xK/xC.c

/*
 * xC.c: a terminal-based IRC client
 *
 * Copyright (c) 2015 - 2024, 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( 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
{
	ATTR_RESET,
#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"

// fmemopen
#define _POSIX_C_SOURCE 200809L
#define _XOPEN_SOURCE 700

#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);
	/// Switch to a different input buffer
	void (*buffer_switch) (void *input, input_buffer_t);
	/// Return all history lines in the locale encoding
	struct strv (*buffer_get_history) (void *input, input_buffer_t);
	/// Add a history line in the locale encoding
	void (*buffer_add_history) (void *input, input_buffer_t, const char *);

	/// 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 (buffer_get_history) XX (buffer_add_history)                            \
	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;

	// Readline >= 8.0 otherwise prints spurious newlines on EOF.
	if (RL_VERSION_MAJOR >= 8)
		rl_variable_bind ("enable-bracketed-paste", "off");

	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 struct strv
input_rl_buffer_get_history (void *input, input_buffer_t input_buffer)
{
	(void) input;
	struct input_rl_buffer *buffer = input_buffer;
	HIST_ENTRY **p =
		buffer->history ? buffer->history->entries : history_list();
	struct strv v = strv_make ();
	while (p && *p)
		strv_append (&v, (*p++)->line);
	return v;
}

static void
input_rl_buffer_add_history (void *input, input_buffer_t input_buffer,
	const char *line)
{
	(void) input;
	struct input_rl_buffer *buffer = input_buffer;

	// For inactive buffers, we'd have to either alloc_history_entry(),
	// construe a timestamp, and manually insert it into saved HISTORY_STATEs,
	// or temporarily switch histories.
	if (!buffer->history)
	{
		bool at_end = where_history () == history_length;
		add_history (line);
		if (at_end)
			next_history ();
	}
}

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 = xcalloc (len + 1, sizeof *info->buffer);
	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);
	// We only know how to reset the history position to be at the end.
	input_el__start_over (self);
	input_el__restore_buffer (self, buffer);
}

static struct strv
input_el_buffer_get_history (void *input, input_buffer_t input_buffer)
{
	(void) input;
	struct input_el_buffer *buffer = input_buffer;
	struct strv v = strv_make ();
	HistEventW ev;
	if (history_w (buffer->history, &ev, H_LAST) < 0)
		return v;

	do
	{
		size_t len = wcstombs (NULL, ev.str, 0);
		if (len++ == (size_t) -1)
			continue;

		char *mb = xmalloc (len);
		mb[wcstombs (mb, ev.str, len)] = 0;
		strv_append_owned (&v, mb);
	}
	while (history_w (buffer->history, &ev, H_PREV) >= 0);
	return v;
}

static void
input_el_buffer_add_history (void *input, input_buffer_t input_buffer,
	const char *line)
{
	(void) input;
	struct input_el_buffer *buffer = input_buffer;

	// When currently iterating history, this makes editline's internal
	// history pointer wrongly point to a newer entry.
	size_t len = mbstowcs (NULL, line, 0);
	if (len++ != (size_t) -1)
	{
		wchar_t *wc = xcalloc (len, sizeof *wc);
		wc[mbstowcs (wc, line, len)] = 0;
		HistEventW ev;
		(void) history_w (buffer->history, &ev, H_ENTER, wc);
		free (wc);
	}
}

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)

// ~~~ Attribute utilities ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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
};

// Similar to code in liberty-tui.c.
struct attrs
{
	short fg;                           ///< Foreground (256-colour cube or -1)
	short bg;                           ///< Background (256-colour cube or -1)
	unsigned attrs;                     ///< TEXT_* mask
};

/// Decode attributes in the value using a subset of the git config format,
/// ignoring all errors since it doesn't affect functionality
static struct attrs
attrs_decode (const char *value)
{
	struct strv v = strv_make ();
	cstr_split (value, " ", true, &v);

	int colors = 0;
	struct attrs attrs = { -1, -1, 0 };
	for (char **it = v.vector; *it; it++)
	{
		char *end = NULL;
		long n = strtol (*it, &end, 10);
		if (*it != end && !*end && n >= SHRT_MIN && n <= SHRT_MAX)
		{
			if (colors == 0) attrs.fg = n;
			if (colors == 1) attrs.bg = n;
			colors++;
		}
		else if (!strcmp (*it, "bold"))    attrs.attrs |= TEXT_BOLD;
		else if (!strcmp (*it, "italic"))  attrs.attrs |= TEXT_ITALIC;
		else if (!strcmp (*it, "ul"))      attrs.attrs |= TEXT_UNDERLINE;
		else if (!strcmp (*it, "reverse")) attrs.attrs |= TEXT_INVERSE;
		else if (!strcmp (*it, "blink"))   attrs.attrs |= TEXT_BLINK;
		else if (!strcmp (*it, "strike"))  attrs.attrs |= TEXT_CROSSED_OUT;
	}
	strv_free (&v);
	return attrs;
}

