inserts an IRC-formatted string (auto-resets at boundaries)
//   #n cuts the nickname from a string and automatically colours it
//   #N is like #n but also appends userhost, if present
//
//   #a inserts named attributes (auto-resets)
//   #r resets terminal attributes
//   #c sets foreground colour
//   #C sets background colour
//
// Modifiers:
//    & free() the string argument after using it

static void
formatter_add_item (struct formatter *self, struct formatter_item template_)
{
	if (template_.text)
		template_.text = xstrdup (template_.text);

	if (self->items_len == self->items_alloc)
		self->items = xreallocarray
			(self->items, sizeof *self->items, (self->items_alloc <<= 1));
	self->items[self->items_len++] = template_;
}

#define FORMATTER_ADD_ITEM(self, type_, ...) formatter_add_item ((self), \
	(struct formatter_item) { .type = FORMATTER_ITEM_ ## type_, __VA_ARGS__ })

#define FORMATTER_ADD_RESET(self) \
	FORMATTER_ADD_ITEM ((self), ATTR, .attribute = ATTR_RESET)
#define FORMATTER_ADD_TEXT(self, text_) \
	FORMATTER_ADD_ITEM ((self), TEXT, .text = (text_))

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

enum
{
	MIRC_WHITE,  MIRC_BLACK,    MIRC_BLUE,   MIRC_GREEN,
	MIRC_L_RED,  MIRC_RED,      MIRC_PURPLE, MIRC_ORANGE,
	MIRC_YELLOW, MIRC_L_GREEN,  MIRC_CYAN,   MIRC_L_CYAN,
	MIRC_L_BLUE, MIRC_L_PURPLE, MIRC_GRAY,   MIRC_L_GRAY,
};

// We use estimates from the 16 colour terminal palette, or the 256 colour cube,
// which is not always available.  The mIRC orange colour is only in the cube.

static const int g_mirc_to_terminal[] =
{
	[MIRC_WHITE]    = COLOR_256 (BRIGHT (WHITE),  231),
	[MIRC_BLACK]    = COLOR_256         (BLACK,    16),
	[MIRC_BLUE]     = COLOR_256         (BLUE,     19),
	[MIRC_GREEN]    = COLOR_256         (GREEN,    34),
	[MIRC_L_RED]    = COLOR_256 (BRIGHT (RED),    196),
	[MIRC_RED]      = COLOR_256         (RED,     124),
	[MIRC_PURPLE]   = COLOR_256         (MAGENTA, 127),
	[MIRC_ORANGE]   = COLOR_256 (BRIGHT (YELLOW), 214),
	[MIRC_YELLOW]   = COLOR_256 (BRIGHT (YELLOW), 226),
	[MIRC_L_GREEN]  = COLOR_256 (BRIGHT (GREEN),   46),
	[MIRC_CYAN]     = COLOR_256         (CYAN,     37),
	[MIRC_L_CYAN]   = COLOR_256 (BRIGHT (CYAN),    51),
	[MIRC_L_BLUE]   = COLOR_256 (BRIGHT (BLUE),    21),
	[MIRC_L_PURPLE] = COLOR_256 (BRIGHT (MAGENTA),201),
	[MIRC_GRAY]     = COLOR_256 (BRIGHT (BLACK),  244),
	[MIRC_L_GRAY]   = COLOR_256         (WHITE,   252),
};

// https://modern.ircdocs.horse/formatting.html
// http://anti.teamidiot.de/static/nei/*/extended_mirc_color_proposal.html
static const int16_t g_extra_to_256[100 - 16] =
{
	 52,  94, 100,  58,  22,  29,  23,  24,  17,  54,  53,  89,
	 88, 130, 142,  64,  28,  35,  30,  25,  18,  91,  90, 125,
	124, 166, 184, 106,  34,  49,  37,  33,  19, 129, 127, 161,
	196, 208, 226, 154,  46,  86 , 51,  75,  21, 171, 201, 198,
	203, 215, 227, 191,  83, 122,  87, 111,  63, 177, 207, 205,
	217, 223, 229, 193, 157, 158, 159, 153, 147, 183, 219, 212,
	 16, 233, 235, 237, 239, 241, 244, 247, 250, 254, 231,  -1
};

static const char *
irc_parse_mirc_color (const char *s, uint8_t *fg, uint8_t *bg)
{
	if (!isdigit_ascii (*s))
	{
		*fg = *bg = 99;
		return s;
	}

	*fg = *s++ - '0';
	if (isdigit_ascii (*s))
		*fg = *fg * 10 + (*s++ - '0');

	if (*s != ',' || !isdigit_ascii (s[1]))
		return s;
	s++;

	*bg = *s++ - '0';
	if (isdigit_ascii (*s))
		*bg = *bg * 10 + (*s++ - '0');
	return s;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct irc_char_attrs
{
	uint8_t fg, bg;                     ///< {Fore,back}ground colour or 99
	uint8_t attributes;                 ///< TEXT_* flags, except TEXT_BLINK
	uint8_t starts_at_boundary;         ///< Possible to split here?
};

static void
irc_serialize_char_attrs (const struct irc_char_attrs *attrs, struct str *out)
{
	soft_assert (attrs->fg < 100 && attrs->bg < 100);

	if (attrs->fg != 99 || attrs->bg != 99)
	{
		str_append_printf (out, "\x03%u", attrs->fg);
		if (attrs->bg != 99)
			str_append_printf (out, ",%02u", attrs->bg);
	}
	if (attrs->attributes & TEXT_BOLD)        str_append_c (out, '\x02');
	if (attrs->attributes & TEXT_ITALIC)      str_append_c (out, '\x1d');
	if (attrs->attributes & TEXT_UNDERLINE)   str_append_c (out, '\x1f');
	if (attrs->attributes & TEXT_INVERSE)     str_append_c (out, '\x16');
	if (attrs->attributes & TEXT_CROSSED_OUT) str_append_c (out, '\x1e');
	if (attrs->attributes & TEXT_MONOSPACE)   str_append_c (out, '\x11');
}

static int
irc_parse_attribute (char c)
{
	switch (c)
	{
	case '\x02' /* ^B */: return TEXT_BOLD;
	case '\x11' /* ^Q */: return TEXT_MONOSPACE;
	case '\x16' /* ^V */: return TEXT_INVERSE;
	case '\x1d' /* ^] */: return TEXT_ITALIC;
	case '\x1e' /* ^^ */: return TEXT_CROSSED_OUT;
	case '\x1f' /* ^_ */: return TEXT_UNDERLINE;
	case '\x0f' /* ^O */: return -1;
	}
	return 0;
}

// The text needs to be NUL-terminated, and a valid UTF-8 string
static struct irc_char_attrs *
irc_analyze_text (const char *text, size_t len)
{
	struct irc_char_attrs *attrs = xcalloc (len, sizeof *attrs),
		blank = { .fg = 99, .bg = 99, .starts_at_boundary = true },
		next = blank, cur = next;

	for (size_t i = 0; i != len; cur = next)
	{
		const char *start = text;
		hard_assert (utf8_decode (&text, len - i) >= 0);

		int attribute = irc_parse_attribute (*start);
		if (*start == '\x03')
			text = irc_parse_mirc_color (text, &next.fg, &next.bg);
		else if (attribute > 0)
			next.attributes ^= attribute;
		else if (attribute < 0)
			next = blank;

		while (start++ != text)
		{
			attrs[i++] = cur;
			cur.starts_at_boundary = false;
		}
	}
	return attrs;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static const char *
formatter_parse_mirc_color (struct formatter *self, const char *s)
{
	uint8_t fg = 255, bg = 255;
	s = irc_parse_mirc_color (s, &fg, &bg);

	if (fg < 16)
		FORMATTER_ADD_ITEM (self, FG_COLOR, .color = g_mirc_to_terminal[fg]);
	else if (fg < 100)
		FORMATTER_ADD_ITEM (self, FG_COLOR,
			.color = COLOR_256 (DEFAULT, g_extra_to_256[fg - 16]));

	if (bg < 16)
		FORMATTER_ADD_ITEM (self, BG_COLOR, .color = g_mirc_to_terminal[bg]);
	else if (bg < 100)
		FORMATTER_ADD_ITEM (self, BG_COLOR,
			.color = COLOR_256 (DEFAULT, g_extra_to_256[bg - 16]));

	return s;
}

static void
formatter_parse_message (struct formatter *self, const char *s)
{
	FORMATTER_ADD_RESET (self);

	struct str buf = str_make ();
	unsigned char c;
	while ((c = *s++))
	{
		if (buf.len && c < 0x20)
		{
			FORMATTER_ADD_TEXT (self, buf.str);
			str_reset (&buf);
		}

		int attribute = irc_parse_attribute (c);
		if (c == '\x03')
			s = formatter_parse_mirc_color (self, s);
		else if (attribute > 0)
			FORMATTER_ADD_ITEM (self, SIMPLE, .attribute = attribute);
		else if (attribute < 0)
			FORMATTER_ADD_RESET (self);
		else
			str_append_c (&buf, c);
	}

	if (buf.len)
		FORMATTER_ADD_TEXT (self, buf.str);

	str_free (&buf);
	FORMATTER_ADD_RESET (self);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
formatter_parse_nick (struct formatter *self, const char *s)
{
	// For outgoing messages; maybe we should add a special #t for them
	// which would also make us not cut off the userhost part, ever
	if (irc_is_channel (self->s, irc_skip_statusmsg (self->s, s)))
	{
		char *tmp = irc_to_utf8 (s);
		FORMATTER_ADD_TEXT (self, tmp);
		free (tmp);
		return;
	}

	char *nick = irc_cut_nickname (s);
	int color = siphash_wrapper (nick, strlen (nick)) % 7;

	// Never use the black colour, could become transparent on black terminals;
	// white is similarly excluded from the range
	if (color == COLOR_BLACK)
		color = (uint16_t) -1;

	// Use a colour from the 256-colour cube if available
	color |= self->ctx->nick_palette[siphash_wrapper (nick,
		strlen (nick)) % self->ctx->nick_palette_len] << 16;

	// We always use the default colour for ourselves
	if (self->s && irc_is_this_us (self->s, nick))
		color = -1;

	FORMATTER_ADD_ITEM (self, FG_COLOR, .color = color);

	char *x = irc_to_utf8 (nick);
	free (nick);
	FORMATTER_ADD_TEXT (self, x);
	free (x);

	// Need to reset the colour afterwards
	FORMATTER_ADD_ITEM (self, FG_COLOR, .color = -1);
}

static void
formatter_parse_nick_full (struct formatter *self, const char *s)
{
	formatter_parse_nick (self, s);

	const char *userhost;
	if (!(userhost = irc_find_userhost (s)))
		return;

	FORMATTER_ADD_TEXT (self, " (");
	FORMATTER_ADD_ITEM (self, ATTR, .attribute = ATTR_USERHOST);

	char *x = irc_to_utf8 (userhost);
	FORMATTER_ADD_TEXT (self, x);
	free (x);

	FORMATTER_ADD_RESET (self);
	FORMATTER_ADD_TEXT (self, ")");
}

static const char *
formatter_parse_field (struct formatter *self,
	const char *field, struct str *buf, va_list *ap)
{
	bool free_string = false;
	char *s = NULL;
	char *tmp = NULL;
	int c;

restart:
	switch ((c = *field++))
	{
		// We can push boring text content to the caller's buffer
		// and let it flush the buffer only when it's actually needed
	case 'd':
		tmp = xstrdup_printf ("%d", va_arg (*ap, int));
		str_append (buf, tmp);
		free (tmp);
		break;
	case 's':
		str_append (buf, (s = va_arg (*ap, char *)));
		break;
	case 'l':
		if (!(tmp = iconv_xstrdup (self->ctx->term_to_utf8,
			(s = va_arg (*ap, char *)), -1, NULL)))
			print_error ("character conversion failed for: %s", "output");
		else
			str_append (buf, tmp);
		free (tmp);
		break;

	case 'S':
		tmp = irc_to_utf8 ((s = va_arg (*ap, char *)));
		str_append (buf, tmp);
		free (tmp);
		break;
	case 'm':
		tmp = irc_to_utf8 ((s = va_arg (*ap, char *)));
		formatter_parse_message (self, tmp);
		free (tmp);
		break;
	case 'n':
		formatter_parse_nick (self, (s = va_arg (*ap, char *)));
		break;
	case 'N':
		formatter_parse_nick_full (self, (s = va_arg (*ap, char *)));
		break;

	case 'a':
		FORMATTER_ADD_ITEM (self, ATTR, .attribute = va_arg (*ap, int));
		break;
	case 'c':
		FORMATTER_ADD_ITEM (self, FG_COLOR, .color = va_arg (*ap, int));
		break;
	case 'C':
		FORMATTER_ADD_ITEM (self, BG_COLOR, .color = va_arg (*ap, int));
		break;
	case 'r':
		FORMATTER_ADD_RESET (self);
		break;

	default:
		if (c == '&' && !free_string)
			free_string = true;
		else if (c)
			hard_assert (!"unexpected format specifier");
		else
			hard_assert (!"unexpected end of format string");
		goto restart;
	}

	if (free_string)
		free (s);
	return field;
}

// I was unable to take a pointer of a bare "va_list" when it was passed in
// as a function argument, so it has to be a pointer from the beginning
static void
formatter_addv (struct formatter *self, const char *format, va_list *ap)
{
	struct str buf = str_make ();
	while (*format)
	{
		if (*format != '#' || *++format == '#')
		{
			str_append_c (&buf, *format++);
			continue;
		}
		if (buf.len)
		{
			FORMATTER_ADD_TEXT (self, buf.str);
			str_reset (&buf);
		}

		format = formatter_parse_field (self, format, &buf, ap);
	}

	if (buf.len)
		FORMATTER_ADD_TEXT (self, buf.str);

	str_free (&buf);
}

static void
formatter_add (struct formatter *self, const char *format, ...)
{
	va_list ap;
	va_start (ap, format);
	formatter_addv (self, format, &ap);
	va_end (ap);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct line_char_attrs
{
	short named;                        ///< Named attribute or -1
	short text;                         ///< Text attributes
	int fg;                             ///< Foreground colour (-1 for default)
	int bg;                             ///< Background colour (-1 for default)
};

// We can get rid of the linked list and do this in one allocation (use strlen()
// for the upper bound)--since we only prepend and/or replace characters, add
// a member to specify the prepended character and how many times to repeat it.
// Tabs may nullify the wide character but it's not necessary.
//
// This would be slighly more optimal but it would also set the algorithm in
// stone and complicate flushing.

struct line_char
{
	LIST_HEADER (struct line_char)

	wchar_t wide;                       ///< The character as a wchar_t
	int width;                          ///< Width of the character in cells
	struct line_char_attrs attrs;       ///< Attributes
};

static struct line_char *
line_char_new (wchar_t wc)
{
	struct line_char *self = xcalloc (1, sizeof *self);
	self->width = wcwidth ((self->wide = wc));

	// Typically various control characters
	if (self->width < 0)
		self->width = 0;

	self->attrs.bg = self->attrs.fg = -1;
	self->attrs.named = ATTR_RESET;
	return self;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct line_wrap_mark
{
	struct line_char *start;            ///< First character
	int used;                           ///< Display cells used
};

static void
line_wrap_mark_push (struct line_wrap_mark *mark, struct line_char *c)
{
	if (!mark->start)
		mark->start = c;
	mark->used += c->width;
}

struct line_wrap_state
{
	struct line_char *result;           ///< Head of result
	struct line_char *result_tail;      ///< Tail of result

	int line_used;                      ///< Line length before marks
	int line_max;                       ///< Maximum line length
	struct line_wrap_mark chunk;        ///< All buffered text
	struct line_wrap_mark overflow;     ///< Overflowing text
};

static void
line_wrap_flush_split (struct line_wrap_state *s, struct line_wrap_mark *before)
{
	struct line_char *nl = line_char_new (L'\n');
	LIST_INSERT_WITH_TAIL (s->result, s->result_tail, nl, before->start);
	s->line_used = before->used;
}

static void
line_wrap_flush (struct line_wrap_state *s, bool force_split)
{
	if (!s->overflow.start)
		s->line_used += s->chunk.used;
	else if (force_split || s->chunk.used > s->line_max)
	{
#ifdef WRAP_UNNECESSARILY
		// When the line wraps at the end of the screen and a background colour
		// is set, the terminal paints the entire new line with that colour.
		// Explicitly inserting a newline with the default attributes fixes it.
		line_wrap_flush_split (s, &s->overflow);
#else
		// Splitting here breaks link searching mechanisms in some terminals,
		// though, so we make a trade-off and let the chunk wrap naturally.
		// Fuck terminals, really.
		s->line_used = s->overflow.used;
#endif
	}
	else
		// Print the chunk in its entirety on a new line
		line_wrap_flush_split (s, &s->chunk);

	memset (&s->chunk,    0, sizeof s->chunk);
	memset (&s->overflow, 0, sizeof s->overflow);
}

static void
line_wrap_nl (struct line_wrap_state *s)
{
	line_wrap_flush (s, true);
	struct line_char *nl = line_char_new (L'\n');
	LIST_APPEND_WITH_TAIL (s->result, s->result_tail, nl);
	s->line_used = 0;
}

static void
line_wrap_tab (struct line_wrap_state *s, struct line_char *c)
{
	line_wrap_flush (s, true);
	if (s->line_used >= s->line_max)
		line_wrap_nl (s);

	// Compute the number of characters needed to get to the next tab stop
	int tab_width = ((s->line_used + 8) & ~7) - s->line_used;
	// On overflow just fill the rest of the line with spaces
	if (s->line_used + tab_width > s->line_max)
		tab_width = s->line_max - s->line_used;

	s->line_used += tab_width;
	while (tab_width--)
	{
		struct line_char *space = line_char_new (L' ');
		space->attrs = c->attrs;
		LIST_APPEND_WITH_TAIL (s->result, s->result_tail, space);
	}
}

static void
line_wrap_push_char (struct line_wrap_state *s, struct line_char *c)
{
	// Note that when processing whitespace here, any non-WS chunk has already
	// been flushed, and thus it matters little if we flush with force split
	if (wcschr (L"\r\f\v", c->wide))
		/* Skip problematic characters */;
	else if (c->wide == L'\n')
		line_wrap_nl (s);
	else if (c->wide == L'\t')
		line_wrap_tab (s, c);
	else
		goto use_as_is;
	free (c);
	return;

use_as_is:
	if (s->overflow.start
	 || s->line_used + s->chunk.used + c->width > s->line_max)
	{
		if (s->overflow.used + c->width > s->line_max)
		{
#ifdef WRAP_UNNECESSARILY
			// If the overflow overflows, restart on a new line
			line_wrap_nl (s);
#else
			// See line_wrap_flush(), we would end up on a new line anyway
			line_wrap_flush (s, true);
			s->line_used = 0;
#endif
		}
		else
			line_wrap_mark_push (&s->overflow, c);
	}
	line_wrap_mark_push (&s->chunk, c);
	LIST_APPEND_WITH_TAIL (s->result, s->result_tail, c);
}

/// Basic word wrapping that respects wcwidth(3) and expands tabs.
/// Besides making text easier to read, it also fixes the problem with
/// formatting spilling over the entire new line on line wrap.
static struct line_char *
line_wrap (struct line_char *line, int max_width)
{
	struct line_wrap_state s = { .line_max = max_width };
	bool last_was_word_char = false;
	LIST_FOR_EACH (struct line_char, c, line)
	{
		// Act on the right boundary of (\s*\S+) chunks
		bool this_is_word_char = !wcschr (L" \t\r\n\f\v", c->wide);
		if (last_was_word_char && !this_is_word_char)
			line_wrap_flush (&s, false);
		last_was_word_char = this_is_word_char;

		LIST_UNLINK (line, c);
		line_wrap_push_char (&s, c);
	}

	// Make sure to process the last word and return the modified list
	line_wrap_flush (&s, false);
	return s.result;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct exploder
{
	struct app_context *ctx;            ///< Application context
	struct line_char *result;           ///< Result
	struct line_char *result_tail;      ///< Tail of result
	struct line_char_attrs attrs;       ///< Current attributes
};

static bool
explode_formatter_attr (struct exploder *self, struct formatter_item *item)
{
	switch (item->type)
	{
	case FORMATTER_ITEM_ATTR:
		self->attrs.named = item->attribute;
		self->attrs.text = 0;
		self->attrs.fg = -1;
		self->attrs.bg = -1;
		return true;
	case FORMATTER_ITEM_SIMPLE:
		self->attrs.named = -1;
		self->attrs.text ^= item->attribute;
		return true;
	case FORMATTER_ITEM_FG_COLOR:
		self->attrs.named = -1;
		self->attrs.fg = item->color;
		return true;
	case FORMATTER_ITEM_BG_COLOR:
		self->attrs.named = -1;
		self->attrs.bg = item->color;
		return true;
	default:
		return false;
	}
}

static void
explode_text (struct exploder *self, const char *text)
{
	// Throw away any potentially harmful control characters first
	struct str filtered = str_make ();
	for (const char *p = text; *p; p++)
		if (!strchr ("\a\b\x0e\x0f\x1b" /* BEL BS SO SI ESC */, *p))
			str_append_c (&filtered, *p);

	size_t term_len = 0, processed = 0, len;
	char *term = iconv_xstrdup (self->ctx->term_from_utf8,
		filtered.str, filtered.len + 1, &term_len);
	str_free (&filtered);

	mbstate_t ps;
	memset (&ps, 0, sizeof ps);

	wchar_t wch;
	while ((len = mbrtowc (&wch, term + processed, term_len - processed, &ps)))
	{
		hard_assert (len != (size_t) -2 && len != (size_t) -1);
		hard_assert ((processed += len) <= term_len);

		struct line_char *c = line_char_new (wch);
		c->attrs = self->attrs;
		LIST_APPEND_WITH_TAIL (self->result, self->result_tail, c);
	}
	free (term);
}

static struct line_char *
formatter_to_chars (struct formatter *formatter)
{
	struct exploder self = { .ctx = formatter->ctx };
	self.attrs.fg = self.attrs.bg = self.attrs.named = -1;

	int attribute_ignore = 0;
	for (size_t i = 0; i < formatter->items_len; i++)
	{
		struct formatter_item *iter = &formatter->items[i];
		if      (iter->type == FORMATTER_ITEM_TEXT)
			explode_text (&self, iter->text);
		else if (iter->type == FORMATTER_ITEM_IGNORE_ATTR)
			attribute_ignore += iter->attribute;
		else if (attribute_ignore <= 0
			&& !explode_formatter_attr (&self, iter))
				hard_assert (!"unhandled formatter item type");
	}
	return self.result;
}

enum
{
	FLUSH_OPT_RAW    = (1 << 0),        ///< Print raw attributes
	FLUSH_OPT_NOWRAP = (1 << 1)         ///< Do not wrap
};

/// The input is a bunch of wide characters--respect shift state encodings
static void
formatter_putc (struct line_char *c, FILE *stream)
{
	static mbstate_t mb;
	char buf[MB_LEN_MAX] = {};
	size_t len = wcrtomb (buf, c ? c->wide : L'\0', &mb);
	if (len != (size_t) -1 && len)
		fwrite (buf, len - !c, 1, stream);
	free (c);
}

static void
formatter_flush (struct formatter *self, FILE *stream, int flush_opts)
{
	struct line_char *line = formatter_to_chars (self);

	bool is_tty = !!get_attribute_printer (stream);
	if (!is_tty && !(flush_opts & FLUSH_OPT_RAW))
	{
		LIST_FOR_EACH (struct line_char, c, line)
			formatter_putc (c, stream);
		formatter_putc (NULL, stream);
		return;
	}

	if (self->ctx->word_wrapping && !(flush_opts & FLUSH_OPT_NOWRAP))
		line = line_wrap (line, g_terminal.columns);

	struct attr_printer state = ATTR_PRINTER_INIT (self->ctx, stream);
	struct line_char_attrs attrs = {};  // Won't compare equal to anything
	LIST_FOR_EACH (struct line_char, c, line)
	{
		if (attrs.fg    != c->attrs.fg
		 || attrs.bg    != c->attrs.bg
		 || attrs.named != c->attrs.named
		 || attrs.text  != c->attrs.text)
		{
			formatter_putc (NULL, stream);

			attrs = c->attrs;
			if (attrs.named != -1)
				attr_printer_apply_named (&state, attrs.named);
			else
				attr_printer_apply (&state, attrs.text, attrs.fg, attrs.bg);
		}

		formatter_putc (c, stream);
	}
	formatter_putc (NULL, stream);
	attr_printer_reset (&state);
}

// --- Buffers -----------------------------------------------------------------

static void
buffer_pop_excess_lines (struct app_context *ctx, struct buffer *self)
{
	int to_delete = (int) self->lines_count - (int) ctx->backlog_limit;
	while (to_delete-- > 0 && self->lines)
	{
		struct buffer_line *excess = self->lines;
		LIST_UNLINK_WITH_TAIL (self->lines, self->lines_tail, excess);
		buffer_line_destroy (excess);
		self->lines_count--;
	}
}

static void
on_config_backlog_limit_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	ctx->backlog_limit = MIN (item->value.integer, INT_MAX);

	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
		buffer_pop_excess_lines (ctx, iter);
}

static void
buffer_update_time (struct app_context *ctx, time_t now, FILE *stream,
	int flush_opts)
{
	struct tm last, current;
	if (!localtime_r (&ctx->last_displayed_msg_time, &last)
	 || !localtime_r (&now, &current))
	{
		// Strange but nonfatal
		print_error ("%s: %s", "localtime_r", strerror (errno));
		return;
	}

	ctx->last_displayed_msg_time = now;
	if (last.tm_year == current.tm_year
	 && last.tm_mon  == current.tm_mon
	 && last.tm_mday == current.tm_mday)
		return;

	char buf[64] = "";
	const char *format =
		get_config_string (ctx->config.root, "general.date_change_line");
	if (!strftime (buf, sizeof buf, format, &current))
	{
		print_error ("%s: %s", "strftime", strerror (errno));
		return;
	}

	struct formatter f = formatter_make (ctx, NULL);
	formatter_add (&f, "#a#s\n", ATTR_DATE_CHANGE, buf);
	formatter_flush (&f, stream, flush_opts);
	// Flush the trailing formatting reset item
	fflush (stream);
	formatter_free (&f);
}

static void
buffer_line_flush (struct buffer_line *line, struct formatter *f, FILE *output,
	int flush_opts)
{
	switch (line->r)
	{
	case BUFFER_LINE_BARE:                               break;
	case BUFFER_LINE_INDENT:  formatter_add (f, "    "); break;
	case BUFFER_LINE_STATUS:  formatter_add (f, " -  "); break;
	case BUFFER_LINE_ERROR:   formatter_add (f, "#a=!=#r ", ATTR_ERROR);  break;
	case BUFFER_LINE_JOIN:    formatter_add (f, "#a-->#r ", ATTR_JOIN);   break;
	case BUFFER_LINE_PART:    formatter_add (f, "#a<--#r ", ATTR_PART);   break;
	case BUFFER_LINE_ACTION:  formatter_add (f, " #a*#r  ", ATTR_ACTION); break;
	}

	for (struct formatter_item *iter = line->items; iter->type; iter++)
		formatter_add_item (f, *iter);

	formatter_add (f, "\n");
	formatter_flush (f, output, flush_opts);
	formatter_free (f);
}

static void
buffer_line_write_time (struct formatter *f, struct buffer_line *line,
	FILE *stream, int flush_opts)
{
	// Normal timestamps don't include the date, make sure the user won't be
	// confused as to when an event has happened
	buffer_update_time (f->ctx, line->when, stream, flush_opts);

	struct tm current;
	char buf[9];
	if (!localtime_r (&line->when, &current))
		print_error ("%s: %s", "localtime_r", strerror (errno));
	else if (!strftime (buf, sizeof buf, "%T", &current))
		print_error ("%s: %s", "strftime", "buffer too small");
	else
		formatter_add (f, "#a#s#r ", ATTR_TIMESTAMP, buf);
}

#define buffer_line_will_show_up(buffer, line) \
	(!(buffer)->hide_unimportant || !((line)->flags & BUFFER_LINE_UNIMPORTANT))

static void
buffer_line_display (struct app_context *ctx,
	struct buffer *buffer, struct buffer_line *line, bool is_external)
{
	if (!buffer_line_will_show_up (buffer, line))
		return;

	CALL (ctx->input, hide);

	struct formatter f = formatter_make (ctx, NULL);
	buffer_line_write_time (&f, line, stdout, 0);

	// Ignore all formatting for messages coming from other buffers, that is
	// either from the global or server buffer.  Instead print them in grey.
	if (is_external)
	{
		formatter_add (&f, "#a", ATTR_EXTERNAL);
		FORMATTER_ADD_ITEM (&f, IGNORE_ATTR, .attribute = 1);
	}
	buffer_line_flush (line, &f, stdout, 0);
	// Flush the trailing formatting reset item
	fflush (stdout);

	CALL (ctx->input, show);
}

static void
buffer_line_write_to_backlog (struct app_context *ctx,
	struct buffer_line *line, FILE *log_file, int flush_opts)
{
	struct formatter f = formatter_make (ctx, NULL);
	buffer_line_write_time (&f, line, log_file, flush_opts);
	buffer_line_flush (line, &f, log_file, flush_opts);
}

static void
buffer_line_write_to_log (struct app_context *ctx,
	struct buffer_line *line, FILE *log_file)
{
	if (line->flags & BUFFER_LINE_SKIP_FILE)
		return;

	struct formatter f = formatter_make (ctx, NULL);
	struct tm current;
	char buf[20];
	if (!gmtime_r (&line->when, &current))
		print_error ("%s: %s", "gmtime_r", strerror (errno));
	else if (!strftime (buf, sizeof buf, "%F %T", &current))
		print_error ("%s: %s", "strftime", "buffer too small");
	else
		formatter_add (&f, "#s ", buf);

	// The target is not a terminal, thus it won't wrap in spite of the 0
	buffer_line_flush (line, &f, log_file, 0);
}

static void
log_formatter (struct app_context *ctx, struct buffer *buffer,
	unsigned flags, enum buffer_line_rendition r, struct formatter *f)
{
	if (!buffer)
		buffer = ctx->global_buffer;

	struct buffer_line *line = buffer_line_new (f);
	line->flags = flags;
	line->r = r;
	// TODO: allow providing custom time (IRCv3.2 server-time)
	line->when = time (NULL);

	buffer_pop_excess_lines (ctx, buffer);
	LIST_APPEND_WITH_TAIL (buffer->lines, buffer->lines_tail, line);
	buffer->lines_count++;

	if (buffer->log_file)
		buffer_line_write_to_log (ctx, line, buffer->log_file);

	relay_prepare_buffer_line (ctx, buffer, line);
	relay_broadcast (ctx);

	bool unseen_pm = buffer->type == BUFFER_PM
		&& buffer != ctx->current_buffer
		&& !(flags & BUFFER_LINE_UNIMPORTANT);
	bool important = (flags & BUFFER_LINE_HIGHLIGHT) || unseen_pm;
	if (ctx->beep_on_highlight && important)
		// XXX: this may disturb any other foreground process
		CALL (ctx->input, ding);

	bool can_leak = false;
	if ((buffer == ctx->global_buffer)
	 || (ctx->current_buffer->type == BUFFER_GLOBAL
		&& buffer->type == BUFFER_SERVER)
	 || (ctx->current_buffer->type != BUFFER_GLOBAL
		&& buffer == ctx->current_buffer->server->buffer))
		can_leak = true;

	bool displayed = true;
	if (ctx->terminal_suspended > 0)
		// Another process is using the terminal
		displayed = false;
	else if (buffer == ctx->current_buffer)
		buffer_line_display (ctx, buffer, line, false);
	else if (!ctx->isolate_buffers && can_leak)
		buffer_line_display (ctx, buffer, line, true);
	else
		displayed = false;

	// Advance the unread marker in active buffers but don't create a new one
	if (!displayed
	 || (buffer == ctx->current_buffer && buffer->new_messages_count))
	{
		buffer->new_messages_count++;
		if (flags & BUFFER_LINE_UNIMPORTANT)
			buffer->new_unimportant_count++;
		buffer->highlighted |= important;
	}
	if (!displayed)
		refresh_prompt (ctx);
}

static void
log_full (struct app_context *ctx, struct server *s, struct buffer *buffer,
	unsigned flags, enum buffer_line_rendition r, const char *format, ...)
{
	va_list ap;
	va_start (ap, format);

	struct formatter f = formatter_make (ctx, s);
	formatter_addv (&f, format, &ap);
	log_formatter (ctx, buffer, flags, r, &f);

	va_end (ap);
}

#define log_global(ctx, flags, r, ...)                                         \
	log_full ((ctx), NULL, (ctx)->global_buffer, (flags), (r), __VA_ARGS__)
#define log_server(s, buffer, flags, r, ...)                                   \
	log_full ((s)->ctx, (s), (buffer), (flags), (r), __VA_ARGS__)

#define log_global_status(ctx, ...)                                            \
	log_global ((ctx), 0, BUFFER_LINE_STATUS, __VA_ARGS__)
#define log_global_error(ctx, ...)                                             \
	log_global ((ctx), 0, BUFFER_LINE_ERROR,  __VA_ARGS__)
#define log_global_indent(ctx, ...)                                            \
	log_global ((ctx), 0, BUFFER_LINE_INDENT, __VA_ARGS__)

#define log_server_status(s, buffer, ...)                                      \
	log_server ((s), (buffer), 0, BUFFER_LINE_STATUS, __VA_ARGS__)
#define log_server_error(s, buffer, ...)                                       \
	log_server ((s), (buffer), 0, BUFFER_LINE_ERROR,  __VA_ARGS__)

#define log_global_debug(ctx, ...)                                             \
	BLOCK_START                                                                \
		if (g_debug_mode)                                                      \
			log_global ((ctx), 0, 0, "(*) " __VA_ARGS__);                      \
	BLOCK_END

#define log_server_debug(s, ...)                                               \
	BLOCK_START                                                                \
		if (g_debug_mode)                                                      \
			log_server ((s), (s)->buffer, 0, 0, "(*) " __VA_ARGS__);           \
	BLOCK_END

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Lines that are used in more than one place

#define log_nick_self(s, buffer, new_)                                         \
	log_server ((s), (buffer), BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_STATUS,    \
		"You are now known as #n", (new_))
#define log_nick(s, buffer, old, new_)                                         \
	log_server ((s), (buffer), BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_STATUS,    \
		"#n is now known as #n", (old), (new_))

#define log_chghost_self(s, buffer, new_)                                      \
	log_server ((s), (buffer), BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_STATUS,    \
		"You are now #N", (new_))
#define log_chghost(s, buffer, old, new_)                                      \
	log_server ((s), (buffer), BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_STATUS,    \
		"#N is now #N", (old), (new_))

#define log_outcoming_notice(s, buffer, who, text)                             \
	log_server_status ((s), (buffer), "#s(#n): #m", "Notice", (who), (text))
#define log_outcoming_privmsg(s, buffer, prefixes, who, text)                  \
	log_server ((s), (buffer), 0, 0, "<#s#n> #m", (prefixes), (who), (text))
#define log_outcoming_action(s, buffer, who, text)                             \
	log_server ((s), (buffer), 0, BUFFER_LINE_ACTION, "#n #m", (who), (text))

#define log_outcoming_orphan_notice(s, target, text)                           \
	log_server_status ((s), (s)->buffer, "Notice -> #n: #m", (target), (text))
#define log_outcoming_orphan_privmsg(s, target, text)                          \
	log_server ((s), (s)->buffer, 0, BUFFER_LINE_STATUS,                       \
		"MSG(#n): #m", (target), (text))
#define log_outcoming_orphan_action(s, target, text)                           \
	log_server ((s), (s)->buffer, 0, BUFFER_LINE_ACTION,                       \
		"MSG(#n): #m", (target), (text))

#define log_ctcp_query(s, target, tag)                                         \
	log_server_status ((s), (s)->buffer, "CTCP query to #S: #S", target, tag)
#define log_ctcp_reply(s, target, reply /* freed! */)                          \
	log_server_status ((s), (s)->buffer, "CTCP reply to #S: #&S", target, reply)

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
make_log_filename (const char *filename, struct str *output)
{
	for (const char *p = filename; *p; p++)
		// XXX: anything more to replace?
		if (strchr ("/\\ ", *p))
			str_append_c (output, '_');
		else
			str_append_c (output, tolower_ascii (*p));
}

static char *
buffer_get_log_path (struct buffer *buffer)
{
	struct str path = str_make ();
	get_xdg_home_dir (&path, "XDG_DATA_HOME", ".local/share");
	str_append_printf (&path, "/%s/%s", PROGRAM_NAME, "logs");

	(void) mkdir_with_parents (path.str, NULL);

	str_append_c (&path, '/');
	// FIXME: This mixes up character encodings.
	make_log_filename (buffer->name, &path);
	str_append (&path, ".log");
	return str_steal (&path);
}

static void
buffer_open_log_file (struct app_context *ctx, struct buffer *buffer)
{
	if (!ctx->logging || buffer->log_file)
		return;

	// TODO: should we try to reopen files wrt. case mapping?
	//  - Need to read the whole directory and look for matches:
	//    irc_server_strcmp(buffer->s, d_name, make_log_filename())
	//    remember to strip the ".log" suffix from d_name, case-sensitively.
	//  - The tolower_ascii() in make_log_filename() is a perfect overlap,
	//    it may stay as-is.
	//  - buffer_get_log_path() will need to return a FILE *,
	//    or an error that includes the below message.
	char *path = buffer_get_log_path (buffer);
	if (!(buffer->log_file = fopen (path, "ab")))
		log_global_error (ctx, "Couldn't open log file `#l': #l",
			path, strerror (errno));
	else
		set_cloexec (fileno (buffer->log_file));
	free (path);
}

static void
buffer_close_log_file (struct buffer *buffer)
{
	if (buffer->log_file)
		(void) fclose (buffer->log_file);
	buffer->log_file = NULL;
}

static void
on_config_logging_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	ctx->logging = item->value.boolean;

	for (struct buffer *buffer = ctx->buffers; buffer; buffer = buffer->next)
		if (ctx->logging)
			buffer_open_log_file (ctx, buffer);
		else
			buffer_close_log_file (buffer);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static struct buffer *
buffer_by_name (struct app_context *ctx, const char *name)
{
	return str_map_find (&ctx->buffers_by_name, name);
}

static void
buffer_add (struct app_context *ctx, struct buffer *buffer)
{
	hard_assert (!buffer_by_name (ctx, buffer->name));

	str_map_set (&ctx->buffers_by_name, buffer->name, buffer);
	LIST_APPEND_WITH_TAIL (ctx->buffers, ctx->buffers_tail, buffer);

	buffer_open_log_file (ctx, buffer);

	relay_prepare_buffer_update (ctx, buffer);
	relay_broadcast (ctx);

	// Normally this doesn't cause changes in the prompt but a prompt hook
	// could decide to show some information for all buffers nonetheless
	refresh_prompt (ctx);
}

static void
buffer_remove (struct app_context *ctx, struct buffer *buffer)
{
	hard_assert (buffer != ctx->current_buffer);
	hard_assert (buffer != ctx->global_buffer);

	CALL_ (ctx->input, buffer_destroy, buffer->input_data);
	buffer->input_data = NULL;

	// And make sure to unlink the buffer from "irc_buffer_map"
	struct server *s = buffer->server;
	if (buffer->channel)
		str_map_set (&s->irc_buffer_map, buffer->channel->name, NULL);
	if (buffer->user)
		str_map_set (&s->irc_buffer_map, buffer->user->nickname, NULL);

	if (buffer == ctx->last_buffer)
		ctx->last_buffer = NULL;
	if (buffer->type == BUFFER_SERVER)
		buffer->server->buffer = NULL;

	relay_prepare_buffer_remove (ctx, buffer);
	relay_broadcast (ctx);

	str_map_set (&ctx->buffers_by_name, buffer->name, NULL);
	LIST_UNLINK_WITH_TAIL (ctx->buffers, ctx->buffers_tail, buffer);
	buffer_unref (buffer);

	refresh_prompt (ctx);
}

static void
buffer_print_read_marker (struct app_context *ctx, FILE *stream, int flush_opts)
{
	struct formatter f = formatter_make (ctx, NULL);
	const int timestamp_width = 8;  // hardcoded to %T right now, simple
	const char *marker_char =
		get_config_string (ctx->config.root, "general.read_marker_char");

	// We could turn this off on FLUSH_OPT_NOWRAP, however our default pager
	// wraps lines for us even if we don't do it ourselves, and thus there's
	// no need to worry about inconsistency.
	if (*marker_char)
	{
		struct str s = str_make ();
		for (int i = 0; i < timestamp_width; i++)
			str_append (&s, marker_char);
		formatter_add (&f, "#a#s#r", ATTR_TIMESTAMP, s.str);
		str_reset (&s);
		for (int i = timestamp_width; i < g_terminal.columns; i++)
			str_append (&s, marker_char);
		formatter_add (&f, "#a#s#r\n", ATTR_READ_MARKER, s.str);
		str_free (&s);
	}
	else
		formatter_add (&f, "#a-- -- -- ---\n", ATTR_READ_MARKER);

	formatter_flush (&f, stream, flush_opts);
	// Flush the trailing formatting reset item
	fflush (stream);
	formatter_free (&f);
}

static void
buffer_print_backlog (struct app_context *ctx, struct buffer *buffer)
{
	// Buffers can be activated, or their lines modified, as automatic actions.
	if (ctx->terminal_suspended)
		return;

	// The prompt can take considerable time to redraw
	CALL (ctx->input, hide);

	// Simulate curses-like fullscreen buffers if the terminal allows it
	if (g_terminal.initialized && clear_screen)
	{
		terminal_printer_fn printer = get_attribute_printer (stdout);
		tputs (clear_screen, 1, printer);
		if (cursor_to_ll)
			tputs (cursor_to_ll, 1, printer);
		else if (row_address)
			tputs (tparm (row_address, g_terminal.lines - 1,
				0, 0, 0, 0, 0, 0, 0, 0), 1, printer);
		else if (cursor_address)
			tputs (tparm (cursor_address, g_terminal.lines - 1,
				0, 0, 0, 0, 0, 0, 0, 0), 1, printer);
		fflush (stdout);

		// We should update "last_displayed_msg_time" here just to be sure
		// that the first date marker, if necessary, is shown, but in practice
		// the value should always be from today when this function is called
	}
	else
	{
		char *buffer_name_localized =
			iconv_xstrdup (ctx->term_from_utf8, buffer->name, -1, NULL);
		print_status ("%s", buffer_name_localized);
		free (buffer_name_localized);
	}

	// That is, minus the readline prompt (taking at least one line)
	int display_limit = MAX (10, g_terminal.lines - 1);
	int to_display = 0;

	struct buffer_line *line;
	for (line = buffer->lines_tail; line; line = line->prev)
	{
		to_display++;
		if (buffer_line_will_show_up (buffer, line))
			display_limit--;
		if (!line->prev || display_limit <= 0)
			break;
	}

	// Once we've found where we want to start with the backlog, print it
	int until_marker = to_display - (int) buffer->new_messages_count;
	for (; line; line = line->next)
	{
		if (until_marker-- == 0
		 && buffer->new_messages_count != buffer->lines_count)
			buffer_print_read_marker (ctx, stdout, 0);
		buffer_line_display (ctx, buffer, line, 0);
	}

	// So that it is obvious if the last line in the buffer is not from today
	buffer_update_time (ctx, time (NULL), stdout, 0);

	refresh_prompt (ctx);
	CALL (ctx->input, show);
}

static void
buffer_activate (struct app_context *ctx, struct buffer *buffer)
{
	if (ctx->current_buffer == buffer)
		return;

	// This is the only place where the unread messages marker
	// and highlight indicator are reset
	if (ctx->current_buffer)
	{
		ctx->current_buffer->new_messages_count = 0;
		ctx->current_buffer->new_unimportant_count = 0;
		ctx->current_buffer->highlighted = false;
	}

	buffer_print_backlog (ctx, buffer);
	CALL_ (ctx->input, buffer_switch, buffer->input_data);

