xK/degesch.c

/*
 * degesch.c: the experimental IRC client
 *
 * Copyright (c) 2015, Přemysl Janouch <p.janouch@gmail.com>
 * All rights reserved.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * 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.
 *
 */

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

// String constants for all attributes we use for output
#define ATTR_PROMPT    "attr_prompt"
#define ATTR_RESET     "attr_reset"
#define ATTR_WARNING   "attr_warning"
#define ATTR_ERROR     "attr_error"

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

#include "config.h"
#undef PROGRAM_NAME
#define PROGRAM_NAME "degesch"

#include "common.c"

#include <langinfo.h>
#include <locale.h>
#include <pwd.h>

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

// Literally cancer
#undef lines
#undef columns

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

// --- Configuration (application-specific) ------------------------------------

// TODO: reject all junk present in the configuration; there can be newlines

static struct config_item g_config_table[] =
{
	{ "nickname",        NULL,    "IRC nickname"                             },
	{ "username",        NULL,    "IRC user name"                            },
	{ "realname",        NULL,    "IRC real name/e-mail"                     },

	{ "irc_host",        NULL,    "Address of the IRC server"                },
	{ "irc_port",        "6667",  "Port of the IRC server"                   },
	{ "ssl",             "off",   "Whether to use SSL"                       },
	{ "ssl_cert",        NULL,    "Client SSL certificate (PEM)"             },
	{ "ssl_verify",      "on",    "Whether to verify certificates"           },
	{ "ssl_ca_file",     NULL,    "OpenSSL CA bundle file"                   },
	{ "ssl_ca_path",     NULL,    "OpenSSL CA bundle path"                   },
	{ "autojoin",        NULL,    "Channels to join on start"                },
	{ "reconnect",       "on",    "Whether to reconnect on error"            },
	{ "reconnect_delay", "5",     "Time between reconnecting"                },

	{ "socks_host",      NULL,    "Address of a SOCKS 4a/5 proxy"            },
	{ "socks_port",      "1080",  "SOCKS port number"                        },
	{ "socks_username",  NULL,    "SOCKS auth. username"                     },
	{ "socks_password",  NULL,    "SOCKS auth. password"                     },

	{ "isolate_buffers", "off",   "Isolate global/server buffers"            },

	{ ATTR_PROMPT,       NULL,    "Terminal attributes for the prompt"       },
	{ ATTR_RESET,        NULL,    "String to reset terminal attributes"      },
	{ ATTR_WARNING,      NULL,    "Terminal attributes for warnings"         },
	{ ATTR_ERROR,        NULL,    "Terminal attributes for errors"           },

	{ NULL,              NULL,    NULL                                       }
};

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

// All text stored in our data structures is encoded in UTF-8.
// Or at least should be.

/// Shorthand to set an error and return failure from the function
#define FAIL(...)                                                              \
	BLOCK_START                                                                \
		error_set (e, __VA_ARGS__);                                            \
		return false;                                                          \
	BLOCK_END

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

enum buffer_line_flags
{
	BUFFER_LINE_HIGHLIGHT   = 1 << 0    ///< The user was highlighted by this
};

enum buffer_line_type
{
	BUFFER_LINE_PRIVMSG,                ///< PRIVMSG
	BUFFER_LINE_ACTION,                 ///< PRIVMSG ACTION
	BUFFER_LINE_NOTICE,                 ///< NOTICE
	BUFFER_LINE_JOIN,                   ///< JOIN
	BUFFER_LINE_PART,                   ///< PART
	BUFFER_LINE_KICK,                   ///< KICK
	BUFFER_LINE_QUIT,                   ///< QUIT
	BUFFER_LINE_STATUS,                 ///< Whatever status messages
	BUFFER_LINE_ERROR                   ///< Whatever error messages
};

struct buffer_line
{
	LIST_HEADER (struct buffer_line)