// ~~~ 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
};

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

	bool clean;                         ///< Assume ATTR_RESET
	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, .clean = true };
	self.items = xcalloc ((self.items_alloc = 16), sizeof *self.items);
	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
	bool closing;                       ///< We're closing the connection

	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);

// ~~~ 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 shut down 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_modes;          ///< Our current user modes
	char *irc_user_host;                ///< Our current user@host
	bool autoaway_active;               ///< Autoaway is currently active

	struct strv outstanding_joins;      ///< JOINs we expect a response to

	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_modes),
	  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_modes = str_make ();

	self->outstanding_joins = strv_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_modes);
	free (self->irc_user_host);

	strv_free (&self->outstanding_joins);
	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
{
	/// Default terminal attributes
	struct attrs theme_defaults[ATTR_COUNT];

	// Configuration:

	struct config config;               ///< Program configuration
	struct attrs theme[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

	// 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

	// 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;

	// 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->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);

	self->relay_fd = -1;
}

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);

	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_theme_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 const 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 const 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 const struct config_schema g_config_theme[] =
{
#define XX(x, y, z) { .name = #y, .comment = #z, .type = CONFIG_ITEM_STRING, \
	.on_change = on_config_theme_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_theme (struct config_item *subtree, void *user_data)
{
	config_schema_apply_to_object (g_config_theme, 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, "theme",   load_config_theme,   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);
}

// --- 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;
}

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

#define ATTR_PRINTER_INIT(attrs, stream) { 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, exit_attribute_mode);

	self->dirty = false;
}

// 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;
}

static void
attr_printer_apply_named (struct attr_printer *self, int attribute)
{
	attr_printer_reset (self);
	if (attribute == ATTR_RESET)
		return;

	// See the COLOR_256 macro or attr_printer_decode_color().
	struct attrs *a = &self->attrs[attribute];
	attr_printer_apply (self, a->attrs,
		a->fg < 16 ? a->fg : (a->fg << 16 | (-1 & 0xFFFF)),
		a->bg < 16 ? a->bg : (a->bg << 16 | (-1 & 0xFFFF)));
	self->dirty = true;
}

// ~~~ Logging redirect ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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;

	struct attr_printer state = ATTR_PRINTER_INIT (ctx->theme, stream);
	if (printer)
		attr_printer_apply_named (&state, attribute);

	vfprintf (stream, fmt, ap);

	if (printer)
		attr_printer_reset (&state);
}

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);
}

// ~~~ Theme ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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

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

static void
on_config_theme_change (struct config_item *item)
{
	struct app_context *ctx = item->user_data;
	ssize_t id = attr_by_name (item->schema->name);
	if (id != -1)
	{
		// TODO: There should be a validator.
		ctx->theme[id] = item->type == CONFIG_ITEM_NULL
			? ctx->theme_defaults[id]
			: attrs_decode (item->value.string.str);
	}
}

static void
init_colors (struct app_context *ctx)
{
	bool have_ti = init_terminal ();

#define INIT_ATTR(id, ...) ctx->theme[ATTR_ ## id] = \
	ctx->theme_defaults[ATTR_ ## id] = (struct attrs) { __VA_ARGS__ }

	INIT_ATTR (PROMPT,      -1, -1, TEXT_BOLD);
	INIT_ATTR (RESET,       -1, -1, 0);
	INIT_ATTR (DATE_CHANGE, -1, -1, TEXT_BOLD);
	INIT_ATTR (READ_MARKER, COLOR_MAGENTA, -1, 0);
	INIT_ATTR (WARNING,     COLOR_YELLOW,  -1, 0);
	INIT_ATTR (ERROR,       COLOR_RED,     -1, 0);

	INIT_ATTR (EXTERNAL,    COLOR_WHITE,   -1, 0);
	INIT_ATTR (TIMESTAMP,   COLOR_WHITE,   -1, 0);
	INIT_ATTR (HIGHLIGHT,   COLOR_BRIGHT (YELLOW), COLOR_MAGENTA, TEXT_BOLD);
	INIT_ATTR (ACTION,      COLOR_RED,     -1, 0);
	INIT_ATTR (USERHOST,    COLOR_CYAN,    -1, 0);
	INIT_ATTR (JOIN,        COLOR_GREEN,   -1, 0);
	INIT_ATTR (PART,        COLOR_RED,     -1, 0);

#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;
}

// --- 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 in an 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_)
{
	// Auto-resetting tends to create unnecessary items,
	// which also end up being relayed to frontends, so filter them out.
	bool reset =
		template_.type == FORMATTER_ITEM_ATTR &&
		template_.attribute == ATTR_RESET;
	if (self->clean && reset)
		return;

	self->clean = reset ||
		(self->clean && template_.type == FORMATTER_ITEM_TEXT);

	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));