	// Now at last we can switch the pointers
	ctx->last_buffer = ctx->current_buffer;
	ctx->current_buffer = buffer;

	relay_prepare_buffer_activate (ctx, buffer);
	relay_broadcast (ctx);

	refresh_prompt (ctx);
}

static void
buffer_merge (struct app_context *ctx,
	struct buffer *buffer, struct buffer *merged)
{
	// XXX: anything better to do?  This situation is arguably rare and I'm
	//   not entirely sure what action to take.
	log_full (ctx, NULL, buffer, 0, BUFFER_LINE_STATUS,
		"Buffer #s was merged into this buffer", merged->name);

	// Find all lines from "merged" newer than the newest line in "buffer"
	struct buffer_line *start = merged->lines;
	if (buffer->lines_tail)
		while (start && start->when < buffer->lines_tail->when)
			start = start->next;
	if (!start)
		return;

	// Count how many of them we have
	size_t n = 0;
	for (struct buffer_line *iter = start; iter; iter = iter->next)
		n++;
	struct buffer_line *tail = merged->lines_tail;

	// Cut them from the original buffer
	if (start == merged->lines)
		merged->lines = NULL;
	else if (start->prev)
		start->prev->next = NULL;
	merged->lines_tail = start->prev;
	merged->lines_count -= n;

	// Append them to current lines in the buffer
	buffer->lines_tail->next = start;
	start->prev = buffer->lines_tail;
	buffer->lines_tail = tail;
	buffer->lines_count += n;

	// And since there is no log_*() call, send them to relays manually
	LIST_FOR_EACH (struct buffer_line, line, start)
	{
		relay_prepare_buffer_line (ctx, buffer, line);
		relay_broadcast (ctx);
	}

	log_full (ctx, NULL, buffer, BUFFER_LINE_SKIP_FILE, BUFFER_LINE_STATUS,
		"End of merged content");
}

static void
buffer_rename (struct app_context *ctx,
	struct buffer *buffer, const char *new_name)
{
	struct buffer *collision = str_map_find (&ctx->buffers_by_name, new_name);
	if (collision == buffer)
		return;

	hard_assert (!collision);

	relay_prepare_buffer_rename (ctx, buffer, new_name);
	relay_broadcast (ctx);

	str_map_set (&ctx->buffers_by_name, buffer->name, NULL);
	str_map_set (&ctx->buffers_by_name, new_name, buffer);

	cstr_set (&buffer->name, xstrdup (new_name));

	buffer_close_log_file (buffer);
	buffer_open_log_file (ctx, buffer);

	// We might have renamed the current buffer
	refresh_prompt (ctx);
}

static void
buffer_clear (struct app_context *ctx, struct buffer *buffer)
{
	LIST_FOR_EACH (struct buffer_line, iter, buffer->lines)
		buffer_line_destroy (iter);

	buffer->lines = buffer->lines_tail = NULL;
	buffer->lines_count = 0;

	relay_prepare_buffer_clear (ctx, buffer);
	relay_broadcast (ctx);
}

static struct buffer *
buffer_at_index (struct app_context *ctx, int n)
{
	int i = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
		if (++i == n)
			return iter;
	return NULL;
}

static struct buffer *
buffer_next (struct app_context *ctx, int count)
{
	struct buffer *new_buffer = ctx->current_buffer;
	while (count-- > 0)
		if (!(new_buffer = new_buffer->next))
			new_buffer = ctx->buffers;
	return new_buffer;
}

static struct buffer *
buffer_previous (struct app_context *ctx, int count)
{
	struct buffer *new_buffer = ctx->current_buffer;
	while (count-- > 0)
		if (!(new_buffer = new_buffer->prev))
			new_buffer = ctx->buffers_tail;
	return new_buffer;
}

static bool
buffer_goto (struct app_context *ctx, int n)
{
	struct buffer *buffer = buffer_at_index (ctx, n);
	if (!buffer)
		return false;

	buffer_activate (ctx, buffer);
	return true;
}

static int
buffer_count (struct app_context *ctx)
{
	int total = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
		total++;
	return total;
}

static void
buffer_move (struct app_context *ctx, struct buffer *buffer, int n)
{
	hard_assert (n >= 1 && n <= buffer_count (ctx));
	LIST_UNLINK_WITH_TAIL (ctx->buffers, ctx->buffers_tail, buffer);

	struct buffer *following = ctx->buffers;
	while (--n && following)
		following = following->next;

	LIST_INSERT_WITH_TAIL (ctx->buffers, ctx->buffers_tail, buffer, following);
	refresh_prompt (ctx);
}

static int
buffer_get_index (struct app_context *ctx, struct buffer *buffer)
{
	int index = 1;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
	{
		if (iter == buffer)
			return index;
		index++;
	}
	return -1;
}

static void
buffer_remove_safe (struct app_context *ctx, struct buffer *buffer)
{
	if (buffer == ctx->current_buffer)
		buffer_activate (ctx, ctx->last_buffer
			? ctx->last_buffer
			: buffer_next (ctx, 1));
	buffer_remove (ctx, buffer);
}

static void
init_global_buffer (struct app_context *ctx)
{
	struct buffer *global = ctx->global_buffer =
		buffer_new (ctx->input, BUFFER_GLOBAL, xstrdup (PROGRAM_NAME));

	buffer_add (ctx, global);
	buffer_activate (ctx, global);
}

// --- Users, channels ---------------------------------------------------------

static char *
irc_make_buffer_name (struct server *s, const char *target)
{
	if (!target)
		return xstrdup (s->name);

	char *target_utf8 = irc_to_utf8 (target);
	char *name = xstrdup_printf ("%s.%s", s->name, target_utf8);
	free (target_utf8);

	struct buffer *conflict = buffer_by_name (s->ctx, name);
	if (!conflict)
		return name;

	hard_assert (conflict->server == s);

	// Fix up any conflicts.  Note that while parentheses aren't allowed
	// in IRC nicknames, they may occur in channel names.
	int i = 0;
	char *unique = xstrdup_printf ("%s(%d)", name, ++i);
	while (buffer_by_name (s->ctx, unique))
		cstr_set (&unique, xstrdup_printf ("%s(%d)", name, ++i));
	free (name);
	return unique;
}

static void
irc_user_on_destroy (void *object, void *user_data)
{
	struct user *user = object;
	struct server *s = user_data;
	if (!s->rehashing)
		str_map_set (&s->irc_users, user->nickname, NULL);
}

static struct user *
irc_make_user (struct server *s, char *nickname)
{
	hard_assert (!str_map_find (&s->irc_users, nickname));

	struct user *user = user_new (nickname);
	(void) user_weak_ref (user, irc_user_on_destroy, s);
	str_map_set (&s->irc_users, user->nickname, user);
	return user;
}

struct user *
irc_get_or_make_user (struct server *s, const char *nickname)
{
	struct user *user = str_map_find (&s->irc_users, nickname);
	if (user)
		return user_ref (user);
	return irc_make_user (s, xstrdup (nickname));
}

static struct buffer *
irc_get_or_make_user_buffer (struct server *s, const char *nickname)
{
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, nickname);
	if (buffer)
		return buffer;

	struct user *user = irc_get_or_make_user (s, nickname);

	// Open a new buffer for the user
	buffer = buffer_new (s->ctx->input,
		BUFFER_PM, irc_make_buffer_name (s, nickname));
	buffer->server = s;
	buffer->user = user;
	str_map_set (&s->irc_buffer_map, user->nickname, buffer);

	buffer_add (s->ctx, buffer);
	return buffer;
}

static void
irc_get_channel_user_prefix (struct server *s,
	struct channel_user *channel_user, struct str *output)
{
	if (s->ctx->show_all_prefixes)
		str_append (output, channel_user->prefixes);
	else if (channel_user->prefixes[0])
		str_append_c (output, channel_user->prefixes[0]);
}

static bool
irc_channel_is_joined (struct channel *channel)
{
	// TODO: find a better way of checking if we're on a channel
	return !!channel->users_len;
}

// Note that this eats the user reference
static void
irc_channel_link_user (struct channel *channel, struct user *user,
	const char *prefixes)
{
	struct user_channel *user_channel = user_channel_new (channel);
	LIST_PREPEND (user->channels, user_channel);

	struct channel_user *channel_user = channel_user_new (user, prefixes);
	LIST_PREPEND (channel->users, channel_user);
	channel->users_len++;
}

static void
irc_channel_unlink_user
	(struct channel *channel, struct channel_user *channel_user)
{
	// First destroy the user's weak references to the channel
	struct user *user = channel_user->user;
	LIST_FOR_EACH (struct user_channel, iter, user->channels)
		if (iter->channel == channel)
		{
			LIST_UNLINK (user->channels, iter);
			user_channel_destroy (iter);
		}

	// TODO: poll the away status for users we don't share a channel with.
	//   It might or might not be worth to auto-set this on with RPL_AWAY.
	if (!user->channels && user != channel->s->irc_user)
		user->away = false;

	// Then just unlink the user from the channel
	LIST_UNLINK (channel->users, channel_user);
	channel_user_destroy (channel_user);
	channel->users_len--;
}

static void
irc_channel_on_destroy (void *object, void *user_data)
{
	struct channel *channel = object;
	struct server *s = user_data;
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
		irc_channel_unlink_user (channel, iter);
	if (!s->rehashing)
		str_map_set (&s->irc_channels, channel->name, NULL);
}

static struct channel *
irc_make_channel (struct server *s, char *name)
{
	hard_assert (!str_map_find (&s->irc_channels, name));

	struct channel *channel = channel_new (s, name);
	(void) channel_weak_ref (channel, irc_channel_on_destroy, s);
	str_map_set (&s->irc_channels, channel->name, channel);
	return channel;
}

static struct channel_user *
irc_channel_get_user (struct channel *channel, struct user *user)
{
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
		if (iter->user == user)
			return iter;
	return NULL;
}

static void
irc_remove_user_from_channel (struct user *user, struct channel *channel)
{
	struct channel_user *channel_user = irc_channel_get_user (channel, user);
	if (channel_user)
		irc_channel_unlink_user (channel, channel_user);
}

static void
irc_left_channel (struct channel *channel)
{
	strv_reset (&channel->names_buf);
	channel->show_names_after_who = false;

	LIST_FOR_EACH (struct channel_user, iter, channel->users)
		irc_channel_unlink_user (channel, iter);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
remove_conflicting_buffer (struct server *s, struct buffer *buffer)
{
	log_server_status (s, s->buffer,
		"Removed buffer #s because of casemapping conflict", buffer->name);
	if (s->ctx->current_buffer == buffer)
		buffer_activate (s->ctx, s->buffer);
	buffer_remove (s->ctx, buffer);
}

static void
irc_try_readd_user (struct server *s,
	struct user *user, struct buffer *buffer)
{
	if (str_map_find (&s->irc_users, user->nickname))
	{
		// Remove user from all channels and destroy any PM buffer
		user_ref (user);
		LIST_FOR_EACH (struct user_channel, iter, user->channels)
			irc_remove_user_from_channel (user, iter->channel);
		if (buffer)
			remove_conflicting_buffer (s, buffer);
		user_unref (user);
	}
	else
	{
		str_map_set (&s->irc_users, user->nickname, user);
		str_map_set (&s->irc_buffer_map, user->nickname, buffer);
	}
}

static void
irc_try_readd_channel (struct channel *channel, struct buffer *buffer)
{
	struct server *s = channel->s;
	if (str_map_find (&s->irc_channels, channel->name))
	{
		// Remove all users from channel and destroy any channel buffer
		channel_ref (channel);
		LIST_FOR_EACH (struct channel_user, iter, channel->users)
			irc_channel_unlink_user (channel, iter);
		if (buffer)
			remove_conflicting_buffer (s, buffer);
		channel_unref (channel);
	}
	else
	{
		str_map_set (&s->irc_channels, channel->name, channel);
		str_map_set (&s->irc_buffer_map, channel->name, buffer);
	}
}

static void
irc_rehash_and_fix_conflicts (struct server *s)
{
	// Save the old maps and initialize new ones
	struct str_map old_users      = s->irc_users;
	struct str_map old_channels   = s->irc_channels;
	struct str_map old_buffer_map = s->irc_buffer_map;

	s->irc_users      = str_map_make (NULL);
	s->irc_channels   = str_map_make (NULL);
	s->irc_buffer_map = str_map_make (NULL);

	s->irc_users     .key_xfrm = s->irc_strxfrm;
	s->irc_channels  .key_xfrm = s->irc_strxfrm;
	s->irc_buffer_map.key_xfrm = s->irc_strxfrm;

	// Prevent channels and users from unsetting themselves
	// from server maps upon removing the last reference to them
	s->rehashing = true;

	// XXX: to be perfectly sure, we should also check
	//   whether any users collide with channels and vice versa

	// Our own user always takes priority, add him first
	if (s->irc_user)
		irc_try_readd_user (s, s->irc_user,
			str_map_find (&old_buffer_map, s->irc_user->nickname));

	struct str_map_iter iter;
	struct user *user;
	struct channel *channel;

	iter = str_map_iter_make (&old_users);
	while ((user = str_map_iter_next (&iter)))
		irc_try_readd_user (s, user,
			str_map_find (&old_buffer_map, user->nickname));

	iter = str_map_iter_make (&old_channels);
	while ((channel = str_map_iter_next (&iter)))
		irc_try_readd_channel (channel,
			str_map_find (&old_buffer_map, channel->name));

	// Hopefully we've either moved or destroyed all the old content
	s->rehashing = false;

	str_map_free (&old_users);
	str_map_free (&old_channels);
	str_map_free (&old_buffer_map);
}

static void
irc_set_casemapping (struct server *s,
	irc_tolower_fn tolower, irc_strxfrm_fn strxfrm)
{
	if (tolower == s->irc_tolower
	 && strxfrm == s->irc_strxfrm)
		return;

	s->irc_tolower = tolower;
	s->irc_strxfrm = strxfrm;

	// Ideally we would never have to do this but I can't think of a workaround
	irc_rehash_and_fix_conflicts (s);
}

// --- Core functionality ------------------------------------------------------

static bool
irc_is_connected (struct server *s)
{
	return s->state != IRC_DISCONNECTED && s->state != IRC_CONNECTING;
}

static void
irc_update_poller (struct server *s, const struct pollfd *pfd)
{
	int new_events = s->transport->get_poll_events (s);
	hard_assert (new_events != 0);

	if (!pfd || pfd->events != new_events)
		poller_fd_set (&s->socket_event, new_events);
}

static void
irc_cancel_timers (struct server *s)
{
	poller_timer_reset (&s->timeout_tmr);
	poller_timer_reset (&s->ping_tmr);
	poller_timer_reset (&s->reconnect_tmr);
	poller_timer_reset (&s->autojoin_tmr);
}

static void
irc_reset_connection_timeouts (struct server *s)
{
	poller_timer_set (&s->timeout_tmr, 3 * 60 * 1000);
	poller_timer_set (&s->ping_tmr, (3 * 60 + 30) * 1000);
	poller_timer_reset (&s->reconnect_tmr);
}

static int64_t
irc_get_reconnect_delay (struct server *s)
{
	int64_t delay = get_config_integer (s->config, "reconnect_delay");
	int64_t delay_factor = get_config_integer
		(s->ctx->config.root, "general.reconnect_delay_growing");
	for (unsigned i = 0; i < s->reconnect_attempt; i++)
	{
		if (delay_factor && delay > INT64_MAX / delay_factor)
			break;
		delay *= delay_factor;
	}

	int64_t delay_max =
		get_config_integer (s->ctx->config.root, "general.reconnect_delay_max");
	return MIN (delay, delay_max);
}

static void
irc_queue_reconnect (struct server *s)
{
	// As long as the user wants us to, that is
	if (!get_config_boolean (s->config, "reconnect"))
		return;

	// XXX: maybe add a state for when a connect is queued?
	hard_assert (s->state == IRC_DISCONNECTED);

	int64_t delay = irc_get_reconnect_delay (s);
	s->reconnect_attempt++;

	log_server_status (s, s->buffer,
		"Trying to reconnect in #&s seconds...",
		xstrdup_printf ("%" PRId64, delay));
	poller_timer_set (&s->reconnect_tmr, delay * 1000);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void irc_process_sent_message
	(const struct irc_message *msg, struct server *s);
static void irc_send (struct server *s,
	const char *format, ...) ATTRIBUTE_PRINTF (2, 3);

static void
irc_send (struct server *s, const char *format, ...)
{
	if (!soft_assert (irc_is_connected (s)))
	{
		log_server_debug (s, "sending a message to a dead server connection");
		return;
	}

	if (s->state == IRC_CLOSING
	 || s->state == IRC_HALF_CLOSED)
		return;

	va_list ap;
	va_start (ap, format);
	struct str str = str_make ();
	str_append_vprintf (&str, format, ap);
	va_end (ap);

	log_server_debug (s, "#a<< \"#S\"#r", ATTR_PART, str.str);

	struct irc_message msg;
	irc_parse_message (&msg, str.str);
	irc_process_sent_message (&msg, s);
	irc_free_message (&msg);

	str_append_str (&s->write_buffer, &str);
	str_free (&str);
	str_append (&s->write_buffer, "\r\n");
	irc_update_poller (s, NULL);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_real_shutdown (struct server *s)
{
	hard_assert (irc_is_connected (s) && s->state != IRC_HALF_CLOSED);

	if (s->transport
	 && s->transport->in_before_shutdown)
		s->transport->in_before_shutdown (s);

	while (shutdown (s->socket, SHUT_WR) == -1)
		// XXX: we get ENOTCONN with OpenSSL (not plain) when a localhost
		// server is aborted, why?  strace says read 0, write 31, shutdown -1.
		if (!soft_assert (errno == EINTR))
			break;

	s->state = IRC_HALF_CLOSED;
}

static void
irc_shutdown (struct server *s)
{
	if (s->state == IRC_CLOSING
	 || s->state == IRC_HALF_CLOSED)
		return;

	// TODO: set a timer to cut the connection if we don't receive an EOF
	s->state = IRC_CLOSING;

	// Either there's still some data in the write buffer and we wait
	// until they're sent, or we send an EOF to the server right away
	if (!s->write_buffer.len)
		irc_real_shutdown (s);
}

static void
irc_destroy_connector (struct server *s)
{
	if (s->connector)
		connector_free (s->connector);
	free (s->connector);
	s->connector = NULL;

	if (s->socks_conn)
		socks_connector_free (s->socks_conn);
	free (s->socks_conn);
	s->socks_conn = NULL;

	// Not connecting anymore
	s->state = IRC_DISCONNECTED;
}

static void
try_finish_quit (struct app_context *ctx)
{
	if (!ctx->quitting)
		return;

	bool disconnected_all = true;
	struct str_map_iter iter = str_map_iter_make (&ctx->servers);
	struct server *s;
	while ((s = str_map_iter_next (&iter)))
		if (irc_is_connected (s))
			disconnected_all = false;

	if (disconnected_all)
		ctx->polling = false;
}

static void
irc_destroy_transport (struct server *s)
{
	if (s->transport
	 && s->transport->cleanup)
		s->transport->cleanup (s);
	s->transport = NULL;

	poller_fd_reset (&s->socket_event);
	xclose (s->socket);
	s->socket = -1;
	s->state = IRC_DISCONNECTED;

	str_reset (&s->read_buffer);
	str_reset (&s->write_buffer);
}

static void
irc_destroy_state (struct server *s)
{
	struct str_map_iter iter = str_map_iter_make (&s->irc_channels);
	struct channel *channel;
	while ((channel = str_map_iter_next (&iter)))
		irc_left_channel (channel);

	if (s->irc_user)
	{
		user_unref (s->irc_user);
		s->irc_user = NULL;
	}

	str_reset (&s->irc_user_mode);
	cstr_set (&s->irc_user_host, NULL);

	strv_reset (&s->cap_ls_buf);
	s->cap_away_notify = false;
	s->cap_echo_message = false;
	s->cap_sasl = false;

	// Need to call this before server_init_specifics()
	irc_set_casemapping (s, irc_tolower, irc_strxfrm);

	server_free_specifics (s);
	server_init_specifics (s);
}

static void
irc_disconnect (struct server *s)
{
	hard_assert (irc_is_connected (s));

	struct str_map_iter iter = str_map_iter_make (&s->irc_buffer_map);
	struct buffer *buffer;
	while ((buffer = str_map_iter_next (&iter)))
		log_server (s, buffer, BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_STATUS,
			"Disconnected from server");

	irc_cancel_timers (s);
	irc_destroy_transport (s);
	irc_destroy_state (s);

	// Take any relevant actions
	if (s->ctx->quitting)
		try_finish_quit (s->ctx);
	else if (s->manual_disconnect)
		s->manual_disconnect = false;
	else
	{
		s->reconnect_attempt = 0;
		irc_queue_reconnect (s);
	}

	refresh_prompt (s->ctx);
}

static void
irc_initiate_disconnect (struct server *s, const char *reason)
{
	hard_assert (irc_is_connected (s));

	// It can take a very long time for sending QUIT to take effect
	if (s->manual_disconnect)
	{
		log_server_error (s, s->buffer, "#s: #s", "Disconnected from server",
			"connection torn down early per user request");
		irc_disconnect (s);
		return;
	}

	if (reason)
		irc_send (s, "QUIT :%s", reason);
	else
		// TODO: make the default QUIT message customizable
		//   -> global/per server/both?
		//   -> implement it with an output hook in a plugin?
		irc_send (s, "QUIT :%s", PROGRAM_NAME " " PROGRAM_VERSION);

	s->manual_disconnect = true;
	irc_shutdown (s);
}

static void
request_quit (struct app_context *ctx, const char *message)
{
	if (!ctx->quitting)
	{
		log_global_status (ctx, "Shutting down");
		ctx->quitting = true;

		// Disable the user interface
		CALL (ctx->input, hide);
	}

	struct str_map_iter iter = str_map_iter_make (&ctx->servers);
	struct server *s;
	while ((s = str_map_iter_next (&iter)))
	{
		// There may be a timer set to reconnect to the server
		poller_timer_reset (&s->reconnect_tmr);

		if (irc_is_connected (s))
			irc_initiate_disconnect (s, message);
		else if (s->state == IRC_CONNECTING)
			irc_destroy_connector (s);
	}

	try_finish_quit (ctx);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
on_irc_ping_timeout (void *user_data)
{
	struct server *s = user_data;
	log_server_error (s, s->buffer,
		"#s: #s", "Disconnected from server", "timeout");
	irc_disconnect (s);
}

static void
on_irc_timeout (void *user_data)
{
	// Provoke a response from the server
	struct server *s = user_data;
	irc_send (s, "PING :%" PRIi64, (int64_t) time (NULL));
}

static void
on_irc_autojoin_timeout (void *user_data)
{
	struct server *s = user_data;

	// Since we may not have information from RPL_ISUPPORT yet,
	// it's our safest bet to send the channels one at a time

	struct str_map joins_sent = str_map_make (NULL);

	// We don't know the casemapping yet either, however ASCII should do
	joins_sent.key_xfrm = tolower_ascii_strxfrm;

	// First join autojoin channels in their given order
	const char *autojoin = get_config_string (s->config, "autojoin");
	if (autojoin)
	{
		struct strv v = strv_make ();
		cstr_split (autojoin, ",", true, &v);
		for (size_t i = 0; i < v.len; i++)
		{
			irc_send (s, "JOIN %s", v.vector[i]);
			str_map_set (&joins_sent, v.vector[i], (void *) 1);
		}
		strv_free (&v);
	}

	// Then also rejoin any channels from the last disconnect
	struct str_map_iter iter = str_map_iter_make (&s->irc_channels);
	struct channel *channel;
	while ((channel = str_map_iter_next (&iter)))
	{
		struct str target = str_make ();
		str_append (&target, channel->name);

		const char *key;
		if ((key = str_map_find (&channel->param_modes, "k")))
			str_append_printf (&target, " %s", key);

		// When a channel is both autojoined and rejoined, both keys are tried
		if (!channel->left_manually
		 && !str_map_find (&joins_sent, target.str))
			irc_send (s, "JOIN %s", target.str);
		str_free (&target);
	}

	str_map_free (&joins_sent);
}

// --- Server I/O --------------------------------------------------------------

static char *
irc_process_hooks (struct server *s, char *input)
{
	log_server_debug (s, "#a>> \"#S\"#r", ATTR_JOIN, input);
	uint64_t hash = siphash_wrapper (input, strlen (input));
	LIST_FOR_EACH (struct hook, iter, s->ctx->irc_hooks)
	{
		struct irc_hook *hook = (struct irc_hook *) iter;
		if (!(input = hook->filter (hook, s, input)))
		{
			log_server_debug (s, "#a>= #s#r", ATTR_JOIN, "thrown away by hook");
			return NULL;
		}

		// The old input may get freed, so we compare against a hash of it
		uint64_t new_hash = siphash_wrapper (input, strlen (input));
		if (new_hash != hash)
			log_server_debug (s, "#a>= \"#S\"#r", ATTR_JOIN, input);
		hash = new_hash;
	}
	return input;
}

static void irc_process_message
	(const struct irc_message *msg, struct server *s);

static void
irc_process_buffer_custom (struct server *s, struct str *buf)
{
	const char *start = buf->str, *end = start + buf->len;
	for (const char *p = start; p + 1 < end; p++)
	{
		// Split the input on newlines
		if (p[0] != '\r' || p[1] != '\n')
			continue;

		char *processed = irc_process_hooks (s, xstrndup (start, p - start));
		start = p + 2;
		if (!processed)
			continue;

		struct irc_message msg;
		irc_parse_message (&msg, processed);
		irc_process_message (&msg, s);
		irc_free_message (&msg);

		free (processed);
	}
	str_remove_slice (buf, 0, start - buf->str);
}

static enum socket_io_result
irc_try_read (struct server *s)
{
	enum socket_io_result result = s->transport->try_read (s);
	if (s->read_buffer.len >= (1 << 20))
	{
		// XXX: this is stupid; if anything, count it in dependence of time;
		//   we could make transport_tls_try_read() limit the immediate amount
		//   of data read like socket_io_try_read() does and remove this check
		log_server_error (s, s->buffer,
			"The IRC server seems to spew out data frantically");
		return SOCKET_IO_ERROR;
	}
	if (s->read_buffer.len)
		irc_process_buffer_custom (s, &s->read_buffer);
	return result;
}

static enum socket_io_result
irc_try_write (struct server *s)
{
	enum socket_io_result result = s->transport->try_write (s);
	if (result == SOCKET_IO_OK)
	{
		// If we're flushing the write buffer and our job is complete, we send
		// an EOF to the server, changing the state to IRC_HALF_CLOSED
		if (s->state == IRC_CLOSING && !s->write_buffer.len)
			irc_real_shutdown (s);
	}
	return result;
}

static bool
irc_try_read_write (struct server *s)
{
	enum socket_io_result read_result;
	enum socket_io_result write_result;
	if ((read_result  = irc_try_read  (s)) == SOCKET_IO_ERROR
	 || (write_result = irc_try_write (s)) == SOCKET_IO_ERROR)
	{
		log_server_error (s, s->buffer, "Server connection failed");
		return false;
	}

	// FIXME: this may probably fire multiple times when we're flushing,
	//   we should probably store a flag next to the state
	if (read_result  == SOCKET_IO_EOF
	 || write_result == SOCKET_IO_EOF)
		log_server_error (s, s->buffer, "Server closed the connection");

	// If the write needs to read and we receive an EOF, we can't flush
	if (write_result == SOCKET_IO_EOF)
		return false;

	if (read_result  == SOCKET_IO_EOF)
	{
		// Eventually initiate shutdown to flush the write buffer
		irc_shutdown (s);

		// If there's nothing to write, we can disconnect now
		if (s->state == IRC_HALF_CLOSED)
			return false;
	}
	return true;
}

static void
on_irc_ready (const struct pollfd *pfd, struct server *s)
{
	if (irc_try_read_write (s))
	{
		// XXX: shouldn't we rather wait for PONG messages?
		irc_reset_connection_timeouts (s);
		irc_update_poller (s, pfd);
	}
	else
		// We don't want to keep the socket anymore
		irc_disconnect (s);
}

// --- Plain transport ---------------------------------------------------------

static enum socket_io_result
transport_plain_try_read (struct server *s)
{
	enum socket_io_result result =
		socket_io_try_read (s->socket, &s->read_buffer);
	if (result == SOCKET_IO_ERROR)
		print_debug ("%s: %s", __func__, strerror (errno));
	return result;
}

static enum socket_io_result
transport_plain_try_write (struct server *s)
{
	enum socket_io_result result =
		socket_io_try_write (s->socket, &s->write_buffer);
	if (result == SOCKET_IO_ERROR)
		print_debug ("%s: %s", __func__, strerror (errno));
	return result;
}

static int
transport_plain_get_poll_events (struct server *s)
{
	int events = POLLIN;
	if (s->write_buffer.len)
		events |= POLLOUT;
	return events;
}

static struct transport g_transport_plain =
{
	.try_read         = transport_plain_try_read,
	.try_write        = transport_plain_try_write,
	.get_poll_events  = transport_plain_get_poll_events,
};

// --- TLS transport -----------------------------------------------------------

struct transport_tls_data
{
	SSL_CTX *ssl_ctx;                   ///< SSL context
	SSL *ssl;                           ///< SSL connection
	bool ssl_rx_want_tx;                ///< SSL_read() wants to write
	bool ssl_tx_want_rx;                ///< SSL_write() wants to read
};

/// The index in SSL_CTX user data for a reference to the server
static int g_transport_tls_data_index = -1;

static int
transport_tls_verify_callback (int preverify_ok, X509_STORE_CTX *ctx)
{
	SSL *ssl = X509_STORE_CTX_get_ex_data
		(ctx, SSL_get_ex_data_X509_STORE_CTX_idx ());
	struct server *s = SSL_CTX_get_ex_data
		(SSL_get_SSL_CTX (ssl), g_transport_tls_data_index);

	X509 *cert = X509_STORE_CTX_get_current_cert (ctx);
	char *subject = X509_NAME_oneline (X509_get_subject_name (cert), NULL, 0);
	char *issuer  = X509_NAME_oneline (X509_get_issuer_name  (cert), NULL, 0);

	log_server_status (s, s->buffer, "Certificate subject: #s", subject);
	log_server_status (s, s->buffer, "Certificate issuer: #s", issuer);

	if (!preverify_ok)
	{
		log_server_error (s, s->buffer,
			"Certificate verification failed: #s",
			X509_verify_cert_error_string (X509_STORE_CTX_get_error (ctx)));
	}

	free (subject);
	free (issuer);
	return preverify_ok;
}

static bool
transport_tls_init_ca_set (SSL_CTX *ssl_ctx, const char *file, const char *path,
	struct error **e)
{
	ERR_clear_error ();

	if (file || path)
	{
		if (SSL_CTX_load_verify_locations (ssl_ctx, file, path))
			return true;

		return error_set (e, "%s: %s",
			"Failed to set locations for the CA certificate bundle",
			xerr_describe_error ());
	}

	if (!SSL_CTX_set_default_verify_paths (ssl_ctx))
		return error_set (e, "%s: %s",
			"Couldn't load the default CA certificate bundle",
			xerr_describe_error ());
	return true;
}

static bool
transport_tls_init_ca (struct server *s, SSL_CTX *ssl_ctx, struct error **e)
{
	const char *ca_file = get_config_string (s->config, "tls_ca_file");
	const char *ca_path = get_config_string (s->config, "tls_ca_path");

	char *full_ca_file = ca_file
		? resolve_filename (ca_file, resolve_relative_config_filename) : NULL;
	char *full_ca_path = ca_path
		? resolve_filename (ca_path, resolve_relative_config_filename) : NULL;

	bool ok = false;
	if      (ca_file && !full_ca_file)
		error_set (e, "Couldn't find the CA bundle file");
	else if (ca_path && !full_ca_path)
		error_set (e, "Couldn't find the CA bundle path");
	else
		ok = transport_tls_init_ca_set (ssl_ctx, full_ca_file, full_ca_path, e);

	free (full_ca_file);
	free (full_ca_path);
	return ok;
}

static bool
transport_tls_init_ctx (struct server *s, SSL_CTX *ssl_ctx, struct error **e)
{
	bool verify = get_config_boolean (s->config, "tls_verify");
	SSL_CTX_set_verify (ssl_ctx, verify ? SSL_VERIFY_PEER : SSL_VERIFY_NONE,
		transport_tls_verify_callback);

	if (g_transport_tls_data_index == -1)
		g_transport_tls_data_index =
			SSL_CTX_get_ex_new_index (0, "server", NULL, NULL, NULL);
	SSL_CTX_set_ex_data (ssl_ctx, g_transport_tls_data_index, s);

	const char *ciphers = get_config_string (s->config, "tls_ciphers");
	if (ciphers && !SSL_CTX_set_cipher_list (ssl_ctx, ciphers))
		log_server_error (s, s->buffer,
			"Failed to select any cipher from the cipher list");
	SSL_CTX_set_mode (ssl_ctx,
		SSL_MODE_ENABLE_PARTIAL_WRITE | SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);

	// Disable deprecated protocols (see RFC 7568)
	SSL_CTX_set_options (ssl_ctx, SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);

	// This seems to consume considerable amounts of memory while not giving
	// that much in return; in addition to that, I'm not sure about security
	// (see RFC 7525, section 3.3)
#ifdef SSL_OP_NO_COMPRESSION
	SSL_CTX_set_options (ssl_ctx, SSL_OP_NO_COMPRESSION);
#endif // SSL_OP_NO_COMPRESSION
#ifdef LOMEM
	SSL_CTX_set_mode (ssl_ctx, SSL_MODE_RELEASE_BUFFERS);
#endif // LOMEM

	struct error *error = NULL;
	if (!transport_tls_init_ca (s, ssl_ctx, &error))
	{
		if (verify)
		{
			error_propagate (e, error);
			return false;
		}

		// Just inform the user if we're not actually verifying
		log_server_error (s, s->buffer, "#s", error->message);
		error_free (error);
	}
	return true;
}

static bool
transport_tls_init_cert (struct server *s, SSL *ssl, struct error **e)
{
	const char *tls_cert = get_config_string (s->config, "tls_cert");
	if (!tls_cert)
		return true;

	ERR_clear_error ();

	bool result = false;
	char *path = resolve_filename (tls_cert, resolve_relative_config_filename);
	if (!path)
		error_set (e, "%s: %s", "Cannot open file", tls_cert);
	// XXX: perhaps we should read the file ourselves for better messages
	else if (!SSL_use_certificate_file (ssl, path, SSL_FILETYPE_PEM)
		|| !SSL_use_PrivateKey_file (ssl, path, SSL_FILETYPE_PEM))
		error_set (e, "%s: %s", "Setting the TLS client certificate failed",
			xerr_describe_error ());
	else
		result = true;
	free (path);
	return result;
}

static bool
transport_tls_init (struct server *s, const char *hostname, struct error **e)
{
	ERR_clear_error ();

	struct error *error = NULL;
	SSL_CTX *ssl_ctx = SSL_CTX_new (SSLv23_client_method ());
	if (!ssl_ctx)
		goto error_ssl_1;
	if (!transport_tls_init_ctx (s, ssl_ctx, &error))
		goto error_ssl_2;

	SSL *ssl = SSL_new (ssl_ctx);
	if (!ssl)
		goto error_ssl_2;

	if (!transport_tls_init_cert (s, ssl, &error))
	{
		// XXX: is this a reason to abort the connection?
		log_server_error (s, s->buffer, "#s", error->message);
		error_free (error);
		error = NULL;
	}

	SSL_set_connect_state (ssl);
	if (!SSL_set_fd (ssl, s->socket))
		goto error_ssl_3;

	// Enable SNI, FWIW; literal IP addresses aren't allowed
	struct in6_addr dummy;
	if (!inet_pton (AF_INET,  hostname, &dummy)
	 && !inet_pton (AF_INET6, hostname, &dummy))
		SSL_set_tlsext_host_name (ssl, hostname);

	struct transport_tls_data *data = xcalloc (1, sizeof *data);
	data->ssl_ctx = ssl_ctx;
	data->ssl = ssl;

	// Forces a handshake even if neither side wants to transmit data
	data->ssl_rx_want_tx = true;

	s->transport_data = data;
	return true;

error_ssl_3:
	SSL_free (ssl);
error_ssl_2:
	SSL_CTX_free (ssl_ctx);
error_ssl_1:
	if (!error)
		error_set (&error, "%s: %s", "Could not initialize TLS",
			xerr_describe_error ());

	error_propagate (e, error);
	return false;
}

static void
transport_tls_cleanup (struct server *s)
{
	struct transport_tls_data *data = s->transport_data;
	if (data->ssl)
		SSL_free (data->ssl);
	if (data->ssl_ctx)
		SSL_CTX_free (data->ssl_ctx);
	free (data);
}

static enum socket_io_result
transport_tls_try_read (struct server *s)
{
	struct transport_tls_data *data = s->transport_data;
	if (data->ssl_tx_want_rx)
		return SOCKET_IO_OK;

	struct str *buf = &s->read_buffer;
	data->ssl_rx_want_tx = false;
	while (true)
	{
		ERR_clear_error ();
		str_reserve (buf, 512);
		int n_read = SSL_read (data->ssl, buf->str + buf->len,
			buf->alloc - buf->len - 1 /* null byte */);

		const char *error_info = NULL;
		switch (xssl_get_error (data->ssl, n_read, &error_info))
		{
		case SSL_ERROR_NONE:
			buf->str[buf->len += n_read] = '\0';
			continue;
		case SSL_ERROR_ZERO_RETURN:
			return SOCKET_IO_EOF;
		case SSL_ERROR_WANT_READ:
			return SOCKET_IO_OK;
		case SSL_ERROR_WANT_WRITE:
			data->ssl_rx_want_tx = true;
			return SOCKET_IO_OK;
		case XSSL_ERROR_TRY_AGAIN:
			continue;
		default:
			LOG_FUNC_FAILURE ("SSL_read", error_info);
			return SOCKET_IO_ERROR;
		}
	}
}

static enum socket_io_result
transport_tls_try_write (struct server *s)
{
	struct transport_tls_data *data = s->transport_data;
	if (data->ssl_rx_want_tx)
		return SOCKET_IO_OK;

	struct str *buf = &s->write_buffer;
	data->ssl_tx_want_rx = false;
	while (buf->len)
	{
		ERR_clear_error ();
		int n_written = SSL_write (data->ssl, buf->str, buf->len);

		const char *error_info = NULL;
		switch (xssl_get_error (data->ssl, n_written, &error_info))
		{
		case SSL_ERROR_NONE:
			str_remove_slice (buf, 0, n_written);
			continue;
		case SSL_ERROR_ZERO_RETURN:
			return SOCKET_IO_EOF;
		case SSL_ERROR_WANT_WRITE:
			return SOCKET_IO_OK;
		case SSL_ERROR_WANT_READ:
			data->ssl_tx_want_rx = true;
			return SOCKET_IO_OK;
		case XSSL_ERROR_TRY_AGAIN:
			continue;
		default:
			LOG_FUNC_FAILURE ("SSL_write", error_info);
			return SOCKET_IO_ERROR;
		}
	}
	return SOCKET_IO_OK;
}

static int
transport_tls_get_poll_events (struct server *s)
{
	struct transport_tls_data *data = s->transport_data;

	int events = POLLIN;
	if (s->write_buffer.len || data->ssl_rx_want_tx)
		events |= POLLOUT;

	// While we're waiting for an opposite event, we ignore the original
	if (data->ssl_rx_want_tx)  events &= ~POLLIN;
	if (data->ssl_tx_want_rx)  events &= ~POLLOUT;
	return events;
}

static void
transport_tls_in_before_shutdown (struct server *s)
{
	struct transport_tls_data *data = s->transport_data;
	(void) SSL_shutdown (data->ssl);
}

static struct transport g_transport_tls =
{
	.init               = transport_tls_init,
	.cleanup            = transport_tls_cleanup,
	.try_read           = transport_tls_try_read,
	.try_write          = transport_tls_try_write,
	.get_poll_events    = transport_tls_get_poll_events,
	.in_before_shutdown = transport_tls_in_before_shutdown,
};

// --- Connection establishment ------------------------------------------------

static bool
irc_autofill_user_info (struct server *s, struct error **e)
{
	const char *nicks    = get_config_string (s->config, "nicks");
	const char *username = get_config_string (s->config, "username");
	const char *realname = get_config_string (s->config, "realname");

	if (nicks && *nicks && username && *username && realname)
		return true;

	// Read POSIX user info and fill the configuration if needed
	errno = 0;
	struct passwd *pwd = getpwuid (geteuid ());
	if (!pwd)
	{
		return error_set (e,
			"cannot retrieve user information: %s", strerror (errno));
	}

	// FIXME: set_config_strings() writes errors on its own
	if (!nicks    || !*nicks)
		set_config_string (s->config, "nicks",    pwd->pw_name);
	if (!username || !*username)
		set_config_string (s->config, "username", pwd->pw_name);

	// Not all systems have the GECOS field but the vast majority does
	if (!realname)
	{
		char *gecos = pwd->pw_gecos;

		// The first comma, if any, ends the user's real name
		char *comma = strchr (gecos, ',');
		if (comma)
			*comma = '\0';

		set_config_string (s->config, "realname", gecos);
	}

	return true;
}

static char *
irc_fetch_next_nickname (struct server *s)
{
	struct strv v = strv_make ();
	cstr_split (get_config_string (s->config, "nicks"), ",", true, &v);

	char *result = NULL;
	if (s->nick_counter >= 0 && (size_t) s->nick_counter < v.len)
		result = xstrdup (v.vector[s->nick_counter++]);
	if ((size_t) s->nick_counter >= v.len)
		// Exhausted all nicknames
		s->nick_counter = -1;

	strv_free (&v);
	return result;
}

static void
irc_register (struct server *s)
{
	// Fill in user information automatically if needed
	irc_autofill_user_info (s, NULL);

	const char *username = get_config_string (s->config, "username");
	const char *realname = get_config_string (s->config, "realname");
	hard_assert (username && realname);

	// Start IRCv3 capability negotiation, with up to 3.2 features;
	// at worst the server will ignore this or send a harmless error message
	irc_send (s, "CAP LS 302");

	const char *password = get_config_string (s->config, "password");
	if (password)
		irc_send (s, "PASS :%s", password);

	s->nick_counter = 0;

	char *nickname = irc_fetch_next_nickname (s);
	if (nickname)
		irc_send (s, "NICK :%s", nickname);
	else
		log_server_error (s, s->buffer, "No nicks present in configuration");
	free (nickname);

	// IRC servers may ignore the last argument if it's empty
	irc_send (s, "USER %s 8 * :%s", username, *realname ? realname : " ");
}

static void
irc_finish_connection (struct server *s, int socket, const char *hostname)
{
	struct app_context *ctx = s->ctx;