	// We use the "type" and "flags" mostly just as formatting hints

	enum buffer_line_type type;         ///< Type of the event
	int flags;                          ///< Flags

	time_t when;                        ///< Time of the event
	char *who;                          ///< Name of the origin or NULL (user)
	char *object;                       ///< Text of message, object of action
	char *reason;                       ///< Reason for PART, KICK, QUIT
};

struct buffer_line *
buffer_line_new (void)
{
	struct buffer_line *self = xcalloc (1, sizeof *self);
	return self;
}

static void
buffer_line_destroy (struct buffer_line *self)
{
	free (self->who);
	free (self->object);
	free (self->reason);
	free (self);
}

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

struct nick_info
{
	char *nickname;                     ///< Literal nickname
	char mode_char;                     ///< Op/voice/... character
	bool away;                          ///< User is away

	// XXX: maybe a good candidate for deduplication (away status)
};

static void
nick_info_destroy (void *p)
{
	struct nick_info *self = p;
	free (self->nickname);
	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)

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

	HISTORY_STATE *history;             ///< Saved history state
	char *saved_line;                   ///< Saved line
	int saved_point;                    ///< Saved position in line
	int saved_mark;                     ///< Saved mark

	// 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 unseen_messages_count;     ///< # messages since last visited

	// Channel information:

	char *mode;                         ///< Channel mode
	char *topic;                        ///< Channel topic
	struct str_map nicks;               ///< Maps nicks to "nick_info"
};

static struct buffer *
buffer_new (void)
{
	struct buffer *self = xcalloc (1, sizeof *self);
	str_map_init (&self->nicks);
	self->nicks.key_xfrm = irc_strxfrm;
	self->nicks.free = nick_info_destroy;
	return self;
}

static void
buffer_destroy (struct buffer *self)
{
	free (self->name);
	// Can't really free "history" here
	free (self->saved_line);
	free (self->mode);
	free (self->topic);
	str_map_free (&self->nicks);
	free (self);
}

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

enum color_mode
{
	COLOR_AUTO,                         ///< Autodetect if colours are available
	COLOR_ALWAYS,                       ///< Always use coloured output
	COLOR_NEVER                         ///< Never use coloured output
};

struct app_context
{
	// Configuration:

	struct str_map config;              ///< User configuration
	enum color_mode color_mode;         ///< Colour output mode
	bool reconnect;                     ///< Whether to reconnect on conn. fail.
	unsigned long reconnect_delay;      ///< Reconnect delay in seconds
	bool isolate_buffers;               ///< Isolate global/server buffers

	// Server connection:

	int irc_fd;                         ///< Socket FD of the server
	struct str read_buffer;             ///< Input yet to be processed
	struct poller_fd irc_event;         ///< IRC FD event
	bool irc_ready;                     ///< Whether we may send messages now

	SSL_CTX *ssl_ctx;                   ///< SSL context
	SSL *ssl;                           ///< SSL connection

	// TODO: initialize and update these two values
	// TODO: probably issue a USERHOST message for ourselves after connecting
	//   to enable proper word-wrapping; then store it here also, separately,
	//   without the nickname at the beginning; also could just use WHOIS
	char *irc_nickname;                 ///< Current nickname
	char *irc_user_mode;                ///< Current user mode

	// Events:

	struct poller_fd tty_event;         ///< Terminal input event
	struct poller_fd signal_event;      ///< Signal FD event
	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 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 str_map buffers_by_name;     ///< Excludes GLOBAL and SERVER
	struct buffer *global_buffer;       ///< The global buffer
	struct buffer *server_buffer;       ///< The server buffer

	struct buffer *current_buffer;      ///< The current buffer

	// TODO: So that we always output proper date change messages
	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
	// XXX: shouldn't it be rather UTF-8 from Latin 1?
	iconv_t term_from_latin1;           ///< ISO Latin 1 to terminal encoding

	int lines;                          ///< Current terminal height
	int columns;                        ///< Current ternimal width

	char *readline_prompt;              ///< The prompt we use for readline
	bool readline_prompt_shown;         ///< Whether the prompt is shown now
}
*g_ctx;

static void on_irc_ping_timeout (void *user_data);
static void on_irc_timeout (void *user_data);
static void on_irc_reconnect_timeout (void *user_data);