	// Most of our output comes from the user one full command at a time and we
	// use output buffering, so it makes a lot of sense to avoid these delays
	int yes = 1;
	soft_assert (setsockopt (socket, IPPROTO_TCP, TCP_NODELAY,
		&yes, sizeof yes) != -1);

	set_blocking (socket, false);
	s->socket = socket;
	s->transport = get_config_boolean (s->config, "tls")
		? &g_transport_tls
		: &g_transport_plain;

	struct error *e = NULL;
	if (s->transport->init && !s->transport->init (s, hostname, &e))
	{
		log_server_error (s, s->buffer, "Connection failed: #s", e->message);
		error_free (e);

		xclose (s->socket);
		s->socket = -1;

		s->transport = NULL;
		return;
	}

	log_server_status (s, s->buffer, "Connection established");
	s->state = IRC_CONNECTED;

	s->socket_event = poller_fd_make (&ctx->poller, s->socket);
	s->socket_event.dispatcher = (poller_fd_fn) on_irc_ready;
	s->socket_event.user_data = s;

	irc_update_poller (s, NULL);
	irc_reset_connection_timeouts (s);
	irc_register (s);

	refresh_prompt (s->ctx);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_on_connector_connecting (void *user_data, const char *address)
{
	struct server *s = user_data;
	log_server_status (s, s->buffer, "Connecting to #s...", address);
}

static void
irc_on_connector_error (void *user_data, const char *error)
{
	struct server *s = user_data;
	log_server_error (s, s->buffer, "Connection failed: #s", error);
}

static void
irc_on_connector_failure (void *user_data)
{
	struct server *s = user_data;
	irc_destroy_connector (s);
	irc_queue_reconnect (s);
}

static void
irc_on_connector_connected (void *user_data, int socket, const char *hostname)
{
	struct server *s = user_data;
	char *hostname_copy = xstrdup (hostname);
	irc_destroy_connector (s);
	irc_finish_connection (s, socket, hostname_copy);
	free (hostname_copy);
}

static void
irc_setup_connector (struct server *s, const struct strv *addresses)
{
	struct connector *connector = xmalloc (sizeof *connector);
	connector_init (connector, &s->ctx->poller);
	s->connector = connector;

	connector->user_data     = s;
	connector->on_connecting = irc_on_connector_connecting;
	connector->on_error      = irc_on_connector_error;
	connector->on_connected  = irc_on_connector_connected;
	connector->on_failure    = irc_on_connector_failure;

	for (size_t i = 0; i < addresses->len; i++)
	{
		const char *port = "6667",
			*host = tokenize_host_port (addresses->vector[i], &port);
		connector_add_target (connector, host, port);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// TODO: see if we can further merge code for the two connectors, for example
//   by making SOCKS 4A and 5 mere plugins for the connector, or by using
//   a virtual interface common to them both (seems more likely)

static void
irc_on_socks_connecting (void *user_data,
	const char *address, const char *via, const char *version)
{
	struct server *s = user_data;
	log_server_status (s, s->buffer,
		"Connecting to #s via #s (#s)...", address, via, version);
}

static bool
irc_setup_connector_socks (struct server *s, const struct strv *addresses,
	struct error **e)
{
	const char *socks_host = get_config_string (s->config, "socks_host");
	int64_t socks_port_int = get_config_integer (s->config, "socks_port");

	if (!socks_host)
		return false;

	struct socks_connector *connector = xmalloc (sizeof *connector);
	socks_connector_init (connector, &s->ctx->poller);
	s->socks_conn = connector;

	connector->user_data     = s;
	connector->on_connecting = irc_on_socks_connecting;
	connector->on_error      = irc_on_connector_error;
	connector->on_connected  = irc_on_connector_connected;
	connector->on_failure    = irc_on_connector_failure;

	for (size_t i = 0; i < addresses->len; i++)
	{
		const char *port = "6667",
			*host = tokenize_host_port (addresses->vector[i], &port);
		if (!socks_connector_add_target (connector, host, port, e))
			return false;
	}

	char *service = xstrdup_printf ("%" PRIi64, socks_port_int);
	socks_connector_run (connector, socks_host, service,
		get_config_string (s->config, "socks_username"),
		get_config_string (s->config, "socks_password"));
	free (service);

	// The SOCKS connector can have already failed; we mustn't return true then
	if (!s->socks_conn)
		return error_set (e, "SOCKS connection failed");
	return true;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_initiate_connect (struct server *s)
{
	hard_assert (s->state == IRC_DISCONNECTED);

	const char *addresses = get_config_string (s->config, "addresses");
	if (!addresses || !addresses[strspn (addresses, ",")])
	{
		// No sense in trying to reconnect
		log_server_error (s, s->buffer,
			"No addresses specified in configuration");
		return;
	}

	struct strv servers = strv_make ();
	cstr_split (addresses, ",", true, &servers);

	struct error *e = NULL;
	if (!irc_setup_connector_socks (s, &servers, &e) && !e)
		irc_setup_connector (s, &servers);

	strv_free (&servers);

	if (e)
	{
		irc_destroy_connector (s);

		log_server_error (s, s->buffer, "#s", e->message);
		error_free (e);
		irc_queue_reconnect (s);
	}
	else if (s->state != IRC_CONNECTED)
		s->state = IRC_CONNECTING;
}

// --- Input prompt ------------------------------------------------------------

static void
make_unseen_prefix (struct app_context *ctx, struct str *active_buffers)
{
	size_t buffer_no = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
	{
		buffer_no++;
		if (!(iter->new_messages_count - iter->new_unimportant_count)
		 || iter == ctx->current_buffer)
			continue;

		if (active_buffers->len)
			str_append_c (active_buffers, ',');
		if (iter->highlighted)
			str_append_c (active_buffers, '!');
		str_append_printf (active_buffers, "%zu", buffer_no);
	}
}

static void
make_chanmode_postfix (struct channel *channel, struct str *modes)
{
	if (channel->no_param_modes.len)
		str_append (modes, channel->no_param_modes.str);

	struct str_map_iter iter = str_map_iter_make (&channel->param_modes);
	char *param;
	while ((param = str_map_iter_next (&iter)))
		str_append_c (modes, iter.link->key[0]);
}

static void
make_server_postfix_registered (struct buffer *buffer, struct str *output)
{
	struct server *s = buffer->server;
	if (buffer->type == BUFFER_CHANNEL)
	{
		struct channel_user *channel_user =
			irc_channel_get_user (buffer->channel, s->irc_user);
		if (channel_user)
			irc_get_channel_user_prefix (s, channel_user, output);
	}
	str_append (output, s->irc_user->nickname);
	if (s->irc_user_mode.len)
		str_append_printf (output, "(%s)", s->irc_user_mode.str);
}

static void
make_server_postfix (struct buffer *buffer, struct str *output)
{
	struct server *s = buffer->server;
	str_append_c (output, ' ');
	if (!irc_is_connected (s))
		str_append (output, "(disconnected)");
	else if (s->state != IRC_REGISTERED)
		str_append (output, "(unregistered)");
	else
		make_server_postfix_registered (buffer, output);
}

static void
make_prompt (struct app_context *ctx, struct str *output)
{
	LIST_FOR_EACH (struct hook, iter, ctx->prompt_hooks)
	{
		struct prompt_hook *hook = (struct prompt_hook *) iter;
		char *made = hook->make (hook);
		if (made)
		{
			str_append (output, made);
			free (made);
			return;
		}
	}

	struct buffer *buffer = ctx->current_buffer;
	if (!buffer)
		return;

	str_append_c (output, '[');

	struct str active_buffers = str_make ();
	make_unseen_prefix (ctx, &active_buffers);
	if (active_buffers.len)
		str_append_printf (output, "(%s) ", active_buffers.str);
	str_free (&active_buffers);

	str_append_printf (output, "%d:%s",
		buffer_get_index (ctx, buffer), buffer->name);
	// We remember old modes, don't show them while we're not on the channel
	if (buffer->type == BUFFER_CHANNEL
	 && buffer->channel->users_len)
	{
		struct str modes = str_make ();
		make_chanmode_postfix (buffer->channel, &modes);
		if (modes.len)
			str_append_printf (output, "(+%s)", modes.str);
		str_free (&modes);

		str_append_printf (output, "{%zu}", buffer->channel->users_len);
	}
	if (buffer->hide_unimportant)
		str_append (output, "<H>");

	if (buffer != ctx->global_buffer)
		make_server_postfix (buffer, output);

	str_append_c (output, ']');
	str_append_c (output, ' ');
}

static void
input_maybe_set_prompt (struct input *self, char *new_prompt)
{
	// Fix libedit's expectations to see a non-control character following
	// the end mark (see prompt.c and literal.c) by cleaning this up
	for (char *p = new_prompt; *p; )
		if (p[0] == INPUT_END_IGNORE && p[1] == INPUT_START_IGNORE)
			memmove (p, p + 2, strlen (p + 2) + 1);
		else
			p++;

	// Redisplay can be an expensive operation
	const char *prompt = CALL (self, get_prompt);
	if (prompt && !strcmp (new_prompt, prompt))
		free (new_prompt);
	else
		CALL_ (self, set_prompt, new_prompt);
}

static void
on_refresh_prompt (struct app_context *ctx)
{
	poller_idle_reset (&ctx->prompt_event);
	bool have_attributes = !!get_attribute_printer (stdout);

	struct str prompt = str_make ();
	make_prompt (ctx, &prompt);

	// libedit has a weird bug where it misapplies ignores when they're not
	// followed by anything else, so let's try to move a trailing space,
	// which will at least fix the default prompt.
	const char *attributed_suffix = "";
#ifdef HAVE_EDITLINE
	if (have_attributes && prompt.len && prompt.str[prompt.len - 1] == ' ')
	{
		prompt.str[--prompt.len] = 0;
		attributed_suffix = " ";
	}

	// Also enable a uniform interface for prompt hooks by assuming it uses
	// GNU Readline escapes: turn this into libedit's almost-flip-flop
	for (size_t i = 0; i < prompt.len; i++)
		if (prompt.str[i] == '\x01' || prompt.str[i] == '\x02')
			prompt.str[i] = INPUT_START_IGNORE /* == INPUT_END_IGNORE */;
#endif // HAVE_EDITLINE

	char *localized = iconv_xstrdup (ctx->term_from_utf8, prompt.str, -1, NULL);
	str_free (&prompt);

	if (have_attributes)
	{
		// XXX: to be completely correct, we should use tputs, but we cannot
		input_maybe_set_prompt (ctx->input, xstrdup_printf ("%c%s%c%s%c%s%c%s",
			INPUT_START_IGNORE, ctx->attrs[ATTR_PROMPT],
			INPUT_END_IGNORE,
			localized,
			INPUT_START_IGNORE, ctx->attrs[ATTR_RESET],
			INPUT_END_IGNORE,
			attributed_suffix));
		free (localized);
	}
	else
		input_maybe_set_prompt (ctx->input, localized);
}

// --- Helpers -----------------------------------------------------------------

static struct buffer *
irc_get_buffer_for_message (struct server *s,
	const struct irc_message *msg, const char *target)
{
	// TODO: display such messages differently
	target = irc_skip_statusmsg (s, target);

	struct buffer *buffer = str_map_find (&s->irc_buffer_map, target);
	if (irc_is_channel (s, target))
	{
		struct channel *channel = str_map_find (&s->irc_channels, target);
		hard_assert (channel || !buffer);

		// This is weird
		if (!channel)
			return NULL;
	}
	else if (!buffer)
	{
		// Outgoing messages needn't have a prefix, no buffer associated
		if (!msg->prefix)
			return NULL;

		// Don't make user buffers for servers (they can send NOTICEs)
		if (!irc_find_userhost (msg->prefix))
			return s->buffer;

		char *nickname = irc_cut_nickname (msg->prefix);
		if (irc_is_this_us (s, target))
			buffer = irc_get_or_make_user_buffer (s, nickname);
		free (nickname);

		// With the IRCv3.2 echo-message capability, we can receive messages
		// as they are delivered to the target; in that case we return NULL
		// and the caller should check the origin
	}
	return buffer;
}

static bool
irc_is_highlight (struct server *s, const char *message)
{
	// This may be called by notices before even successfully registering
	if (!s->irc_user)
		return false;

	// Strip formatting from the message so that it doesn't interfere
	// with nickname detection (colour sequences in particular)
	struct formatter f = formatter_make (s->ctx, NULL);
	formatter_parse_message (&f, message);

	struct str stripped = str_make ();
	for (size_t i = 0; i < f.items_len; i++)
	{
		if (f.items[i].type == FORMATTER_ITEM_TEXT)
			str_append (&stripped, f.items[i].text);
	}
	formatter_free (&f);

	// Well, this is rather crude but it should make most users happy.
	// We could do this in proper Unicode but that's two more conversions per
	// message when both the nickname and the message are likely valid UTF-8.
	char *copy = str_steal (&stripped);
	cstr_transform (copy, s->irc_tolower);

	char *nick = xstrdup (s->irc_user->nickname);
	cstr_transform (nick, s->irc_tolower);

	// Special characters allowed in nicknames by RFC 2812: []\`_^{|} and -
	// Also excluded from the ASCII: common user channel prefixes: +%@&~
	// XXX: why did I exclude those?  It won't match when IRC newbies use them.
	const char *delimiters = ",.;:!?()<>/=#$* \t\r\n\v\f\"'";

	bool result = false;
	char *save = NULL;
	for (char *token = strtok_r (copy, delimiters, &save);
		token; token = strtok_r (NULL, delimiters, &save))
		if (!strcmp (token, nick))
		{
			result = true;
			break;
		}

	free (copy);
	free (nick);
	return result;
}

static char *
irc_get_privmsg_prefix (struct server *s, struct user *user, const char *target)
{
	struct str prefix = str_make ();
	if (user && irc_is_channel (s, (target = irc_skip_statusmsg (s, target))))
	{
		struct channel *channel;
		struct channel_user *channel_user;
		if ((channel = str_map_find (&s->irc_channels, target))
		 && (channel_user = irc_channel_get_user (channel, user)))
			irc_get_channel_user_prefix (s, channel_user, &prefix);
	}
	return str_steal (&prefix);
}

// --- Mode processor ----------------------------------------------------------

struct mode_processor
{
	char **params;                      ///< Mode string parameters
	bool adding;                        ///< Currently adding modes
	char mode_char;                     ///< Currently processed mode char

	// User data:

	struct server *s;                   ///< Server
	struct channel *channel;            ///< The channel being modified
	unsigned changes;                   ///< Count of all changes
	unsigned usermode_changes;          ///< Count of all usermode changes
};

/// Process a single mode character
typedef bool (*mode_processor_apply_fn) (struct mode_processor *);

static const char *
mode_processor_next_param (struct mode_processor *self)
{
	if (!*self->params)
		return NULL;
	return *self->params++;
}

static void
mode_processor_run (struct mode_processor *self,
	char **params, mode_processor_apply_fn apply_cb)
{
	self->params = params;

	const char *mode_string;
	while ((mode_string = mode_processor_next_param (self)))
	{
		self->adding = true;
		while ((self->mode_char = *mode_string++))
		{
			if      (self->mode_char == '+') self->adding = true;
			else if (self->mode_char == '-') self->adding = false;
			else if (!apply_cb (self))
				break;
		}
	}
}

static int
mode_char_cmp (const void *a, const void *b)
{
	return *(const char *) a - *(const char *) b;
}

/// Add/remove the current mode character to/from the given ordered list
static void
mode_processor_toggle (struct mode_processor *self, struct str *modes)
{
	const char *pos = strchr (modes->str, self->mode_char);
	if (self->adding == !!pos)
		return;

	if (self->adding)
	{
		str_append_c (modes, self->mode_char);
		qsort (modes->str, modes->len, 1, mode_char_cmp);
	}
	else
		str_remove_slice (modes, pos - modes->str, 1);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
mode_processor_do_user (struct mode_processor *self)
{
	const char *nickname;
	struct user *user;
	struct channel_user *channel_user;
	if (!(nickname = mode_processor_next_param (self))
	 || !(user = str_map_find (&self->s->irc_users, nickname))
	 || !(channel_user = irc_channel_get_user (self->channel, user)))
		return;

	// Translate mode character to user prefix character
	const char *all_prefixes = self->s->irc_chanuser_prefixes;
	const char *all_modes    = self->s->irc_chanuser_modes;

	const char *mode = strchr (all_modes, self->mode_char);
	hard_assert (mode && (size_t) (mode - all_modes) < strlen (all_prefixes));
	char prefix = all_prefixes[mode - all_modes];

	char **prefixes = &channel_user->prefixes;
	char *pos = strchr (*prefixes, prefix);
	if (self->adding == !!pos)
		return;

	if (self->adding)
	{
		// Add the new mode prefix while retaining the right order
		struct str buf = str_make ();
		for (const char *p = all_prefixes; *p; p++)
			if (*p == prefix || strchr (*prefixes, *p))
				str_append_c (&buf, *p);
		cstr_set (prefixes, str_steal (&buf));
	}
	else
		memmove (pos, pos + 1, strlen (pos));
}

static void
mode_processor_do_param_always (struct mode_processor *self)
{
	const char *param = NULL;
	if (!(param = mode_processor_next_param (self)))
		return;

	char key[2] = { self->mode_char, 0 };
	str_map_set (&self->channel->param_modes, key,
		self->adding ? xstrdup (param) : NULL);
}

static void
mode_processor_do_param_when_set (struct mode_processor *self)
{
	const char *param = NULL;
	if (self->adding && !(param = mode_processor_next_param (self)))
		return;

	char key[2] = { self->mode_char, 0 };
	str_map_set (&self->channel->param_modes, key,
		self->adding ? xstrdup (param) : NULL);
}

static bool
mode_processor_apply_channel (struct mode_processor *self)
{
	self->changes++;
	if      (strchr (self->s->irc_chanuser_modes,           self->mode_char))
	{
		self->usermode_changes++;
		mode_processor_do_user (self);
	}
	else if (strchr (self->s->irc_chanmodes_list,           self->mode_char))
		// Nothing to do here, just skip the next argument if there's any
		(void) mode_processor_next_param (self);
	else if (strchr (self->s->irc_chanmodes_param_always,   self->mode_char))
		mode_processor_do_param_always (self);
	else if (strchr (self->s->irc_chanmodes_param_when_set, self->mode_char))
		mode_processor_do_param_when_set (self);
	else if (strchr (self->s->irc_chanmodes_param_never,    self->mode_char))
		mode_processor_toggle (self, &self->channel->no_param_modes);
	else
		// It's not safe to continue, results could be undesired
		return false;
	return true;
}

/// Returns whether the change has only affected channel user modes
static bool
irc_handle_mode_channel (struct channel *channel, char **params)
{
	struct mode_processor p = { .s = channel->s, .channel = channel };
	mode_processor_run (&p, params, mode_processor_apply_channel);
	return p.changes == p.usermode_changes;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool
mode_processor_apply_user (struct mode_processor *self)
{
	mode_processor_toggle (self, &self->s->irc_user_mode);
	return true;
}

static void
irc_handle_mode_user (struct server *s, char **params)
{
	struct mode_processor p = { .s = s };
	mode_processor_run (&p, params, mode_processor_apply_user);
}

// --- Output processing -------------------------------------------------------

// Both user and plugins can send whatever the heck they want to,
// we need to parse it back so that it's evident what's happening

static void
irc_handle_sent_cap (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 1)
		return;

	const char *subcommand = msg->params.vector[0];
	const char *args = (msg->params.len > 1) ? msg->params.vector[1] : "";
	if (!strcasecmp_ascii (subcommand, "REQ"))
		log_server_status (s, s->buffer,
			"#s: #S", "Capabilities requested", args);
}

static void
irc_handle_sent_notice_text (struct server *s,
	const struct irc_message *msg, struct str *text)
{
	const char *target = msg->params.vector[0];
	struct buffer *buffer = irc_get_buffer_for_message (s, msg, target);
	if (buffer && soft_assert (s->irc_user))
		log_outcoming_notice (s, buffer, s->irc_user->nickname, text->str);
	else
		log_outcoming_orphan_notice (s, target, text->str);
}

static void
irc_handle_sent_notice (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2 || s->cap_echo_message)
		return;

	// This ignores empty messages which we should not normally send
	struct ctcp_chunk *chunks = ctcp_parse (msg->params.vector[1]);
	LIST_FOR_EACH (struct ctcp_chunk, iter, chunks)
	{
		if (iter->is_extended)
			log_ctcp_reply (s, msg->params.vector[0],
				xstrdup_printf ("%s %s", iter->tag.str, iter->text.str));
		else
			irc_handle_sent_notice_text (s, msg, &iter->text);
	}
	ctcp_destroy (chunks);
}

static void
irc_handle_sent_privmsg_text (struct server *s,
	const struct irc_message *msg, struct str *text, bool is_action)
{
	const char *target = msg->params.vector[0];
	struct buffer *buffer = irc_get_buffer_for_message (s, msg, target);
	if (buffer && soft_assert (s->irc_user))
	{
		char *prefixes = irc_get_privmsg_prefix (s, s->irc_user, target);
		if (is_action)
			log_outcoming_action (s, buffer, s->irc_user->nickname, text->str);
		else
			log_outcoming_privmsg (s, buffer,
				prefixes, s->irc_user->nickname, text->str);
		free (prefixes);
	}
	else if (is_action)
		log_outcoming_orphan_action (s, target, text->str);
	else
		log_outcoming_orphan_privmsg (s, target, text->str);
}

static void
irc_handle_sent_privmsg (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2 || s->cap_echo_message)
		return;

	// This ignores empty messages which we should not normally send
	// and the server is likely going to reject with an error reply anyway
	struct ctcp_chunk *chunks = ctcp_parse (msg->params.vector[1]);
	LIST_FOR_EACH (struct ctcp_chunk, iter, chunks)
	{
		if (!iter->is_extended)
			irc_handle_sent_privmsg_text (s, msg, &iter->text, false);
		else if (!strcmp (iter->tag.str, "ACTION"))
			irc_handle_sent_privmsg_text (s, msg, &iter->text, true);
		else
			log_ctcp_query (s, msg->params.vector[0], iter->tag.str);
	}
	ctcp_destroy (chunks);
}

static struct irc_handler
{
	const char *name;
	void (*handler) (struct server *s, const struct irc_message *msg);
}
g_irc_sent_handlers[] =
{
	// This list needs to stay sorted
	{ "CAP",     irc_handle_sent_cap     },
	{ "NOTICE",  irc_handle_sent_notice  },
	{ "PRIVMSG", irc_handle_sent_privmsg },
};

static int
irc_handler_cmp_by_name (const void *a, const void *b)
{
	const struct irc_handler *first  = a;
	const struct irc_handler *second = b;
	return strcasecmp_ascii (first->name, second->name);
}

static void
irc_process_sent_message (const struct irc_message *msg, struct server *s)
{
	// The server is free to reject even a matching prefix
	// XXX: even though no prefix should normally be present, this is racy
	if (msg->prefix && !irc_is_this_us (s, msg->prefix))
		return;

	struct irc_handler key = { .name = msg->command };
	struct irc_handler *handler = bsearch (&key, g_irc_sent_handlers,
		N_ELEMENTS (g_irc_sent_handlers), sizeof key, irc_handler_cmp_by_name);
	if (handler)
		handler->handler (s, msg);
}

// --- Input handling ----------------------------------------------------------

static void
irc_handle_authenticate (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 1)
		return;

	// Empty challenge -> empty response for e.g. SASL EXTERNAL,
	// abort anything else as it doesn't make much sense to let the user do it
	if (!strcmp (msg->params.vector[0], "+"))
		irc_send (s, "AUTHENTICATE +");
	else
		irc_send (s, "AUTHENTICATE *");
}

static void
irc_handle_away (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix)
		return;

	char *nickname = irc_cut_nickname (msg->prefix);
	struct user *user = str_map_find (&s->irc_users, nickname);
	free (nickname);

	// Let's allow the server to make us away
	if (user)
		user->away = !!msg->params.len;
}

static void
irc_process_cap_ls (struct server *s)
{
	log_server_status (s, s->buffer,
		"#s: #&S", "Capabilities supported", strv_join (&s->cap_ls_buf, " "));

	struct strv chosen = strv_make ();
	struct strv use    = strv_make ();

	cstr_split (get_config_string (s->config, "capabilities"), ",", true, &use);

	// Filter server capabilities for ones we can make use of
	for (size_t i = 0; i < s->cap_ls_buf.len; i++)
	{
		const char *cap = s->cap_ls_buf.vector[i];
		size_t cap_name_len = strcspn (cap, "=");
		for (size_t k = 0; k < use.len; k++)
			if (!strncasecmp_ascii (use.vector[k], cap, cap_name_len))
				strv_append_owned (&chosen, xstrndup (cap, cap_name_len));
	}
	strv_reset (&s->cap_ls_buf);

	char *chosen_str = strv_join (&chosen, " ");
	strv_free (&chosen);
	strv_free (&use);

	// XXX: with IRCv3.2, this may end up being too long for one message,
	// and we need to be careful with CAP END.  One probably has to count
	// the number of sent CAP REQ vs the number of received CAP ACK/NAK.
	if (s->state == IRC_CONNECTED)
		irc_send (s, "CAP REQ :%s", chosen_str);

	free (chosen_str);
}

static void
irc_toggle_cap (struct server *s, const char *cap, bool active)
{
	if (!strcasecmp_ascii (cap, "echo-message")) s->cap_echo_message = active;
	if (!strcasecmp_ascii (cap, "away-notify"))  s->cap_away_notify  = active;
	if (!strcasecmp_ascii (cap, "sasl"))         s->cap_sasl         = active;
}

static void
irc_try_finish_cap_negotiation (struct server *s)
{
	// It does not make sense to do this post-registration, although it would
	// not hurt either, as the server must ignore it in that case
	if (s->state == IRC_CONNECTED)
		irc_send (s, "CAP END");
}

static void
irc_handle_cap (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	struct strv v = strv_make ();
	const char *args = "";
	if (msg->params.len > 2)
		cstr_split ((args = msg->params.vector[2]), " ", true, &v);

	const char *subcommand = msg->params.vector[1];
	if (!strcasecmp_ascii (subcommand, "ACK"))
	{
		log_server_status (s, s->buffer,
			"#s: #S", "Capabilities acknowledged", args);
		for (size_t i = 0; i < v.len; i++)
		{
			const char *cap = v.vector[i];
			bool active = true;
			if (*cap == '-')
			{
				active = false;
				cap++;
			}
			irc_toggle_cap (s, cap, active);
		}
		if (s->cap_sasl && s->transport == &g_transport_tls)
			irc_send (s, "AUTHENTICATE EXTERNAL");
		else
			irc_try_finish_cap_negotiation (s);
	}
	else if (!strcasecmp_ascii (subcommand, "NAK"))
	{
		log_server_error (s, s->buffer,
			"#s: #S", "Capabilities not acknowledged", args);
		irc_try_finish_cap_negotiation (s);
	}
	else if (!strcasecmp_ascii (subcommand, "DEL"))
	{
		log_server_error (s, s->buffer,
			"#s: #S", "Capabilities deleted", args);
		for (size_t i = 0; i < v.len; i++)
			irc_toggle_cap (s, v.vector[i], false);
	}
	else if (!strcasecmp_ascii (subcommand, "LS"))
	{

		if (msg->params.len > 3 && !strcmp (args, "*"))
			cstr_split (msg->params.vector[3], " ", true, &s->cap_ls_buf);
		else
		{
			strv_append_vector (&s->cap_ls_buf, v.vector);
			irc_process_cap_ls (s);
		}
	}

	strv_free (&v);
}

static void
irc_handle_chghost (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	char *nickname = irc_cut_nickname (msg->prefix);
	struct user *user = str_map_find (&s->irc_users, nickname);
	free (nickname);
	if (!user)
		return;

	char *new_prefix = xstrdup_printf ("%s!%s@%s", user->nickname,
		msg->params.vector[0], msg->params.vector[1]);

	if (irc_is_this_us (s, msg->prefix))
	{
		cstr_set (&s->irc_user_host, xstrdup_printf ("%s@%s",
			msg->params.vector[0], msg->params.vector[1]));

		log_chghost_self (s, s->buffer, new_prefix);

		// Log a message in all open buffers on this server
		struct str_map_iter iter = str_map_iter_make (&s->irc_buffer_map);
		struct buffer *buffer;
		while ((buffer = str_map_iter_next (&iter)))
			log_chghost_self (s, buffer, new_prefix);
	}
	else
	{
		// Log a message in any PM buffer
		struct buffer *buffer =
			str_map_find (&s->irc_buffer_map, user->nickname);
		if (buffer)
			log_chghost (s, buffer, msg->prefix, new_prefix);

		// Log a message in all channels the user is in
		LIST_FOR_EACH (struct user_channel, iter, user->channels)
		{
			buffer = str_map_find (&s->irc_buffer_map, iter->channel->name);
			hard_assert (buffer != NULL);
			log_chghost (s, buffer, msg->prefix, new_prefix);
		}
	}

	free (new_prefix);
}

static void
irc_handle_error (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 1)
		return;

	log_server_error (s, s->buffer, "#m", msg->params.vector[0]);
}

static void
irc_handle_invite (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	const char *target       = msg->params.vector[0];
	const char *channel_name = msg->params.vector[1];

	struct buffer *buffer;
	if (!(buffer = str_map_find (&s->irc_buffer_map, channel_name)))
		buffer = s->buffer;

	// IRCv3.2 invite-notify extension allows the target to be someone else
	if (irc_is_this_us (s, target))
		log_server_status (s, buffer,
			"#n has invited you to #S", msg->prefix, channel_name);
	else
		log_server_status (s, buffer,
			"#n has invited #n to #S", msg->prefix, target, channel_name);
}

static void
irc_handle_join (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 1)
		return;

	const char *channel_name = msg->params.vector[0];
	if (!irc_is_channel (s, channel_name))
		return;

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	// We've joined a new channel
	if (!channel)
	{
		// This is weird, ignoring
		if (!irc_is_this_us (s, msg->prefix))
			return;

		buffer = buffer_new (s->ctx->input,
			BUFFER_CHANNEL, irc_make_buffer_name (s, channel_name));
		buffer->server = s;
		buffer->channel = channel =
			irc_make_channel (s, xstrdup (channel_name));
		str_map_set (&s->irc_buffer_map, channel->name, buffer);

		buffer_add (s->ctx, buffer);

		char *input = CALL_ (s->ctx->input, get_line, NULL);
		if (!*input)
			buffer_activate (s->ctx, buffer);
		else
			buffer->highlighted = true;
		free (input);
	}

	if (irc_is_this_us (s, msg->prefix))
	{
		// Reset the field so that we rejoin the channel after reconnecting
		channel->left_manually = false;

		// Request the channel mode as we don't get it automatically
		str_reset (&channel->no_param_modes);
		str_map_clear (&channel->param_modes);
		irc_send (s, "MODE %s", channel_name);

		if ((channel->show_names_after_who = s->cap_away_notify))
			irc_send (s, "WHO %s", channel_name);
	}

	// Add the user to the channel
	char *nickname = irc_cut_nickname (msg->prefix);
	irc_channel_link_user (channel, irc_get_or_make_user (s, nickname), "");
	free (nickname);

	// Finally log the message
	if (buffer)
	{
		log_server (s, buffer, BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_JOIN,
			"#N #a#s#r #S", msg->prefix, ATTR_JOIN, "has joined", channel_name);
	}
}

static void
irc_handle_kick (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	const char *channel_name = msg->params.vector[0];
	const char *target = msg->params.vector[1];
	if (!irc_is_channel (s, channel_name)
	 || irc_is_channel (s, target))
		return;

	const char *message = NULL;
	if (msg->params.len > 2)
		message = msg->params.vector[2];

	struct user *user = str_map_find (&s->irc_users, target);
	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	// It would be weird for this to be false
	if (user && channel)
	{
		if (irc_is_this_us (s, target))
			irc_left_channel (channel);
		else
			irc_remove_user_from_channel (user, channel);
	}

	if (buffer)
	{
		struct formatter f = formatter_make (s->ctx, s);
		formatter_add (&f, "#N #a#s#r #n",
			msg->prefix, ATTR_PART, "has kicked", target);
		if (message)
			formatter_add (&f, " (#m)", message);
		log_formatter (s->ctx, buffer, 0, BUFFER_LINE_PART, &f);
	}
}

static void
irc_handle_kill (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	const char *target  = msg->params.vector[0];
	const char *comment = msg->params.vector[1];

	if (irc_is_this_us (s, target))
		log_server_status (s, s->buffer,
			"You've been killed by #n (#m)", msg->prefix, comment);
}

static void
irc_handle_mode (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 1)
		return;

	const char *context = msg->params.vector[0];

	// Join the modes back to a single string
	struct strv copy = strv_make ();
	strv_append_vector (&copy, msg->params.vector + 1);
	char *modes = strv_join (&copy, " ");
	strv_free (&copy);

	if (irc_is_channel (s, context))
	{
		struct channel *channel = str_map_find (&s->irc_channels, context);
		struct buffer *buffer = str_map_find (&s->irc_buffer_map, context);
		hard_assert (channel || !buffer);

		int flags = 0;
		if (channel
		 && irc_handle_mode_channel (channel, msg->params.vector + 1))
			// This is 90% automode spam, let's not let it steal attention,
			// maybe this behaviour should be configurable though
			flags = BUFFER_LINE_UNIMPORTANT;

		if (buffer)
		{
			log_server (s, buffer, flags, BUFFER_LINE_STATUS,
				"Mode #S [#S] by #n", context, modes, msg->prefix);
		}
	}
	else if (irc_is_this_us (s, context))
	{
		irc_handle_mode_user (s, msg->params.vector + 1);
		log_server_status (s, s->buffer,
			"User mode [#S] by #n", modes, msg->prefix);
	}

	free (modes);
}

static void
irc_handle_nick (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 1)
		return;

	const char *new_nickname = msg->params.vector[0];

	char *nickname = irc_cut_nickname (msg->prefix);
	struct user *user = str_map_find (&s->irc_users, nickname);
	free (nickname);
	if (!user)
		return;

	bool lexicographically_different =
		!!irc_server_strcmp (s, user->nickname, new_nickname);

	// What the fuck, someone renamed themselves to ourselves
	// TODO: probably log a message and force a reconnect
	if (lexicographically_different
	 && !irc_server_strcmp (s, new_nickname, s->irc_user->nickname))
		return;

	// Log a message in any PM buffer (we may even have one for ourselves)
	struct buffer *pm_buffer =
		str_map_find (&s->irc_buffer_map, user->nickname);
	if (pm_buffer)
	{
		if (irc_is_this_us (s, msg->prefix))
			log_nick_self (s, pm_buffer, new_nickname);
		else
			log_nick (s, pm_buffer, msg->prefix, new_nickname);
	}

	// The new nickname may collide with a user referenced by a PM buffer,
	// or in case of data inconsistency with the server, channels.
	// In the latter case we need the colliding user to leave all of them.
	struct user *user_collision = NULL;
	if (lexicographically_different
	 && (user_collision = str_map_find (&s->irc_users, new_nickname)))
		LIST_FOR_EACH (struct user_channel, iter, user_collision->channels)
			irc_remove_user_from_channel (user_collision, iter->channel);

	struct buffer *buffer_collision = NULL;
	if (lexicographically_different
	 && (buffer_collision = str_map_find (&s->irc_buffer_map, new_nickname)))
	{
		hard_assert (buffer_collision->type == BUFFER_PM);
		hard_assert (buffer_collision->user == user_collision);

		user_unref (buffer_collision->user);
		buffer_collision->user = user_ref (user);
	}

	if (pm_buffer && buffer_collision)
	{
		// There's not much else we can do other than somehow try to merge
		// one buffer into the other.  In our case, the original buffer wins.
		buffer_merge (s->ctx, buffer_collision, pm_buffer);
		if (s->ctx->current_buffer == pm_buffer)
			buffer_activate (s->ctx, buffer_collision);
		buffer_remove (s->ctx, pm_buffer);
		pm_buffer = buffer_collision;
	}

	// The colliding user should be completely gone by now
	if (lexicographically_different)
		hard_assert (!str_map_find (&s->irc_users, new_nickname));

	// Now we can rename the PM buffer to reflect the new nickname
	if (pm_buffer)
	{
		str_map_set (&s->irc_buffer_map, user->nickname, NULL);
		str_map_set (&s->irc_buffer_map, new_nickname, pm_buffer);

		char *x = irc_make_buffer_name (s, new_nickname);
		buffer_rename (s->ctx, pm_buffer, x);
		free (x);
	}

	if (irc_is_this_us (s, msg->prefix))
	{
		log_nick_self (s, s->buffer, new_nickname);

		// Log a message in all open buffers on this server
		struct str_map_iter iter = str_map_iter_make (&s->irc_buffer_map);
		struct buffer *buffer;
		while ((buffer = str_map_iter_next (&iter)))
		{
			// We've already done that
			if (buffer != pm_buffer)
				log_nick_self (s, buffer, new_nickname);
		}
	}
	else
	{
		// Log a message in all channels the user is in
		LIST_FOR_EACH (struct user_channel, iter, user->channels)
		{
			struct buffer *buffer =
				str_map_find (&s->irc_buffer_map, iter->channel->name);
			hard_assert (buffer != NULL);
			log_nick (s, buffer, msg->prefix, new_nickname);
		}
	}

	// Finally rename the user as it should be safe now
	str_map_set (&s->irc_users, user->nickname, NULL);
	str_map_set (&s->irc_users, new_nickname, user);

	cstr_set (&user->nickname, xstrdup (new_nickname));
}

static void
irc_handle_ctcp_reply (struct server *s,
	const struct irc_message *msg, struct ctcp_chunk *chunk)
{
	const char *target = msg->params.vector[0];
	if (irc_is_this_us (s, msg->prefix))
		log_ctcp_reply (s, target,
			xstrdup_printf ("%s %s", chunk->tag.str, chunk->text.str));
	else
		log_server_status (s, s->buffer, "CTCP reply from #n: #S #S",
			msg->prefix, chunk->tag.str, chunk->text.str);
}

static void
irc_handle_notice_text (struct server *s,
	const struct irc_message *msg, struct str *text)
{
	const char *target = msg->params.vector[0];
	struct buffer *buffer = irc_get_buffer_for_message (s, msg, target);
	if (!buffer)
	{
		if (irc_is_this_us (s, msg->prefix))
			log_outcoming_orphan_notice (s, target, text->str);
		return;
	}

	char *nick = irc_cut_nickname (msg->prefix);
	// IRCv3.2 echo-message could otherwise cause us to highlight ourselves
	if (!irc_is_this_us (s, msg->prefix) && irc_is_highlight (s, text->str))
		log_server (s, buffer, BUFFER_LINE_HIGHLIGHT, BUFFER_LINE_STATUS,
			"#a#s(#S)#r: #m", ATTR_HIGHLIGHT, "Notice", nick, text->str);
	else
		log_outcoming_notice (s, buffer, msg->prefix, text->str);
	free (nick);
}

static void
irc_handle_notice (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	// This ignores empty messages which we should never receive anyway
	struct ctcp_chunk *chunks = ctcp_parse (msg->params.vector[1]);
	LIST_FOR_EACH (struct ctcp_chunk, iter, chunks)
		if (!iter->is_extended)
			irc_handle_notice_text (s, msg, &iter->text);
		else
			irc_handle_ctcp_reply (s, msg, iter);
	ctcp_destroy (chunks);
}

static void
irc_handle_part (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 1)
		return;

	const char *channel_name = msg->params.vector[0];
	if (!irc_is_channel (s, channel_name))
		return;

	const char *message = NULL;
	if (msg->params.len > 1)
		message = msg->params.vector[1];

	char *nickname = irc_cut_nickname (msg->prefix);
	struct user *user = str_map_find (&s->irc_users, nickname);
	free (nickname);

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	// It would be weird for this to be false
	if (user && channel)
	{
		if (irc_is_this_us (s, msg->prefix))
			irc_left_channel (channel);
		else
			irc_remove_user_from_channel (user, channel);
	}

	if (buffer)
	{
		struct formatter f = formatter_make (s->ctx, s);
		formatter_add (&f, "#N #a#s#r #S",
			msg->prefix, ATTR_PART, "has left", channel_name);
		if (message)
			formatter_add (&f, " (#m)", message);
		log_formatter (s->ctx, buffer,
			BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_PART, &f);
	}
}

static void
irc_handle_ping (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len)
		irc_send (s, "PONG :%s", msg->params.vector[0]);
	else
		irc_send (s, "PONG");
}

static char *
ctime_now (char buf[26])
{
	struct tm tm_;
	time_t now = time (NULL);
	if (!asctime_r (localtime_r (&now, &tm_), buf))
		return NULL;

	// Annoying thing
	*strchr (buf, '\n') = '\0';
	return buf;
}

static void irc_send_ctcp_reply (struct server *s, const char *recipient,
	const char *format, ...) ATTRIBUTE_PRINTF (3, 4);

static void
irc_send_ctcp_reply (struct server *s,
	const char *recipient, const char *format, ...)
{
	struct str m = str_make ();

	va_list ap;
	va_start (ap, format);
	str_append_vprintf (&m, format, ap);
	va_end (ap);

	irc_send (s, "NOTICE %s :\x01%s\x01", recipient, m.str);
	str_free (&m);
}

static void
irc_handle_ctcp_request (struct server *s,
	const struct irc_message *msg, struct ctcp_chunk *chunk)
{
	const char *target = msg->params.vector[0];
	if (irc_is_this_us (s, msg->prefix))
	{
		if (s->cap_echo_message)
			log_ctcp_query (s, target, chunk->tag.str);
		if (!irc_is_this_us (s, target))
			return;
	}

	struct formatter f = formatter_make (s->ctx, s);
	formatter_add (&f, "CTCP requested by #n", msg->prefix);
	if (irc_is_channel (s, irc_skip_statusmsg (s, target)))
		formatter_add (&f, " (to #S)", target);
	formatter_add (&f, ": #S", chunk->tag.str);
	log_formatter (s->ctx, s->buffer, 0, BUFFER_LINE_STATUS, &f);

	char *nickname = irc_cut_nickname (msg->prefix);

	if (!strcmp (chunk->tag.str, "CLIENTINFO"))
		irc_send_ctcp_reply (s, nickname, "CLIENTINFO %s %s %s %s",
			"PING", "VERSION", "TIME", "CLIENTINFO");
	else if (!strcmp (chunk->tag.str, "PING"))
		irc_send_ctcp_reply (s, nickname, "PING %s", chunk->text.str);
	else if (!strcmp (chunk->tag.str, "VERSION"))
	{
		struct utsname info;
		if (uname (&info))
			LOG_LIBC_FAILURE ("uname");
		else
			irc_send_ctcp_reply (s, nickname, "VERSION %s %s on %s %s",
				PROGRAM_NAME, PROGRAM_VERSION, info.sysname, info.machine);
	}
	else if (!strcmp (chunk->tag.str, "TIME"))
	{
		char buf[26];
		if (!ctime_now (buf))
			LOG_LIBC_FAILURE ("asctime_r");
		else
			irc_send_ctcp_reply (s, nickname, "TIME %s", buf);
	}

	free (nickname);
}

static void
irc_handle_privmsg_text (struct server *s,
	const struct irc_message *msg, struct str *text, bool is_action)
{
	const char *target = msg->params.vector[0];
	struct buffer *buffer = irc_get_buffer_for_message (s, msg, target);
	if (!buffer)
	{
		if (irc_is_this_us (s, msg->prefix))
			log_outcoming_orphan_privmsg (s, target, text->str);
		return;
	}

	char *nickname = irc_cut_nickname (msg->prefix);
	char *prefixes = irc_get_privmsg_prefix
		(s, str_map_find (&s->irc_users, nickname), target);

	// Make autocomplete offer recent speakers first on partial matches
	// (note that freshly joined users also move to the front)
	struct user *user;
	struct channel_user *channel_user;
	if (!irc_is_this_us (s, msg->prefix) && buffer->channel
	 && (user = str_map_find (&s->irc_users, nickname))
	 && (channel_user = irc_channel_get_user (buffer->channel, user)))
	{
		LIST_UNLINK (buffer->channel->users, channel_user);
		LIST_PREPEND (buffer->channel->users, channel_user);
	}

	// IRCv3.2 echo-message could otherwise cause us to highlight ourselves
	if (irc_is_this_us (s, msg->prefix) || !irc_is_highlight (s, text->str))
	{
		if (is_action)
			log_outcoming_action (s, buffer, nickname, text->str);
		else
			log_outcoming_privmsg (s, buffer, prefixes, nickname, text->str);
	}
	else if (is_action)
		log_server (s, buffer, BUFFER_LINE_HIGHLIGHT, 0,
			" #a*#r  #n #m", ATTR_HIGHLIGHT, msg->prefix, text->str);
	else
		log_server (s, buffer, BUFFER_LINE_HIGHLIGHT, 0,
			"#a<#S#S>#r #m", ATTR_HIGHLIGHT, prefixes, nickname, text->str);

	free (nickname);
	free (prefixes);
}

static void
irc_handle_privmsg (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	// This ignores empty messages which we should never receive anyway
	struct ctcp_chunk *chunks = ctcp_parse (msg->params.vector[1]);
	LIST_FOR_EACH (struct ctcp_chunk, iter, chunks)
		if (!iter->is_extended)
			irc_handle_privmsg_text (s, msg, &iter->text, false);
		else if (!strcmp (iter->tag.str, "ACTION"))
			irc_handle_privmsg_text (s, msg, &iter->text, true);
		else
			irc_handle_ctcp_request (s, msg, iter);
	ctcp_destroy (chunks);
}

static void
log_quit (struct server *s,
	struct buffer *buffer, const char *prefix, const char *reason)
{
	struct formatter f = formatter_make (s->ctx, s);
	formatter_add (&f, "#N #a#s#r", prefix, ATTR_PART, "has quit");
	if (reason)
		formatter_add (&f, " (#m)", reason);
	log_formatter (s->ctx, buffer,
		BUFFER_LINE_UNIMPORTANT, BUFFER_LINE_PART, &f);
}

static void
irc_handle_quit (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix)
		return;

	// What the fuck, the server never sends this back
	if (irc_is_this_us (s, msg->prefix))
		return;

	char *nickname = irc_cut_nickname (msg->prefix);
	struct user *user = str_map_find (&s->irc_users, nickname);
	free (nickname);
	if (!user)
		return;

	const char *message = NULL;
	if (msg->params.len > 0)
		message = msg->params.vector[0];

	// Log a message in any PM buffer
	struct buffer *buffer =
		str_map_find (&s->irc_buffer_map, user->nickname);
	if (buffer)
	{
		log_quit (s, buffer, msg->prefix, message);

		// TODO: set some kind of a flag in the buffer and when the user
		//   reappears on a channel (JOIN), log a "is back online" message.
		//   Also set this flag when we receive a "no such nick" numeric
		//   and reset it when we send something to the buffer.
	}

	// Log a message in all channels the user is in
	LIST_FOR_EACH (struct user_channel, iter, user->channels)
	{
		if ((buffer = str_map_find (&s->irc_buffer_map, iter->channel->name)))
			log_quit (s, buffer, msg->prefix, message);

		// This destroys "iter" which doesn't matter to us
		irc_remove_user_from_channel (user, iter->channel);
	}
}

static void
irc_handle_tagmsg (struct server *s, const struct irc_message *msg)
{
	// TODO: here we can process "typing" tags, once we find this useful
	(void) s;
	(void) msg;
}

static void
irc_handle_topic (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 2)
		return;

	const char *channel_name = msg->params.vector[0];
	const char *topic = msg->params.vector[1];
	if (!irc_is_channel (s, channel_name))
		return;

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	// It would be weird for this to be false
	if (channel)
		cstr_set (&channel->topic, xstrdup (topic));

	if (buffer)
	{
		log_server (s, buffer, 0, BUFFER_LINE_STATUS, "#n #s \"#m\"",
			msg->prefix, "has changed the topic to", topic);
	}
}

static void
irc_handle_wallops (struct server *s, const struct irc_message *msg)
{
	if (!msg->prefix || msg->params.len < 1)
		return;

	const char *message = msg->params.vector[0];
	log_server (s, s->buffer, 0, 0, "<#n> #m", msg->prefix, message);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static struct irc_handler g_irc_handlers[] =
{
	// This list needs to stay sorted
	{ "AUTHENTICATE", irc_handle_authenticate },
	{ "AWAY",         irc_handle_away         },
	{ "CAP",          irc_handle_cap          },
	{ "CHGHOST",      irc_handle_chghost      },
	{ "ERROR",        irc_handle_error        },
	{ "INVITE",       irc_handle_invite       },
	{ "JOIN",         irc_handle_join         },
	{ "KICK",         irc_handle_kick         },
	{ "KILL",         irc_handle_kill         },
	{ "MODE",         irc_handle_mode         },
	{ "NICK",         irc_handle_nick         },
	{ "NOTICE",       irc_handle_notice       },
	{ "PART",         irc_handle_part         },
	{ "PING",         irc_handle_ping         },
	{ "PRIVMSG",      irc_handle_privmsg      },
	{ "QUIT",         irc_handle_quit         },
	{ "TAGMSG",       irc_handle_tagmsg       },
	{ "TOPIC",        irc_handle_topic        },
	{ "WALLOPS",      irc_handle_wallops      },
};

static bool
irc_try_parse_word_for_userhost (struct server *s, const char *word)
{
	regex_t re;
	int err = regcomp (&re, "^[^!@]+!([^!@]+@[^!@]+)$", REG_EXTENDED);
	if (!soft_assert (!err))
		return false;

	regmatch_t matches[2];
	bool result = false;
	if (!regexec (&re, word, 2, matches, 0))
	{
		cstr_set (&s->irc_user_host, xstrndup (word + matches[1].rm_so,
			matches[1].rm_eo - matches[1].rm_so));
		result = true;
	}
	regfree (&re);
	return result;
}

static void
irc_try_parse_welcome_for_userhost (struct server *s, const char *m)
{
	struct strv v = strv_make ();
	cstr_split (m, " ", true, &v);
	for (size_t i = 0; i < v.len; i++)
		if (irc_try_parse_word_for_userhost (s, v.vector[i]))
			break;
	strv_free (&v);
}

static bool process_input_utf8
	(struct app_context *, struct buffer *, const char *, int);
static void on_autoaway_timer (struct app_context *ctx);

static void
irc_on_registered (struct server *s, const char *nickname)
{
	s->irc_user = irc_get_or_make_user (s, nickname);
	str_reset (&s->irc_user_mode);
	cstr_set (&s->irc_user_host, NULL);

	s->state = IRC_REGISTERED;
	refresh_prompt (s->ctx);

	// XXX: we can also use WHOIS if it's not supported (optional by RFC 2812)
	// TODO: maybe rather always use RPL_ISUPPORT NICKLEN & USERLEN & HOSTLEN
	//   since we don't seem to follow any subsequent changes in userhost;
	//   unrealircd sends RPL_HOSTHIDDEN (396), which has an optional user part,
	//   and there is also CAP CHGHOST which /may/ send it to ourselves
	irc_send (s, "USERHOST %s", s->irc_user->nickname);

	// A little hack that reinstates auto-away status when we get disconnected
	if (s->autoaway_active)
		on_autoaway_timer (s->ctx);

	const char *command = get_config_string (s->config, "command");
	if (command)
	{
		log_server_debug (s, "Executing \"#s\"", command);
		(void) process_input_utf8 (s->ctx, s->buffer, command, 0);
	}

	int64_t command_delay = get_config_integer (s->config, "command_delay");
	log_server_debug (s, "Autojoining channels in #&s seconds...",
		xstrdup_printf ("%" PRId64, command_delay));
	poller_timer_set (&s->autojoin_tmr, command_delay * 1000);
}

static void
irc_handle_rpl_userhost (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	const char *response = msg->params.vector[1];
	struct strv v = strv_make ();
	cstr_split (response, " ", true, &v);

	for (size_t i = 0; i < v.len; i++)
	{
		char *nick = v.vector[i];
		char *equals = strchr (nick, '=');

		if (!equals || equals == nick)
			continue;

		// User is an IRC operator
		if (equals[-1] == '*')
			equals[-1] = '\0';
		else
			equals[ 0] = '\0';

		// TODO: make use of this (away status polling?)
		char away_status = equals[1];
		if (!strchr ("+-", away_status))
			continue;

		char *userhost = equals + 2;
		if (irc_is_this_us (s, nick))
			cstr_set (&s->irc_user_host, xstrdup (userhost));
	}
	strv_free (&v);
}

static void
irc_handle_rpl_umodeis (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	str_reset (&s->irc_user_mode);
	irc_handle_mode_user (s, msg->params.vector + 1);

	// XXX: do we want to log a message?
}

static void
irc_handle_rpl_namreply (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 4)
		return;

	const char *channel_name = msg->params.vector[2];
	const char *nicks        = msg->params.vector[3];

	// Just push the nicknames to a string vector to process later
	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	if (channel)
		cstr_split (nicks, " ", true, &channel->names_buf);
	else
		log_server_status (s, s->buffer, "Users on #S: #S",
			channel_name, nicks);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct channel_user_sort_entry
{
	struct server *s;                   ///< Server (because of the qsort API)
	struct channel_user *channel_user;  ///< Channel user
};

static int
channel_user_sort_entry_cmp (const void *entry_a, const void *entry_b)
{
	const struct channel_user_sort_entry *a = entry_a;
	const struct channel_user_sort_entry *b = entry_b;
	struct server *s = a->s;

	// First order by the most significant channel user prefix
	const char *prio_a = strchr (s->irc_chanuser_prefixes,
		a->channel_user->prefixes[0]);
	const char *prio_b = strchr (s->irc_chanuser_prefixes,
		b->channel_user->prefixes[0]);

	// Put unrecognized prefixes at the end of the list
	if (prio_a || prio_b)
	{
		if (!prio_a) return  1;
		if (!prio_b) return -1;

		if (prio_a != prio_b)
			return prio_a - prio_b;
	}

	return irc_server_strcmp (s,
		a->channel_user->user->nickname,
		b->channel_user->user->nickname);
}

static void
irc_sort_channel_users (struct channel *channel)
{
	size_t n_users = channel->users_len;
	struct channel_user_sort_entry entries[n_users], *p = entries;
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
	{
		p->s = channel->s;
		p->channel_user = iter;
		p++;
	}

	qsort (entries, n_users, sizeof *entries, channel_user_sort_entry_cmp);

	channel->users = NULL;
	while (p-- != entries)
		LIST_PREPEND (channel->users, p->channel_user);
}

static char *
make_channel_users_list (struct channel *channel)
{
	size_t n_users = channel->users_len;
	struct channel_user_sort_entry entries[n_users], *p = entries;
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
	{
		p->s = channel->s;
		p->channel_user = iter;
		p++;
	}

	qsort (entries, n_users, sizeof *entries, channel_user_sort_entry_cmp);

	// Make names of users that are away italicised, constructing a formatter
	// and adding a new attribute seems like unnecessary work
	struct str list = str_make ();
	for (size_t i = 0; i < n_users; i++)
	{
		struct channel_user *channel_user = entries[i].channel_user;
		if (channel_user->user->away) str_append_c (&list, '\x1d');
		irc_get_channel_user_prefix (channel->s, channel_user, &list);
		str_append (&list, channel_user->user->nickname);
		if (channel_user->user->away) str_append_c (&list, '\x1d');
		str_append_c (&list, ' ');
	}
	if (list.len)
		list.str[--list.len] = '\0';
	return str_steal (&list);
}

static void
irc_sync_channel_user (struct channel *channel, const char *nickname,
	const char *prefixes)
{
	struct user *user = irc_get_or_make_user (channel->s, nickname);
	struct channel_user *channel_user =
		irc_channel_get_user (channel, user);
	if (!channel_user)
	{
		irc_channel_link_user (channel, user, prefixes);
		return;
	}

	user_unref (user);

	// If our idea of the user's modes disagrees with what the server's
	// sent us (the most powerful modes differ), use the latter one
	if (channel_user->prefixes[0] != prefixes[0])
		cstr_set (&channel_user->prefixes, xstrdup (prefixes));
}

static void
irc_process_names_finish (struct channel *channel)
{
	struct server *s = channel->s;
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel->name);
	if (buffer)
	{
		log_server_status (channel->s, buffer, "Users on #S: #&m",
			channel->name, make_channel_users_list (channel));
	}
}

static void
irc_process_names (struct channel *channel)
{
	struct str_map present = str_map_make (NULL);
	present.key_xfrm = channel->s->irc_strxfrm;

	// Either that, or there is no other inhabitant, and sorting does nothing
	bool we_have_just_joined = channel->users_len == 1;

	struct strv *updates = &channel->names_buf;
	for (size_t i = 0; i < updates->len; i++)
	{
		const char *item = updates->vector[i];
		size_t n_prefixes = strspn (item, channel->s->irc_chanuser_prefixes);
		const char *nickname = item + n_prefixes;

		// Store the nickname in a hashset
		str_map_set (&present, nickname, (void *) 1);

		char *prefixes = xstrndup (item, n_prefixes);
		irc_sync_channel_user (channel, nickname, prefixes);
		free (prefixes);
	}

	// Get rid of channel users missing from "updates"
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
		if (!str_map_find (&present, iter->user->nickname))
			irc_channel_unlink_user (channel, iter);

	str_map_free (&present);
	strv_reset (&channel->names_buf);

	if (we_have_just_joined)
		irc_sort_channel_users (channel);
	if (!channel->show_names_after_who)
		irc_process_names_finish (channel);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_handle_rpl_endofnames (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	const char *channel_name = msg->params.vector[1];
	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	if (!strcmp (channel_name, "*"))
	{
		struct str_map_iter iter = str_map_iter_make (&s->irc_channels);
		struct channel *channel;
		while ((channel = str_map_iter_next (&iter)))
			irc_process_names (channel);
	}
	else if (channel)
		irc_process_names (channel);
}

static bool
irc_handle_rpl_whoreply (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 7)
		return false;

	// Sequence: channel, user, host, server, nick, chars
	const char *channel_name = msg->params.vector[1];
	const char *nickname     = msg->params.vector[5];
	const char *chars        = msg->params.vector[6];

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct user *user = str_map_find (&s->irc_users, nickname);

	// This makes sense to set only with the away-notify capability so far.
	if (!channel || !channel->show_names_after_who)
		return false;

	// We track ourselves by other means and we can't track PM-only users yet.
	if (user && user != s->irc_user && user->channels)
		user->away = *chars == 'G';
	return true;
}

static bool
irc_handle_rpl_endofwho (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return false;

	const char *target = msg->params.vector[1];

	struct channel *channel = str_map_find (&s->irc_channels, target);
	if (!channel || !channel->show_names_after_who)
		return false;

	irc_process_names_finish (channel);
	channel->show_names_after_who = false;
	return true;
}

static void
irc_handle_rpl_topic (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 3)
		return;

	const char *channel_name = msg->params.vector[1];
	const char *topic        = msg->params.vector[2];

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	if (channel)
		cstr_set (&channel->topic, xstrdup (topic));

	if (buffer)
		log_server_status (s, buffer, "The topic is: #m", topic);
}

static void
irc_handle_rpl_channelmodeis (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	const char *channel_name = msg->params.vector[1];

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	if (channel)
	{
		str_reset (&channel->no_param_modes);
		str_map_clear (&channel->param_modes);

		irc_handle_mode_channel (channel, msg->params.vector + 1);
	}

	// XXX: do we want to log a message?
}

static char *
make_time_string (time_t time)
{
	char buf[32];
	struct tm tm;
	strftime (buf, sizeof buf, "%a %b %d %Y %T", localtime_r (&time, &tm));
	return xstrdup (buf);
}

static void
irc_handle_rpl_creationtime (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 3)
		return;

	const char *channel_name  = msg->params.vector[1];
	const char *creation_time = msg->params.vector[2];

	unsigned long created;
	if (!xstrtoul (&created, creation_time, 10))
		return;

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	if (buffer)
	{
		log_server_status (s, buffer, "Channel created on #&s",
			make_time_string (created));
	}
}

static void
irc_handle_rpl_topicwhotime (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 4)
		return;

	const char *channel_name = msg->params.vector[1];
	const char *who          = msg->params.vector[2];
	const char *change_time  = msg->params.vector[3];

	unsigned long changed;
	if (!xstrtoul (&changed, change_time, 10))
		return;

	struct channel *channel = str_map_find (&s->irc_channels, channel_name);
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, channel_name);
	hard_assert (channel || !buffer);

	if (buffer)
	{
		log_server_status (s, buffer, "Topic set by #N on #&s",
			who, make_time_string (changed));
	}
}

static void
irc_handle_rpl_inviting (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 3)
		return;

	const char *nickname     = msg->params.vector[1];
	const char *channel_name = msg->params.vector[2];

	struct buffer *buffer;
	if (!(buffer = str_map_find (&s->irc_buffer_map, channel_name)))
		buffer = s->buffer;

	log_server_status (s, buffer,
		"You have invited #n to #S", nickname, channel_name);
}

static void
irc_handle_err_nicknameinuse (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	log_server_error (s, s->buffer,
		"Nickname is already in use: #S", msg->params.vector[1]);

	// Only do this while we haven't successfully registered yet
	if (s->state != IRC_CONNECTED)
		return;

	char *nickname = irc_fetch_next_nickname (s);
	if (nickname)
	{
		log_server_status (s, s->buffer, "Retrying with #s...", nickname);
		irc_send (s, "NICK :%s", nickname);
		free (nickname);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_handle_isupport_prefix (struct server *s, char *value)
{
	char *modes = value;
	char *prefixes = strchr (value, ')');
	size_t n_prefixes = prefixes - modes;
	if (*modes++ != '(' || !prefixes++ || strlen (value) != 2 * n_prefixes--)
		return;

	cstr_set (&s->irc_chanuser_modes,    xstrndup (modes,    n_prefixes));
	cstr_set (&s->irc_chanuser_prefixes, xstrndup (prefixes, n_prefixes));
}

static void
irc_handle_isupport_casemapping (struct server *s, char *value)
{
	if      (!strcmp (value, "ascii"))
		irc_set_casemapping (s, tolower_ascii,      tolower_ascii_strxfrm);
	else if (!strcmp (value, "rfc1459"))
		irc_set_casemapping (s, irc_tolower,        irc_strxfrm);
	else if (!strcmp (value, "rfc1459-strict"))
		irc_set_casemapping (s, irc_tolower_strict, irc_strxfrm_strict);
}

static void
irc_handle_isupport_chantypes (struct server *s, char *value)
{
	cstr_set (&s->irc_chantypes, xstrdup (value));
}

static void
irc_handle_isupport_idchan (struct server *s, char *value)
{
	struct str prefixes = str_make ();
	struct strv v = strv_make ();
	cstr_split (value, ",", true, &v);
	for (size_t i = 0; i < v.len; i++)
	{
		// Not using or validating the numeric part
		const char *pair = v.vector[i];
		const char *colon = strchr (pair, ':');
		if (colon)
			str_append_data (&prefixes, pair, colon - pair);
	}
	strv_free (&v);
	cstr_set (&s->irc_idchan_prefixes, str_steal (&prefixes));
}

static void
irc_handle_isupport_statusmsg (struct server *s, char *value)
{
	cstr_set (&s->irc_statusmsg, xstrdup (value));
}

static void
irc_handle_isupport_extban (struct server *s, char *value)
{
	s->irc_extban_prefix = 0;
	if (*value && *value != ',')
		s->irc_extban_prefix = *value++;

	cstr_set (&s->irc_extban_types, xstrdup (*value == ',' ? ++value : ""));
}

static void
irc_handle_isupport_chanmodes (struct server *s, char *value)
{
	struct strv v = strv_make ();
	cstr_split (value, ",", true, &v);
	if (v.len >= 4)
	{
		cstr_set (&s->irc_chanmodes_list,           xstrdup (v.vector[0]));
		cstr_set (&s->irc_chanmodes_param_always,   xstrdup (v.vector[1]));
		cstr_set (&s->irc_chanmodes_param_when_set, xstrdup (v.vector[2]));
		cstr_set (&s->irc_chanmodes_param_never,    xstrdup (v.vector[3]));
	}
	strv_free (&v);
}

static void
irc_handle_isupport_modes (struct server *s, char *value)
{
	unsigned long modes;
	if (!*value)
		s->irc_max_modes = UINT_MAX;
	else if (xstrtoul (&modes, value, 10) && modes && modes <= UINT_MAX)
		s->irc_max_modes = modes;
}

static void
unescape_isupport_value (const char *value, struct str *output)
{
	const char *alphabet = "0123456789abcdef", *a, *b;
	for (const char *p = value; *p; p++)
	{
		if (p[0] == '\\'
		 && p[1] == 'x'
		 && p[2] && (a = strchr (alphabet, tolower_ascii (p[2])))
		 && p[3] && (b = strchr (alphabet, tolower_ascii (p[3]))))
		{
			str_append_c (output, (a - alphabet) << 4 | (b - alphabet));
			p += 3;
		}
		else
			str_append_c (output, *p);
	}
}

static void
dispatch_isupport (struct server *s, const char *name, char *value)
{
#define MATCH(from, to) if (!strcmp (name, (from))) { (to) (s, value); return; }

	// TODO: also make use of TARGMAX to split client commands as necessary

	MATCH ("PREFIX",      irc_handle_isupport_prefix);
	MATCH ("CASEMAPPING", irc_handle_isupport_casemapping);
	MATCH ("CHANTYPES",   irc_handle_isupport_chantypes);
	MATCH ("IDCHAN",      irc_handle_isupport_idchan);
	MATCH ("STATUSMSG",   irc_handle_isupport_statusmsg);
	MATCH ("EXTBAN",      irc_handle_isupport_extban);
	MATCH ("CHANMODES",   irc_handle_isupport_chanmodes);
	MATCH ("MODES",       irc_handle_isupport_modes);

#undef MATCH
}

static void
irc_handle_rpl_isupport (struct server *s, const struct irc_message *msg)
{
	if (msg->params.len < 2)
		return;

	for (size_t i = 1; i < msg->params.len - 1; i++)
	{
		// TODO: if the parameter starts with "-", it resets to default
		char *param = msg->params.vector[i];
		char *value = param + strcspn (param, "=");
		if (*value) *value++ = '\0';

		struct str value_unescaped = str_make ();
		unescape_isupport_value (value, &value_unescaped);
		dispatch_isupport (s, param, value_unescaped.str);
		str_free (&value_unescaped);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
irc_adjust_motd (char **motd)
{
	// Heuristic, force MOTD to be monospace in graphical frontends.
	if (!strchr (*motd, '\x11'))
	{
		struct str s = str_make ();
		str_append_c (&s, '\x11');
		for (const char *p = *motd; *p; p++)
		{
			str_append_c (&s, *p);
			if (*p == '\x0f')
				str_append_c (&s, '\x11');
		}
		cstr_set (motd, str_steal (&s));
	}
}

static void
irc_process_numeric (struct server *s,
	const struct irc_message *msg, unsigned long numeric)
{
	// Numerics typically have human-readable information

	// Get rid of the first parameter, if there's any at all,
	// as it contains our nickname and is of no practical use to the user
	struct strv copy = strv_make ();
	strv_append_vector (&copy, msg->params.vector + !!msg->params.len);

	struct buffer *buffer = s->buffer;
	int flags = 0;
	switch (numeric)
	{
	case IRC_RPL_WELCOME:
		irc_on_registered (s, msg->params.vector[0]);

		// We still issue a USERHOST anyway as this is in general unreliable
		if (msg->params.len == 2)
			irc_try_parse_welcome_for_userhost (s, msg->params.vector[1]);
		break;
	case IRC_RPL_MOTDSTART:
	case IRC_RPL_MOTD:
		if (copy.len)
			irc_adjust_motd (&copy.vector[0]);
		break;

	case IRC_RPL_ISUPPORT:
		irc_handle_rpl_isupport      (s, msg);                break;
	case IRC_RPL_USERHOST:
		irc_handle_rpl_userhost      (s, msg);                break;
	case IRC_RPL_UMODEIS:
		irc_handle_rpl_umodeis       (s, msg); buffer = NULL; break;
	case IRC_RPL_NAMREPLY:
		irc_handle_rpl_namreply      (s, msg); buffer = NULL; break;
	case IRC_RPL_ENDOFNAMES:
		irc_handle_rpl_endofnames    (s, msg); buffer = NULL; break;
	case IRC_RPL_TOPIC:
		irc_handle_rpl_topic         (s, msg); buffer = NULL; break;
	case IRC_RPL_CHANNELMODEIS:
		irc_handle_rpl_channelmodeis (s, msg); buffer = NULL; break;
	case IRC_RPL_CREATIONTIME:
		irc_handle_rpl_creationtime  (s, msg); buffer = NULL; break;
	case IRC_RPL_TOPICWHOTIME:
		irc_handle_rpl_topicwhotime  (s, msg); buffer = NULL; break;
	case IRC_RPL_INVITING:
		irc_handle_rpl_inviting      (s, msg); buffer = NULL; break;

	case IRC_ERR_NICKNAMEINUSE:
		irc_handle_err_nicknameinuse (s, msg); buffer = NULL; break;

		// Auto-away spams server buffers with activity
	case IRC_RPL_NOWAWAY:
		flags |= BUFFER_LINE_UNIMPORTANT;
		if (s->irc_user) s->irc_user->away = true;
		break;
	case IRC_RPL_UNAWAY:
		flags |= BUFFER_LINE_UNIMPORTANT;
		if (s->irc_user) s->irc_user->away = false;
		break;

	case IRC_RPL_WHOREPLY:
		if (irc_handle_rpl_whoreply (s, msg))  buffer = NULL;
		break;
	case IRC_RPL_ENDOFWHO:
		if (irc_handle_rpl_endofwho (s, msg))  buffer = NULL;
		break;

	case IRC_ERR_NICKLOCKED:
	case IRC_RPL_SASLSUCCESS:
	case IRC_ERR_SASLFAIL:
	case IRC_ERR_SASLTOOLONG:
	case IRC_ERR_SASLABORTED:
	case IRC_ERR_SASLALREADY:
		irc_try_finish_cap_negotiation (s);
		break;

	case IRC_RPL_LIST:

	case IRC_ERR_UNKNOWNCOMMAND:
	case IRC_ERR_NEEDMOREPARAMS:
		// Just preventing these commands from getting printed in a more
		// specific buffer as that would be unwanted
		break;

	default:
		// If the second parameter is something we have a buffer for
		// (a channel, a PM buffer), log it in that buffer.  This is very basic.
		// TODO: whitelist/blacklist a lot more replies in here.
		// TODO: we should either strip the first parameter from the resulting
		//   buffer line, or at least put it in brackets
		if (msg->params.len > 1)
		{
			struct buffer *x;
			if ((x = str_map_find (&s->irc_buffer_map, msg->params.vector[1])))
				buffer = x;
		}
	}

	if (buffer)
	{
		// Join the parameter vector back and send it to the server buffer
		log_server (s, buffer, flags, BUFFER_LINE_STATUS,
			"#&m", strv_join (&copy, " "));
	}

	strv_free (&copy);
}

static void
irc_sanitize_cut_off_utf8 (char **line)
{
	// A variation on utf8_validate(), we need to detect the -2 return
	const char *p = *line, *end = strchr (p, 0);
	int32_t codepoint;
	while ((codepoint = utf8_decode (&p, end - p)) >= 0
		&& utf8_validate_cp (codepoint))
		;
	if (codepoint != -2)
		return;

	struct str fixed_up = str_make ();
	str_append_data (&fixed_up, *line, p - *line);
	str_append (&fixed_up, "\xEF\xBF\xBD" /* U+FFFD */);
	cstr_set (line, str_steal (&fixed_up));
}

static void
irc_process_message (const struct irc_message *msg, struct server *s)
{
	if (msg->params.len)
		irc_sanitize_cut_off_utf8 (&msg->params.vector[msg->params.len - 1]);

	// TODO: make use of IRCv3.2 server-time (with fallback to unixtime_msec())
	//   -> change all calls to log_{server,nick,chghost,outcoming,ctcp}*()
	//   to take an extra numeric argument specifying time
	struct irc_handler key = { .name = msg->command };
	struct irc_handler *handler = bsearch (&key, g_irc_handlers,
		N_ELEMENTS (g_irc_handlers), sizeof key, irc_handler_cmp_by_name);
	if (handler)
		handler->handler (s, msg);

	unsigned long numeric;
	if (xstrtoul (&numeric, msg->command, 10))
		irc_process_numeric (s, msg, numeric);

	// Better always make sure everything is in sync rather than care about
	// each case explicitly whether anything might have changed
	refresh_prompt (s->ctx);
}

// --- Message autosplitting magic ---------------------------------------------

// This is a rather basic algorithm; something like ICU with proper
// locale specification would be needed to make it work better.

static size_t
wrap_text_for_single_line (const char *text, struct irc_char_attrs *attrs,
	size_t text_len, size_t target_len, struct str *output)
{
	size_t eaten = 0;

	// First try going word by word
	const char *word_start;
	const char *word_end = text + strcspn (text, " ");
	size_t word_len = word_end - text;
	while (target_len && word_len <= target_len)
	{
		if (word_len)
		{
			str_append_data (output, text, word_len);

			text += word_len;
			eaten += word_len;
			target_len -= word_len;
		}

		// Find the next word's end
		word_start = text + strspn (text, " ");
		word_end = word_start + strcspn (word_start, " ");
		word_len = word_end - text;
	}

	if (eaten)
		// Discard whitespace between words if split
		return eaten + (word_start - text);

	// And if that doesn't help, cut the longest valid block of characters
	for (size_t i = 1; i <= text_len && i <= target_len; i++)
		if (i == text_len || attrs[i].starts_at_boundary)
			eaten = i;

	str_append_data (output, text, eaten);
	return eaten;
}

// In practice, this should never fail at all, although it's not guaranteed
static bool
wrap_message (const char *message,
	int line_max, struct strv *output, struct error **e)
{
	size_t message_left = strlen (message), i = 0;
	struct irc_char_attrs *attrs = irc_analyze_text (message, message_left);
	struct str m = str_make ();
	if (line_max <= 0)
		goto error;

	while (m.len + message_left > (size_t) line_max)
	{
		size_t eaten = wrap_text_for_single_line
			(message + i, attrs + i, message_left, line_max - m.len, &m);
		if (!eaten)
			goto error;

		strv_append_owned (output, str_steal (&m));
		m = str_make ();

		i += eaten;
		if (!(message_left -= eaten))
			break;

		irc_serialize_char_attrs (attrs + i, &m);
		if (m.len >= (size_t) line_max)
		{
			print_debug ("formatting continuation too long");
			str_reset (&m);
		}
	}
	if (message_left)
		strv_append_owned (output,
			xstrdup_printf ("%s%s", m.str, message + i));

	free (attrs);
	str_free (&m);
	return true;

error:
	free (attrs);
	str_free (&m);
	return error_set (e,
		"Message splitting was unsuccessful as there was "
		"too little room for UTF-8 characters");
}

/// Automatically splits messages that arrive at other clients with our prefix
/// so that they don't arrive cut off by the server
static bool
irc_autosplit_message (struct server *s, const char *message,
	int fixed_part, struct strv *output, struct error **e)
{
	// :<nick>!<user>@<host> <fixed-part><message>
	int space_in_one_message = 0;
	if (s->irc_user && s->irc_user_host)
		space_in_one_message = 510
			- 1 - (int) strlen (s->irc_user->nickname)
			- 1 - (int) strlen (s->irc_user_host)
			- 1 - fixed_part;

	// However we don't always have the full info for message splitting
	if (!space_in_one_message)
		strv_append (output, message);
	else if (!wrap_message (message, space_in_one_message, output, e))
		return false;
	return true;
}

static void
send_autosplit_message (struct server *s,
	const char *command, const char *target, const char *message,
	const char *prefix, const char *suffix)
{
	struct buffer *buffer = str_map_find (&s->irc_buffer_map, target);
	int fixed_part = strlen (command) + 1 + strlen (target) + 1 + 1
		+ strlen (prefix) + strlen (suffix);

	// We might also want to preserve attributes across splits but
	// that would make this code a lot more complicated

	struct strv lines = strv_make ();
	struct error *e = NULL;
	if (!irc_autosplit_message (s, message, fixed_part, &lines, &e))
	{
		log_server_error (s, buffer ? buffer : s->buffer, "#s", e->message);
		error_free (e);
	}
	else
	{
		for (size_t i = 0; i < lines.len; i++)
			irc_send (s, "%s %s :%s%s%s", command, target,
				prefix, lines.vector[i], suffix);
	}
	strv_free (&lines);
}

#define SEND_AUTOSPLIT_ACTION(s, target, message)                              \
	send_autosplit_message ((s), "PRIVMSG", (target), (message),               \
		"\x01" "ACTION ", "\x01")

#define SEND_AUTOSPLIT_PRIVMSG(s, target, message)                             \
	send_autosplit_message ((s), "PRIVMSG", (target), (message), "", "")

#define SEND_AUTOSPLIT_NOTICE(s, target, message)                              \
	send_autosplit_message ((s), "NOTICE", (target), (message), "", "")

// --- Configuration dumper ----------------------------------------------------

struct config_dump_data
{
	struct strv path;                   ///< Levels
	struct strv *output;                ///< Where to place new entries
};

static void config_dump_item
	(struct config_item *item, struct config_dump_data *data);

static void
config_dump_children
	(struct config_item *object, struct config_dump_data *data)
{
	hard_assert (object->type == CONFIG_ITEM_OBJECT);

	struct str_map_iter iter = str_map_iter_make (&object->value.object);
	struct config_item *child;
	while ((child = str_map_iter_next (&iter)))
	{
		strv_append_owned (&data->path, iter.link->key);
		config_dump_item (child, data);
		strv_steal (&data->path, data->path.len - 1);
	}
}

static void
config_dump_item (struct config_item *item, struct config_dump_data *data)
{
	// Empty objects will show as such
	if (item->type == CONFIG_ITEM_OBJECT
	 && item->value.object.len)
	{
		config_dump_children (item, data);
		return;
	}

	// Currently there's no reason for us to dump unknown items
	struct config_schema *schema = item->schema;
	if (!schema)
		return;

	struct str line = str_make ();
	if (data->path.len)
		str_append (&line, data->path.vector[0]);
	for (size_t i = 1; i < data->path.len; i++)
		str_append_printf (&line, ".%s", data->path.vector[i]);

	struct str value = str_make ();
	config_item_write (item, false, &value);

	// Don't bother writing out null values everywhere
	bool has_default = schema && schema->default_;
	if (item->type != CONFIG_ITEM_NULL || has_default)
	{
		str_append (&line, " = ");
		str_append_str (&line, &value);
	}

	if (!schema)
		str_append (&line, " (unrecognized)");
	else if (has_default && strcmp (schema->default_, value.str))
		str_append_printf (&line, " (default: %s)", schema->default_);
	else if (!has_default && item->type != CONFIG_ITEM_NULL)
		str_append_printf (&line, " (default: %s)", "null");

	str_free (&value);
	strv_append_owned (data->output, str_steal (&line));
}

static void
config_dump (struct config_item *root, struct strv *output)
{
	struct config_dump_data data;
	data.path = strv_make ();
	data.output = output;

	config_dump_item (root, &data);

	hard_assert (!data.path.len);
	strv_free (&data.path);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
strv_sort_cb (const void *a, const void *b)
{
	return strcmp (*(const char **) a, *(const char **) b);
}

static void
strv_sort (struct strv *self)
{
	qsort (self->vector, self->len, sizeof *self->vector, strv_sort_cb);
}

static void
dump_matching_options
	(struct config_item *root, const char *mask, struct strv *output)
{
	config_dump (root, output);
	strv_sort (output);

	// Filter out results by wildcard matching
	for (size_t i = 0; i < output->len; i++)
	{
		// Yeah, I know
		char *key = cstr_cut_until (output->vector[i], " ");
		if (fnmatch (mask, key, 0))
			strv_remove (output, i--);
		free (key);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
save_configuration (struct app_context *ctx)
{
	struct str data = str_make ();
	serialize_configuration (ctx->config.root, &data);

	struct error *e = NULL;
	char *filename = write_configuration_file (NULL, &data, &e);
	str_free (&data);

	if (!filename)
	{
		log_global_error (ctx,
			"#s: #s", "Saving configuration failed", e->message);
		error_free (e);
	}
	else
		log_global_status (ctx, "Configuration written to `#s'", filename);
	free (filename);
}

// --- Server management -------------------------------------------------------

static bool
validate_server_name (const char *name)
{
	for (const unsigned char *p = (const unsigned char *) name; *p; p++)
		if (iscntrl_ascii (*p) || *p == '.')
			return false;
	return true;
}

static const char *
check_server_name_for_addition (struct app_context *ctx, const char *name)
{
	if (!strcasecmp_ascii (name, ctx->global_buffer->name))
		return "name collides with the global buffer";
	if (str_map_find (&ctx->servers, name))
		return "server already exists";
	if (!validate_server_name (name))
		return "invalid server name";
	return NULL;
}

static struct server *
server_add (struct app_context *ctx,
	const char *name, struct config_item *subtree)
{
	hard_assert (!str_map_find (&ctx->servers, name));

	struct server *s = server_new (&ctx->poller);
	s->ctx = ctx;
	s->name = xstrdup (name);
	str_map_set (&ctx->servers, s->name, s);
	s->config = subtree;

	// Add a buffer and activate it
	struct buffer *buffer = s->buffer = buffer_new (ctx->input,
		BUFFER_SERVER, irc_make_buffer_name (s, NULL));
	buffer->server = s;

	buffer_add (ctx, buffer);
	buffer_activate (ctx, buffer);

	config_schema_apply_to_object (g_config_server, subtree, s);
	config_schema_call_changed (subtree);

	if (get_config_boolean (s->config, "autoconnect"))
		// Connect to the server ASAP
		poller_timer_set (&s->reconnect_tmr, 0);
	return s;
}

static void
server_add_new (struct app_context *ctx, const char *name)
{
	// Note that there may already be something in the configuration under
	// that key that we've ignored earlier, and there may also be
	// a case-insensitive conflict.  Those things may only happen as a result
	// of manual edits to the configuration, though, and they're not really
	// going to break anything.  They only cause surprises when loading.
	struct str_map *servers = get_servers_config (ctx);
	struct config_item *subtree = config_item_object ();
	str_map_set (servers, name, subtree);

	struct server *s = server_add (ctx, name, subtree);
	struct error *e = NULL;
	if (!irc_autofill_user_info (s, &e))
	{
		log_server_error (s, s->buffer,
			"#s: #s", "Failed to fill in user details", e->message);
		error_free (e);
	}
}

static void
server_remove (struct app_context *ctx, struct server *s)
{
	hard_assert (!irc_is_connected (s));

	if (s->buffer)
		buffer_remove_safe (ctx, s->buffer);

	struct str_map_unset_iter iter =
		str_map_unset_iter_make (&s->irc_buffer_map);
	struct buffer *buffer;
	while ((buffer = str_map_unset_iter_next (&iter)))
		buffer_remove_safe (ctx, buffer);
	str_map_unset_iter_free (&iter);

	hard_assert (!s->buffer);
	hard_assert (!s->irc_buffer_map.len);
	hard_assert (!s->irc_channels.len);
	soft_assert (!s->irc_users.len);

	str_map_set (get_servers_config (ctx), s->name, NULL);
	s->config = NULL;

	// This actually destroys the server as it's owned by the map
	str_map_set (&ctx->servers, s->name, NULL);
}

static void
server_rename (struct app_context *ctx, struct server *s, const char *new_name)
{
	hard_assert (!str_map_find (&ctx->servers, new_name));
	str_map_set (&ctx->servers, new_name,
		str_map_steal (&ctx->servers, s->name));

	struct str_map *servers = get_servers_config (ctx);
	str_map_set (servers, new_name, str_map_steal (servers, s->name));

	cstr_set (&s->name, xstrdup (new_name));
	buffer_rename (ctx, s->buffer, new_name);

	struct str_map_iter iter = str_map_iter_make (&s->irc_buffer_map);
	struct buffer *buffer;
	while ((buffer = str_map_iter_next (&iter)))
	{
		char *x = NULL;
		switch (buffer->type)
		{
		case BUFFER_PM:
			x = irc_make_buffer_name (s, buffer->user->nickname);
			break;
		case BUFFER_CHANNEL:
			x = irc_make_buffer_name (s, buffer->channel->name);
			break;
		default:
			hard_assert (!"unexpected type of server-related buffer");
		}
		buffer_rename (ctx, buffer, x);
		free (x);
	}
}

// --- Plugins -----------------------------------------------------------------

/// Returns the basename of the plugin's name without any extensions,
/// or NULL if the name isn't suitable (starts with a dot)
static char *
plugin_config_name (struct plugin *self)
{
	const char *begin = self->name;
	for (const char *p = begin; *p; )
		if (*p++ == '/')
			begin = p;

	size_t len = strcspn (begin, ".");
	if (!len)
		return NULL;

	// XXX: we might also allow arbitrary strings as object keys (except dots)
	char *copy = xstrndup (begin, len);
	for (char *p = copy; *p; p++)
		if (!config_tokenizer_is_word_char (*p))
			*p = '_';
	return copy;
}

// --- Lua ---------------------------------------------------------------------

// Each plugin has its own Lua state object, so that a/ they don't disturb each
// other and b/ unloading a plugin releases all resources.
//
// References to internal objects (buffers, servers) are all weak.