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

	str_map_init (&self->config);
	self->config.free = free;
	load_config_defaults (&self->config, g_config_table);

	self->irc_fd = -1;
	str_init (&self->read_buffer);
	self->irc_ready = false;

	str_map_init (&self->buffers_by_name);
	self->buffers_by_name.key_xfrm = irc_strxfrm;

	self->last_displayed_msg_time = time (NULL);

	poller_init (&self->poller);

	char *encoding = nl_langinfo (CODESET);
#ifdef __linux__
	encoding = xstrdup_printf ("%s//TRANSLIT", encoding);
#else // ! __linux__
	encoding = xstrdup (encoding);
#endif // ! __linux__

	if ((self->term_from_utf8 =
		iconv_open (encoding, "UTF-8")) == (iconv_t) -1
	 || (self->term_from_latin1 =
		iconv_open (encoding, "ISO-8859-1")) == (iconv_t) -1
	 || (self->term_to_utf8 =
		iconv_open ("UTF-8", nl_langinfo (CODESET))) == (iconv_t) -1)
		exit_fatal ("creating the UTF-8 conversion object failed: %s",
			strerror (errno));

	free (encoding);
}

static void
app_context_free (struct app_context *self)
{
	str_map_free (&self->config);
	str_free (&self->read_buffer);

	if (self->irc_fd != -1)
	{
		xclose (self->irc_fd);
		poller_fd_reset (&self->irc_event);
	}
	if (self->ssl)
		SSL_free (self->ssl);
	if (self->ssl_ctx)
		SSL_CTX_free (self->ssl_ctx);

	free (self->irc_nickname);
	free (self->irc_user_mode);

	LIST_FOR_EACH (struct buffer, iter, self->buffers)
		buffer_destroy (iter);
	str_map_free (&self->buffers_by_name);

	poller_free (&self->poller);

	iconv_close (self->term_from_latin1);
	iconv_close (self->term_from_utf8);
	iconv_close (self->term_to_utf8);

	free (self->readline_prompt);
}

static void refresh_prompt (struct app_context *ctx);

// --- Attributed output -------------------------------------------------------

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

	char *color_set[8];                 ///< Codes to set the foreground colour
}
g_terminal;

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 || !enter_bold_mode || !exit_attribute_mode)
	{
		del_curterm (cur_term);
		return false;
	}

	for (size_t i = 0; i < N_ELEMENTS (g_terminal.color_set); i++)
		g_terminal.color_set[i] = xstrdup (tparm (set_a_foreground,
			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 (size_t i = 0; i < N_ELEMENTS (g_terminal.color_set); i++)
		free (g_terminal.color_set[i]);
	del_curterm (cur_term);
}

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

struct app_readline_state
{
	char *saved_line;
	int saved_point;
	int saved_mark;
};

static void
app_readline_hide (struct app_readline_state *state)
{
	state->saved_point = rl_point;
	state->saved_point = rl_mark;
	state->saved_line = rl_copy_text (0, rl_end);
	rl_set_prompt ("");
	rl_replace_line ("", 0);
	rl_redisplay ();
}

static void
app_readline_restore (struct app_readline_state *state, const char *prompt)
{
	rl_set_prompt (prompt);
	rl_replace_line (state->saved_line, 0);
	rl_point = state->saved_point;
	rl_mark = state->saved_mark;
	rl_redisplay ();
	free (state->saved_line);
}

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

typedef int (*terminal_printer_fn) (int);

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

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

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

	if (printer)
	{
		const char *value = str_map_find (&ctx->config, attribute);
		tputs (value, 1, printer);
	}

	vfprintf (stream, fmt, ap);

	if (printer)
	{
		const char *value = str_map_find (&ctx->config, ATTR_RESET);
		tputs (value, 1, printer);
	}
}

static void
print_attributed (struct app_context *ctx,
	FILE *stream, const char *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;

	// GNU readline is a huge piece of total crap; it seems that we must do
	// these incredible shenanigans in order to intersperse readline output
	// with asynchronous status messages
	struct app_readline_state state;
	if (g_ctx->readline_prompt_shown)
		app_readline_hide (&state);

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

	if (g_ctx->readline_prompt_shown)
		app_readline_restore (&state, g_ctx->readline_prompt);
}

static void
init_colors (struct app_context *ctx)
{
	// Use escape sequences from terminfo if possible, and SGR as a fallback
	if (init_terminal ())
	{
		const char *attrs[][2] =
		{
			{ ATTR_PROMPT,   enter_bold_mode         },
			{ ATTR_RESET,    exit_attribute_mode     },
			{ ATTR_WARNING,  g_terminal.color_set[3] },
			{ ATTR_ERROR,    g_terminal.color_set[1] },
		};
		for (size_t i = 0; i < N_ELEMENTS (attrs); i++)
			str_map_set (&ctx->config, attrs[i][0], xstrdup (attrs[i][1]));
	}
	else
	{
		const char *attrs[][2] =
		{
			{ ATTR_PROMPT,   "\x1b[1m"               },
			{ ATTR_RESET,    "\x1b[0m"               },
			{ ATTR_WARNING,  "\x1b[33m"              },
			{ ATTR_ERROR,    "\x1b[31m"              },
		};
		for (size_t i = 0; i < N_ELEMENTS (attrs); i++)
			str_map_set (&ctx->config, attrs[i][0], xstrdup (attrs[i][1]));
	}

	switch (ctx->color_mode)
	{
	case COLOR_ALWAYS:
		g_terminal.stdout_is_tty = true;
		g_terminal.stderr_is_tty = true;
		break;
	case COLOR_AUTO:
		if (!g_terminal.initialized)
		{
	case COLOR_NEVER:
			g_terminal.stdout_is_tty = false;
			g_terminal.stderr_is_tty = false;
		}
	}

	g_log_message_real = log_message_attributed;
}

// --- Signals -----------------------------------------------------------------

static int g_signal_pipe[2];            ///< A pipe used to signal... signals

/// Program termination has been requested by a signal
static volatile sig_atomic_t g_termination_requested;
/// The window has changed in size
static volatile sig_atomic_t g_winch_received;

static void
sigterm_handler (int signum)
{
	(void) signum;

	g_termination_requested = true;

	int original_errno = errno;
	if (write (g_signal_pipe[1], "t", 1) == -1)
		soft_assert (errno == EAGAIN);
	errno = original_errno;
}

static void
sigwinch_handler (int signum)
{
	(void) signum;

	g_winch_received = true;

	int original_errno = errno;
	if (write (g_signal_pipe[1], "w", 1) == -1)
		soft_assert (errno == EAGAIN);
	errno = original_errno;
}

static void
setup_signal_handlers (void)
{
	if (pipe (g_signal_pipe) == -1)
		exit_fatal ("%s: %s", "pipe", strerror (errno));

	set_cloexec (g_signal_pipe[0]);
	set_cloexec (g_signal_pipe[1]);

	// So that the pipe cannot overflow; it would make write() block within
	// the signal handler, which is something we really don't want to happen.
	// The same holds true for read().
	set_blocking (g_signal_pipe[0], false);
	set_blocking (g_signal_pipe[1], false);

	signal (SIGPIPE, SIG_IGN);

	struct sigaction sa;
	sa.sa_flags = SA_RESTART;
	sa.sa_handler = sigwinch_handler;
	sigemptyset (&sa.sa_mask);

	if (sigaction (SIGWINCH, &sa, NULL) == -1)
		exit_fatal ("sigaction: %s", strerror (errno));

	sa.sa_handler = sigterm_handler;
	if (sigaction (SIGINT, &sa, NULL) == -1
	 || sigaction (SIGTERM, &sa, NULL) == -1)
		exit_fatal ("sigaction: %s", strerror (errno));
}