#ifdef HAVE_LUA

struct lua_plugin
{
	struct plugin super;                ///< The structure we're deriving
	struct app_context *ctx;            ///< Application context
	lua_State *L;                       ///< Lua state for the main thread

	struct lua_schema_item *schemas;    ///< Registered schema items
};

static void
lua_plugin_gc (struct plugin *self_)
{
	struct lua_plugin *self = (struct lua_plugin *) self_;
	lua_gc (self->L, LUA_GCCOLLECT, 0 /* Lua 5.3 required, 5.4 varargs */);
}

static void
lua_plugin_free (struct plugin *self_)
{
	struct lua_plugin *self = (struct lua_plugin *) self_;
	lua_close (self->L);
}

struct plugin_vtable lua_plugin_vtable =
{
	.gc   = lua_plugin_gc,
	.free = lua_plugin_free,
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// The registry can be used as a cache for weakly referenced objects

static bool
lua_cache_get (lua_State *L, void *object)
{
	lua_rawgetp (L, LUA_REGISTRYINDEX, object);
	if (lua_isnil (L, -1))
	{
		lua_pop (L, 1);
		return false;
	}
	return true;
}

static void
lua_cache_store (lua_State *L, void *object, int index)
{
	lua_pushvalue (L, index);
	lua_rawsetp (L, LUA_REGISTRYINDEX, object);
}

static void
lua_cache_invalidate (lua_State *L, void *object)
{
	lua_pushnil (L);
	lua_rawsetp (L, LUA_REGISTRYINDEX, object);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/// Append a traceback to all errors so that we can later extract it
static int
lua_plugin_error_handler (lua_State *L)
{
	luaL_traceback (L, L, luaL_checkstring (L, 1), 1);
	return 1;
}

static bool
lua_plugin_process_error (struct lua_plugin *self, const char *message,
	struct error **e)
{
	struct strv v = strv_make ();
	cstr_split (message, "\n", true, &v);

	if (v.len < 2)
		error_set (e, "%s", message);
	else
	{
		error_set (e, "%s", v.vector[0]);
		log_global_debug (self->ctx, "Lua: plugin \"#s\": #s",
			self->super.name, v.vector[1]);
		for (size_t i = 2; i < v.len; i++)
			log_global_debug (self->ctx, " #s", v.vector[i]);
	}

	strv_free (&v);
	return false;
}

/// Call a Lua function and process errors using our special error handler
static bool
lua_plugin_call (struct lua_plugin *self,
	int n_params, int n_results, struct error **e)
{
	// XXX: this may eventually be called from a thread, then this is wrong
	lua_State *L = self->L;

	// We need to pop the error handler at the end
	lua_pushcfunction (L, lua_plugin_error_handler);
	int error_handler_idx = -n_params - 2;
	lua_insert (L, error_handler_idx);

	if (!lua_pcall (L, n_params, n_results, error_handler_idx))
	{
		lua_remove (L, -n_results - 1);
		return true;
	}

	(void) lua_plugin_process_error (self, lua_tostring (L, -1), e);
	lua_pop (L, 2);
	return false;
}

/// Convenience function; replaces the "original" string or produces an error
static bool
lua_plugin_handle_string_filter_result (struct lua_plugin *self,
	char **original, bool utf8, struct error **e)
{
	lua_State *L = self->L;
	if (lua_isnil (L, -1))
	{
		cstr_set (original, NULL);
		return true;
	}
	if (!lua_isstring (L, -1))
		return error_set (e, "must return either a string or nil");

	size_t len;
	const char *processed = lua_tolstring (L, -1, &len);
	if (utf8 && !utf8_validate (processed, len))
		return error_set (e, "must return valid UTF-8");

	// Only replace the string if it's different
	if (strcmp (processed, *original))
		cstr_set (original, xstrdup (processed));
	return true;
}

static const char *
lua_plugin_check_utf8 (lua_State *L, int arg)
{
	size_t len;
	const char *s = luaL_checklstring (L, arg, &len);
	luaL_argcheck (L, utf8_validate (s, len), arg, "must be valid UTF-8");
	return s;
}

static void
lua_plugin_log_error
	(struct lua_plugin *self, const char *where, struct error *error)
{
	log_global_error (self->ctx, "Lua: plugin \"#s\": #s: #s",
		self->super.name, where, error->message);
	error_free (error);
}

/// Pop "n" values from the stack into a table, using their indexes as keys
static void
lua_plugin_pack (lua_State *L, int n)
{
	lua_createtable (L, n, 0);
	lua_insert (L, -n - 1);
	for (int i = n; i; i--)
		lua_rawseti (L, -i - 1, i);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
lua_plugin_kv (lua_State *L, const char *key, const char *value)
{
	lua_pushstring (L, value);
	lua_setfield (L, -2, key);
}

static void
lua_plugin_push_message (lua_State *L, const struct irc_message *msg)
{
	lua_createtable (L, 0, 4);

	lua_createtable (L, msg->tags.len, 0);
	struct str_map_iter iter = str_map_iter_make (&msg->tags);
	const char *value;
	while ((value = str_map_iter_next (&iter)))
		lua_plugin_kv (L, iter.link->key, value);
	lua_setfield (L, -2, "tags");

	// TODO: parse the prefix further?
	if (msg->prefix)   lua_plugin_kv (L, "prefix",  msg->prefix);
	if (msg->command)  lua_plugin_kv (L, "command", msg->command);

	lua_createtable (L, msg->params.len, 0);
	for (size_t i = 0; i < msg->params.len; i++)
	{
		lua_pushstring (L, msg->params.vector[i]);
		lua_rawseti (L, -2, i + 1);
	}
	lua_setfield (L, -2, "params");
}

static int
lua_plugin_parse (lua_State *L)
{
	struct irc_message msg;
	irc_parse_message (&msg, luaL_checkstring (L, 1));
	lua_plugin_push_message (L, &msg);
	irc_free_message (&msg);
	return 1;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Lua code can use weakly referenced wrappers for internal objects.

typedef struct weak_ref_link *
	(*lua_weak_ref_fn) (void *object, destroy_cb_fn cb, void *user_data);
typedef void (*lua_weak_unref_fn) (void *object, struct weak_ref_link **link);

struct lua_weak_info
{
	const char *name;                   ///< Metatable name
	struct ispect_field *ispect;        ///< Introspection data

	lua_weak_ref_fn ref;                ///< Weak link invalidator
	lua_weak_unref_fn unref;            ///< Weak link generator
};

struct lua_weak
{
	struct lua_plugin *plugin;          ///< The plugin we belong to
	struct lua_weak_info *info;         ///< Introspection data
	void *object;                       ///< The object
	struct weak_ref_link *weak_ref;     ///< A weak reference link
};

static void
lua_weak_invalidate (void *object, void *user_data)
{
	struct lua_weak *wrapper = user_data;
	wrapper->object = NULL;
	wrapper->weak_ref = NULL;
	// This can in theory call the GC, order isn't arbitrary here
	lua_cache_invalidate (wrapper->plugin->L, object);
}

static void
lua_weak_push (lua_State *L, struct lua_plugin *plugin, void *object,
	struct lua_weak_info *info)
{
	if (!object)
	{
		lua_pushnil (L);
		return;
	}
	if (lua_cache_get (L, object))
		return;

	struct lua_weak *wrapper = lua_newuserdata (L, sizeof *wrapper);
	luaL_setmetatable (L, info->name);
	wrapper->plugin = plugin;
	wrapper->info = info;
	wrapper->object = object;
	wrapper->weak_ref = NULL;
	if (info->ref)
		wrapper->weak_ref = info->ref (object, lua_weak_invalidate, wrapper);
	lua_cache_store (L, object, -1);
}

static int
lua_weak_gc (lua_State *L, const struct lua_weak_info *info)
{
	struct lua_weak *wrapper = luaL_checkudata (L, 1, info->name);
	if (wrapper->object)
	{
		lua_cache_invalidate (L, wrapper->object);
		if (info->unref)
			info->unref (wrapper->object, &wrapper->weak_ref);
		wrapper->object = NULL;
	}
	return 0;
}

static struct lua_weak *
lua_weak_deref (lua_State *L, const struct lua_weak_info *info)
{
	struct lua_weak *weak = luaL_checkudata (L, 1, info->name);
	luaL_argcheck (L, weak->object, 1, "dead reference used");
	return weak;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#define LUA_WEAK_DECLARE(id, metatable_id)                                     \
	static struct lua_weak_info lua_ ## id ## _info =                          \
	{                                                                          \
		.name   = metatable_id,                                                \
		.ispect = g_ ## id ## _ispect,                                         \
		.ref    = (lua_weak_ref_fn)   id ## _weak_ref,                         \
		.unref  = (lua_weak_unref_fn) id ## _weak_unref,                       \
	};

#define XLUA_USER_METATABLE    "user"     ///< Identifier for Lua metatable
#define XLUA_CHANNEL_METATABLE "channel"  ///< Identifier for Lua metatable
#define XLUA_BUFFER_METATABLE  "buffer"   ///< Identifier for Lua metatable
#define XLUA_SERVER_METATABLE  "server"   ///< Identifier for Lua metatable

LUA_WEAK_DECLARE (user,    XLUA_USER_METATABLE)
LUA_WEAK_DECLARE (channel, XLUA_CHANNEL_METATABLE)
LUA_WEAK_DECLARE (buffer,  XLUA_BUFFER_METATABLE)
LUA_WEAK_DECLARE (server,  XLUA_SERVER_METATABLE)

// The global context is kind of fake and doesn't have any ref-counting,
// however it's still very much an object
static struct lua_weak_info lua_ctx_info =
{
	.name = PROGRAM_NAME,
	.ispect = g_ctx_ispect,
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_user_gc (lua_State *L)
{
	return lua_weak_gc (L, &lua_user_info);
}

static int
lua_user_get_channels (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_user_info);
	struct user *user = wrapper->object;

	int i = 1;
	lua_newtable (L);
	LIST_FOR_EACH (struct user_channel, iter, user->channels)
	{
		lua_weak_push (L, wrapper->plugin, iter->channel, &lua_channel_info);
		lua_rawseti (L, -2, i++);
	}
	return 1;
}

static luaL_Reg lua_user_table[] =
{
	{ "__gc",         lua_user_gc           },
	{ "get_channels", lua_user_get_channels },
	{ NULL,           NULL                  }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_channel_gc (lua_State *L)
{
	return lua_weak_gc (L, &lua_channel_info);
}

static int
lua_channel_get_users (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_channel_info);
	struct channel *channel = wrapper->object;

	int i = 1;
	lua_newtable (L);
	LIST_FOR_EACH (struct channel_user, iter, channel->users)
	{
		lua_createtable (L, 0, 2);
		lua_weak_push (L, wrapper->plugin, iter->user, &lua_user_info);
		lua_setfield (L, -2, "user");
		lua_plugin_kv (L, "prefixes", iter->prefixes);

		lua_rawseti (L, -2, i++);
	}
	return 1;
}

static luaL_Reg lua_channel_table[] =
{
	{ "__gc",      lua_channel_gc        },
	{ "get_users", lua_channel_get_users },
	{ NULL,        NULL                  }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_buffer_gc (lua_State *L)
{
	return lua_weak_gc (L, &lua_buffer_info);
}

static int
lua_buffer_log (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_buffer_info);
	struct buffer *buffer = wrapper->object;
	const char *message = lua_plugin_check_utf8 (L, 2);
	log_full (wrapper->plugin->ctx, buffer->server, buffer,
		0, BUFFER_LINE_STATUS, "#s", message);
	return 0;
}

static int
lua_buffer_execute (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_buffer_info);
	struct buffer *buffer = wrapper->object;
	const char *line = lua_plugin_check_utf8 (L, 2);
	(void) process_input_utf8 (wrapper->plugin->ctx, buffer, line, 0);
	return 0;
}

static luaL_Reg lua_buffer_table[] =
{
	{ "__gc",        lua_buffer_gc          },
	{ "log",         lua_buffer_log         },
	{ "execute",     lua_buffer_execute     },
	{ NULL,          NULL                   }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_server_gc (lua_State *L)
{
	return lua_weak_gc (L, &lua_server_info);
}

static int
lua_server_get_state (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_server_info);
	struct server *server = wrapper->object;
	switch (server->state)
	{
	case IRC_DISCONNECTED: lua_pushstring (L, "disconnected"); break;
	case IRC_CONNECTING:   lua_pushstring (L, "connecting");   break;
	case IRC_CONNECTED:    lua_pushstring (L, "connected");    break;
	case IRC_REGISTERED:   lua_pushstring (L, "registered");   break;
	case IRC_CLOSING:      lua_pushstring (L, "closing");      break;
	case IRC_HALF_CLOSED:  lua_pushstring (L, "half_closed");  break;
	}
	return 1;
}

static int
lua_server_send (lua_State *L)
{
	struct lua_weak *wrapper = lua_weak_deref (L, &lua_server_info);
	struct server *server = wrapper->object;
	irc_send (server, "%s", luaL_checkstring (L, 2));
	return 0;
}

static luaL_Reg lua_server_table[] =
{
	{ "__gc",       lua_server_gc         },
	{ "get_state",  lua_server_get_state  },
	{ "send",       lua_server_send       },
	{ NULL,         NULL                  }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#define XLUA_HOOK_METATABLE "hook"      ///< Identifier for the Lua metatable

enum lua_hook_type
{
	XLUA_HOOK_DEFUNCT,                  ///< No longer functional
	XLUA_HOOK_INPUT,                    ///< Input hook
	XLUA_HOOK_IRC,                      ///< IRC hook
	XLUA_HOOK_PROMPT,                   ///< Prompt hook
	XLUA_HOOK_COMPLETION,               ///< Autocomplete
};

struct lua_hook
{
	struct lua_plugin *plugin;          ///< The plugin we belong to
	enum lua_hook_type type;            ///< Type of the hook
	int ref_callback;                   ///< Reference to the callback
	union
	{
		struct hook hook;               ///< Hook base structure
		struct input_hook input_hook;   ///< Input hook
		struct irc_hook irc_hook;       ///< IRC hook
		struct prompt_hook prompt_hook; ///< IRC hook
		struct completion_hook c_hook;  ///< Autocomplete hook
	}
	data;                               ///< Hook data
};

static int
lua_hook_unhook (lua_State *L)
{
	struct lua_hook *hook = luaL_checkudata (L, 1, XLUA_HOOK_METATABLE);
	switch (hook->type)
	{
	case XLUA_HOOK_INPUT:
		LIST_UNLINK (hook->plugin->ctx->input_hooks,      &hook->data.hook);
		break;
	case XLUA_HOOK_IRC:
		LIST_UNLINK (hook->plugin->ctx->irc_hooks,        &hook->data.hook);
		break;
	case XLUA_HOOK_PROMPT:
		LIST_UNLINK (hook->plugin->ctx->prompt_hooks,     &hook->data.hook);
		refresh_prompt (hook->plugin->ctx);
		break;
	case XLUA_HOOK_COMPLETION:
		LIST_UNLINK (hook->plugin->ctx->completion_hooks, &hook->data.hook);
		break;
	default:
		hard_assert (!"invalid hook type");
	case XLUA_HOOK_DEFUNCT:
		break;
	}

	luaL_unref (L, LUA_REGISTRYINDEX, hook->ref_callback);
	hook->ref_callback = LUA_REFNIL;

	// The hook no longer has to stay alive
	hook->type = XLUA_HOOK_DEFUNCT;
	lua_cache_invalidate (L, hook);
	return 0;
}

// The hook dies either when the plugin requests it or at plugin unload
static luaL_Reg lua_hook_table[] =
{
	{ "unhook", lua_hook_unhook },
	{ "__gc",   lua_hook_unhook },
	{ NULL,     NULL            }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static char *
lua_input_hook_filter (struct input_hook *self, struct buffer *buffer,
	char *input)
{
	struct lua_hook *hook =
		CONTAINER_OF (self, struct lua_hook, data.input_hook);
	struct lua_plugin *plugin = hook->plugin;
	lua_State *L = plugin->L;

	lua_rawgeti (L, LUA_REGISTRYINDEX, hook->ref_callback);
	lua_rawgetp (L, LUA_REGISTRYINDEX, hook);             // 1: hook
	lua_weak_push (L, plugin, buffer, &lua_buffer_info);  // 2: buffer
	lua_pushstring (L, input);                            // 3: input

	struct error *e = NULL;
	if (lua_plugin_call (plugin, 3, 1, &e))
	{
		lua_plugin_handle_string_filter_result (plugin, &input, true, &e);
		lua_pop (L, 1);
	}
	if (e)
		lua_plugin_log_error (plugin, "input hook", e);
	return input;
}

static char *
lua_irc_hook_filter (struct irc_hook *self, struct server *s, char *message)
{
	struct lua_hook *hook =
		CONTAINER_OF (self, struct lua_hook, data.irc_hook);
	struct lua_plugin *plugin = hook->plugin;
	lua_State *L = plugin->L;

	lua_rawgeti (L, LUA_REGISTRYINDEX, hook->ref_callback);
	lua_rawgetp (L, LUA_REGISTRYINDEX, hook);        // 1: hook
	lua_weak_push (L, plugin, s, &lua_server_info);  // 2: server
	lua_pushstring (L, message);                     // 3: message

	struct error *e = NULL;
	if (lua_plugin_call (plugin, 3, 1, &e))
	{
		lua_plugin_handle_string_filter_result (plugin, &message, false, &e);
		lua_pop (L, 1);
	}
	if (e)
		lua_plugin_log_error (plugin, "IRC hook", e);
	return message;
}

static char *
lua_prompt_hook_make (struct prompt_hook *self)
{
	struct lua_hook *hook =
		CONTAINER_OF (self, struct lua_hook, data.prompt_hook);
	struct lua_plugin *plugin = hook->plugin;
	lua_State *L = plugin->L;

	lua_rawgeti (L, LUA_REGISTRYINDEX, hook->ref_callback);
	lua_rawgetp (L, LUA_REGISTRYINDEX, hook);  // 1: hook

	struct error *e = NULL;
	char *prompt = xstrdup ("");
	if (lua_plugin_call (plugin, 1, 1, &e))
	{
		lua_plugin_handle_string_filter_result (plugin, &prompt, true, &e);
		lua_pop (L, 1);
	}
	if (e)
		lua_plugin_log_error (plugin, "prompt hook", e);
	return prompt;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
lua_plugin_push_completion (lua_State *L, struct completion *data)
{
	lua_createtable (L, 0, 3);

	lua_pushstring (L, data->line);
	lua_setfield (L, -2, "line");

	lua_createtable (L, data->words_len, 0);
	for (size_t i = 0; i < data->words_len; i++)
	{
		lua_pushlstring (L, data->line + data->words[i].start,
			data->words[i].end - data->words[i].start);
		lua_rawseti (L, -2, i + 1);
	}
	lua_setfield (L, -2, "words");

	lua_pushinteger (L, data->location);
	lua_setfield (L, -2, "location");
}

static bool
lua_completion_hook_process_value (lua_State *L, struct strv *output,
	struct error **e)
{
	if (lua_type (L, -1) != LUA_TSTRING)
	{
		return error_set (e,
			"%s: %s", "invalid type", lua_typename (L, lua_type (L, -1)));
	}

	size_t len;
	const char *value = lua_tolstring (L, -1, &len);
	if (!utf8_validate (value, len))
		return error_set (e, "must be valid UTF-8");

	strv_append (output, value);
	return true;
}

static bool
lua_completion_hook_process (lua_State *L, struct strv *output,
	struct error **e)
{
	if (lua_isnil (L, -1))
		return true;
	if (!lua_istable (L, -1))
		return error_set (e, "must return either a table or nil");

	bool success = true;
	for (lua_Integer i = 1; success && lua_rawgeti (L, -1, i); i++)
		if ((success = lua_completion_hook_process_value (L, output, e)))
			lua_pop (L, 1);
	lua_pop (L, 1);
	return success;
}

static void
lua_completion_hook_complete (struct completion_hook *self,
	struct completion *data, const char *word, struct strv *output)
{
	struct lua_hook *hook =
		CONTAINER_OF (self, struct lua_hook, data.c_hook);
	struct lua_plugin *plugin = hook->plugin;
	lua_State *L = plugin->L;

	lua_rawgeti (L, LUA_REGISTRYINDEX, hook->ref_callback);
	lua_rawgetp (L, LUA_REGISTRYINDEX, hook);  // 1: hook
	lua_plugin_push_completion (L, data);      // 2: data

	lua_weak_push (L, plugin, plugin->ctx->current_buffer, &lua_buffer_info);
	lua_setfield (L, -2, "buffer");

	lua_pushstring (L, word);                  // 3: word

	struct error *e = NULL;
	if (lua_plugin_call (plugin, 3, 1, &e))
	{
		lua_completion_hook_process (L, output, &e);
		lua_pop (L, 1);
	}
	if (e)
		lua_plugin_log_error (plugin, "autocomplete hook", e);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static struct lua_hook *
lua_plugin_push_hook (lua_State *L, struct lua_plugin *plugin,
	int callback_index, enum lua_hook_type type, int priority)
{
	luaL_checktype (L, callback_index, LUA_TFUNCTION);

	struct lua_hook *hook = lua_newuserdata (L, sizeof *hook);
	luaL_setmetatable (L, XLUA_HOOK_METATABLE);
	memset (hook, 0, sizeof *hook);
	hook->data.hook.priority = priority;
	hook->type = type;
	hook->plugin = plugin;

	lua_pushvalue (L, callback_index);
	hook->ref_callback = luaL_ref (L, LUA_REGISTRYINDEX);

	// Make sure the hook doesn't get garbage collected and return it
	lua_cache_store (L, hook, -1);
	return hook;
}

static int
lua_plugin_hook_input (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	struct lua_hook *hook = lua_plugin_push_hook
		(L, plugin, 1, XLUA_HOOK_INPUT, luaL_optinteger (L, 2, 0));
	hook->data.input_hook.filter = lua_input_hook_filter;
	plugin->ctx->input_hooks =
		hook_insert (plugin->ctx->input_hooks, &hook->data.hook);
	return 1;
}

static int
lua_plugin_hook_irc (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	struct lua_hook *hook = lua_plugin_push_hook
		(L, plugin, 1, XLUA_HOOK_IRC, luaL_optinteger (L, 2, 0));
	hook->data.irc_hook.filter = lua_irc_hook_filter;
	plugin->ctx->irc_hooks =
		hook_insert (plugin->ctx->irc_hooks, &hook->data.hook);
	return 1;
}

static int
lua_plugin_hook_prompt (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	struct lua_hook *hook = lua_plugin_push_hook
		(L, plugin, 1, XLUA_HOOK_PROMPT, luaL_optinteger (L, 2, 0));
	hook->data.prompt_hook.make = lua_prompt_hook_make;
	plugin->ctx->prompt_hooks =
		hook_insert (plugin->ctx->prompt_hooks, &hook->data.hook);
	refresh_prompt (plugin->ctx);
	return 1;
}

static int
lua_plugin_hook_completion (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	struct lua_hook *hook = lua_plugin_push_hook
		(L, plugin, 1, XLUA_HOOK_COMPLETION, luaL_optinteger (L, 2, 0));
	hook->data.c_hook.complete = lua_completion_hook_complete;
	plugin->ctx->completion_hooks =
		hook_insert (plugin->ctx->completion_hooks, &hook->data.hook);
	return 1;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

#define XLUA_SCHEMA_METATABLE "schema"  ///< Identifier for the Lua metatable

struct lua_schema_item
{
	LIST_HEADER (struct lua_schema_item)

	struct lua_plugin *plugin;          ///< The plugin we belong to
	struct config_item *item;           ///< The item managed by the schema
	struct config_schema schema;        ///< Schema itself

	int ref_validate;                   ///< Reference to "validate" callback
	int ref_on_change;                  ///< Reference to "on_change" callback
};

static void
lua_schema_item_discard (struct lua_schema_item *self)
{
	if (self->item)
	{
		self->item->schema = NULL;
		self->item->user_data = NULL;
		self->item = NULL;
		LIST_UNLINK (self->plugin->schemas, self);
	}

	// Now that we've disconnected from the item, allow garbage collection
	lua_cache_invalidate (self->plugin->L, self);
}

static int
lua_schema_item_gc (lua_State *L)
{
	struct lua_schema_item *self =
		luaL_checkudata (L, 1, XLUA_SCHEMA_METATABLE);
	lua_schema_item_discard (self);

	free ((char *) self->schema.name);
	free ((char *) self->schema.comment);
	free ((char *) self->schema.default_);

	luaL_unref (L, LUA_REGISTRYINDEX, self->ref_validate);
	luaL_unref (L, LUA_REGISTRYINDEX, self->ref_on_change);
	return 0;
}

static luaL_Reg lua_schema_table[] =
{
	{ "__gc", lua_schema_item_gc },
	{ NULL,   NULL               }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/// Unfortunately this has the same problem as JSON libraries in that Lua
/// cannot store null values in containers (it has no distinct "undefined" type)
static void
lua_plugin_push_config_item (lua_State *L, const struct config_item *item)
{
	switch (item->type)
	{
	case CONFIG_ITEM_NULL:
		lua_pushnil (L);
		break;
	case CONFIG_ITEM_OBJECT:
	{
		lua_createtable (L, 0, item->value.object.len);

		struct str_map_iter iter = str_map_iter_make (&item->value.object);
		struct config_item *child;
		while ((child = str_map_iter_next (&iter)))
		{
			lua_plugin_push_config_item (L, child);
			lua_setfield (L, -2, iter.link->key);
		}
		break;
	}
	case CONFIG_ITEM_BOOLEAN:
		lua_pushboolean (L, item->value.boolean);
		break;
	case CONFIG_ITEM_INTEGER:
		lua_pushinteger (L, item->value.integer);
		break;
	case CONFIG_ITEM_STRING:
	case CONFIG_ITEM_STRING_ARRAY:
		lua_pushlstring (L, item->value.string.str, item->value.string.len);
		break;
	}
}

static bool
lua_schema_item_validate (const struct config_item *item, struct error **e)
{
	struct lua_schema_item *self = item->user_data;
	if (self->ref_validate == LUA_REFNIL)
		return true;

	lua_State *L = self->plugin->L;
	lua_rawgeti (L, LUA_REGISTRYINDEX, self->ref_validate);
	lua_plugin_push_config_item (L, item);

	// The callback can make use of error("...", 0) to produce nice messages
	return lua_plugin_call (self->plugin, 1, 0, e);
}

static void
lua_schema_item_on_change (struct config_item *item)
{
	struct lua_schema_item *self = item->user_data;
	if (self->ref_on_change == LUA_REFNIL)
		return;

	lua_State *L = self->plugin->L;
	lua_rawgeti (L, LUA_REGISTRYINDEX, self->ref_on_change);
	lua_plugin_push_config_item (L, item);

	struct error *e = NULL;
	if (!lua_plugin_call (self->plugin, 1, 0, &e))
		lua_plugin_log_error (self->plugin, "schema on_change", e);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_plugin_decode_config_item_type (const char *type)
{
	if (!strcmp (type, "null"))         return CONFIG_ITEM_NULL;
	if (!strcmp (type, "object"))       return CONFIG_ITEM_OBJECT;
	if (!strcmp (type, "boolean"))      return CONFIG_ITEM_BOOLEAN;
	if (!strcmp (type, "integer"))      return CONFIG_ITEM_INTEGER;
	if (!strcmp (type, "string"))       return CONFIG_ITEM_STRING;
	if (!strcmp (type, "string_array")) return CONFIG_ITEM_STRING_ARRAY;
	return -1;
}

static bool
lua_plugin_check_field (lua_State *L, int idx, const char *name,
	int expected, bool optional)
{
	int found = lua_getfield (L, idx, name);
	if (found == expected)
		return true;
	if (optional && found == LUA_TNIL)
		return false;

	const char *message = optional
		? "invalid field \"%s\" (found: %s, expected: %s or nil)"
		: "invalid or missing field \"%s\" (found: %s, expected: %s)";
	return luaL_error (L, message, name,
		lua_typename (L, found), lua_typename (L, expected));
}

static int
lua_plugin_add_config_schema (lua_State *L, struct lua_plugin *plugin,
	struct config_item *subtree, const char *name)
{
	struct config_item *item = str_map_find (&subtree->value.object, name);
	// This should only ever happen because of a conflict with another plugin;
	// this is the price we pay for simplicity
	if (item && item->schema)
	{
		struct lua_schema_item *owner = item->user_data;
		return luaL_error (L, "conflicting schema item: %s (owned by: %s)",
			name, owner->plugin->super.name);
	}

	// Create and initialize a full userdata wrapper for the schema item
	struct lua_schema_item *self = lua_newuserdata (L, sizeof *self);
	luaL_setmetatable (L, XLUA_SCHEMA_METATABLE);
	memset (self, 0, sizeof *self);

	self->plugin = plugin;
	self->ref_on_change = LUA_REFNIL;
	self->ref_validate = LUA_REFNIL;

	struct config_schema *schema = &self->schema;
	schema->name      = xstrdup (name);
	schema->comment   = NULL;
	schema->default_  = NULL;
	schema->type      = CONFIG_ITEM_NULL;
	schema->on_change = lua_schema_item_on_change;
	schema->validate  = lua_schema_item_validate;

	// Try to update the defaults with values provided by the plugin
	int values = lua_absindex (L, -2);
	(void) lua_plugin_check_field (L, values, "type", LUA_TSTRING, false);
	int item_type = schema->type =
		lua_plugin_decode_config_item_type (lua_tostring (L, -1));
	if (item_type == -1)
		return luaL_error (L, "invalid type of schema item");

	if (lua_plugin_check_field (L, values, "comment",   LUA_TSTRING, true))
		schema->comment = xstrdup (lua_tostring (L, -1));
	if (lua_plugin_check_field (L, values, "default",   LUA_TSTRING, true))
		schema->default_ = xstrdup (lua_tostring (L, -1));

	lua_pop (L, 3);

	(void) lua_plugin_check_field (L, values, "on_change", LUA_TFUNCTION, true);
	self->ref_on_change = luaL_ref (L, LUA_REGISTRYINDEX);
	(void) lua_plugin_check_field (L, values, "validate",  LUA_TFUNCTION, true);
	self->ref_validate = luaL_ref (L, LUA_REGISTRYINDEX);

	// Try to install the created schema item into our configuration
	struct error *warning = NULL, *e = NULL;
	item = config_schema_initialize_item
		(&self->schema, subtree, self, &warning, &e);

	if (warning)
	{
		log_global_error (plugin->ctx, "Lua: plugin \"#s\": #s",
			plugin->super.name, warning->message);
		error_free (warning);
	}
	if (e)
	{
		const char *error = lua_pushstring (L, e->message);
		error_free (e);
		return luaL_error (L, "%s", error);
	}

	self->item = item;
	LIST_PREPEND (plugin->schemas, self);

	// On the stack there should be the schema table and the resulting object;
	// we need to make sure Lua doesn't GC the second and get rid of them both
	lua_cache_store (L, self, -1);
	lua_pop (L, 2);
	return 0;
}

static int
lua_plugin_setup_config (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	luaL_checktype (L, 1, LUA_TTABLE);

	struct app_context *ctx = plugin->ctx;
	char *config_name = plugin_config_name (&plugin->super);
	if (!config_name)
		return luaL_error (L, "unsuitable plugin name");

	struct str_map *plugins = get_plugins_config (ctx);
	struct config_item *subtree = str_map_find (plugins, config_name);
	if (!subtree || subtree->type != CONFIG_ITEM_OBJECT)
		str_map_set (plugins, config_name, (subtree = config_item_object ()));
	free (config_name);

	LIST_FOR_EACH (struct lua_schema_item, iter, plugin->schemas)
		lua_schema_item_discard (iter);

	// Load all schema items and apply them to the plugin's subtree
	lua_pushnil (L);
	while (lua_next (L, 1))
	{
		if (lua_type (L, -2) != LUA_TSTRING
		 || lua_type (L, -1) != LUA_TTABLE)
			return luaL_error (L, "%s: %s -> %s", "invalid types",
				lua_typename (L, lua_type (L, -2)),
				lua_typename (L, lua_type (L, -1)));
		lua_plugin_add_config_schema (L, plugin, subtree, lua_tostring (L, -2));
	}

	// Let the plugin read out configuration via on_change callbacks
	config_schema_call_changed (subtree);
	return 0;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/// Identifier for the Lua metatable
#define XLUA_CONNECTION_METATABLE "connection"

struct lua_connection
{
	struct lua_plugin *plugin;          ///< The plugin we belong to
	struct poller_fd socket_event;      ///< Socket is ready
	int socket_fd;                      ///< Underlying connected socket

	bool got_eof;                       ///< Half-closed by remote host
	bool closing;                       ///< We're closing the connection

	struct str read_buffer;             ///< Read buffer
	struct str write_buffer;            ///< Write buffer
};

static void
lua_connection_update_poller (struct lua_connection *self)
{
	poller_fd_set (&self->socket_event,
		self->write_buffer.len ? (POLLIN | POLLOUT) : POLLIN);
}

static int
lua_connection_send (lua_State *L)
{
	struct lua_connection *self =
		luaL_checkudata (L, 1, XLUA_CONNECTION_METATABLE);
	if (self->socket_fd == -1)
		return luaL_error (L, "connection has been closed");

	size_t len;
	const char *s = luaL_checklstring (L, 2, &len);
	str_append_data (&self->write_buffer, s, len);
	lua_connection_update_poller (self);
	return 0;
}

static void
lua_connection_discard (struct lua_connection *self)
{
	if (self->socket_fd != -1)
	{
		poller_fd_reset (&self->socket_event);
		xclose (self->socket_fd);
		self->socket_fd = -1;

		str_free (&self->read_buffer);
		str_free (&self->write_buffer);
	}

	// Connection is dead, we don't need to hold onto any resources anymore
	lua_cache_invalidate (self->plugin->L, self);
}

static int
lua_connection_close (lua_State *L)
{
	struct lua_connection *self =
		luaL_checkudata (L, 1, XLUA_CONNECTION_METATABLE);
	if (self->socket_fd != -1)
	{
		self->closing = true;
		// NOTE: this seems to do nothing on Linux
		(void) shutdown (self->socket_fd, SHUT_RD);

		// Right now we want to wait until all data is flushed to the socket
		// and can't call close() here immediately -- a rewrite to use async
		// would enable the user to await on either :send() or :flush();
		// a successful send() doesn't necessarily mean anything though
		if (!self->write_buffer.len)
			lua_connection_discard (self);
	}
	return 0;
}

static int
lua_connection_gc (lua_State *L)
{
	lua_connection_discard (luaL_checkudata (L, 1, XLUA_CONNECTION_METATABLE));
	return 0;
}

static luaL_Reg lua_connection_table[] =
{
	{ "send",  lua_connection_send  },
	{ "close", lua_connection_close },
	{ "__gc",  lua_connection_gc    },
	{ NULL,    NULL                 }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_connection_check_fn (lua_State *L)
{
	lua_plugin_check_field (L, 1, luaL_checkstring (L, 2), LUA_TFUNCTION, true);
	return 1;
}

// We need to run it in a protected environment because of lua_getfield()
static bool
lua_connection_cb_lookup (struct lua_connection *self, const char *name,
	struct error **e)
{
	lua_State *L = self->plugin->L;
	lua_pushcfunction (L, lua_connection_check_fn);
	hard_assert (lua_cache_get (L, self));
	lua_pushstring (L, name);
	return lua_plugin_call (self->plugin, 2, 1, e);
}

// Ideally lua_connection_cb_lookup() would return a ternary value
static bool
lua_connection_eat_nil (struct lua_connection *self)
{
	if (lua_toboolean (self->plugin->L, -1))
		return false;
	lua_pop (self->plugin->L, 1);
	return true;
}

static bool
lua_connection_invoke_on_data (struct lua_connection *self, struct error **e)
{
	if (!lua_connection_cb_lookup (self, "on_data", e))
		return false;
	if (lua_connection_eat_nil (self))
		return true;

	lua_pushlstring (self->plugin->L,
		self->read_buffer.str, self->read_buffer.len);
	return lua_plugin_call (self->plugin, 1, 0, e);
}

static bool
lua_connection_invoke_on_eof (struct lua_connection *self, struct error **e)
{
	if (!lua_connection_cb_lookup (self, "on_eof", e))
		return false;
	if (lua_connection_eat_nil (self))
		return true;
	return lua_plugin_call (self->plugin, 0, 0, e);
}

static bool
lua_connection_invoke_on_error (struct lua_connection *self,
	const char *error, struct error **e)
{
	// XXX: not sure if ignoring errors after :close() is always desired;
	//   code might want to make sure that data are transferred successfully
	if (!self->closing
	 && lua_connection_cb_lookup (self, "on_error", e)
	 && !lua_connection_eat_nil (self))
	{
		lua_pushstring (self->plugin->L, error);
		lua_plugin_call (self->plugin, 1, 0, e);
	}
	return false;
}

static bool
lua_connection_try_read (struct lua_connection *self, struct error **e)
{
	// Avoid the read call when it's obviously not going to return any data
	// and would only cause unwanted invocation of callbacks
	if (self->closing || self->got_eof)
		return true;

	enum socket_io_result read_result =
		socket_io_try_read (self->socket_fd, &self->read_buffer);
	const char *error = strerror (errno);

	// Dispatch any data that we got before an EOF or any error
	if (self->read_buffer.len)
	{
		if (!lua_connection_invoke_on_data (self, e))
			return false;
		str_reset (&self->read_buffer);
	}

	if (read_result == SOCKET_IO_EOF)
	{
		if (!lua_connection_invoke_on_eof (self, e))
			return false;
		self->got_eof = true;
	}
	if (read_result == SOCKET_IO_ERROR)
		return lua_connection_invoke_on_error (self, error, e);
	return true;
}

static bool
lua_connection_try_write (struct lua_connection *self, struct error **e)
{
	enum socket_io_result write_result =
		socket_io_try_write (self->socket_fd, &self->write_buffer);
	const char *error = strerror (errno);

	if (write_result == SOCKET_IO_ERROR)
		return lua_connection_invoke_on_error (self, error, e);
	return !self->closing || self->write_buffer.len;
}

static void
lua_connection_on_ready (const struct pollfd *pfd, struct lua_connection *self)
{
	(void) pfd;

	// Hold a reference so that it doesn't get collected on close()
	hard_assert (lua_cache_get (self->plugin->L, self));

	struct error *e = NULL;
	bool keep = lua_connection_try_read (self, &e)
		&& lua_connection_try_write (self, &e);
	if (e)
		lua_plugin_log_error (self->plugin, "network I/O", e);
	if (keep)
		lua_connection_update_poller (self);
	else
		lua_connection_discard (self);

	lua_pop (self->plugin->L, 1);
}

static struct lua_connection *
lua_plugin_push_connection (struct lua_plugin *plugin, int socket_fd)
{
	lua_State *L = plugin->L;

	struct lua_connection *self = lua_newuserdata (L, sizeof *self);
	luaL_setmetatable (L, XLUA_CONNECTION_METATABLE);
	memset (self, 0, sizeof *self);
	self->plugin = plugin;

	set_blocking (socket_fd, false);
	self->socket_event = poller_fd_make
		(&plugin->ctx->poller, (self->socket_fd = socket_fd));
	self->socket_event.dispatcher = (poller_fd_fn) lua_connection_on_ready;
	self->socket_event.user_data = self;
	poller_fd_set (&self->socket_event, POLLIN);

	self->read_buffer = str_make ();
	self->write_buffer = str_make ();

	// Make sure the connection doesn't get garbage collected and return it
	lua_cache_store (L, self, -1);
	return self;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// The script can create as many wait channels as wanted.  They only actually
// do anything once they get yielded to the main lua_resume() call.

/// Identifier for the Lua metatable
#define XLUA_WCHANNEL_METATABLE "wchannel"

struct lua_wait_channel
{
	LIST_HEADER (struct lua_wait_channel)

	struct lua_task *task;              ///< The task we're active in

	/// Check if the event is ready and eventually push values to the thread;
	/// the channel then may release any resources
	bool (*check) (struct lua_wait_channel *self);

	/// Release all resources held by the subclass
	void (*cleanup) (struct lua_wait_channel *self);
};

static int
lua_wchannel_gc (lua_State *L)
{
	struct lua_wait_channel *self =
		luaL_checkudata (L, 1, XLUA_WCHANNEL_METATABLE);
	if (self->cleanup)
		self->cleanup (self);
	return 0;
}

static luaL_Reg lua_wchannel_table[] =
{
	{ "__gc", lua_wchannel_gc },
	{ NULL,   NULL            }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// A task encapsulates a thread so that wait channels yielded from its main
// function get waited upon by the event loop

#define XLUA_TASK_METATABLE  "task"     ///< Identifier for the Lua metatable

struct lua_task
{
	LIST_HEADER (struct lua_task)

	struct lua_plugin *plugin;          ///< The plugin we belong to
	lua_State *thread;                  ///< Lua thread
	struct lua_wait_channel *active;    ///< Channels we're waiting on
	struct poller_idle idle;            ///< Idle job
};

static void
lua_task_unregister_channels (struct lua_task *self)
{
	LIST_FOR_EACH (struct lua_wait_channel, iter, self->active)
	{
		iter->task = NULL;
		LIST_UNLINK (self->active, iter);
		lua_cache_invalidate (self->plugin->L, iter);
	}
}

static void
lua_task_cancel_internal (struct lua_task *self)
{
	if (self->thread)
	{
		lua_cache_invalidate (self->plugin->L, self->thread);
		self->thread = NULL;
	}
	lua_task_unregister_channels (self);
	poller_idle_reset (&self->idle);

	// The task no longer has to stay alive
	lua_cache_invalidate (self->plugin->L, self);
}

static int
lua_task_cancel (lua_State *L)
{
	struct lua_task *self = luaL_checkudata (L, 1, XLUA_TASK_METATABLE);
	// We could also yield and make lua_task_resume() check "self->thread",
	// however the main issue here is that the script should just return
	luaL_argcheck (L, L != self->thread, 1,
		"cannot cancel task from within itself");
	lua_task_cancel_internal (self);
	return 0;
}

#define lua_task_wakeup(self) poller_idle_set (&(self)->idle)

static bool
lua_task_schedule (struct lua_task *self, int n, struct error **e)
{
	lua_State *L = self->thread;
	for (int i = -1; -i <= n; i--)
	{
		struct lua_wait_channel *channel =
			luaL_testudata (L, i, XLUA_WCHANNEL_METATABLE);
		if (!channel)
			return error_set (e, "bad argument #%d to yield: %s", -i + n + 1,
				"tasks can only yield wait channels");
		if (channel->task)
			return error_set (e, "bad argument #%d to yield: %s", -i + n + 1,
				"wait channels can only be active in one task at most");
	}
	for (int i = -1; -i <= n; i--)
	{
		// Quietly ignore duplicate channels
		struct lua_wait_channel *channel = lua_touserdata (L, i);
		if (channel->task)
			continue;

		// By going in reverse the list ends up in the right order
		channel->task = self;
		LIST_PREPEND (self->active, channel);
		lua_cache_store (self->plugin->L, channel, i);
	}
	lua_pop (L, n);

	// There doesn't have to be a single channel
	// We can also be waiting on a channel that is already ready
	lua_task_wakeup (self);
	return true;
}

static void
lua_task_resume (struct lua_task *self, int index)
{
	lua_State *L = self->thread;
	bool waiting_on_multiple = self->active && self->active->next;

	// Since we've ended the wait, we don't need to hold on to them anymore
	lua_task_unregister_channels (self);

	// On the first run we also have the main function on the stack,
	// before any initial arguments
	int n = lua_gettop (L) - (lua_status (L) == LUA_OK);

	// Pack the values in a table and prepend the index of the channel, so that
	// the caller doesn't need to care about the number of return values
	if (waiting_on_multiple)
	{
		lua_plugin_pack (L, n);
		lua_pushinteger (L, index);
		lua_insert (L, -2);
		n = 2;
	}

#if LUA_VERSION_NUM >= 504
	int nresults = 0;
	int res = lua_resume (L, NULL, n, &nresults);
#else
	int res = lua_resume (L, NULL, n);
	int nresults = lua_gettop (L);
#endif

	struct error *error = NULL;
	if (res == LUA_YIELD)
	{
		// AFAIK we don't get any good error context information from here
		if (lua_task_schedule (self, nresults, &error))
			return;
	}
	// For simplicity ignore any results from successful returns
	else if (res != LUA_OK)
	{
		luaL_traceback (L, L, lua_tostring (L, -1), 0 /* or 1? */);
		lua_plugin_process_error (self->plugin, lua_tostring (L, -1), &error);
		lua_pop (L, 2);
	}
	if (error)
		lua_plugin_log_error (self->plugin, "task", error);
	lua_task_cancel_internal (self);
}

static void
lua_task_check (struct lua_task *self)
{
	poller_idle_reset (&self->idle);

	lua_Integer i = 0;
	LIST_FOR_EACH (struct lua_wait_channel, iter, self->active)
	{
		i++;
		if (iter->check (iter))
		{
			lua_task_resume (self, i);
			return;
		}
	}
	if (!self->active)
		lua_task_resume (self, i);
}

// The task dies either when it finishes, it is cancelled, or at plugin unload
static luaL_Reg lua_task_table[] =
{
	{ "cancel", lua_task_cancel },
	{ "__gc",   lua_task_cancel },
	{ NULL,     NULL            }
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct lua_wait_timer
{
	struct lua_wait_channel super;      ///< The structure we're deriving
	struct poller_timer timer;          ///< Timer event
	bool expired;                       ///< Whether the timer has expired
};

static bool
lua_wait_timer_check (struct lua_wait_channel *wchannel)
{
	struct lua_wait_timer *self =
		CONTAINER_OF (wchannel, struct lua_wait_timer, super);
	return self->super.task && self->expired;
}

static void
lua_wait_timer_cleanup (struct lua_wait_channel *wchannel)
{
	struct lua_wait_timer *self =
		CONTAINER_OF (wchannel, struct lua_wait_timer, super);
	poller_timer_reset (&self->timer);
}

static void
lua_wait_timer_dispatch (struct lua_wait_timer *self)
{
	self->expired = true;
	if (self->super.task)
		lua_task_wakeup (self->super.task);
}

static int
lua_plugin_push_wait_timer (struct lua_plugin *plugin, lua_State *L,
	lua_Integer timeout)
{
	struct lua_wait_timer *self = lua_newuserdata (L, sizeof *self);
	luaL_setmetatable (L, XLUA_WCHANNEL_METATABLE);
	memset (self, 0, sizeof *self);

	self->super.check = lua_wait_timer_check;
	self->super.cleanup = lua_wait_timer_cleanup;

	self->timer = poller_timer_make (&plugin->ctx->poller);
	self->timer.dispatcher = (poller_timer_fn) lua_wait_timer_dispatch;
	self->timer.user_data = self;

	if (timeout)
		poller_timer_set (&self->timer, timeout);
	else
		self->expired = true;
	return 1;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

struct lua_wait_dial
{
	struct lua_wait_channel super;      ///< The structure we're deriving

	struct lua_plugin *plugin;          ///< The plugin we belong to
	struct connector connector;         ///< Connector object
	bool active;                        ///< Whether the connector is alive

	struct lua_connection *connection;  ///< Established connection
	char *hostname;                     ///< Target hostname
	char *last_error;                   ///< Connecting error, if any
};

static bool
lua_wait_dial_check (struct lua_wait_channel *wchannel)
{
	struct lua_wait_dial *self =
		CONTAINER_OF (wchannel, struct lua_wait_dial, super);

	lua_State *L = self->super.task->thread;
	if (self->connection)
	{
		// FIXME: this way the connection may leak -- we pass the value to the
		//   task manager on the stack and forget about it but still leave the
		//   connection in the cache.  That is because right now, when Lua code
		//   sets up callbacks in the connection object and returns, it might
		//   get otherwise GC'd since nothing else keeps referencing it.
		//   By rewriting lua_connection using async, tasks and wait channels
		//   would hold a reference, allowing us to remove it from the cache.
		lua_cache_get (L, self->connection);
		lua_pushstring (L, self->hostname);
		self->connection = NULL;
	}
	else if (self->last_error)
	{
		lua_pushnil (L);
		lua_pushnil (L);
		lua_pushstring (L, self->last_error);
	}
	else
		return false;
	return true;
}

static void
lua_wait_dial_cancel (struct lua_wait_dial *self)
{
	if (self->active)
	{
		connector_free (&self->connector);
		self->active = false;
	}
}

static void
lua_wait_dial_cleanup (struct lua_wait_channel *wchannel)
{
	struct lua_wait_dial *self =
		CONTAINER_OF (wchannel, struct lua_wait_dial, super);

	lua_wait_dial_cancel (self);
	if (self->connection)
		lua_connection_discard (self->connection);

	free (self->hostname);
	free (self->last_error);
}

static void
lua_wait_dial_on_connected (void *user_data, int socket, const char *hostname)
{
	struct lua_wait_dial *self = user_data;
	if (self->super.task)
		lua_task_wakeup (self->super.task);

	self->connection = lua_plugin_push_connection (self->plugin, socket);
	// TODO: use the hostname for SNI once TLS is implemented
	self->hostname = xstrdup (hostname);
	lua_wait_dial_cancel (self);
}

static void
lua_wait_dial_on_failure (void *user_data)
{
	struct lua_wait_dial *self = user_data;
	if (self->super.task)
		lua_task_wakeup (self->super.task);
	lua_wait_dial_cancel (self);
}

static void
lua_wait_dial_on_error (void *user_data, const char *error)
{
	struct lua_wait_dial *self = user_data;
	cstr_set (&self->last_error, xstrdup (error));
}

static int
lua_plugin_push_wait_dial (struct lua_plugin *plugin, lua_State *L,
	const char *host, const char *service)
{
	struct lua_wait_dial *self = lua_newuserdata (L, sizeof *self);
	luaL_setmetatable (L, XLUA_WCHANNEL_METATABLE);
	memset (self, 0, sizeof *self);

	self->super.check = lua_wait_dial_check;
	self->super.cleanup = lua_wait_dial_cleanup;

	struct connector *connector = &self->connector;
	connector_init (connector, &plugin->ctx->poller);
	connector_add_target (connector, host, service);

	connector->on_connected  = lua_wait_dial_on_connected;
	connector->on_connecting = NULL;
	connector->on_error      = lua_wait_dial_on_error;
	connector->on_failure    = lua_wait_dial_on_failure;
	connector->user_data     = self;

	self->plugin = plugin;
	self->active = true;
	return 1;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_async_go (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	luaL_checktype (L, 1, LUA_TFUNCTION);

	lua_State *thread = lua_newthread (L);
	lua_cache_store (L, thread, -1);
	lua_pop (L, 1);