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

static void buffer_send (struct app_context *ctx, struct buffer *buffer,
	enum buffer_line_type type, int flags, const char *origin,
	const char *reason, const char *format, ...) ATTRIBUTE_PRINTF (7, 8);

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

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

	char buf[32] = "";
	if (soft_assert (strftime (buf, sizeof buf, "%F", &current)))
		print_status ("%s", buf);
	// Else the buffer was too small, which is pretty weird
}

static void
buffer_line_display (struct app_context *ctx, struct buffer_line *line)
{
	// Normal timestamps don't include the date, this way the user won't be
	// confused as to when an event has happened
	buffer_update_time (ctx, line->when);

	struct str text;
	str_init (&text);

	struct tm current;
	if (!localtime_r (&line->when, &current))
		print_error ("%s: %s", "localtime_r", strerror (errno));
	else
		str_append_printf (&text, "%02d:%02d:%02d ",
			current.tm_hour, current.tm_min, current.tm_sec);

	char *who    = iconv_xstrdup (ctx->term_from_utf8, line->who,    -1, NULL);
	char *object = iconv_xstrdup (ctx->term_from_utf8, line->object, -1, NULL);
	char *reason = iconv_xstrdup (ctx->term_from_utf8, line->reason, -1, NULL);

	// TODO: colorize the output, note that we shouldn't put everything through
	//   tputs but only the attribute strings.  That might prove a bit
	//   challenging.  Maybe we could create a helper object to pust text
	//   and formatting into.  We could have a varargs function to make it a bit
	//   more friendly, e.g. push(&x, ATTR_JOIN, "--> ", ATTR_RESET, who, NULL)

	switch (line->type)
	{
	case BUFFER_LINE_PRIVMSG:
		str_append_printf (&text, "<%s> %s", who, object);
		break;
	case BUFFER_LINE_ACTION:
		str_append_printf (&text, " *  %s %s", who, object);
		break;
	case BUFFER_LINE_NOTICE:
		str_append_printf (&text, " -  Notice(%s): %s", who, object);
		break;
	case BUFFER_LINE_JOIN:
		if (who)
			str_append_printf (&text, "--> %s has joined %s", who, object);
		else
			str_append_printf (&text, "--> You have joined %s", object);
		break;
	case BUFFER_LINE_PART:
		if (who)
			str_append_printf (&text, "<-- %s has left %s (%s)",
				who, object, reason);
		else
			str_append_printf (&text, "<-- You have left %s (%s)",
				object, reason);
		break;
	case BUFFER_LINE_KICK:
		if (who)
			str_append_printf (&text, "<-- %s has kicked %s (%s)",
				who, object, reason);
		else
			str_append_printf (&text, "<-- You have kicked %s (%s)",
				object, reason);
		break;
	case BUFFER_LINE_QUIT:
		if (who)
			str_append_printf (&text, "<-- %s has quit (%s)", who, reason);
		else
			str_append_printf (&text, "<-- You have quit (%s)", reason);
		break;
	case BUFFER_LINE_STATUS:
		str_append_printf (&text, " -  %s", object);
		break;
	case BUFFER_LINE_ERROR:
		str_append_printf (&text, "=!= %s", object);
	}

	free (who);
	free (object);
	free (reason);

	struct app_readline_state state;
	if (ctx->readline_prompt_shown)
		app_readline_hide (&state);

	// TODO: write the line to a log file; note that the global and server
	//   buffers musn't collide with filenames

	printf ("%s\n", text.str);
	str_free (&text);

	if (ctx->readline_prompt_shown)
		app_readline_restore (&state, ctx->readline_prompt);
}

static void
buffer_send (struct app_context *ctx, struct buffer *buffer,
	enum buffer_line_type type, int flags,
	const char *origin, const char *reason, const char *format, ...)
{
	va_list ap;
	va_start (ap, format);
	struct str text;
	str_init (&text);
	str_append_vprintf (&text, format, ap);
	va_end (ap);

	struct buffer_line *line = buffer_line_new ();
	line->type = type;
	line->flags = flags;
	line->when = time (NULL);
	line->who = xstrdup (origin);
	line->object = str_steal (&text);
	line->reason = xstrdup (reason);