	// Move the main function w/ arguments to the thread
	lua_xmove (L, thread, lua_gettop (L));

	struct lua_task *task = lua_newuserdata (L, sizeof *task);
	luaL_setmetatable (L, XLUA_TASK_METATABLE);
	memset (task, 0, sizeof *task);
	task->plugin = plugin;
	task->thread = thread;

	task->idle = poller_idle_make (&plugin->ctx->poller);
	task->idle.dispatcher = (poller_idle_fn) lua_task_check;
	task->idle.user_data = task;
	poller_idle_set (&task->idle);

	// Make sure the task doesn't get garbage collected and return it
	lua_cache_store (L, task, -1);
	return 1;
}

static int
lua_async_timer_ms (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	lua_Integer timeout = luaL_checkinteger (L, 1);
	if (timeout < 0)
		luaL_argerror (L, 1, "timeout mustn't be negative");
	return lua_plugin_push_wait_timer (plugin, L, timeout);
}

static int
lua_async_dial (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	return lua_plugin_push_wait_dial (plugin, L,
		luaL_checkstring (L, 1), luaL_checkstring (L, 2));
}

static luaL_Reg lua_async_library[] =
{
	{ "go",       lua_async_go       },
	{ "timer_ms", lua_async_timer_ms },
	{ "dial",     lua_async_dial     },
	{ NULL,       NULL               },
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static int
lua_plugin_get_screen_size (lua_State *L)
{
	lua_pushinteger (L, g_terminal.lines);
	lua_pushinteger (L, g_terminal.columns);
	return 2;
}

static int
lua_plugin_measure (lua_State *L)
{
	struct lua_plugin *plugin = lua_touserdata (L, lua_upvalueindex (1));
	const char *line = lua_plugin_check_utf8 (L, 1);

	size_t term_len = 0, processed = 0, width = 0, len;
	char *term = iconv_xstrdup (plugin->ctx->term_from_utf8,
		(char *) line, strlen (line) + 1, &term_len);

	mbstate_t ps;
	memset (&ps, 0, sizeof ps);

	wchar_t wch;
	while ((len = mbrtowc (&wch, term + processed, term_len - processed, &ps)))
	{
		hard_assert (len != (size_t) -2 && len != (size_t) -1);
		hard_assert ((processed += len) <= term_len);

		int wch_width = wcwidth (wch);
		width += MAX (0, wch_width);
	}
	free (term);
	lua_pushinteger (L, width);
	return 1;
}

static int
lua_ctx_gc (lua_State *L)
{
	return lua_weak_gc (L, &lua_ctx_info);
}

static luaL_Reg lua_plugin_library[] =
{
	// These are global functions:

	{ "parse",           lua_plugin_parse           },
	{ "hook_input",      lua_plugin_hook_input      },
	{ "hook_irc",        lua_plugin_hook_irc        },
	{ "hook_prompt",     lua_plugin_hook_prompt     },
	{ "hook_completion", lua_plugin_hook_completion },
	{ "setup_config",    lua_plugin_setup_config    },

	// And these are methods:

	{ "get_screen_size", lua_plugin_get_screen_size },
	{ "measure",         lua_plugin_measure         },
	{ "__gc",            lua_ctx_gc                 },
	{ NULL,              NULL                       },
};

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void *
lua_plugin_alloc (void *ud, void *ptr, size_t o_size, size_t n_size)
{
	(void) ud;
	(void) o_size;

	if (n_size)
		return realloc (ptr, n_size);

	free (ptr);
	return NULL;
}

static int
lua_plugin_panic (lua_State *L)
{
	// XXX: we might be able to do something better
	print_fatal ("Lua panicked: %s", lua_tostring (L, -1));
	lua_close (L);
	exit (EXIT_FAILURE);
	return 0;
}

static void
lua_plugin_push_ref (lua_State *L, struct lua_plugin *self, void *object,
	struct ispect_field *field)
{
	// We create a mapping on object type registration
	hard_assert (lua_rawgetp (L, LUA_REGISTRYINDEX, field->fields));
	struct lua_weak_info *info = lua_touserdata (L, -1);
	lua_pop (L, 1);

	if (!field->is_list)
	{
		lua_weak_push (L, self, object, info);
		return;
	}

	// As a rule in this codebase, these fields are right at the top of structs
	struct list_header { LIST_HEADER (void) };

	int i = 1;
	lua_newtable (L);
	LIST_FOR_EACH (struct list_header, iter, object)
	{
		lua_weak_push (L, self, iter, info);
		lua_rawseti (L, -2, i++);
	}
}

static void lua_plugin_push_map_field (lua_State *L, struct lua_plugin *self,
	const char *key, void *p, struct ispect_field *field);

static void
lua_plugin_push_struct (lua_State *L, struct lua_plugin *self,
	enum ispect_type type, void *value, struct ispect_field *field)
{
	if (type == ISPECT_STR)
	{
		const struct str *s = value;
		lua_pushlstring (L, s->str, s->len);
		return;
	}
	if (type == ISPECT_STR_MAP)
	{
		struct str_map_iter iter = str_map_iter_make (value);

		void *value;
		lua_newtable (L);
		while ((value = str_map_iter_next (&iter)))
			lua_plugin_push_map_field (L, self, iter.link->key, value, field);
		return;
	}
	hard_assert (!"unhandled introspection object type");
}

static void
lua_plugin_push_map_field (lua_State *L, struct lua_plugin *self,
	const char *key, void *p, struct ispect_field *field)
{
	// That would mean maps in maps ad infinitum
	hard_assert (field->subtype != ISPECT_STR_MAP);

	intptr_t n = (intptr_t) p;
	switch (field->subtype)
	{
	// Here the types are generally casted to a void pointer
	case ISPECT_BOOL:   lua_pushboolean (L, (bool     ) n); break;
	case ISPECT_INT:    lua_pushinteger (L, (int      ) n); break;
	case ISPECT_UINT:   lua_pushinteger (L, (unsigned ) n); break;
	case ISPECT_SIZE:   lua_pushinteger (L, (size_t   ) n); break;
	case ISPECT_STRING: lua_pushstring  (L,             p); break;
	case ISPECT_REF: lua_plugin_push_ref (L, self, p, field); break;
	default: lua_plugin_push_struct (L, self, field->subtype, p, field);
	}
	lua_setfield (L, -2, key);
}

static bool
lua_plugin_property_get_ispect (lua_State *L, const char *property_name)
{
	struct lua_weak_info *info = lua_touserdata (L, lua_upvalueindex (1));
	if (!info || !info->ispect)
		return false;

	struct lua_weak *weak = luaL_checkudata (L, 1, info->name);
	// TODO: I think we can do better than this, maybe binary search at least?
	struct ispect_field *field;
	for (field = info->ispect; field->name; field++)
		if (!strcmp (property_name, field->name))
			break;
	if (!field->name)
		return false;

	struct lua_plugin *self = weak->plugin;
	void *p = (uint8_t *) weak->object + field->offset;
	switch (field->type)
	{
	// Here the types are really what's under the pointer
	case ISPECT_BOOL:   lua_pushboolean (L, *(bool     *) p); break;
	case ISPECT_INT:    lua_pushinteger (L, *(int      *) p); break;
	case ISPECT_UINT:   lua_pushinteger (L, *(unsigned *) p); break;
	case ISPECT_SIZE:   lua_pushinteger (L, *(size_t   *) p); break;
	case ISPECT_STRING: lua_pushstring  (L, *(char    **) p); break;
	case ISPECT_REF: lua_plugin_push_ref (L, self, *(void **) p, field); break;
	default: lua_plugin_push_struct (L, self, field->type, p, field);
	}
	return true;
}

static int
lua_plugin_property_get (lua_State *L)
{
	luaL_checktype (L, 1, LUA_TUSERDATA);
	const char *property_name = luaL_checkstring (L, 2);

	// Either it's directly present in the metatable
	if (luaL_getmetafield (L, 1, property_name))
		return 1;

	// Or we try to find and eventually call a getter method
	char *getter_name = xstrdup_printf ("get_%s", property_name);
	bool found = luaL_getmetafield (L, 1, getter_name);
	free (getter_name);

	if (found)
	{
		lua_pushvalue (L, 1);
		lua_call (L, 1, 1);
		return 1;
	}

	// Maybe we can find it via introspection
	if (lua_plugin_property_get_ispect (L, property_name))
		return 1;

	// Or we look for a property set by the user (__gc cannot be overriden)
	if (lua_getuservalue (L, 1) != LUA_TTABLE)
		lua_pushnil (L);
	else
		lua_getfield (L, -1, property_name);
	return 1;
}

static int
lua_plugin_property_set (lua_State *L)
{
	luaL_checktype (L, 1, LUA_TUSERDATA);
	const char *property_name = luaL_checkstring (L, 2);
	luaL_checkany (L, 3);

	// We use the associated value to store user-defined properties
	int type = lua_getuservalue (L, 1);
	if (type == LUA_TNIL)
	{
		lua_pop (L, 1);
		lua_newtable (L);
		lua_pushvalue (L, -1);
		lua_setuservalue (L, 1);
	}
	else if (type != LUA_TTABLE)
		return luaL_error (L, "associated value is not a table");

	// Beware that we do not check for conflicts here;
	// if Lua code writes a conflicting field, it is effectively ignored
	lua_pushvalue (L, 3);
	lua_setfield (L, -2, property_name);
	return 0;
}

static void
lua_plugin_add_accessors (lua_State *L, struct lua_weak_info *info)
{
	// Emulate properties for convenience
	lua_pushlightuserdata (L, info);
	lua_pushcclosure (L, lua_plugin_property_get, 1);
	lua_setfield (L, -2, "__index");
	lua_pushcfunction (L, lua_plugin_property_set);
	lua_setfield (L, -2, "__newindex");
}

static void
lua_plugin_reg_meta (lua_State *L, const char *name, luaL_Reg *fns)
{
	luaL_newmetatable (L, name);
	luaL_setfuncs (L, fns, 0);
	lua_plugin_add_accessors (L, NULL);
	lua_pop (L, 1);
}

static void
lua_plugin_reg_weak (lua_State *L, struct lua_weak_info *info, luaL_Reg *fns)
{
	// Create a mapping from the object type (info->ispect) back to metadata
	// so that we can figure out what to create from ISPECT_REF fields
	lua_pushlightuserdata (L, info);
	lua_rawsetp (L, LUA_REGISTRYINDEX, info->ispect);

	luaL_newmetatable (L, info->name);
	luaL_setfuncs (L, fns, 0);
	lua_plugin_add_accessors (L, info);
	lua_pop (L, 1);
}

static struct plugin *
lua_plugin_load (struct app_context *ctx, const char *filename,
	struct error **e)
{
	lua_State *L = lua_newstate (lua_plugin_alloc, NULL);
	if (!L)
	{
		error_set (e, "Lua initialization failed");
		return NULL;
	}

	lua_atpanic (L, lua_plugin_panic);
	luaL_openlibs (L);

	struct lua_plugin *plugin = xcalloc (1, sizeof *plugin);
	plugin->super.name = xstrdup (filename);
	plugin->super.vtable = &lua_plugin_vtable;
	plugin->ctx = ctx;
	plugin->L = L;

	luaL_checkversion (L);

	// Register the xC library as a singleton with "plugin" as an upvalue
	// (mostly historical, but rather convenient)
	luaL_newmetatable (L, lua_ctx_info.name);
	lua_pushlightuserdata (L, plugin);
	luaL_setfuncs (L, lua_plugin_library, 1);
	lua_plugin_add_accessors (L, &lua_ctx_info);

	// Add the asynchronous library underneath
	lua_newtable (L);
	lua_pushlightuserdata (L, plugin);
	luaL_setfuncs (L, lua_async_library, 1);
	lua_setfield (L, -2, "async");
	lua_pop (L, 1);

	lua_weak_push (L, plugin, ctx, &lua_ctx_info);
	lua_setglobal (L, lua_ctx_info.name);

	// Create metatables for our objects
	lua_plugin_reg_meta (L, XLUA_HOOK_METATABLE,       lua_hook_table);
	lua_plugin_reg_weak (L, &lua_user_info,            lua_user_table);
	lua_plugin_reg_weak (L, &lua_channel_info,         lua_channel_table);
	lua_plugin_reg_weak (L, &lua_buffer_info,          lua_buffer_table);
	lua_plugin_reg_weak (L, &lua_server_info,          lua_server_table);
	lua_plugin_reg_meta (L, XLUA_SCHEMA_METATABLE,     lua_schema_table);
	lua_plugin_reg_meta (L, XLUA_CONNECTION_METATABLE, lua_connection_table);

	lua_plugin_reg_meta (L, XLUA_TASK_METATABLE,       lua_task_table);
	lua_plugin_reg_meta (L, XLUA_WCHANNEL_METATABLE,   lua_wchannel_table);

	struct error *error = NULL;
	if (luaL_loadfile (L, filename))
		error_set (e, "%s: %s", "Lua", lua_tostring (L, -1));
	else if (!lua_plugin_call (plugin, 0, 0, &error))
	{
		error_set (e, "%s: %s", "Lua", error->message);
		error_free (error);
	}
	else
		return &plugin->super;

	plugin_destroy (&plugin->super);
	return NULL;
}

#endif // HAVE_LUA

// --- Plugins -----------------------------------------------------------------

typedef struct plugin *(*plugin_load_fn)
	(struct app_context *ctx, const char *filename, struct error **e);

// We can potentially add support for other scripting languages if so desired,
// however this possibility is just a byproduct of abstraction
static plugin_load_fn g_plugin_loaders[] =
{
#ifdef HAVE_LUA
	lua_plugin_load,
#endif // HAVE_LUA
};

static struct plugin *
plugin_load_from_filename (struct app_context *ctx, const char *filename,
	struct error **e)
{
	struct plugin *plugin = NULL;
	struct error *error = NULL;
	for (size_t i = 0; i < N_ELEMENTS (g_plugin_loaders); i++)
		if ((plugin = g_plugin_loaders[i](ctx, filename, &error)) || error)
			break;

	if (error)
		error_propagate (e, error);
	else if (!plugin)
	{
		error_set (e, "no plugin handler for \"%s\"", filename);
		return NULL;
	}
	return plugin;
}

static struct plugin *
plugin_find (struct app_context *ctx, const char *name)
{
	LIST_FOR_EACH (struct plugin, iter, ctx->plugins)
		if (!strcmp (name, iter->name))
			return iter;
	return NULL;
}

static char *
plugin_resolve_relative_filename (const char *filename)
{
	struct strv paths = strv_make ();
	get_xdg_data_dirs (&paths);
	char *result = resolve_relative_filename_generic
		(&paths, PROGRAM_NAME "/plugins/", filename);
	strv_free (&paths);
	return result;
}

static struct plugin *
plugin_load_by_name (struct app_context *ctx, const char *name,
	struct error **e)
{
	struct plugin *plugin = plugin_find (ctx, name);
	if (plugin)
	{
		error_set (e, "plugin already loaded");
		return NULL;
	}

	// As a side effect, a plugin can be loaded multiple times by giving
	// various relative or non-relative paths to the function; this is not
	// supposed to be fool-proof though, that requires other mechanisms
	char *filename = resolve_filename (name, plugin_resolve_relative_filename);
	if (!filename)
	{
		error_set (e, "file not found");
		return NULL;
	}

	plugin = plugin_load_from_filename (ctx, filename, e);
	free (filename);
	return plugin;
}

static void
plugin_load (struct app_context *ctx, const char *name)
{
	struct error *e = NULL;
	struct plugin *plugin = plugin_load_by_name (ctx, name, &e);
	if (plugin)
	{
		// FIXME: this way the real name isn't available to the plugin on load,
		//   which has effect on e.g. plugin_config_name()
		cstr_set (&plugin->name, xstrdup (name));

		log_global_status (ctx, "Plugin \"#s\" loaded", name);
		LIST_PREPEND (ctx->plugins, plugin);
	}
	else
	{
		log_global_error (ctx, "Can't load plugin \"#s\": #s",
			name, e->message);
		error_free (e);
	}
}

static void
plugin_unload (struct app_context *ctx, const char *name)
{
	struct plugin *plugin = plugin_find (ctx, name);
	if (!plugin)
		log_global_error (ctx, "Can't unload plugin \"#s\": #s",
			name, "plugin not loaded");
	else
	{
		log_global_status (ctx, "Plugin \"#s\" unloaded", name);
		LIST_UNLINK (ctx->plugins, plugin);
		plugin_destroy (plugin);
	}
}

static void
load_plugins (struct app_context *ctx)
{
	const char *plugins =
		get_config_string (ctx->config.root, "general.plugin_autoload");
	if (plugins)
	{
		struct strv v = strv_make ();
		cstr_split (plugins, ",", true, &v);
		for (size_t i = 0; i < v.len; i++)
			plugin_load (ctx, v.vector[i]);
		strv_free (&v);
	}
}

// --- User input handling -----------------------------------------------------

// HANDLER_NEEDS_REG is primarily for message sending commands,
// as they may want to log buffer lines and use our current nickname

enum handler_flags
{
	HANDLER_SERVER        = (1 << 0),   ///< Server context required
	HANDLER_NEEDS_REG     = (1 << 1),   ///< Server registration required
	HANDLER_CHANNEL_FIRST = (1 << 2),   ///< Channel required, first argument
	HANDLER_CHANNEL_LAST  = (1 << 3)    ///< Channel required, last argument
};

struct handler_args
{
	struct app_context *ctx;            ///< Application context
	struct buffer *buffer;              ///< Current buffer
	struct server *s;                   ///< Related server
	const char *channel_name;           ///< Related channel name
	char *arguments;                    ///< Command arguments
};

/// Cuts the longest non-whitespace portion of text and advances the pointer
static char *
cut_word (char **s)
{
	char *start = *s;
	size_t word_len = strcspn (*s, WORD_BREAKING_CHARS);
	char *end = start + word_len;
	*s = end + strspn (end, WORD_BREAKING_CHARS);
	*end = '\0';
	return start;
}

/// Validates a word to be cut from a string
typedef bool (*word_validator_fn) (void *, char *);

static char *
maybe_cut_word (char **s, word_validator_fn validator, void *user_data)
{
	char *start = *s;
	size_t word_len = strcspn (*s, WORD_BREAKING_CHARS);

	char *word = xstrndup (start, word_len);
	bool ok = validator (user_data, word);
	free (word);

	if (!ok)
		return NULL;

	char *end = start + word_len;
	*s = end + strspn (end, WORD_BREAKING_CHARS);
	*end = '\0';
	return start;
}

static char *
maybe_cut_word_from_end (char **s, word_validator_fn validator, void *user_data)
{
	// Find the start and end of the last word
	// Contrary to maybe_cut_word(), we ignore all whitespace at the end
	char *start = *s, *end = start + strlen (start);
	while (end  > start &&  strchr (WORD_BREAKING_CHARS, end [-1]))
		end--;
	char *word = end;
	while (word > start && !strchr (WORD_BREAKING_CHARS, word[-1]))
		word--;

	// There's just one word at maximum, starting at the beginning
	if (word == start)
		return maybe_cut_word (s, validator, user_data);

	char *tmp = xstrndup (word, word - start);
	bool ok = validator (user_data, tmp);
	free (tmp);

	if (!ok)
		return NULL;

	// It doesn't start at the beginning, cut it off and return it
	word[-1] = *end = '\0';
	return word;
}

static bool
validate_channel_name (void *user_data, char *word)
{
	return irc_is_channel (user_data, word);
}

static char *
try_get_channel (struct handler_args *a,
	char *(*cutter) (char **, word_validator_fn, void *))
{
	char *channel_name = cutter (&a->arguments, validate_channel_name, a->s);
	if (channel_name)
		return channel_name;
	if (a->buffer->type == BUFFER_CHANNEL)
		return a->buffer->channel->name;
	return NULL;
}

static bool
try_handle_buffer_goto (struct app_context *ctx, const char *word)
{
	unsigned long n;
	if (!xstrtoul (&n, word, 10))
		return false;

	if (n > INT_MAX || !buffer_goto (ctx, n))
		log_global_error (ctx, "#s: #s", "No such buffer", word);
	return true;
}

static struct buffer *
try_decode_buffer (struct app_context *ctx, const char *word)
{
	unsigned long n;
	struct buffer *buffer = NULL;
	if (xstrtoul (&n, word, 10) && n <= INT_MAX)
		buffer = buffer_at_index (ctx, n);
	if (buffer || (buffer = buffer_by_name (ctx, word)))
		return buffer;

	// Basic case insensitive partial matching -- at most one buffer can match
	int n_matches = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
	{
		char *string  = xstrdup (iter->name);
		char *pattern = xstrdup_printf ("*%s*", word);
		for (char *p = string;  *p; p++) *p = tolower_ascii (*p);
		for (char *p = pattern; *p; p++) *p = tolower_ascii (*p);
		if (!fnmatch (pattern, string, 0))
		{
			n_matches++;
			buffer = iter;
		}
		free (string);
		free (pattern);
	}
	return n_matches == 1 ? buffer : NULL;
}

static void
show_buffers_list (struct app_context *ctx)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "Buffers list:");

	int i = 1;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
	{
		struct str s = str_make ();
		int new = iter->new_messages_count - iter->new_unimportant_count;
		if (new && iter != ctx->current_buffer)
			str_append_printf (&s, " (%d%s)", new, &"!"[!iter->highlighted]);
		log_global_indent (ctx,
			"  [#d] #s#&s", i++, iter->name, str_steal (&s));
	}
}

static void
part_channel (struct server *s, const char *channel_name, const char *reason)
{
	if (*reason)
		irc_send (s, "PART %s :%s", channel_name, reason);
	else
		irc_send (s, "PART %s", channel_name);

	struct channel *channel;
	if ((channel = str_map_find (&s->irc_channels, channel_name)))
		channel->left_manually = true;
}

static bool
handle_buffer_goto (struct app_context *ctx, struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	const char *which = cut_word (&a->arguments);
	struct buffer *buffer = try_decode_buffer (ctx, which);
	if (buffer)
		buffer_activate (ctx, buffer);
	else
		log_global_error (ctx, "#s: #s", "No such buffer", which);
	return true;
}

static void
handle_buffer_close (struct app_context *ctx, struct handler_args *a)
{
	struct buffer *buffer = NULL;
	const char *which = NULL;
	if (!*a->arguments)
		buffer = a->buffer;
	else
		buffer = try_decode_buffer (ctx, (which = cut_word (&a->arguments)));

	if (!buffer)
		log_global_error (ctx, "#s: #s", "No such buffer", which);
	else if (buffer == ctx->global_buffer)
		log_global_error (ctx, "Can't close the global buffer");
	else if (buffer->type == BUFFER_SERVER)
		log_global_error (ctx, "Can't close a server buffer");
	else
	{
		// The user would be unable to recreate the buffer otherwise
		if (buffer->type == BUFFER_CHANNEL
		 && irc_channel_is_joined (buffer->channel))
			part_channel (buffer->server, buffer->channel->name, "");
		buffer_remove_safe (ctx, buffer);
	}
}

static bool
handle_buffer_move (struct app_context *ctx, struct handler_args *a)
{
	unsigned long request;
	if (!xstrtoul (&request, a->arguments, 10))
		return false;

	if (request == 0 || request > (unsigned long) buffer_count (ctx))
	{
		log_global_error (ctx, "#s: #s",
			"Can't move buffer", "requested position is out of range");
		return true;
	}
	buffer_move (ctx, a->buffer, request);
	return true;
}

static bool
handle_command_buffer (struct handler_args *a)
{
	struct app_context *ctx = a->ctx;
	char *action = cut_word (&a->arguments);
	if (try_handle_buffer_goto (ctx, action))
		return true;

	bool result = true;
	if (!*action || !strcasecmp_ascii (action, "list"))
		show_buffers_list (ctx);
	else if (!strcasecmp_ascii (action, "clear"))
	{
		buffer_clear (ctx, a->buffer);
		if (a->buffer == ctx->current_buffer)
			buffer_print_backlog (ctx, a->buffer);
	}
	else if (!strcasecmp_ascii (action, "move"))
		result = handle_buffer_move (ctx, a);
	else if (!strcasecmp_ascii (action, "goto"))
		result = handle_buffer_goto (ctx, a);
	else if (!strcasecmp_ascii (action, "close"))
		handle_buffer_close (ctx, a);
	else
		result = false;
	return result;
}

static bool
handle_command_set_add
	(struct strv *items, const struct strv *values, struct error **e)
{
	for (size_t i = 0; i < values->len; i++)
	{
		const char *value = values->vector[i];
		if (strv_find (items, values->vector[i]) != -1)
			return error_set (e, "already present in the array: %s", value);
		strv_append (items, value);
	}
	return true;
}

static bool
handle_command_set_remove
	(struct strv *items, const struct strv *values, struct error **e)
{
	for (size_t i = 0; i < values->len; i++)
	{
		const char *value = values->vector[i];
		ssize_t i = strv_find (items, value);
		if (i == -1)
			return error_set (e, "not present in the array: %s", value);
		strv_remove (items, i);
	}
	return true;
}

static bool
handle_command_set_modify
	(struct config_item *item, const char *value, bool add, struct error **e)
{
	struct strv items = strv_make ();
	if (item->type != CONFIG_ITEM_NULL)
		cstr_split (item->value.string.str, ",", false, &items);
	if (items.len == 1 && !*items.vector[0])
		strv_reset (&items);

	struct strv values = strv_make ();
	cstr_split (value, ",", false, &values);
	bool result = add
		? handle_command_set_add (&items, &values, e)
		: handle_command_set_remove (&items, &values, e);

	if (result)
	{
		char *changed = strv_join (&items, ",");
		struct str tmp = { .str = changed, .len = strlen (changed) };
		result = config_item_set_from (item,
			config_item_string_array (&tmp), e);
		free (changed);
	}

	strv_free (&items);
	strv_free (&values);
	return result;
}

static bool
handle_command_set_assign_item (struct app_context *ctx,
	char *key, struct config_item *new_, bool add, bool remove)
{
	struct config_item *item =
		config_item_get (ctx->config.root, key, NULL);
	hard_assert (item);

	struct error *e = NULL;
	if (!item->schema)
		error_set (&e, "option not recognized");
	else if (!add && !remove)
		config_item_set_from (item, config_item_clone (new_), &e);
	else if (item->schema->type != CONFIG_ITEM_STRING_ARRAY)
		error_set (&e, "not a string array");
	else
		handle_command_set_modify (item, new_->value.string.str, add, &e);

	if (e)
	{
		log_global_error (ctx,
			"Failed to set option \"#s\": #s", key, e->message);
		error_free (e);
		return false;
	}

	struct strv tmp = strv_make ();
	dump_matching_options (ctx->config.root, key, &tmp);
	log_global_status (ctx, "Option changed: #s", tmp.vector[0]);
	strv_free (&tmp);
	return true;
}

static bool
handle_command_set_assign
	(struct app_context *ctx, struct strv *all, char *arguments)
{
	hard_assert (all->len > 0);

	char *op = cut_word (&arguments);
	bool add = false;
	bool remove = false;

	if      (!strcmp (op, "+="))  add = true;
	else if (!strcmp (op, "-="))  remove = true;
	else if  (strcmp (op, "="))   return false;

	if (!*arguments)
		return false;

	struct error *e = NULL;
	struct config_item *new_ =
		config_item_parse (arguments, strlen (arguments), true, &e);
	if (e)
	{
		log_global_error (ctx, "Invalid value: #s", e->message);
		error_free (e);
		return true;
	}

	if ((add | remove) && !config_item_type_is_string (new_->type))
	{
		log_global_error (ctx, "+= / -= operators need a string argument");
		config_item_destroy (new_);
		return true;
	}

	bool changed = false;
	for (size_t i = 0; i < all->len; i++)
	{
		char *key = cstr_cut_until (all->vector[i], " ");
		if (handle_command_set_assign_item (ctx, key, new_, add, remove))
			changed = true;
		free (key);
	}
	config_item_destroy (new_);

	if (changed && get_config_boolean (ctx->config.root, "general.autosave"))
		save_configuration (ctx);
	return true;
}

static bool
handle_command_set (struct handler_args *a)
{
	struct app_context *ctx = a->ctx;
	char *option = "*";
	if (*a->arguments)
		option = cut_word (&a->arguments);

	struct strv all = strv_make ();
	dump_matching_options (ctx->config.root, option, &all);

	bool result = true;
	if (!all.len)
		log_global_error (ctx, "No matches: #s", option);
	else if (!*a->arguments)
	{
		log_global_indent (ctx, "");
		for (size_t i = 0; i < all.len; i++)
			log_global_indent (ctx, "#s", all.vector[i]);
	}
	else
		result = handle_command_set_assign (ctx, &all, a->arguments);

	strv_free (&all);
	return result;
}

static bool
handle_command_save (struct handler_args *a)
{
	if (*a->arguments)
		return false;

	save_configuration (a->ctx);
	return true;
}

static void
show_plugin_list (struct app_context *ctx)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "Plugins:");
	LIST_FOR_EACH (struct plugin, iter, ctx->plugins)
		log_global_indent (ctx, "  #s", iter->name);
}

static bool
handle_command_plugin (struct handler_args *a)
{
	char *action = cut_word (&a->arguments);
	if (!*action || !strcasecmp_ascii (action, "list"))
		show_plugin_list (a->ctx);
	else if (!strcasecmp_ascii (action, "load"))
	{
		if (!*a->arguments)
			return false;

		plugin_load (a->ctx, cut_word (&a->arguments));
	}
	else if (!strcasecmp_ascii (action, "unload"))
	{
		if (!*a->arguments)
			return false;

		plugin_unload (a->ctx, cut_word (&a->arguments));
	}
	else
		return false;
	return true;
}

static bool
handle_command_relay (struct handler_args *a)
{
	if (*a->arguments)
		return false;

	int len = 0;
	LIST_FOR_EACH (struct client, c, a->ctx->clients)
		len++;

	if (a->ctx->relay_fd == -1)
		log_global_status (a->ctx, "The relay is not enabled");
	else
		log_global_status (a->ctx, "The relay has #d clients", len);
	return true;
}

static bool
show_aliases_list (struct app_context *ctx)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "Aliases:");

	struct str_map *aliases = get_aliases_config (ctx);
	if (!aliases->len)
	{
		log_global_indent (ctx, "  (none)");
		return true;
	}

	struct str_map_iter iter = str_map_iter_make (aliases);
	struct config_item *alias;
	while ((alias = str_map_iter_next (&iter)))
	{
		struct str definition = str_make ();
		if (config_item_type_is_string (alias->type))
			config_item_write_string (&definition, &alias->value.string);
		else
			str_append (&definition, "alias definition is not a string");
		log_global_indent (ctx, "  /#s: #s", iter.link->key, definition.str);
		str_free (&definition);
	}
	return true;
}

static bool
handle_command_alias (struct handler_args *a)
{
	if (!*a->arguments)
		return show_aliases_list (a->ctx);

	char *name = cut_word (&a->arguments);
	if (!*a->arguments)
		return false;
	if (*name == '/')
		name++;

	struct config_item *alias = config_item_string_from_cstr (a->arguments);

	struct str definition = str_make ();
	config_item_write_string (&definition, &alias->value.string);
	str_map_set (get_aliases_config (a->ctx), name, alias);
	log_global_status (a->ctx, "Created alias /#s: #s", name, definition.str);
	str_free (&definition);
	return true;
}

static bool
handle_command_unalias (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	struct str_map *aliases = get_aliases_config (a->ctx);
	while (*a->arguments)
	{
		char *name = cut_word (&a->arguments);
		if (!str_map_find (aliases, name))
			log_global_error (a->ctx, "No such alias: #s", name);
		else
		{
			str_map_set (aliases, name, NULL);
			log_global_status (a->ctx, "Alias removed: #s", name);
		}
	}
	return true;
}

static bool
handle_command_msg (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (!*a->arguments)
		log_server_error (a->s, a->s->buffer, "No text to send");
	else
		SEND_AUTOSPLIT_PRIVMSG (a->s, target, a->arguments);
	return true;
}

static bool
handle_command_query (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (irc_is_channel (a->s, irc_skip_statusmsg (a->s, target)))
		log_server_error (a->s, a->s->buffer, "Cannot query a channel");
	else if (!*a->arguments)
		buffer_activate (a->ctx, irc_get_or_make_user_buffer (a->s, target));
	else
	{
		buffer_activate (a->ctx, irc_get_or_make_user_buffer (a->s, target));
		SEND_AUTOSPLIT_PRIVMSG (a->s, target, a->arguments);
	}
	return true;
}

static bool
handle_command_notice (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (!*a->arguments)
		log_server_error (a->s, a->s->buffer, "No text to send");
	else
		SEND_AUTOSPLIT_NOTICE (a->s, target, a->arguments);
	return true;
}

static bool
handle_command_squery (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (!*a->arguments)
		log_server_error (a->s, a->s->buffer, "No text to send");
	else
		irc_send (a->s, "SQUERY %s :%s", target, a->arguments);
	return true;
}

static bool
handle_command_ctcp (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (!*a->arguments)
		return false;

	char *tag = cut_word (&a->arguments);
	cstr_transform (tag, toupper_ascii);

	if (*a->arguments)
		irc_send (a->s, "PRIVMSG %s :\x01%s %s\x01", target, tag, a->arguments);
	else
		irc_send (a->s, "PRIVMSG %s :\x01%s\x01", target, tag);
	return true;
}

static bool
handle_command_me (struct handler_args *a)
{
	if (a->buffer->type == BUFFER_CHANNEL)
		SEND_AUTOSPLIT_ACTION (a->s,
			a->buffer->channel->name, a->arguments);
	else if (a->buffer->type == BUFFER_PM)
		SEND_AUTOSPLIT_ACTION (a->s,
			a->buffer->user->nickname, a->arguments);
	else
		log_server_error (a->s, a->s->buffer,
			"Can't do this from a server buffer (#s)",
			"send CTCP actions");
	return true;
}

static bool
handle_command_quit (struct handler_args *a)
{
	request_quit (a->ctx, *a->arguments ? a->arguments : NULL);
	return true;
}

static bool
handle_command_join (struct handler_args *a)
{
	// XXX: send the last known channel key?
	if (irc_is_channel (a->s, a->arguments))
		// XXX: we may want to split the list of channels
		irc_send (a->s, "JOIN %s", a->arguments);
	else if (a->buffer->type != BUFFER_CHANNEL)
		log_server_error (a->s, a->buffer, "#s: #s", "Can't join",
			"no channel name given and this buffer is not a channel");
	else if (irc_channel_is_joined (a->buffer->channel))
		log_server_error (a->s, a->buffer, "#s: #s", "Can't join",
			"you already are on the channel");
	else if (*a->arguments)
		irc_send (a->s, "JOIN %s :%s", a->buffer->channel->name, a->arguments);
	else
		irc_send (a->s, "JOIN %s", a->buffer->channel->name);
	return true;
}

static bool
handle_command_part (struct handler_args *a)
{
	if (irc_is_channel (a->s, a->arguments))
	{
		struct strv v = strv_make ();
		cstr_split (cut_word (&a->arguments), ",", true, &v);
		for (size_t i = 0; i < v.len; i++)
			part_channel (a->s, v.vector[i], a->arguments);
		strv_free (&v);
	}
	else if (a->buffer->type != BUFFER_CHANNEL)
		log_server_error (a->s, a->buffer, "#s: #s", "Can't part",
			"no channel name given and this buffer is not a channel");
	else if (!irc_channel_is_joined (a->buffer->channel))
		log_server_error (a->s, a->buffer, "#s: #s", "Can't part",
			"you're not on the channel");
	else
		part_channel (a->s, a->buffer->channel->name, a->arguments);
	return true;
}

static void
cycle_channel (struct server *s, const char *channel_name, const char *reason)
{
	// If a channel key is set, we must specify it when rejoining
	const char *key = NULL;
	struct channel *channel;
	if ((channel = str_map_find (&s->irc_channels, channel_name)))
		key = str_map_find (&channel->param_modes, "k");

	if (*reason)
		irc_send (s, "PART %s :%s", channel_name, reason);
	else
		irc_send (s, "PART %s", channel_name);

	if (key)
		irc_send (s, "JOIN %s :%s", channel_name, key);
	else
		irc_send (s, "JOIN %s", channel_name);
}

static bool
handle_command_cycle (struct handler_args *a)
{
	if (irc_is_channel (a->s, a->arguments))
	{
		struct strv v = strv_make ();
		cstr_split (cut_word (&a->arguments), ",", true, &v);
		for (size_t i = 0; i < v.len; i++)
			cycle_channel (a->s, v.vector[i], a->arguments);
		strv_free (&v);
	}
	else if (a->buffer->type != BUFFER_CHANNEL)
		log_server_error (a->s, a->buffer, "#s: #s", "Can't cycle",
			"no channel name given and this buffer is not a channel");
	else if (!irc_channel_is_joined (a->buffer->channel))
		log_server_error (a->s, a->buffer, "#s: #s", "Can't cycle",
			"you're not on the channel");
	else
		cycle_channel (a->s, a->buffer->channel->name, a->arguments);
	return true;
}

static bool
handle_command_mode (struct handler_args *a)
{
	// Channel names prefixed by "+" collide with mode strings,
	// so we just disallow specifying these channels
	char *target = NULL;
	if (strchr ("+-\0", *a->arguments))
	{
		if (a->buffer->type == BUFFER_CHANNEL)
			target = a->buffer->channel->name;
		if (a->buffer->type == BUFFER_PM)
			target = a->buffer->user->nickname;
		if (a->buffer->type == BUFFER_SERVER)
			target = a->s->irc_user->nickname;
	}
	else
		// If there a->arguments and they don't begin with a mode string,
		// they're either a user name or a channel name
		target = cut_word (&a->arguments);

	if (!target)
		log_server_error (a->s, a->buffer, "#s: #s", "Can't change mode",
			"no target given and this buffer is neither a PM nor a channel");
	else if (*a->arguments)
		// XXX: split channel mode params as necessary using irc_max_modes?
		irc_send (a->s, "MODE %s %s", target, a->arguments);
	else
		irc_send (a->s, "MODE %s", target);
	return true;
}

static bool
handle_command_topic (struct handler_args *a)
{
	if (*a->arguments)
		// FIXME: there's no way to start the topic with whitespace
		// FIXME: there's no way to unset the topic;
		//   we could adopt the Tcl style of "-switches" with "--" sentinels,
		//   or we could accept "strings" in the config format
		irc_send (a->s, "TOPIC %s :%s", a->channel_name, a->arguments);
	else
		irc_send (a->s, "TOPIC %s", a->channel_name);
	return true;
}

static bool
handle_command_kick (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (*a->arguments)
		irc_send (a->s, "KICK %s %s :%s",
			a->channel_name, target, a->arguments);
	else
		irc_send (a->s, "KICK %s %s", a->channel_name, target);
	return true;
}

static bool
handle_command_kickban (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (strpbrk (target, "!@*?"))
		return false;

	// XXX: how about other masks?
	irc_send (a->s, "MODE %s +b %s!*@*", a->channel_name, target);
	if (*a->arguments)
		irc_send (a->s, "KICK %s %s :%s",
			a->channel_name, target, a->arguments);
	else
		irc_send (a->s, "KICK %s %s", a->channel_name, target);
	return true;
}

static void
mass_channel_mode (struct server *s, const char *channel_name,
	bool adding, char mode_char, struct strv *v)
{
	size_t n;
	for (size_t i = 0; i < v->len; i += n)
	{
		struct str modes  = str_make ();
		struct str params = str_make ();

		n = MIN (v->len - i, s->irc_max_modes);
		str_append_printf (&modes, "MODE %s %c", channel_name, "-+"[adding]);
		for (size_t k = 0; k < n; k++)
		{
			str_append_c (&modes, mode_char);
			str_append_printf (&params, " %s", v->vector[i + k]);
		}

		irc_send (s, "%s%s", modes.str, params.str);

		str_free (&modes);
		str_free (&params);
	}
}

static void
mass_channel_mode_mask_list
	(struct handler_args *a, bool adding, char mode_char)
{
	struct strv v = strv_make ();
	cstr_split (a->arguments, " ", true, &v);