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

	if (buffer == ctx->current_buffer)
		buffer_line_display (ctx, line);
}

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

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

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

	// In theory this can't cause changes in the prompt
	refresh_prompt (ctx);
}

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

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

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

	// It's not a good idea to remove these buffers, but it's even a worse
	// one to leave the pointers point to invalid memory
	if (buffer == ctx->global_buffer)
		ctx->global_buffer = NULL;
	if (buffer == ctx->server_buffer)
		ctx->server_buffer = NULL;

	refresh_prompt (ctx);
}

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

	print_status ("%s", buffer->name);

	// That is, minus the buffer switch line and the readline prompt
	int to_display = MAX (10, ctx->lines - 2);
	struct buffer_line *line = buffer->lines_tail;
	while (line && line->prev && --to_display > 0)
		line = line->prev;

	// Once we've found where we want to start with the backlog, print it
	for (; line; line = line->next)
		buffer_line_display (ctx, line);

	// 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.

	// 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 (ctx->current_buffer)
	{
		ctx->current_buffer->history = history_get_history_state ();
		ctx->current_buffer->saved_line = rl_copy_text (0, rl_end);
		ctx->current_buffer->saved_point = rl_point;
		ctx->current_buffer->saved_mark = rl_mark;
	}
	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

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

	// Restore the target buffer's history
	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;
		history_set_history_state (state);
		free (state);
	}

	// Try to restore the target buffer's readline state
	if (buffer->saved_line)
	{
		rl_replace_line (buffer->saved_line, 0);
		rl_point = buffer->saved_point;
		rl_mark = buffer->saved_mark;
		free (buffer->saved_line);

		if (ctx->readline_prompt_shown)
			rl_redisplay ();
	}

	refresh_prompt (ctx);
}

/// Activate the n-th buffer, counting from one
static bool
buffer_goto (struct app_context *ctx, int n)
{
	int i = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
		if (++i == n)
		{
			buffer_activate (ctx, iter);
			return true;
		}
	return false;
}

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

static void
init_buffers (struct app_context *ctx)
{
	// At the moment  we have only two global everpresent buffers
	struct buffer *global = ctx->global_buffer = buffer_new ();
	struct buffer *server = ctx->server_buffer = buffer_new ();

	global->type = BUFFER_GLOBAL;
	global->name = xstrdup (PROGRAM_NAME);

	server->type = BUFFER_SERVER;
	server->name = xstrdup (str_map_find (&ctx->config, "irc_host"));

	LIST_APPEND_WITH_TAIL (ctx->buffers, ctx->buffers_tail, global);
	LIST_APPEND_WITH_TAIL (ctx->buffers, ctx->buffers_tail, server);
}

// --- Supporting code ---------------------------------------------------------

static void
irc_shutdown (struct app_context *ctx)
{
	// TODO: set a timer after which we cut the connection?
	// Generally non-critical
	if (ctx->ssl)
		soft_assert (SSL_shutdown (ctx->ssl) != -1);
	else
		soft_assert (shutdown (ctx->irc_fd, SHUT_WR) == 0);
}

static void
try_finish_quit (struct app_context *ctx)
{
	if (ctx->quitting && ctx->irc_fd == -1)
		ctx->polling = false;
}

static void
initiate_quit (struct app_context *ctx)
{
	print_status ("shutting down");
	if (ctx->irc_fd != -1)
		irc_shutdown (ctx);

	ctx->quitting = true;
	try_finish_quit (ctx);
}

static bool irc_send (struct app_context *ctx,
	const char *format, ...) ATTRIBUTE_PRINTF (2, 3);

static bool
irc_send (struct app_context *ctx, const char *format, ...)
{
	va_list ap;

	if (g_debug_mode)
	{
		struct app_readline_state state;
		if (ctx->readline_prompt_shown)
			app_readline_hide (&state);