	// XXX: this may be a bit too trivial; we could also map nicknames
	//   to information from WHO polling or userhost-in-names
	for (size_t i = 0; i < v.len; i++)
	{
		char *target = v.vector[i];
		if (strpbrk (target, "!@*?") || irc_is_extban (a->s, target))
			continue;

		v.vector[i] = xstrdup_printf ("%s!*@*", target);
		free (target);
	}

	mass_channel_mode (a->s, a->channel_name, adding, mode_char, &v);
	strv_free (&v);
}

static bool
handle_command_ban (struct handler_args *a)
{
	if (*a->arguments)
		mass_channel_mode_mask_list (a, true, 'b');
	else
		irc_send (a->s, "MODE %s +b", a->channel_name);
	return true;
}

static bool
handle_command_unban (struct handler_args *a)
{
	if (*a->arguments)
		mass_channel_mode_mask_list (a, false, 'b');
	else
		return false;
	return true;
}

static bool
handle_command_invite (struct handler_args *a)
{
	struct strv v = strv_make ();
	cstr_split (a->arguments, " ", true, &v);

	bool result = !!v.len;
	for (size_t i = 0; i < v.len; i++)
		irc_send (a->s, "INVITE %s %s", v.vector[i], a->channel_name);

	strv_free (&v);
	return result;
}

static struct server *
resolve_server (struct app_context *ctx, struct handler_args *a,
	const char *command_name)
{
	struct server *s = NULL;
	if (*a->arguments)
	{
		char *server_name = cut_word (&a->arguments);
		if (!(s = str_map_find (&ctx->servers, server_name)))
			log_global_error (ctx, "/#s: #s: #s",
				command_name, "no such server", server_name);
	}
	else if (a->buffer->type == BUFFER_GLOBAL)
		log_global_error (ctx, "/#s: #s",
			command_name, "no server name given and this buffer is global");
	else
		s = a->buffer->server;
	return s;
}

static bool
handle_command_connect (struct handler_args *a)
{
	struct server *s = NULL;
	if (!(s = resolve_server (a->ctx, a, "connect")))
		return true;

	if (irc_is_connected (s))
	{
		log_server_error (s, s->buffer, "Already connected");
		return true;
	}
	if (s->state == IRC_CONNECTING)
		irc_destroy_connector (s);

	irc_cancel_timers (s);

	s->reconnect_attempt = 0;
	irc_initiate_connect (s);
	return true;
}

static bool
handle_command_disconnect (struct handler_args *a)
{
	struct server *s = NULL;
	if (!(s = resolve_server (a->ctx, a, "disconnect")))
		return true;

	if (s->state == IRC_CONNECTING)
	{
		log_server_status (s, s->buffer, "Connecting aborted");
		irc_destroy_connector (s);
	}
	else if (poller_timer_is_active (&s->reconnect_tmr))
	{
		log_server_status (s, s->buffer, "Connecting aborted");
		poller_timer_reset (&s->reconnect_tmr);
	}
	else if (!irc_is_connected (s))
		log_server_error (s, s->buffer, "Not connected");
	else
		irc_initiate_disconnect (s, *a->arguments ? a->arguments : NULL);
	return true;
}

static bool
show_servers_list (struct app_context *ctx)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "Servers list:");

	struct str_map_iter iter = str_map_iter_make (&ctx->servers);
	struct server *s;
	while ((s = str_map_iter_next (&iter)))
		log_global_indent (ctx, "  #s", s->name);
	return true;
}

static bool
handle_server_add (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	struct app_context *ctx = a->ctx;
	char *name = cut_word (&a->arguments);
	const char *err;
	if ((err = check_server_name_for_addition (ctx, name)))
		log_global_error (ctx, "Cannot create server `#s': #s", name, err);
	else
	{
		server_add_new (ctx, name);
		log_global_status (ctx, "Server added: #s", name);
	}
	return true;
}

static bool
handle_server_remove (struct handler_args *a)
{
	struct app_context *ctx = a->ctx;
	struct server *s = NULL;
	if (!(s = resolve_server (ctx, a, "server")))
		return true;

	if (irc_is_connected (s))
		log_server_error (s, s->buffer, "Can't remove a connected server");
	else
	{
		char *name = xstrdup (s->name);
		server_remove (ctx, s);
		log_global_status (ctx, "Server removed: #s", name);
		free (name);
	}
	return true;
}

static bool
handle_server_rename (struct handler_args *a)
{
	struct app_context *ctx = a->ctx;
	if (!*a->arguments)
		return false;
	char *old_name = cut_word (&a->arguments);
	if (!*a->arguments)
		return false;
	char *new_name = cut_word (&a->arguments);

	struct server *s;
	const char *err;
	if (!(s = str_map_find (&ctx->servers, old_name)))
		log_global_error (ctx, "/#s: #s: #s",
			"server", "no such server", old_name);
	else if ((err = check_server_name_for_addition (ctx, new_name)))
		log_global_error (ctx,
			"Cannot rename server to `#s': #s", new_name, err);
	else
	{
		server_rename (ctx, s, new_name);
		log_global_status (ctx, "Server renamed: #s to #s", old_name, new_name);
	}
	return true;
}

static bool
handle_command_server (struct handler_args *a)
{
	if (!*a->arguments)
		return show_servers_list (a->ctx);

	char *action = cut_word (&a->arguments);
	if (!strcasecmp_ascii (action, "list"))
		return show_servers_list (a->ctx);
	if (!strcasecmp_ascii (action, "add"))
		return handle_server_add (a);
	if (!strcasecmp_ascii (action, "remove"))
		return handle_server_remove (a);
	if (!strcasecmp_ascii (action, "rename"))
		return handle_server_rename (a);
	return false;
}

static bool
handle_command_names (struct handler_args *a)
{
	char *channel_name = try_get_channel (a, maybe_cut_word);
	if (channel_name)
		irc_send (a->s, "NAMES %s", channel_name);
	else
		irc_send (a->s, "NAMES");
	return true;
}

static bool
handle_command_whois (struct handler_args *a)
{
	if (*a->arguments)
		irc_send (a->s, "WHOIS %s", a->arguments);
	else if (a->buffer->type == BUFFER_PM)
		irc_send (a->s, "WHOIS %s", a->buffer->user->nickname);
	else if (a->buffer->type == BUFFER_SERVER)
		irc_send (a->s, "WHOIS %s", a->s->irc_user->nickname);
	else
		log_server_error (a->s, a->buffer, "#s: #s", "Can't request info",
			"no target given and this buffer is neither a PM nor a server");
	return true;
}

static bool
handle_command_whowas (struct handler_args *a)
{
	if (*a->arguments)
		irc_send (a->s, "WHOWAS %s", a->arguments);
	else if (a->buffer->type == BUFFER_PM)
		irc_send (a->s, "WHOWAS %s", a->buffer->user->nickname);
	else
		log_server_error (a->s, a->buffer, "#s: #s", "Can't request info",
			"no target given and this buffer is not a PM");
	return true;
}

static bool
handle_command_kill (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	char *target = cut_word (&a->arguments);
	if (*a->arguments)
		irc_send (a->s, "KILL %s :%s", target, a->arguments);
	else
		irc_send (a->s, "KILL %s", target);
	return true;
}

static bool
handle_command_nick (struct handler_args *a)
{
	if (!*a->arguments)
		return false;

	irc_send (a->s, "NICK %s", cut_word (&a->arguments));
	return true;
}

static bool
handle_command_quote (struct handler_args *a)
{
	irc_send (a->s, "%s", a->arguments);
	return true;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool
handle_command_channel_mode
	(struct handler_args *a, bool adding, char mode_char)
{
	const char *targets = a->arguments;
	if (!*targets)
	{
		if (adding)
			return false;

		targets = a->s->irc_user->nickname;
	}

	struct strv v = strv_make ();
	cstr_split (targets, " ", true, &v);
	mass_channel_mode (a->s, a->channel_name, adding, mode_char, &v);
	strv_free (&v);
	return true;
}

#define CHANMODE_HANDLER(name, adding, mode_char)                              \
	static bool                                                                \
	handle_command_ ## name (struct handler_args *a)                           \
	{                                                                          \
		return handle_command_channel_mode (a, (adding), (mode_char));         \
	}

CHANMODE_HANDLER (op,      true,  'o')  CHANMODE_HANDLER (deop,    false, 'o')
CHANMODE_HANDLER (voice,   true,  'v')  CHANMODE_HANDLER (devoice, false, 'v')

#define TRIVIAL_HANDLER(name, command)                                         \
	static bool                                                                \
	handle_command_ ## name (struct handler_args *a)                           \
	{                                                                          \
		if (*a->arguments)                                                     \
			irc_send (a->s, command " %s", a->arguments);                      \
		else                                                                   \
			irc_send (a->s, command);                                          \
		return true;                                                           \
	}

TRIVIAL_HANDLER (list,  "LIST")
TRIVIAL_HANDLER (who,   "WHO")
TRIVIAL_HANDLER (motd,  "MOTD")
TRIVIAL_HANDLER (oper,  "OPER")
TRIVIAL_HANDLER (stats, "STATS")
TRIVIAL_HANDLER (away,  "AWAY")

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool handle_command_help (struct handler_args *);

static struct command_handler
{
	const char *name;
	const char *description;
	const char *usage;
	bool (*handler) (struct handler_args *a);
	enum handler_flags flags;
}
g_command_handlers[] =
{
	{ "help",       "Show help",
	  "[<command> | <option>]",
	  handle_command_help,       0 },
	{ "quit",       "Quit the program",
	  "[<message>]",
	  handle_command_quit,       0 },
	{ "buffer",     "Manage buffers",
	  "<N> | list | clear | move <N> | goto <N or name> | close [<N or name>]",
	  handle_command_buffer,     0 },
	{ "set",        "Manage configuration",
	  "[<option>]",
	  handle_command_set,        0 },
	{ "save",       "Save configuration",
	  NULL,
	  handle_command_save,       0 },
	{ "plugin",     "Manage plugins",
	  "list | load <name> | unload <name>",
	  handle_command_plugin,     0 },
	{ "relay",      "Show relay information",
	  NULL,
	  handle_command_relay,      0 },

	{ "alias",      "List or set aliases",
	  "[<name> <definition>]",
	  handle_command_alias,      0 },
	{ "unalias",    "Unset aliases",
	  "<name>...",
	  handle_command_unalias,    0 },

	{ "msg",        "Send message to a nick or channel",
	  "<target> <message>",
	  handle_command_msg,        HANDLER_SERVER | HANDLER_NEEDS_REG },
	{ "query",      "Send a private message to a nick",
	  "<nick> <message>",
	  handle_command_query,      HANDLER_SERVER | HANDLER_NEEDS_REG },
	{ "notice",     "Send notice to a nick or channel",
	  "<target> <message>",
	  handle_command_notice,     HANDLER_SERVER | HANDLER_NEEDS_REG },
	{ "squery",     "Send a message to a service",
	  "<service> <message>",
	  handle_command_squery,     HANDLER_SERVER | HANDLER_NEEDS_REG },
	{ "ctcp",       "Send a CTCP query",
	  "<target> <tag>",
	  handle_command_ctcp,       HANDLER_SERVER | HANDLER_NEEDS_REG },
	{ "me",         "Send a CTCP action",
	  "<message>",
	  handle_command_me,         HANDLER_SERVER | HANDLER_NEEDS_REG },

	{ "join",       "Join channels",
	  "[<channel>[,<channel>...]] [<key>[,<key>...]]",
	  handle_command_join,       HANDLER_SERVER },
	{ "part",       "Leave channels",
	  "[<channel>[,<channel>...]] [<reason>]",
	  handle_command_part,       HANDLER_SERVER },
	{ "cycle",      "Rejoin channels",
	  "[<channel>[,<channel>...]] [<reason>]",
	  handle_command_cycle,      HANDLER_SERVER },

	{ "op",         "Give channel operator status",
	  "<nick>...",
	  handle_command_op,         HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "deop",       "Remove channel operator status",
	  "[<nick>...]",
	  handle_command_deop,       HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "voice",      "Give voice",
	  "<nick>...",
	  handle_command_voice,      HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "devoice",    "Remove voice",
	  "[<nick>...]",
	  handle_command_devoice,    HANDLER_SERVER | HANDLER_CHANNEL_FIRST },

	{ "mode",       "Change mode",
	  "[<channel>] [<mode>...]",
	  handle_command_mode,       HANDLER_SERVER },
	{ "topic",      "Change topic",
	  "[<channel>] [<topic>]",
	  handle_command_topic,      HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "kick",       "Kick user from channel",
	  "[<channel>] <user> [<reason>]",
	  handle_command_kick,       HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "kickban",    "Kick and ban user from channel",
	  "[<channel>] <user> [<reason>]",
	  handle_command_kickban,    HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "ban",        "Ban user from channel",
	  "[<channel>] [<mask>...]",
	  handle_command_ban,        HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "unban",      "Unban user from channel",
	  "[<channel>] <mask>...",
	  handle_command_unban,      HANDLER_SERVER | HANDLER_CHANNEL_FIRST },
	{ "invite",     "Invite user to channel",
	  "<user>... [<channel>]",
	  handle_command_invite,     HANDLER_SERVER | HANDLER_CHANNEL_LAST },

	{ "server",     "Manage servers",
	  "list | add <name> | remove <name> | rename <old> <new>",
	  handle_command_server,     0 },
	{ "connect",    "Connect to the server",
	  "[<server>]",
	  handle_command_connect,    0 },
	{ "disconnect", "Disconnect from the server",
	  "[<server> [<reason>]]",
	  handle_command_disconnect, 0 },

	{ "list",       "List channels and their topic",
	  "[<channel>[,<channel>...]] [<target>]",
	  handle_command_list,       HANDLER_SERVER },
	{ "names",      "List users on channel",
	  "[<channel>[,<channel>...]]",
	  handle_command_names,      HANDLER_SERVER },
	{ "who",        "List users",
	  "[<mask> [o]]",
	  handle_command_who,        HANDLER_SERVER },
	{ "whois",      "Get user information",
	  "[<target>] <mask>",
	  handle_command_whois,      HANDLER_SERVER },
	{ "whowas",     "Get user information",
	  "<user> [<count> [<target>]]",
	  handle_command_whowas,     HANDLER_SERVER },

	{ "motd",       "Get the Message of The Day",
	  "[<target>]",
	  handle_command_motd,       HANDLER_SERVER },
	{ "oper",       "Authenticate as an IRC operator",
	  "<name> <password>",
	  handle_command_oper,       HANDLER_SERVER },
	{ "kill",       "Kick another user from the server",
	  "<user> <comment>",
	  handle_command_kill,       HANDLER_SERVER },
	{ "stats",      "Query server statistics",
	  "[<query> [<target>]]",
	  handle_command_stats,      HANDLER_SERVER },
	{ "away",       "Set away status",
	  "[<text>]",
	  handle_command_away,       HANDLER_SERVER },
	{ "nick",       "Change current nick",
	  "<nickname>",
	  handle_command_nick,       HANDLER_SERVER },
	{ "quote",      "Send a raw command to the server",
	  "<command>",
	  handle_command_quote,      HANDLER_SERVER },
};

static bool
try_handle_command_help_option (struct app_context *ctx, const char *name)
{
	struct config_item *item =
		config_item_get (ctx->config.root, name, NULL);
	if (!item)
		return false;

	struct config_schema *schema = item->schema;
	if (!schema)
	{
		log_global_error (ctx, "#s: #s", "Option not recognized", name);
		return true;
	}

	log_global_indent (ctx, "");
	log_global_indent (ctx, "Option \"#s\":", name);
	log_global_indent (ctx, "  Description: #s",
		schema->comment ? schema->comment : "(none)");
	log_global_indent (ctx, "  Type: #s", config_item_type_name (schema->type));
	log_global_indent (ctx, "  Default: #s",
		schema->default_ ? schema->default_ : "null");

	struct str tmp = str_make ();
	config_item_write (item, false, &tmp);
	log_global_indent (ctx, "  Current value: #s", tmp.str);
	str_free (&tmp);
	return true;
}

static bool
show_command_list (struct app_context *ctx)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "Commands:");

	int longest = 0;
	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
	{
		int len = strlen (g_command_handlers[i].name);
		longest = MAX (longest, len);
	}
	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
	{
		struct command_handler *handler = &g_command_handlers[i];
		log_global_indent (ctx, "  #&s", xstrdup_printf
			("%-*s  %s", longest, handler->name, handler->description));
	}
	return true;
}

static bool
show_command_help (struct app_context *ctx, struct command_handler *handler)
{
	log_global_indent (ctx, "");
	log_global_indent (ctx, "/#s: #s", handler->name, handler->description);
	log_global_indent (ctx, "  Arguments: #s",
		handler->usage ? handler->usage : "(none)");
	return true;
}

static bool
handle_command_help (struct handler_args *a)
{
	struct app_context *ctx = a->ctx;
	if (!*a->arguments)
		return show_command_list (ctx);

	const char *word = cut_word (&a->arguments);

	const char *command = word + (*word == '/');
	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
	{
		struct command_handler *handler = &g_command_handlers[i];
		if (!strcasecmp_ascii (command, handler->name))
			return show_command_help (ctx, handler);
	}

	if (try_handle_command_help_option (ctx, word))
		return true;

	if (str_map_find (get_aliases_config (ctx), command))
		log_global_status (ctx, "/#s is an alias", command);
	else
		log_global_error (ctx, "#s: #s", "No such command or option", word);
	return true;
}

static void
init_user_command_map (struct str_map *map)
{
	*map = str_map_make (NULL);
	map->key_xfrm = tolower_ascii_strxfrm;

	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
	{
		struct command_handler *handler = &g_command_handlers[i];
		str_map_set (map, handler->name, handler);
	}
}

static bool
process_user_command (struct app_context *ctx, struct buffer *buffer,
	const char *command_name, char *input)
{
	static bool initialized = false;
	static struct str_map map;
	if (!initialized)
	{
		init_user_command_map (&map);
		initialized = true;
	}

	if (try_handle_buffer_goto (ctx, command_name))
		return true;

	struct handler_args args =
	{
		.ctx = ctx,
		.buffer = buffer,
		.arguments = input,
	};

	struct command_handler *handler;
	if (!(handler = str_map_find (&map, command_name)))
		return false;
	hard_assert (handler->flags == 0 || (handler->flags & HANDLER_SERVER));

	if ((handler->flags & HANDLER_SERVER)
		&& args.buffer->type == BUFFER_GLOBAL)
		log_global_error (ctx, "/#s: #s",
			command_name, "can't do this from a global buffer");
	else if ((handler->flags & HANDLER_SERVER)
		&& !irc_is_connected ((args.s = args.buffer->server)))
		log_server_error (args.s, args.s->buffer, "Not connected");
	else if ((handler->flags & HANDLER_NEEDS_REG)
		&& args.s->state != IRC_REGISTERED)
		log_server_error (args.s, args.s->buffer, "Not registered");
	else if (((handler->flags & HANDLER_CHANNEL_FIRST)
			&& !(args.channel_name =
				try_get_channel (&args, maybe_cut_word)))
		|| ((handler->flags & HANDLER_CHANNEL_LAST)
			&& !(args.channel_name =
				try_get_channel (&args, maybe_cut_word_from_end))))
		log_server_error (args.s, args.buffer, "/#s: #s", command_name,
			"no channel name given and this buffer is not a channel");
	else if (!handler->handler (&args))
		log_global_error (ctx,
			"#s: /#s #s", "Usage", handler->name, handler->usage);
	return true;
}

static const char *
expand_alias_escape (const char *p, const char *arguments, struct str *output)
{
	struct strv words = strv_make ();
	cstr_split (arguments, " ", true, &words);

	// TODO: eventually also add support for argument ranges
	//  - Can use ${0}, ${0:}, ${:0}, ${1:-1} with strtol, dispose of $1 syntax
	//    (default aliases don't use numeric arguments).
	//  - Start numbering from zero, since we'd have to figure out what to do
	//    in case we encounter a zero if we keep the current approach.
	//  - Ignore the sequence altogether if no closing '}' can be found,
	//    or if the internal format doesn't fit the above syntax.
	if (*p >= '1' && *p <= '9')
	{
		size_t offset = *p - '1';
		if (offset < words.len)
			str_append (output, words.vector[offset]);
	}
	else if (*p == '*')
		str_append (output, arguments);
	else if (strchr ("$;", *p))
		str_append_c (output, *p);
	else
		str_append_printf (output, "$%c", *p);

	strv_free (&words);
	return ++p;
}

static void
expand_alias_definition (const char *definition, const char *arguments,
	struct strv *commands)
{
	struct str expanded = str_make ();
	bool escape = false;
	for (const char *p = definition; *p; p++)
	{
		if (escape)
		{
			p = expand_alias_escape (p, arguments, &expanded) - 1;
			escape = false;
		}
		else if (*p == ';')
		{
			strv_append_owned (commands, str_steal (&expanded));
			expanded = str_make ();
		}
		else if (*p == '$' && p[1])
			escape = true;
		else
			str_append_c (&expanded, *p);
	}
	strv_append_owned (commands, str_steal (&expanded));
}

static bool
expand_alias (struct app_context *ctx,
	const char *alias_name, char *input, struct strv *commands)
{
	struct config_item *entry =
		str_map_find (get_aliases_config (ctx), alias_name);
	if (!entry)
		return false;

	if (!config_item_type_is_string (entry->type))
	{
		log_global_error (ctx, "Error executing `/#s': #s",
			alias_name, "alias definition is not a string");
		return false;
	}

	expand_alias_definition (entry->value.string.str, input, commands);
	return true;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
send_message_to_target (struct server *s,
	const char *target, char *message, struct buffer *buffer)
{
	if (!irc_is_connected (s))
		log_server_error (s, buffer, "Not connected");
	else
		SEND_AUTOSPLIT_PRIVMSG (s, target, message);
}

static void
send_message_to_buffer (struct app_context *ctx, struct buffer *buffer,
	char *message)
{
	hard_assert (buffer != NULL);

	switch (buffer->type)
	{
	case BUFFER_CHANNEL:
		send_message_to_target (buffer->server,
			buffer->channel->name, message, buffer);
		break;
	case BUFFER_PM:
		send_message_to_target (buffer->server,
			buffer->user->nickname, message, buffer);
		break;
	default:
		log_full (ctx, NULL, buffer, 0, BUFFER_LINE_ERROR,
			"This buffer is not a channel");
	}
}

static bool
process_alias (struct app_context *ctx, struct buffer *buffer,
	struct strv *commands, int level)
{
	for (size_t i = 0; i < commands->len; i++)
		log_global_debug (ctx, "Alias expanded to: ###d: \"#s\"",
			(int) i, commands->vector[i]);
	for (size_t i = 0; i < commands->len; i++)
		if (!process_input_utf8 (ctx, buffer, commands->vector[i], ++level))
			return false;
	return true;
}

static bool
process_input_utf8_posthook (struct app_context *ctx, struct buffer *buffer,
	char *input, int alias_level)
{
	if (*input != '/' || *++input == '/')
	{
		send_message_to_buffer (ctx, buffer, input);
		return true;
	}

	char *name = cut_word (&input);
	if (process_user_command (ctx, buffer, name, input))
		return true;

	struct strv commands = strv_make ();
	bool result = false;
	if (!expand_alias (ctx, name, input, &commands))
		log_global_error (ctx, "#s: /#s", "No such command or alias", name);
	else if (alias_level != 0)
		log_global_error (ctx, "#s: /#s", "Aliases can't nest", name);
	else
		result = process_alias (ctx, buffer, &commands, alias_level);

	strv_free (&commands);
	return result;
}

static char *
process_input_hooks (struct app_context *ctx, struct buffer *buffer,
	char *input)
{
	uint64_t hash = siphash_wrapper (input, strlen (input));
	LIST_FOR_EACH (struct hook, iter, ctx->input_hooks)
	{
		struct input_hook *hook = (struct input_hook *) iter;
		if (!(input = hook->filter (hook, buffer, input)))
		{
			log_global_debug (ctx, "Input thrown away by hook");
			return NULL;
		}

		uint64_t new_hash = siphash_wrapper (input, strlen (input));
		if (new_hash != hash)
			log_global_debug (ctx, "Input transformed to \"#s\"#r", input);
		hash = new_hash;
	}
	return input;
}

static bool
process_input_utf8 (struct app_context *ctx, struct buffer *buffer,
	const char *input, int alias_level)
{
	// Note that this also gets called on expanded aliases,
	// which might or might not be desirable (we can forward "alias_level")
	char *processed = process_input_hooks (ctx, buffer, xstrdup (input));
	bool result = !processed
		|| process_input_utf8_posthook (ctx, buffer, processed, alias_level);
	free (processed);
	return result;
}

static void
process_input (struct app_context *ctx, char *user_input)
{
	char *input;
	if (!(input = iconv_xstrdup (ctx->term_to_utf8, user_input, -1, NULL)))
		print_error ("character conversion failed for: %s", "user input");
	else
	{
		struct strv lines = strv_make ();
		cstr_split (input, "\r\n", false, &lines);
		for (size_t i = 0; i < lines.len; i++)
			(void) process_input_utf8 (ctx,
				ctx->current_buffer, lines.vector[i], 0);

		strv_free (&lines);
	}
	free (input);
}

// --- Word completion ---------------------------------------------------------

// The amount of crap that goes into this is truly insane.
// It's mostly because of Editline's total ignorance of this task.

static void
completion_free (struct completion *self)
{
	free (self->line);
	free (self->words);
}

static void
completion_add_word (struct completion *self, size_t start, size_t end)
{
	if (!self->words)
		self->words = xcalloc ((self->words_alloc = 4), sizeof *self->words);
	if (self->words_len == self->words_alloc)
		self->words = xreallocarray (self->words,
			(self->words_alloc <<= 1), sizeof *self->words);
	self->words[self->words_len++] = (struct completion_word) { start, end };
}

static struct completion
completion_make (const char *line, size_t len)
{
	struct completion self = { .line = xstrndup (line, len) };

	// The first and the last word may be empty
	const char *s = self.line;
	while (true)
	{
		const char *start = s;
		size_t word_len = strcspn (s, WORD_BREAKING_CHARS);
		const char *end = start + word_len;
		s = end + strspn (end, WORD_BREAKING_CHARS);

		completion_add_word (&self, start - self.line, end - self.line);
		if (s == end)
			break;
	}
	return self;
}

static void
completion_locate (struct completion *self, size_t offset)
{
	size_t i = 0;
	for (; i < self->words_len; i++)
		if (self->words[i].start > offset)
			break;
	self->location = i - 1;
}

static char *
completion_word (struct completion *self, int word)
{
	hard_assert (word >= 0 && word < (int) self->words_len);
	return xstrndup (self->line + self->words[word].start,
		self->words[word].end - self->words[word].start);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// XXX: this isn't completely right because Unicode, but let's keep it simple.
//   At worst it will stop before a combining mark, or fail to compare
//   non-ASCII identifiers case-insensitively.

static size_t
utf8_common_prefix (const char **vector, size_t len)
{
	size_t prefix = 0;
	if (!vector || !len)
		return 0;

	struct utf8_iter a[len];
	for (size_t i = 0; i < len; i++)
		a[i] = utf8_iter_make (vector[i]);

	size_t ch_len;
	int32_t ch;
	while ((ch = utf8_iter_next (&a[0], &ch_len)) >= 0)
	{
		for (size_t i = 1; i < len; i++)
		{
			int32_t other = utf8_iter_next (&a[i], NULL);
			if (ch == other)
				continue;
			// Not bothering with lowercasing non-ASCII
			if (ch >= 0x80 || other >= 0x80
			 || tolower_ascii (ch) != tolower_ascii (other))
				return prefix;
		}
		prefix += ch_len;
	}
	return prefix;
}

static void
complete_command (struct app_context *ctx, struct completion *data,
	const char *word, struct strv *output)
{
	(void) data;

	const char *prefix = "";
	if (*word == '/')
	{
		word++;
		prefix = "/";
	}

	size_t word_len = strlen (word);
	for (size_t i = 0; i < N_ELEMENTS (g_command_handlers); i++)
	{
		struct command_handler *handler = &g_command_handlers[i];
		if (!strncasecmp_ascii (word, handler->name, word_len))
			strv_append_owned (output,
				xstrdup_printf ("%s%s", prefix, handler->name));
	}

	struct str_map_iter iter = str_map_iter_make (get_aliases_config (ctx));
	struct config_item *alias;
	while ((alias = str_map_iter_next (&iter)))
	{
		if (!strncasecmp_ascii (word, iter.link->key, word_len))
			strv_append_owned (output,
				xstrdup_printf ("%s%s", prefix, iter.link->key));
	}
}

static void
complete_option (struct app_context *ctx, struct completion *data,
	const char *word, struct strv *output)
{
	(void) data;

	struct strv options = strv_make ();
	config_dump (ctx->config.root, &options);
	strv_sort (&options);

	// Wildcard expansion is an interesting side-effect
	char *mask = xstrdup_printf ("%s*", word);
	for (size_t i = 0; i < options.len; i++)
	{
		char *key = cstr_cut_until (options.vector[i], " ");
		if (!fnmatch (mask, key, 0))
			strv_append_owned (output, key);
		else
			free (key);
	}
	free (mask);
	strv_free (&options);
}

static void
complete_set_value (struct config_item *item, const char *word,
	struct strv *output)
{
	struct str serialized = str_make ();
	config_item_write (item, false, &serialized);
	if (!strncmp (serialized.str, word, strlen (word)))
		strv_append_owned (output, str_steal (&serialized));
	else
		str_free (&serialized);
}

static void
complete_set_value_array (struct config_item *item, const char *word,
	struct strv *output)
{
	if (!item->schema || item->schema->type != CONFIG_ITEM_STRING_ARRAY)
		return;

	struct strv items = strv_make ();
	cstr_split (item->value.string.str, ",", false, &items);
	for (size_t i = 0; i < items.len; i++)
	{
		struct str wrapped = str_from_cstr (items.vector[i]);
		struct str serialized = str_make ();
		config_item_write_string (&serialized, &wrapped);
		str_free (&wrapped);

		if (!strncmp (serialized.str, word, strlen (word)))
			strv_append_owned (output, str_steal (&serialized));
		else
			str_free (&serialized);
	}
	strv_free (&items);
}

static void
complete_set (struct app_context *ctx, struct completion *data,
	const char *word, struct strv *output)
{
	if (data->location == 1)
	{
		complete_option (ctx, data, word, output);
		return;
	}
	if (data->location != 3)
		return;

	char *key = completion_word (data, 1);
	struct config_item *item = config_item_get (ctx->config.root, key, NULL);
	if (item)
	{
		char *op = completion_word (data, 2);
		if (!strcmp (op, "-=")) complete_set_value_array (item, word, output);
		if (!strcmp (op,  "=")) complete_set_value       (item, word, output);
		free (op);
	}
	free (key);
}

static void
complete_topic (struct buffer *buffer, struct completion *data,
	const char *word, struct strv *output)
{
	(void) data;

	// TODO: make it work in other server-related buffers, too, i.e. when we're
	//   completing the third word and the second word is a known channel name
	if (buffer->type != BUFFER_CHANNEL)
		return;

	const char *topic = buffer->channel->topic;
	if (topic && !strncasecmp_ascii (word, topic, strlen (word)))
	{
		// We must prepend the channel name if the topic itself starts
		// with something that could be regarded as a channel name
		strv_append_owned (output, irc_is_channel (buffer->server, topic)
			? xstrdup_printf ("%s %s", buffer->channel->name, topic)
			: xstrdup (topic));
	}
}

static void
complete_nicknames (struct buffer *buffer, struct completion *data,
	const char *word, struct strv *output)
{
	if (buffer->type == BUFFER_SERVER)
	{
		struct user *self_user = buffer->server->irc_user;
		if (self_user)
			strv_append (output, self_user->nickname);
	}
	if (buffer->type != BUFFER_CHANNEL)
		return;

	size_t word_len = strlen (word);
	LIST_FOR_EACH (struct channel_user, iter, buffer->channel->users)
	{
		const char *nickname = iter->user->nickname;
		if (irc_server_strncmp (buffer->server, word, nickname, word_len))
			continue;
		strv_append_owned (output, data->location == 0
			? xstrdup_printf ("%s:", nickname)
			: xstrdup (nickname));
	}
}

static struct strv
complete_word (struct app_context *ctx, struct buffer *buffer,
	struct completion *data, const char *word)
{
	char *initial = completion_word (data, 0);

	// Start with a placeholder for the longest common prefix
	struct strv words = strv_make ();
	strv_append_owned (&words, NULL);

	if      (data->location == 0 && *initial == '/')
		complete_command   (ctx, data, word, &words);
	else if (data->location >= 1 && !strcmp (initial, "/set"))
		complete_set       (ctx, data, word, &words);
	else if (data->location == 1 && !strcmp (initial, "/help"))
	{
		complete_command   (ctx, data, word, &words);
		complete_option    (ctx, data, word, &words);
	}
	else if (data->location == 1 && !strcmp (initial, "/topic"))
	{
		complete_topic     (buffer, data, word, &words);
		complete_nicknames (buffer, data, word, &words);
	}
	else
		complete_nicknames (buffer, data, word, &words);

	cstr_set (&initial, NULL);
	LIST_FOR_EACH (struct hook, iter, ctx->completion_hooks)
	{
		struct completion_hook *hook = (struct completion_hook *) iter;
		hook->complete (hook, data, word, &words);
	}

	if (words.len <= 2)
	{
		// When nothing matches, this copies the sentinel value
		words.vector[0] = words.vector[1];
		words.vector[1] = NULL;
		words.len--;
	}
	else
	{
		size_t prefix = utf8_common_prefix
			((const char **) words.vector + 1, words.len - 1);
		if (!prefix)
			words.vector[0] = xstrdup (word);
		else
			words.vector[0] = xstrndup (words.vector[1], prefix);
	}
	return words;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

/// A special wrapper for iconv_xstrdup() that also fixes indexes into the
/// original string to point to the right location in the output.
/// Thanks, Readline!  Without you I would have never needed to deal with this.
static char *
locale_to_utf8 (struct app_context *ctx, const char *locale,
	int *indexes[], size_t n_indexes)
{
	mbstate_t state;
	memset (&state, 0, sizeof state);

	size_t remaining = strlen (locale) + 1;
	const char *p = locale;

	// Reset the shift state, FWIW
	// TODO: Don't use this iconv handle directly at all, elsewhere in xC.
	//   And ideally use U+FFFD with EILSEQ.
	(void) iconv (ctx->term_to_utf8, NULL, NULL, NULL, NULL);

	bool fixed[n_indexes];
	memset (fixed, 0, sizeof fixed);

	struct str utf8 = str_make ();
	while (true)
	{
		size_t len = mbrlen (p, remaining, &state);

		// Incomplete multibyte character or illegal sequence (probably)
		if (len == (size_t) -2
		 || len == (size_t) -1)
		{
			str_free (&utf8);
			return NULL;
		}

		// Convert indexes into the multibyte string to UTF-8
		for (size_t i = 0; i < n_indexes; i++)
			if (!fixed[i] && *indexes[i] <= p - locale)
			{
				*indexes[i] = utf8.len;
				fixed[i] = true;
			}

		// End of string
		if (!len)
			break;

		// EINVAL (incomplete sequence) should never happen and
		// EILSEQ neither because we've already checked for that with mbrlen().
		// E2BIG is what iconv_xstrdup solves.  This must succeed.
		size_t ch_len;
		char *ch = iconv_xstrdup (ctx->term_to_utf8, (char *) p, len, &ch_len);
		hard_assert (ch != NULL);
		str_append_data (&utf8, ch, ch_len);
		free (ch);

		p += len;
		remaining -= len;
	}
	return str_steal (&utf8);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static struct strv
make_completions (struct app_context *ctx, struct buffer *buffer,
	const char *line_utf8, size_t start, size_t end)
{
	struct completion comp = completion_make (line_utf8, strlen (line_utf8));
	completion_locate (&comp, start);
	char *word = xstrndup (line_utf8 + start, end - start);
	struct strv completions = complete_word (ctx, buffer, &comp, word);
	free (word);
	completion_free (&comp);
	return completions;
}

/// Takes a line in locale-specific encoding and position of a word to complete,
/// returns a vector of matches in locale-specific encoding.
static char **
make_input_completions
	(struct app_context *ctx, const char *line, int start, int end)
{
	int *fixes[] = { &start, &end };
	char *line_utf8 = locale_to_utf8 (ctx, line, fixes, N_ELEMENTS (fixes));
	if (!line_utf8)
		return NULL;

	hard_assert (start >= 0 && end >= 0 && start <= end);

	struct strv completions =
		make_completions (ctx, ctx->current_buffer, line_utf8, start, end);
	free (line_utf8);
	if (!completions.len)
	{
		strv_free (&completions);
		return NULL;
	}
	for (size_t i = 0; i < completions.len; i++)
	{
		char *converted = iconv_xstrdup
			(ctx->term_from_utf8, completions.vector[i], -1, NULL);
		if (!soft_assert (converted))
			converted = xstrdup ("?");
		cstr_set (&completions.vector[i], converted);
	}
	return completions.vector;
}

// --- Common code for user actions --------------------------------------------

static void
toggle_bracketed_paste (bool enable)
{
	fprintf (stdout, "\x1b[?2004%c", "lh"[enable]);
	fflush (stdout);
}

static void
suspend_terminal (struct app_context *ctx)
{
	// Terminal can get suspended by both the pager and SIGTSTP handling
	if (ctx->terminal_suspended++ > 0)
		return;

	toggle_bracketed_paste (false);
	CALL (ctx->input, hide);
	poller_fd_reset (&ctx->tty_event);

	CALL_ (ctx->input, prepare, false);
}

static void
resume_terminal (struct app_context *ctx)
{
	if (--ctx->terminal_suspended > 0)
		return;

	update_screen_size ();
	CALL_ (ctx->input, prepare, true);
	CALL (ctx->input, on_tty_resized);

	toggle_bracketed_paste (true);
	// In theory we could just print all unseen messages but this is safer
	buffer_print_backlog (ctx, ctx->current_buffer);
	// Now it's safe to process any user input
	poller_fd_set (&ctx->tty_event, POLLIN);
	CALL (ctx->input, show);
}

static pid_t
spawn_helper_child (struct app_context *ctx)
{
	suspend_terminal (ctx);
	pid_t child = fork ();
	switch (child)
	{
	case -1:
	{
		int saved_errno = errno;
		resume_terminal (ctx);
		errno = saved_errno;
		break;
	}
	case 0:
		// Put the child in a new foreground process group
		hard_assert (setpgid (0, 0) != -1);
		hard_assert (tcsetpgrp (STDOUT_FILENO, getpgid (0)) != -1);
		break;
	default:
		// Make sure of it in the parent as well before continuing
		(void) setpgid (child, child);
	}
	return child;
}

static void
redraw_screen (struct app_context *ctx)
{
	// If by some circumstance we had the wrong idea
	CALL (ctx->input, on_tty_resized);
	update_screen_size ();

	CALL (ctx->input, hide);
	buffer_print_backlog (ctx, ctx->current_buffer);
	CALL (ctx->input, show);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool
dump_input_to_file (struct app_context *ctx, char *template, struct error **e)
{
	mode_t mask = umask (S_IXUSR | S_IRWXG | S_IRWXO);
	int fd = mkstemp (template);
	(void) umask (mask);

	if (fd < 0)
		return error_set (e, "%s", strerror (errno));

	char *input = CALL_ (ctx->input, get_line, NULL);
	bool success = xwrite (fd, input, strlen (input), e);
	free (input);

	if (!success)
		(void) unlink (template);

	xclose (fd);
	return success;
}

static char *
try_dump_input_to_file (struct app_context *ctx)
{
	char *template = resolve_filename
		("input.XXXXXX", resolve_relative_runtime_template);

	struct error *e = NULL;
	if (dump_input_to_file (ctx, template, &e))
		return template;

	log_global_error (ctx, "#s: #s",
		"Failed to create a temporary file for editing", e->message);
	error_free (e);
	free (template);
	return NULL;
}

static struct strv
build_editor_command (struct app_context *ctx, const char *filename)
{
	struct strv argv = strv_make ();
	const char *editor = get_config_string (ctx->config.root, "general.editor");
	if (!editor)
	{
		const char *command;
		if (!(command = getenv ("VISUAL"))
		 && !(command = getenv ("EDITOR")))
			command = "vi";

		// Although most visual editors support a "+LINE" argument
		// (every editor mentioned in the default value of general.editor,
		// plus vi, mcedit, vis, ...), it isn't particularly useful by itself.
		// We need to be able to specify the column number.
		//
		// Seeing as less popular software may try to process this as a filename
		// and fail, do not bother with this "undocumented standard feature".
		strv_append (&argv, command);
		strv_append (&argv, filename);
		return argv;
	}

	int cursor = 0;
	char *input = CALL_ (ctx->input, get_line, &cursor);
	hard_assert (cursor >= 0);

	mbstate_t ps;
	memset (&ps, 0, sizeof ps);

	wchar_t wch;
	size_t len, processed = 0, line_one_based = 1, column = 0;
	while (processed < (size_t) cursor
		&& (len = mbrtowc (&wch, input + processed, cursor - processed, &ps))
		&& len != (size_t) -2 && len != (size_t) -1)
	{
		// Both VIM and Emacs use the caret notation with columns.
		// Consciously leaving tabs broken, they're too difficult to handle.
		int width = wcwidth (wch);
		if (width < 0)
			width = 2;

		processed += len;
		if (wch == '\n')
		{
			line_one_based++;
			column = 0;
		}
		else
			column += width;
	}
	free (input);

	// Trivially split the command on spaces and substitute our values
	struct str argument = str_make ();
	for (; *editor; editor++)
	{
		if (*editor == ' ')
		{
			if (argument.len)
			{
				strv_append_owned (&argv, str_steal (&argument));
				argument = str_make ();
			}
			continue;
		}
		if (*editor != '%' || !editor[1])
		{
			str_append_c (&argument, *editor);
			continue;
		}

		// None of them are zero-length, thus words don't get lost
		switch (*++editor)
		{
		case 'F':
			str_append (&argument, filename);
			continue;
		case 'L':
			str_append_printf (&argument, "%zu", line_one_based);
			continue;
		case 'C':
			str_append_printf (&argument, "%zu", column + 1);
			continue;
		case 'B':
			str_append_printf (&argument, "%d",  cursor + 1);
			continue;
		case '%':
		case ' ':
			str_append_c (&argument, *editor);
			continue;
		}

		const char *p = editor;
		if (soft_assert (utf8_decode (&p, strlen (p)) > 0))
		{
			log_global_error (ctx, "Unknown substitution variable: %#&s",
				xstrndup (editor, p - editor));
		}
	}
	if (argument.len)
		strv_append_owned (&argv, str_steal (&argument));
	else
		str_free (&argument);
	return argv;
}

static bool
on_edit_input (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	struct app_context *ctx = user_data;

	char *filename;
	if (!(filename = try_dump_input_to_file (ctx)))
		return false;

	struct strv argv = build_editor_command (ctx, filename);
	if (!argv.len)
		strv_append (&argv, "true");

	hard_assert (!ctx->running_editor);
	switch (spawn_helper_child (ctx))
	{
	case 0:
		execvp (argv.vector[0], argv.vector);
		print_error ("%s: %s",
			"Failed to launch editor", strerror (errno));
		_exit (EXIT_FAILURE);
	case -1:
		log_global_error (ctx, "#s: #l",
			"Failed to launch editor", strerror (errno));
		free (filename);
		break;
	default:
		ctx->running_editor = true;
		ctx->editor_filename = filename;
	}
	strv_free (&argv);
	return true;
}

static void
input_editor_process (struct app_context *ctx)
{
	struct str input = str_make ();
	struct error *e = NULL;
	if (!read_file (ctx->editor_filename, &input, &e))
	{
		log_global_error (ctx, "#s: #s", "Input editing failed", e->message);
		error_free (e);
	}
	else
		CALL (ctx->input, clear_line);

	if (!CALL_ (ctx->input, insert, input.str))
		log_global_error (ctx, "#s: #s", "Input editing failed",
			"could not re-insert the modified text");

	str_free (&input);
}

static void
input_editor_cleanup (struct app_context *ctx)
{
	if (unlink (ctx->editor_filename))
		log_global_error (ctx, "Could not unlink `#l': #l",
			ctx->editor_filename, strerror (errno));

	cstr_set (&ctx->editor_filename, NULL);
	ctx->running_editor = false;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
launch_pager (struct app_context *ctx,
	int fd, const char *name, const char *path)
{
	hard_assert (!ctx->running_pager);
	switch (spawn_helper_child (ctx))
	{
	case 0:
		dup2 (fd, STDIN_FILENO);
		char *localized_name =
			iconv_xstrdup (ctx->term_from_utf8, (char *) name, -1, NULL);
		execl ("/bin/sh", "/bin/sh", "-c",
			get_config_string (ctx->config.root, "general.pager"),
			PROGRAM_NAME, localized_name, path, NULL);
		print_error ("%s: %s", "Failed to launch pager", strerror (errno));
		_exit (EXIT_FAILURE);
	case -1:
		log_global_error (ctx, "#s: #l",
			"Failed to launch pager", strerror (errno));
		break;
	default:
		ctx->running_pager = true;
	}
}

static bool
display_backlog (struct app_context *ctx, int flush_opts)
{
	FILE *backlog = tmpfile ();
	if (!backlog)
	{
		log_global_error (ctx, "#s: #l",
			"Failed to create a temporary file", strerror (errno));
		return false;
	}

	if (!get_config_boolean (ctx->config.root,
		"general.pager_strip_formatting"))
		flush_opts |= FLUSH_OPT_RAW;

	struct buffer *buffer = ctx->current_buffer;
	int until_marker =
		(int) buffer->lines_count - (int) buffer->new_messages_count;
	for (struct buffer_line *line = buffer->lines; line; line = line->next)
	{
		if (until_marker-- == 0
		 && buffer->new_messages_count != buffer->lines_count)
			buffer_print_read_marker (ctx, backlog, flush_opts);
		if (buffer_line_will_show_up (buffer, line))
			buffer_line_write_to_backlog (ctx, line, backlog, flush_opts);
	}

	// So that it is obvious if the last line in the buffer is not from today
	buffer_update_time (ctx, time (NULL), backlog, flush_opts);

	rewind (backlog);
	set_cloexec (fileno (backlog));
	launch_pager (ctx, fileno (backlog), buffer->name, NULL);
	fclose (backlog);
	return true;
}

static bool
on_display_backlog (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	return display_backlog (user_data, 0);
}

static bool
on_display_backlog_nowrap (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	return display_backlog (user_data, FLUSH_OPT_NOWRAP);
}

static FILE *
open_log_path (struct app_context *ctx, struct buffer *buffer, const char *path)
{
	FILE *fp = fopen (path, "rb");
	if (!fp)
	{
		log_global_error (ctx,
			"Failed to open `#l': #l", path, strerror (errno));
		return NULL;
	}

	if (buffer->log_file)
		// The regular flush will log any error eventually
		(void) fflush (buffer->log_file);

	set_cloexec (fileno (fp));
	return fp;
}

static bool
on_display_full_log (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	struct app_context *ctx = user_data;

	struct buffer *buffer = ctx->current_buffer;
	char *path = buffer_get_log_path (buffer);
	FILE *full_log = open_log_path (ctx, buffer, path);
	if (!full_log)
	{
		free (path);
		return false;
	}

	launch_pager (ctx, fileno (full_log), buffer->name, path);
	fclose (full_log);
	free (path);
	return true;
}

static bool
on_toggle_unimportant (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	struct app_context *ctx = user_data;
	ctx->current_buffer->hide_unimportant ^= true;
	buffer_print_backlog (ctx, ctx->current_buffer);
	return true;
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static bool
on_goto_buffer (int count, int key, void *user_data)
{
	(void) count;
	struct app_context *ctx = user_data;

	int n = key - '0';
	if (n < 0 || n > 9)
		return false;