		fputs ("[IRC] <== \"", stderr);
		va_start (ap, format);
		vfprintf (stderr, format, ap);
		va_end (ap);
		fputs ("\"\n", stderr);

		if (ctx->readline_prompt_shown)
			app_readline_restore (&state, ctx->readline_prompt);
	}

	if (!soft_assert (ctx->irc_fd != -1))
		return false;

	va_start (ap, format);
	struct str str;
	str_init (&str);
	str_append_vprintf (&str, format, ap);
	str_append (&str, "\r\n");
	va_end (ap);

	bool result = true;
	if (ctx->ssl)
	{
		// TODO: call SSL_get_error() to detect if a clean shutdown has occured
		if (SSL_write (ctx->ssl, str.str, str.len) != (int) str.len)
		{
			print_debug ("%s: %s: %s", __func__, "SSL_write",
				ERR_error_string (ERR_get_error (), NULL));
			result = false;
		}
	}
	else if (write (ctx->irc_fd, str.str, str.len) != (ssize_t) str.len)
	{
		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
		result = false;
	}

	str_free (&str);
	return result;
}

static bool
irc_get_boolean_from_config
	(struct app_context *ctx, const char *name, bool *value, struct error **e)
{
	const char *str = str_map_find (&ctx->config, name);
	hard_assert (str != NULL);

	if (set_boolean_if_valid (value, str))
		return true;

	error_set (e, "invalid configuration value for `%s'", name);
	return false;
}

static bool
irc_initialize_ssl_ctx (struct app_context *ctx, struct error **e)
{
	// XXX: maybe we should call SSL_CTX_set_options() for some workarounds

	bool verify;
	if (!irc_get_boolean_from_config (ctx, "ssl_verify", &verify, e))
		return false;

	if (!verify)
		SSL_CTX_set_verify (ctx->ssl_ctx, SSL_VERIFY_NONE, NULL);

	const char *ca_file = str_map_find (&ctx->config, "ca_file");
	const char *ca_path = str_map_find (&ctx->config, "ca_path");

	struct error *error = NULL;
	if (ca_file || ca_path)
	{
		if (SSL_CTX_load_verify_locations (ctx->ssl_ctx, ca_file, ca_path))
			return true;

		error_set (&error, "%s: %s",
			"failed to set locations for the CA certificate bundle",
			ERR_reason_error_string (ERR_get_error ()));
		goto ca_error;
	}

	if (!SSL_CTX_set_default_verify_paths (ctx->ssl_ctx))
	{
		error_set (&error, "%s: %s",
			"couldn't load the default CA certificate bundle",
			ERR_reason_error_string (ERR_get_error ()));
		goto ca_error;
	}
	return true;

ca_error:
	if (verify)
	{
		error_propagate (e, error);
		return false;
	}

	// Only inform the user if we're not actually verifying
	// FIXME: print to the server buffer
	print_warning ("%s", error->message);
	error_free (error);
	return true;
}

static bool
irc_initialize_ssl (struct app_context *ctx, struct error **e)
{
	const char *error_info = NULL;
	ctx->ssl_ctx = SSL_CTX_new (SSLv23_client_method ());
	if (!ctx->ssl_ctx)
		goto error_ssl_1;
	if (!irc_initialize_ssl_ctx (ctx, e))
		goto error_ssl_2;

	ctx->ssl = SSL_new (ctx->ssl_ctx);
	if (!ctx->ssl)
		goto error_ssl_2;

	const char *ssl_cert = str_map_find (&ctx->config, "ssl_cert");
	if (ssl_cert)
	{
		char *path = resolve_config_filename (ssl_cert);
		if (!path)
			// FIXME: print to the global buffer
			print_error ("%s: %s", "cannot open file", ssl_cert);
		// XXX: perhaps we should read the file ourselves for better messages
		else if (!SSL_use_certificate_file (ctx->ssl, path, SSL_FILETYPE_PEM)
			|| !SSL_use_PrivateKey_file (ctx->ssl, path, SSL_FILETYPE_PEM))
			// FIXME: print to the global buffer
			print_error ("%s: %s", "setting the SSL client certificate failed",
				ERR_error_string (ERR_get_error (), NULL));
		free (path);
	}