	// There's no buffer zero
	if (n == 0)
		n = 10;

	if (!ctx->last_buffer || buffer_get_index (ctx, ctx->current_buffer) != n)
		return buffer_goto (ctx, n);

	// Fast switching between two buffers
	buffer_activate (ctx, ctx->last_buffer);
	return true;
}

static bool
on_previous_buffer (int count, int key, void *user_data)
{
	(void) key;
	buffer_activate (user_data, buffer_previous (user_data, count));
	return true;
}

static bool
on_next_buffer (int count, int key, void *user_data)
{
	(void) key;
	buffer_activate (user_data, buffer_next (user_data, count));
	return true;
}

static bool
on_switch_buffer (int count, int key, void *user_data)
{
	(void) count;
	(void) key;
	struct app_context *ctx = user_data;

	if (!ctx->last_buffer)
		return false;
	buffer_activate (ctx, ctx->last_buffer);
	return true;
}

static bool
on_goto_highlight (int count, int key, void *user_data)
{
	(void) count;
	(void) key;

	struct app_context *ctx = user_data;
	struct buffer *iter = ctx->current_buffer;;
	do
	{
		if (!(iter = iter->next))
			iter = ctx->buffers;
		if (iter == ctx->current_buffer)
			return false;
	}
	while (!iter->highlighted);
	buffer_activate (ctx, iter);
	return true;
}

static bool
on_goto_activity (int count, int key, void *user_data)
{
	(void) count;
	(void) key;

	struct app_context *ctx = user_data;
	struct buffer *iter = ctx->current_buffer;
	do
	{
		if (!(iter = iter->next))
			iter = ctx->buffers;
		if (iter == ctx->current_buffer)
			return false;
	}
	while (iter->new_messages_count == iter->new_unimportant_count);
	buffer_activate (ctx, iter);
	return true;
}

static bool
on_move_buffer_left (int count, int key, void *user_data)
{
	(void) key;

	struct app_context *ctx = user_data;
	int total = buffer_count (ctx);
	int n = buffer_get_index (ctx, ctx->current_buffer) - count;
	buffer_move (ctx, ctx->current_buffer, n <= 0
		? (total + n % total)
		: ((n - 1) % total + 1));
	return true;
}

static bool
on_move_buffer_right (int count, int key, void *user_data)
{
	return on_move_buffer_left (-count, key, user_data);
}

static bool
on_redraw_screen (int count, int key, void *user_data)
{
	(void) count;
	(void) key;

	redraw_screen (user_data);
	return true;
}

static bool
on_insert_attribute (int count, int key, void *user_data)
{
	(void) count;
	(void) key;

	struct app_context *ctx = user_data;
	ctx->awaiting_formatting_escape = true;
	return true;
}

static bool
on_start_paste_mode (int count, int key, void *user_data)
{
	(void) count;
	(void) key;

	struct app_context *ctx = user_data;
	ctx->in_bracketed_paste = true;
	return true;
}

static void
input_add_functions (void *user_data)
{
	struct app_context *ctx = user_data;
#define XX(...) CALL_ (ctx->input, register_fn, __VA_ARGS__, ctx);
	XX ("previous-buffer",    "Previous buffer",   on_previous_buffer)
	XX ("next-buffer",        "Next buffer",       on_next_buffer)
	XX ("goto-buffer",        "Go to buffer",      on_goto_buffer)
	XX ("switch-buffer",      "Switch buffer",     on_switch_buffer)
	XX ("goto-highlight",     "Go to highlight",   on_goto_highlight)
	XX ("goto-activity",      "Go to activity",    on_goto_activity)
	XX ("move-buffer-left",   "Move buffer left",  on_move_buffer_left)
	XX ("move-buffer-right",  "Move buffer right", on_move_buffer_right)
	XX ("display-backlog",    "Show backlog",      on_display_backlog)
	XX ("display-backlog-nw", "Non-wrapped log",   on_display_backlog_nowrap)
	XX ("display-full-log",   "Show full log",     on_display_full_log)
	XX ("toggle-unimportant", "Toggle junk msgs",  on_toggle_unimportant)
	XX ("edit-input",         "Edit input",        on_edit_input)
	XX ("redraw-screen",      "Redraw screen",     on_redraw_screen)
	XX ("insert-attribute",   "IRC formatting",    on_insert_attribute)
	XX ("start-paste-mode",   "Bracketed paste",   on_start_paste_mode)
#undef XX
}

static void
bind_common_keys (struct app_context *ctx)
{
	struct input *self = ctx->input;
	CALL_ (self, bind_control, 'p', "previous-buffer");
	CALL_ (self, bind_control, 'n', "next-buffer");

	// Redefine M-0 through M-9 to switch buffers
	for (int i = 0; i <= 9; i++)
		CALL_ (self, bind_meta, '0' + i, "goto-buffer");

	CALL_ (self, bind_meta, '\t', "switch-buffer");
	CALL_ (self, bind_meta, '!', "goto-highlight");
	CALL_ (self, bind_meta, 'a', "goto-activity");
	CALL_ (self, bind_meta, 'm', "insert-attribute");
	CALL_ (self, bind_meta, 'h', "display-full-log");
	CALL_ (self, bind_meta, 'H', "toggle-unimportant");
	CALL_ (self, bind_meta, 'e', "edit-input");

	if (key_f5)     CALL_ (self, bind, key_f5, "previous-buffer");
	if (key_f6)     CALL_ (self, bind, key_f6, "next-buffer");
	if (key_ppage)  CALL_ (self, bind, key_ppage, "display-backlog");

	if (clear_screen)
		CALL_ (self, bind_control, 'l', "redraw-screen");

	CALL_ (self, bind, "\x1b[200~", "start-paste-mode");
}

// --- GNU Readline user actions -----------------------------------------------

#ifdef HAVE_READLINE

static int
on_readline_return (int count, int key)
{
	(void) count;
	(void) key;

	// Let readline pass the line to our input handler
	rl_done = 1;

	struct app_context *ctx = g_ctx;
	struct input_rl *self = (struct input_rl *) ctx->input;

	// Hide the line, don't redisplay it
	CALL (ctx->input, hide);
	input_rl__restore (self);
	return 0;
}

static void
on_readline_input (char *line)
{
	struct app_context *ctx = g_ctx;
	struct input_rl *self = (struct input_rl *) ctx->input;

	if (line)
	{
		if (*line)
			add_history (line);

		// readline always erases the input line after returning from here,
		// but we don't want that to happen if the command to be executed
		// would switch the buffer (we'd keep the already executed command in
		// the old buffer and delete any input restored from the new buffer)
		strv_append_owned (&ctx->pending_input, line);
		poller_idle_set (&ctx->input_event);
	}
	else
	{
		// Prevent readline from showing the prompt twice for w/e reason
		CALL (ctx->input, hide);
		input_rl__restore (self);

		CALL (ctx->input, ding);
	}

	if (self->active)
		// Readline automatically redisplays it
		self->prompt_shown = 1;
}

static char **
app_readline_completion (const char *text, int start, int end)
{
	// We will reconstruct that ourselves
	(void) text;

	// Don't iterate over filenames and stuff
	rl_attempted_completion_over = true;

	return make_input_completions (g_ctx, rl_line_buffer, start, end);
}

static int
app_readline_init (void)
{
	struct app_context *ctx = g_ctx;
	struct input *self = ctx->input;

	// XXX: maybe use rl_make_bare_keymap() and start from there;
	//   our dear user could potentionally rig things up in a way that might
	//   result in some funny unspecified behaviour

	// For vi mode, enabling "show-mode-in-prompt" is recommended as there is
	// no easy way to indicate mode changes otherwise.

	rl_add_defun ("send-line", on_readline_return, -1);
	bind_common_keys (ctx);

	// Move native history commands
	CALL_ (self, bind_meta, 'p', "previous-history");
	CALL_ (self, bind_meta, 'n', "next-history");

	// We need to hide the prompt and input first
	rl_bind_key (RETURN, rl_named_function ("send-line"));
	CALL_ (self, bind_control, 'j', "send-line");

	rl_variable_bind ("completion-ignore-case", "on");
	rl_bind_key (TAB, rl_named_function ("menu-complete"));
	if (key_btab)
		CALL_ (self, bind, key_btab, "menu-complete-backward");
	return 0;
}

#endif // HAVE_READLINE

// --- BSD Editline user actions -----------------------------------------------

#ifdef HAVE_EDITLINE

static unsigned char
on_editline_complete (EditLine *editline, int key)
{
	(void) key;
	struct app_context *ctx = g_ctx;

	// First prepare what Readline would have normally done for us...
	const LineInfo *info_mb = el_line (editline);
	int len = info_mb->lastchar - info_mb->buffer;
	int point = info_mb->cursor - info_mb->buffer;
	char *copy = xstrndup (info_mb->buffer, len);

	// XXX: possibly incorrect wrt. shift state encodings
	int el_start = point, el_end = point;
	while (el_start && !strchr (WORD_BREAKING_CHARS, copy[el_start - 1]))
		el_start--;

	char **completions = make_input_completions (ctx, copy, el_start, el_end);

	// XXX: possibly incorrect wrt. shift state encodings
	copy[el_end] = '\0';
	int el_len = mbstowcs (NULL, copy + el_start, 0);
	free (copy);

	if (!completions)
		return CC_REFRESH_BEEP;

	// Remove the original word
	el_wdeletestr (editline, el_len);

	// Insert the best match instead
	el_insertstr (editline, completions[0]);

	// I'm not sure if Readline's menu-complete can at all be implemented
	// with Editline--we have no way of detecting what the last executed handler
	// was.  Employ the formatter's wrapping feature to spew all options.
	bool only_match = !completions[1];
	if (!only_match)
	{
		CALL (ctx->input, hide);
		redraw_screen (ctx);

		struct formatter f = formatter_make (ctx, NULL);
		for (char **p = completions; *++p; )
			formatter_add (&f, " #l", *p);
		formatter_add (&f, "\n");
		formatter_flush (&f, stdout, 0);
		formatter_free (&f);

		CALL (ctx->input, show);
	}

	for (char **p = completions; *p; p++)
		free (*p);
	free (completions);
	if (!only_match)
		return CC_REFRESH_BEEP;

	// If there actually is just one match, finish the word
	el_insertstr (editline, " ");
	return CC_REFRESH;
}

static unsigned char
on_editline_return (EditLine *editline, int key)
{
	(void) key;
	struct app_context *ctx = g_ctx;
	struct input_el *self = (struct input_el *) ctx->input;

	const LineInfoW *info = el_wline (editline);
	int len = info->lastchar - info->buffer;
	wchar_t *line = calloc (sizeof *info->buffer, len + 1);
	memcpy (line, info->buffer, sizeof *info->buffer * len);

	if (*line)
	{
		HistEventW ev;
		history_w (self->current->history, &ev, H_ENTER, line);
	}
	free (line);

	// process_input() expects a multibyte string
	const LineInfo *info_mb = el_line (editline);
	strv_append_owned (&ctx->pending_input,
		xstrndup (info_mb->buffer, info_mb->lastchar - info_mb->buffer));
	poller_idle_set (&ctx->input_event);

	// We must invoke ch_reset(), which isn't done for us with EL_UNBUFFERED.
	input_el__start_over (self);
	return CC_REFRESH;
}

static void
app_editline_init (struct input_el *self)
{
	// el_set() leaks memory in 20150325 and other versions, we need wchar_t
	el_wset (self->editline, EL_ADDFN,
		L"send-line", L"Send line",     on_editline_return);
	el_wset (self->editline, EL_ADDFN,
		L"complete",  L"Complete word", on_editline_complete);

	struct input *input = &self->super;
	input->add_functions (input->user_data);
	bind_common_keys (g_ctx);

	// Move native history commands
	CALL_ (input, bind_meta, 'p', "ed-prev-history");
	CALL_ (input, bind_meta, 'n', "ed-next-history");

	// No, editline, it's not supposed to kill the entire line
	CALL_ (input, bind_control, 'w', "ed-delete-prev-word");
	// Just what are you doing?
	CALL_ (input, bind_control, 'u', "vi-kill-line-prev");

	// We need to hide the prompt and input first
	CALL_ (input, bind, "\r", "send-line");
	CALL_ (input, bind, "\n", "send-line");

	CALL_ (input, bind_control, 'i', "complete");

	// Source the user's defaults file
	el_source (self->editline, NULL);

	// See input_el__redisplay(), functionally important
	CALL_ (input, bind_control, 'q', "ed-redisplay");
	// This is what buffered el_wgets() does, functionally important
	CALL_ (input, bind_control, 'c', "ed-start-over");
}

#endif // HAVE_EDITLINE

// --- Configuration loading ---------------------------------------------------

static const char *g_first_time_help[] =
{
	"",
	"\x02Welcome to xC!",
	"",
	"To get a list of all commands, type \x02/help\x02.  To obtain",
	"more information on a command or option, simply add it as",
	"a parameter, e.g. \x02/help set\x02 or \x02/help general.logging\x02.",
	"",
	"To switch between buffers, press \x02"
		"F5/Ctrl-P\x02 or \x02" "F6/Ctrl-N\x02.",
	"",
	"Finally, adding a network is as simple as:",
	" - \x02/server add IRCnet\x02",
	" - \x02/set servers.IRCnet.addresses = \"open.ircnet.net\"\x02",
	" - \x02/connect IRCnet\x02",
	"",
	"That should be enough to get you started.  Have fun!",
	""
};

static void
show_first_time_help (struct app_context *ctx)
{
	for (size_t i = 0; i < N_ELEMENTS (g_first_time_help); i++)
		log_global_indent (ctx, "#m", g_first_time_help[i]);
}

const char *g_default_aliases[][2] =
{
	{ "c",     "/buffer clear" }, { "close", "/buffer close" },
	{ "j",     "/join $*"      }, { "p",     "/part $*"      },
	{ "k",     "/kick $*"      }, { "kb",    "/kickban $*"   },
	{ "m",     "/msg $*"       }, { "q",     "/query $*"     },
	{ "n",     "/names $*"     }, { "t",     "/topic $*"     },
	{ "w",     "/who $*"       }, { "wi",    "/whois $*"     },
	{ "ww",    "/whowas $*"    },
};

static void
load_default_aliases (struct app_context *ctx)
{
	struct str_map *aliases = get_aliases_config (ctx);
	for (size_t i = 0; i < N_ELEMENTS (g_default_aliases); i++)
	{
		const char **pair = g_default_aliases[i];
		str_map_set (aliases, pair[0], config_item_string_from_cstr (pair[1]));
	}
}

static void
load_configuration (struct app_context *ctx)
{
	// In theory, we could ensure that only one instance is running by locking
	// the configuration file and ensuring here that it exists.  This is
	// however brittle, as it may be unlinked without the application noticing.

	struct config_item *root = NULL;
	struct error *e = NULL;

	char *filename = resolve_filename
		(PROGRAM_NAME ".conf", resolve_relative_config_filename);
	if (filename)
		root = config_read_from_file (filename, &e);
	else
		log_global_error (ctx, "Configuration file not found");
	free (filename);

	if (e)
	{
		log_global_error (ctx, "Cannot load configuration: #s", e->message);
		log_global_error (ctx,
			"Please either fix the configuration file or remove it");
		error_free (e);
		exit (EXIT_FAILURE);
	}

	if (root)
	{
		config_load (&ctx->config, root);
		log_global_status (ctx, "Configuration loaded");
	}
	else
	{
		show_first_time_help (ctx);
		load_default_aliases (ctx);
	}
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
load_servers (struct app_context *ctx)
{
	struct str_map_iter iter = str_map_iter_make (get_servers_config (ctx));

	struct config_item *subtree;
	while ((subtree = str_map_iter_next (&iter)))
	{
		const char *name = iter.link->key;
		const char *err;
		if (subtree->type != CONFIG_ITEM_OBJECT)
			log_global_error (ctx, "Error in configuration: "
				"ignoring server `#s' as it's not an object", name);
		else if ((err = check_server_name_for_addition (ctx, name)))
			log_global_error (ctx, "Cannot load server `#s': #s", name, err);
		else
			server_add (ctx, name, subtree);
	}
}

// --- Signals -----------------------------------------------------------------

static int g_signal_pipe[2];            ///< A pipe used to signal... signals

/// Program termination has been requested by a signal
static volatile sig_atomic_t g_termination_requested;
/// The window has changed in size
static volatile sig_atomic_t g_winch_received;

static void
postpone_signal_handling (char id)
{
	int original_errno = errno;
	if (write (g_signal_pipe[1], &id, 1) == -1)
		soft_assert (errno == EAGAIN);
	errno = original_errno;
}

static void
signal_superhandler (int signum)
{
	switch (signum)
	{
	case SIGWINCH:
		g_winch_received = true;
		postpone_signal_handling ('w');
		break;
	case SIGINT:
	case SIGTERM:
		g_termination_requested = true;
		postpone_signal_handling ('t');
		break;
	case SIGCHLD:
		postpone_signal_handling ('c');
		break;
	case SIGTSTP:
		postpone_signal_handling ('s');
		break;
	default:
		hard_assert (!"unhandled signal");
	}
}

static void
setup_signal_handlers (void)
{
	if (pipe (g_signal_pipe) == -1)
		exit_fatal ("%s: %s", "pipe", strerror (errno));

	set_cloexec (g_signal_pipe[0]);
	set_cloexec (g_signal_pipe[1]);

	// So that the pipe cannot overflow; it would make write() block within
	// the signal handler, which is something we really don't want to happen.
	// The same holds true for read().
	set_blocking (g_signal_pipe[0], false);
	set_blocking (g_signal_pipe[1], false);

	signal (SIGPIPE, SIG_IGN);

	// So that we can write to the terminal while we're running a pager.
	// This is also inherited by the child so that it doesn't stop
	// when it calls tcsetpgrp().
	signal (SIGTTOU, SIG_IGN);

	struct sigaction sa;
	sa.sa_flags = SA_RESTART;
	sa.sa_handler = signal_superhandler;
	sigemptyset (&sa.sa_mask);

	if (sigaction (SIGWINCH, &sa, NULL) == -1
	 || sigaction (SIGINT,   &sa, NULL) == -1
	 || sigaction (SIGTERM,  &sa, NULL) == -1
	 || sigaction (SIGTSTP,  &sa, NULL) == -1
	 || sigaction (SIGCHLD,  &sa, NULL) == -1)
		exit_fatal ("sigaction: %s", strerror (errno));
}

// --- I/O event handlers ------------------------------------------------------

static bool
try_reap_child (struct app_context *ctx)
{
	int status;
	pid_t zombie = waitpid (-1, &status, WNOHANG | WUNTRACED);

	if (zombie == -1)
	{
		if (errno == ECHILD)  return false;
		if (errno == EINTR)   return true;
		exit_fatal ("%s: %s", "waitpid", strerror (errno));
	}
	if (!zombie)
		return false;

	if (WIFSTOPPED (status))
	{
		// We could also send SIGCONT but what's the point
		log_global_debug (ctx,
			"A child has been stopped, killing its process group");
		kill (-zombie, SIGKILL);
		return true;
	}

	if (ctx->running_pager)
		ctx->running_pager = false;
	else if (!ctx->running_editor)
	{
		log_global_debug (ctx, "An unknown child has died");
		return true;
	}

	hard_assert (tcsetpgrp (STDOUT_FILENO, getpgid (0)) != -1);
	resume_terminal (ctx);

	if (WIFSIGNALED (status))
		log_global_error (ctx,
			"Child died from signal #d", WTERMSIG (status));
	else if (WIFEXITED (status) && WEXITSTATUS (status) != 0)
		log_global_error (ctx,
			"Child returned status #d", WEXITSTATUS (status));
	else if (ctx->running_editor)
		input_editor_process (ctx);

	if (ctx->running_editor)
		input_editor_cleanup (ctx);
	return true;
}

static void
on_signal_pipe_readable (const struct pollfd *fd, struct app_context *ctx)
{
	char id = 0;
	(void) read (fd->fd, &id, 1);

	// Stop ourselves cleanly, even if it makes little sense to do this
	if (id == 's')
	{
		suspend_terminal (ctx);
		kill (getpid (), SIGSTOP);
		g_winch_received = true;
		resume_terminal (ctx);
	}

	// Reap all dead children (since the signal pipe may overflow etc. we run
	// waitpid() in a loop to return all the zombies it knows about).
	while (try_reap_child (ctx))
		;

	if (g_termination_requested)
	{
		g_termination_requested = false;
		request_quit (ctx, NULL);
	}
	if (g_winch_received)
	{
		g_winch_received = false;
		redraw_screen (ctx);
	}
}

static void
process_formatting_escape (const struct pollfd *fd, struct app_context *ctx)
{
	// There's no other way with libedit, as both el_getc() in a function
	// handler and CC_ARGHACK would block execution
	struct str *buf = &ctx->input_buffer;
	str_reserve (buf, 1);
	if (read (fd->fd, buf->str + buf->len, 1) != 1)
		goto error;
	buf->str[++buf->len] = '\0';

	// XXX: I think this should be global and shared with Readline/libedit
	mbstate_t state;
	memset (&state, 0, sizeof state);

	size_t len = mbrlen (buf->str, buf->len, &state);

	// Illegal sequence
	if (len == (size_t) -1)
		goto error;

	// Incomplete multibyte character
	if (len == (size_t) -2)
		return;

	if (buf->len != 1)
		goto error;
	switch (buf->str[0])
	{
	case 'b' ^ 96:
	case 'b': CALL_ (ctx->input, insert, "\x02"); break;
	case 'c': CALL_ (ctx->input, insert, "\x03"); break;
	case 'i' ^ 96:
	case 'i':
	case ']': CALL_ (ctx->input, insert, "\x1d"); break;
	case 'x' ^ 96:
	case 'x':
	case '^': CALL_ (ctx->input, insert, "\x1e"); break;
	case 'u' ^ 96:
	case 'u':
	case '_': CALL_ (ctx->input, insert, "\x1f"); break;
	case 'v': CALL_ (ctx->input, insert, "\x16"); break;
	case 'o': CALL_ (ctx->input, insert, "\x0f"); break;

	default:
		goto error;
	}
	goto done;

error:
	CALL (ctx->input, ding);
done:
	str_reset (buf);
	ctx->awaiting_formatting_escape = false;
}

#define BRACKETED_PASTE_LIMIT 102400    ///< How much text can be pasted

static bool
insert_paste (struct app_context *ctx, char *paste, size_t len)
{
	if (!get_config_boolean (ctx->config.root, "general.process_pasted_text"))
		return CALL_ (ctx->input, insert, paste);

	// Without ICRNL, which Editline keeps but Readline doesn't,
	// the terminal sends newlines as carriage returns (seen on urxvt)
	for (size_t i = 0; i < len; i++)
		if (paste[i] == '\r')
			paste[i] = '\n';

	int position = 0;
	char *input = CALL_ (ctx->input, get_line, &position);
	bool quote_first_slash = !position || strchr ("\r\n", input[position - 1]);
	free (input);

	// Executing commands by accident is much more common than pasting them
	// intentionally, although the latter may also have security consequences
	struct str processed = str_make ();
	str_reserve (&processed, len);
	for (size_t i = 0; i < len; i++)
	{
		if (paste[i] == '/'
			&& ((!i && quote_first_slash) || (i && paste[i - 1] == '\n')))
			str_append_c (&processed, paste[i]);
		str_append_c (&processed, paste[i]);
	}

	bool success = CALL_ (ctx->input, insert, processed.str);
	str_free (&processed);
	return success;
}

static void
process_bracketed_paste (const struct pollfd *fd, struct app_context *ctx)
{
	struct str *buf = &ctx->input_buffer;
	str_reserve (buf, 1);
	if (read (fd->fd, buf->str + buf->len, 1) != 1)
		goto error;
	buf->str[++buf->len] = '\0';

	static const char stop_mark[] = "\x1b[201~";
	static const size_t stop_mark_len = sizeof stop_mark - 1;
	if (buf->len < stop_mark_len)
		return;

	size_t text_len = buf->len - stop_mark_len;
	if (memcmp (buf->str + text_len, stop_mark, stop_mark_len))
		return;

	// Avoid endless flooding of the buffer
	if (text_len > BRACKETED_PASTE_LIMIT)
		log_global_error (ctx, "Paste trimmed to #d bytes",
			(int) (text_len = BRACKETED_PASTE_LIMIT));

	buf->str[text_len] = '\0';
	if (insert_paste (ctx, buf->str, text_len))
		goto done;

error:
	CALL (ctx->input, ding);
	log_global_error (ctx, "Paste failed");
done:
	str_reset (buf);
	ctx->in_bracketed_paste = false;
}

static void
reset_autoaway (struct app_context *ctx)
{
	// Stop the last one if it's been disabled altogether in the meantime
	poller_timer_reset (&ctx->autoaway_tmr);

	// Unset any automated statuses that are active right at this moment
	struct str_map_iter iter = str_map_iter_make (&ctx->servers);
	struct server *s;
	while ((s = str_map_iter_next (&iter)))
	{
		if (s->autoaway_active
		 && s->irc_user
		 && s->irc_user->away)
			irc_send (s, "AWAY");

		s->autoaway_active = false;
	}

	// And potentially start a new auto-away timer
	int64_t delay = get_config_integer
		(ctx->config.root, "general.autoaway_delay");
	if (delay)
		poller_timer_set (&ctx->autoaway_tmr, delay * 1000);
}

static void
on_autoaway_timer (struct app_context *ctx)
{
	// An empty message would unset any away status, so let's ignore that
	const char *message = get_config_string
		(ctx->config.root, "general.autoaway_message");
	if (!message || !*message)
		return;

	struct str_map_iter iter = str_map_iter_make (&ctx->servers);
	struct server *s;
	while ((s = str_map_iter_next (&iter)))
	{
		// If the user has already been marked as away,
		// don't override his current away status
		if (s->irc_user
		 && s->irc_user->away)
			continue;

		irc_send (s, "AWAY :%s", message);
		s->autoaway_active = true;
	}
}

static void
on_tty_readable (const struct pollfd *fd, struct app_context *ctx)
{
	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);

	if (ctx->awaiting_formatting_escape)
		process_formatting_escape (fd, ctx);
	else if (ctx->in_bracketed_paste)
		process_bracketed_paste (fd, ctx);
	else if (!ctx->quitting)
		CALL (ctx->input, on_tty_readable);

	// User activity detected, stop current auto-away and start anew;
	// since they might have just changed the settings, do this last
	reset_autoaway (ctx);
}

static void
rearm_flush_timer (struct app_context *ctx)
{
	poller_timer_set (&ctx->flush_timer, 60 * 1000);
}

static void
on_flush_timer (struct app_context *ctx)
{
	// I guess we don't need to do anything more complicated
	fflush (NULL);

	// It would be a bit problematic to handle it properly, so do this at least
	LIST_FOR_EACH (struct buffer, buffer, ctx->buffers)
	{
		if (!buffer->log_file || !ferror (buffer->log_file))
			continue;

		// Might be a transient error such as running out of disk space,
		// keep notifying of the problem until it disappears
		clearerr (buffer->log_file);
		log_global (ctx, BUFFER_LINE_SKIP_FILE, BUFFER_LINE_ERROR,
			"Log write failure detected for #s", buffer->name);
	}

#ifdef LOMEM
	// Lua should normally be reasonable and collect garbage when needed,
	// though we can try to push it.  This is a reasonable place.
	LIST_FOR_EACH (struct plugin, iter, ctx->plugins)
		if (iter->vtable->gc)
			iter->vtable->gc (iter);
#endif // LOMEM

	rearm_flush_timer (ctx);
}

static void
rearm_date_change_timer (struct app_context *ctx)
{
	struct tm tm_;
	const time_t now = time (NULL);
	if (!soft_assert (localtime_r (&now, &tm_)))
		return;

	tm_.tm_sec = tm_.tm_min = tm_.tm_hour = 0;
	tm_.tm_mday++;
	tm_.tm_isdst = -1;

	const time_t midnight = mktime (&tm_);
	if (!soft_assert (midnight != (time_t) -1))
		return;
	poller_timer_set (&ctx->date_chg_tmr, (midnight - now) * 1000);
}

static void
on_date_change_timer (struct app_context *ctx)
{
	if (ctx->terminal_suspended <= 0)
	{
		CALL (ctx->input, hide);
		buffer_update_time (ctx, time (NULL), stdout, 0);
		CALL (ctx->input, show);
	}
	rearm_date_change_timer (ctx);
}

static void
on_pending_input (struct app_context *ctx)
{
	poller_idle_reset (&ctx->input_event);
	for (size_t i = 0; i < ctx->pending_input.len; i++)
		process_input (ctx, ctx->pending_input.vector[i]);
	strv_reset (&ctx->pending_input);
}

static void
init_poller_events (struct app_context *ctx)
{
	ctx->signal_event = poller_fd_make (&ctx->poller, g_signal_pipe[0]);
	ctx->signal_event.dispatcher = (poller_fd_fn) on_signal_pipe_readable;
	ctx->signal_event.user_data = ctx;
	poller_fd_set (&ctx->signal_event, POLLIN);

	ctx->tty_event = poller_fd_make (&ctx->poller, STDIN_FILENO);
	ctx->tty_event.dispatcher = (poller_fd_fn) on_tty_readable;
	ctx->tty_event.user_data = ctx;
	poller_fd_set (&ctx->tty_event, POLLIN);

	ctx->flush_timer = poller_timer_make (&ctx->poller);
	ctx->flush_timer.dispatcher = (poller_timer_fn) on_flush_timer;
	ctx->flush_timer.user_data = ctx;
	rearm_flush_timer (ctx);

	ctx->date_chg_tmr = poller_timer_make (&ctx->poller);
	ctx->date_chg_tmr.dispatcher = (poller_timer_fn) on_date_change_timer;
	ctx->date_chg_tmr.user_data = ctx;
	rearm_date_change_timer (ctx);

	ctx->autoaway_tmr = poller_timer_make (&ctx->poller);
	ctx->autoaway_tmr.dispatcher = (poller_timer_fn) on_autoaway_timer;
	ctx->autoaway_tmr.user_data = ctx;

	ctx->prompt_event = poller_idle_make (&ctx->poller);
	ctx->prompt_event.dispatcher = (poller_idle_fn) on_refresh_prompt;
	ctx->prompt_event.user_data = ctx;

	ctx->input_event = poller_idle_make (&ctx->poller);
	ctx->input_event.dispatcher = (poller_idle_fn) on_pending_input;
	ctx->input_event.user_data = ctx;
}

// --- Relay processing --------------------------------------------------------

// XXX: This could be below completion code if reset_autoaway() was higher up.

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
client_resync (struct client *c)
{
	LIST_FOR_EACH (struct buffer, buffer, c->ctx->buffers)
	{
		relay_prepare_buffer_update (c->ctx, buffer);
		relay_send (c);

		LIST_FOR_EACH (struct buffer_line, line, buffer->lines)
		{
			relay_prepare_buffer_line (c->ctx, buffer, line);
			relay_send (c);
		}
	}

	relay_prepare_buffer_activate (c->ctx, c->ctx->current_buffer);
	relay_send (c);
}

static const char *
client_message_buffer_name (const struct relay_command_message *m)
{
	switch (m->data.command)
	{
	case RELAY_COMMAND_BUFFER_COMPLETE:
		return m->data.buffer_input.buffer_name.str;
	case RELAY_COMMAND_BUFFER_INPUT:
		return m->data.buffer_input.buffer_name.str;
	case RELAY_COMMAND_BUFFER_ACTIVATE:
		return m->data.buffer_activate.buffer_name.str;
	case RELAY_COMMAND_BUFFER_LOG:
		return m->data.buffer_log.buffer_name.str;
	default:
		return NULL;
	}
}

static void
client_process_buffer_complete (struct client *c, uint32_t seq,
	struct buffer *buffer, struct relay_command_data_buffer_complete *req)
{
	struct str *line = &req->text;
	uint32_t end = req->position;
	if (line->len < end || line->len != strlen (line->str))
	{
		relay_prepare_error (c->ctx, seq, "Invalid arguments");
		goto out;
	}

	uint32_t start = end;
	while (start && !strchr (WORD_BREAKING_CHARS, line->str[start - 1]))
		start--;

	struct strv completions =
		make_completions (c->ctx, buffer, line->str, start, end);
	if (completions.len > UINT32_MAX)
	{
		relay_prepare_error (c->ctx, seq, "Internal error");
		goto out_internal;
	}

	struct relay_event_data_response *e =
		&relay_prepare (c->ctx)->data.response;
	e->event = RELAY_EVENT_RESPONSE;
	e->command_seq = seq;
	e->data.command = RELAY_COMMAND_BUFFER_COMPLETE;

	struct relay_response_data_buffer_complete *resp =
		&e->data.buffer_complete;
	resp->start = start;
	resp->completions_len = completions.len;
	resp->completions = xcalloc (completions.len, sizeof *resp->completions);
	for (size_t i = 0; i < completions.len; i++)
		resp->completions[i] = str_from_cstr (completions.vector[i]);

out_internal:
	strv_free (&completions);
out:
	relay_send (c);
}

static void
client_process_buffer_log
	(struct client *c, uint32_t seq, struct buffer *buffer)
{
	struct relay_event_data_response *e =
		&relay_prepare (c->ctx)->data.response;
	e->event = RELAY_EVENT_RESPONSE;
	e->command_seq = seq;
	e->data.command = RELAY_COMMAND_BUFFER_LOG;

	char *path = buffer_get_log_path (buffer);
	FILE *fp = open_log_path (c->ctx, buffer, path);
	if (fp)
	{
		struct str log = str_make ();
		char buf[BUFSIZ];
		size_t len;
		while ((len = fread (buf, 1, sizeof buf, fp)))
			str_append_data (&log, buf, len);
		if (ferror (fp))
			log_global_error (c->ctx, "Failed to read `#l': #l",
				path, strerror (errno));

		// On overflow, it will later fail serialization.
		e->data.buffer_log.log_len = MIN (UINT32_MAX, log.len);
		e->data.buffer_log.log = (uint8_t *) str_steal (&log);
		fclose (fp);
	}

	// XXX: We log failures to the global buffer,
	//   so the client just receives nothing if there is no log file.

	free (path);
	relay_send (c);
}

static bool
client_process_message (struct client *c,
	struct msg_unpacker *r, struct relay_command_message *m)
{
	if (!relay_command_message_deserialize (m, r)
	 || msg_unpacker_get_available (r))
	{
		log_global_error (c->ctx, "Deserialization failed, killing client");
		return false;
	}

	const char *buffer_name = client_message_buffer_name (m);
	struct buffer *buffer = NULL;
	if (buffer_name && !(buffer = buffer_by_name (c->ctx, buffer_name)))
	{
		relay_prepare_error (c->ctx, m->command_seq, "Unknown buffer");
		relay_send (c);
		return true;
	}

	switch (m->data.command)
	{
	case RELAY_COMMAND_HELLO:
		if (m->data.hello.version != RELAY_VERSION)
		{
			// TODO: This should send back an error message and shut down.
			log_global_error (c->ctx,
				"Protocol version mismatch, killing client");
			return false;
		}
		c->initialized = true;
		client_resync (c);
		break;
	case RELAY_COMMAND_PING:
		relay_prepare_ping (c->ctx);
		relay_send (c);
		break;
	case RELAY_COMMAND_ACTIVE:
		reset_autoaway (c->ctx);
		break;
	case RELAY_COMMAND_BUFFER_COMPLETE:
		client_process_buffer_complete (c, m->command_seq, buffer,
			&m->data.buffer_complete);
		break;
	case RELAY_COMMAND_BUFFER_INPUT:
		(void) process_input_utf8 (c->ctx,
			buffer, m->data.buffer_input.text.str, 0);
		break;
	case RELAY_COMMAND_BUFFER_ACTIVATE:
		buffer_activate (c->ctx, buffer);
		break;
	case RELAY_COMMAND_BUFFER_LOG:
		client_process_buffer_log (c, m->command_seq, buffer);
		break;
	default:
		log_global_debug (c->ctx, "Unhandled client command");
		relay_prepare_error (c->ctx, m->command_seq, "Unknown command");
		relay_send (c);
	}
	return true;
}

static bool
client_process_buffer (struct client *c)
{
	struct str *buf = &c->read_buffer;
	size_t offset = 0;
	while (true)
	{
		uint32_t frame_len = 0;
		struct msg_unpacker r =
			msg_unpacker_make (buf->str + offset, buf->len - offset);
		if (!msg_unpacker_u32 (&r, &frame_len))
			break;

		r.len = MIN (r.len, sizeof frame_len + frame_len);
		if (msg_unpacker_get_available (&r) < frame_len)
			break;

		struct relay_command_message m = {};
		bool ok = client_process_message (c, &r, &m);
		relay_command_message_free (&m);
		if (!ok)
			return false;

		offset += r.offset;
	}

	str_remove_slice (buf, 0, offset);
	return true;
}

// --- Tests -------------------------------------------------------------------

// The application is quite monolithic and can only be partially unit-tested.
// Locale-, terminal- and filesystem-dependent tests are also somewhat tricky.

#ifdef TESTING

static struct config_schema g_config_test[] =
{
	{ .name = "foo",    .type = CONFIG_ITEM_BOOLEAN, .default_ = "off" },
	{ .name = "bar",    .type = CONFIG_ITEM_INTEGER, .default_ = "1" },
	{ .name = "foobar", .type = CONFIG_ITEM_STRING,  .default_ = "\"x\\x01\"" },
	{}
};

static void
test_config (void)
{
	struct config_item *foo = config_item_object ();
	config_schema_apply_to_object (g_config_test, foo, NULL);
	struct config_item *root = config_item_object ();
	str_map_set (&root->value.object, "top", foo);

	struct strv v = strv_make ();
	dump_matching_options (root, "*foo*", &v);
	hard_assert (v.len == 2);
	hard_assert (!strcmp (v.vector[0], "top.foo = off"));
	hard_assert (!strcmp (v.vector[1], "top.foobar = \"x\\x01\""));
	strv_free (&v);

	config_item_destroy (root);
}

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

static void
test_aliases (void)
{
	struct strv v = strv_make ();
	expand_alias_definition ("/foo; /bar $* $$$;;;$1$2$3$4", "foo bar baz", &v);
	hard_assert (v.len == 4);
	hard_assert (!strcmp (v.vector[0], "/foo"));
	hard_assert (!strcmp (v.vector[1], " /bar foo bar baz $;"));
	hard_assert (!strcmp (v.vector[2], ""));
	hard_assert (!strcmp (v.vector[3], "foobarbaz"));
	strv_free (&v);
}

static void
test_wrapping (void)
{
	static const char *message = " foo bar foobar fóóbárbáz\002 a\0031 b";
	// XXX: formatting continuation order is implementation-dependent here
	//   (irc_serialize_char_attrs() makes a choice in serialization)
	static const char *split[] = { " foo", "bar", "foob", "ar",
		"fó", "ób", "árb", "áz\x02", "\002a\0031", "\0031\002b" };

	struct strv v = strv_make ();
	hard_assert (wrap_message (message, 4, &v, NULL));
	hard_assert (v.len == N_ELEMENTS (split));
	for (size_t i = 0; i < N_ELEMENTS (split); i++)
		hard_assert (!strcmp (v.vector[i], split[i]));
	strv_free (&v);
}

static void
test_utf8 (void)
{
	static const char *a[] = { "fřoo", "Fřooř", "fřOOŘ" };
	hard_assert (utf8_common_prefix (a, N_ELEMENTS (a)) == 5);

	char *cut_off = xstrdup ("ё\xD0");
	irc_sanitize_cut_off_utf8 (&cut_off);
	hard_assert (!strcmp (cut_off, "ё\xEF\xBF\xBD"));
	free (cut_off);
}

int
main (int argc, char *argv[])
{
	struct test test;
	test_init (&test, argc, argv);
	test_add_simple (&test, "/config",   NULL, test_config);
	test_add_simple (&test, "/aliases",  NULL, test_aliases);
	test_add_simple (&test, "/wrapping", NULL, test_wrapping);
	test_add_simple (&test, "/utf8",     NULL, test_utf8);
	return test_run (&test);
}

#define main main_shadowed
#endif // TESTING

// --- Main program ------------------------------------------------------------

static const char *g_logo[] =
{
	"",
	"\x02" PROGRAM_NAME "\x02  " PROGRAM_VERSION,
	"",
};

static void
show_logo (struct app_context *ctx)
{
	for (size_t i = 0; i < N_ELEMENTS (g_logo); i++)
		log_global_indent (ctx, "#m", g_logo[i]);
}

static void
format_input_and_die (struct app_context *ctx)
{
	char buf[513];
	while (fgets (buf, sizeof buf, stdin))
	{
		struct formatter f = formatter_make (ctx, NULL);
		formatter_add (&f, "#m", buf);
		formatter_flush (&f, stdout, FLUSH_OPT_NOWRAP);
		formatter_free (&f);
	}
	exit (EXIT_SUCCESS);
}

int
main (int argc, char *argv[])
{
	// We include a generated file from xD including this array we don't use;
	// let's just keep it there and silence the compiler warning instead
	(void) g_default_replies;

	static const struct opt opts[] =
	{
		{ 'h', "help", NULL, 0, "display this help and exit" },
		{ 'V', "version", NULL, 0, "output version information and exit" },
		// This is mostly intended for previewing formatted MOTD files
		{ 'f', "format", NULL, OPT_LONG_ONLY, "format IRC text from stdin" },
		{ 0, NULL, NULL, 0, NULL }
	};

	struct opt_handler oh =
		opt_handler_make (argc, argv, opts, NULL, "Terminal-based IRC client.");
	bool format_mode = false;

	int c;
	while ((c = opt_handler_get (&oh)) != -1)
	switch (c)
	{
	case 'h':
		opt_handler_usage (&oh, stdout);
		exit (EXIT_SUCCESS);
	case 'V':
		printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
		exit (EXIT_SUCCESS);
	case 'f':
		format_mode = true;
		break;
	default:
		print_error ("wrong options");
		opt_handler_usage (&oh, stderr);
		exit (EXIT_FAILURE);
	}
	if (optind != argc)
	{
		opt_handler_usage (&oh, stderr);
		exit (EXIT_FAILURE);
	}
	opt_handler_free (&oh);

	// We only need to convert to and from the terminal encoding
	setlocale (LC_CTYPE, "");

	struct app_context ctx;
	app_context_init (&ctx);
	g_ctx = &ctx;

	init_openssl ();

	// Bootstrap configuration, so that we can access schema items at all
	register_config_modules (&ctx);
	config_load (&ctx.config, config_item_object ());

	// The following part is a bit brittle because of interdependencies
	init_colors (&ctx);
	if (format_mode)  format_input_and_die (&ctx);
	init_global_buffer (&ctx);
	show_logo (&ctx);
	setup_signal_handlers ();
	init_poller_events (&ctx);
	load_configuration (&ctx);

	// At this moment we can safely call any "on_change" callbacks
	config_schema_call_changed (ctx.config.root);

	// Initialize input so that we can switch to new buffers
	on_refresh_prompt (&ctx);
	ctx.input->add_functions = input_add_functions;
	CALL_ (ctx.input, start, argv[0]);
	toggle_bracketed_paste (true);
	reset_autoaway (&ctx);

	// Finally, we juice the configuration for some servers to create
	load_plugins (&ctx);
	load_servers (&ctx);

	ctx.polling = true;
	while (ctx.polling)
		poller_run (&ctx.poller);

	CALL (ctx.input, stop);

	app_context_free (&ctx);
	toggle_bracketed_paste (false);
	free_terminal ();
	return EXIT_SUCCESS;
}