	SSL_set_connect_state (ctx->ssl);
	if (!SSL_set_fd (ctx->ssl, ctx->irc_fd))
		goto error_ssl_3;
	// Avoid SSL_write() returning SSL_ERROR_WANT_READ
	SSL_set_mode (ctx->ssl, SSL_MODE_AUTO_RETRY);

	switch (xssl_get_error (ctx->ssl, SSL_connect (ctx->ssl), &error_info))
	{
	case SSL_ERROR_NONE:
		return true;
	case SSL_ERROR_ZERO_RETURN:
		error_info = "server closed the connection";
	default:
		break;
	}

error_ssl_3:
	SSL_free (ctx->ssl);
	ctx->ssl = NULL;
error_ssl_2:
	SSL_CTX_free (ctx->ssl_ctx);
	ctx->ssl_ctx = NULL;
error_ssl_1:
	// XXX: these error strings are really nasty; also there could be
	//   multiple errors on the OpenSSL stack.
	if (!error_info)
		error_info = ERR_error_string (ERR_get_error (), NULL);
	error_set (e, "%s: %s", "could not initialize SSL", error_info);
	return false;
}

static bool
irc_establish_connection (struct app_context *ctx,
	const char *host, const char *port, struct error **e)
{
	struct addrinfo gai_hints, *gai_result, *gai_iter;
	memset (&gai_hints, 0, sizeof gai_hints);
	gai_hints.ai_socktype = SOCK_STREAM;

	int err = getaddrinfo (host, port, &gai_hints, &gai_result);
	if (err)
	{
		error_set (e, "%s: %s: %s",
			"connection failed", "getaddrinfo", gai_strerror (err));
		return false;
	}

	int sockfd;
	for (gai_iter = gai_result; gai_iter; gai_iter = gai_iter->ai_next)
	{
		sockfd = socket (gai_iter->ai_family,
			gai_iter->ai_socktype, gai_iter->ai_protocol);
		if (sockfd == -1)
			continue;
		set_cloexec (sockfd);

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

		const char *real_host = host;

		// Let's try to resolve the address back into a real hostname;
		// we don't really need this, so we can let it quietly fail
		char buf[NI_MAXHOST];
		err = getnameinfo (gai_iter->ai_addr, gai_iter->ai_addrlen,
			buf, sizeof buf, NULL, 0, NI_NUMERICHOST);
		if (err)
			print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
		else
			real_host = buf;

		char *address = format_host_port_pair (real_host, port);
		// FIXME: print to the server buffer
		print_status ("connecting to %s...", address);
		free (address);

		if (!connect (sockfd, gai_iter->ai_addr, gai_iter->ai_addrlen))
			break;

		xclose (sockfd);
	}

	freeaddrinfo (gai_result);

	if (!gai_iter)
	{
		error_set (e, "connection failed");
		return false;
	}

	ctx->irc_fd = sockfd;
	return true;
}

// --- More readline funky stuff -----------------------------------------------

static char *
get_unseen_prefix (struct app_context *ctx)
{
	struct str active_buffers;
	str_init (&active_buffers);

	size_t i = 0;
	LIST_FOR_EACH (struct buffer, iter, ctx->buffers)
	{
		i++;
		if (!iter->unseen_messages_count)
			continue;

		if (active_buffers.len)
			str_append_c (&active_buffers, ',');
		str_append_printf (&active_buffers, "%zu", i);
	}

	if (active_buffers.len)
		return str_steal (&active_buffers);

	str_free (&active_buffers);
	return NULL;
}

static void
refresh_prompt (struct app_context *ctx)
{
	bool have_attributes = !!get_attribute_printer (stdout);

	struct str prompt;
	str_init (&prompt);

	if (!ctx->irc_ready)
		str_append (&prompt, "(disconnected)");
	else if (soft_assert (ctx->current_buffer))
	{
		struct buffer *buffer = ctx->current_buffer;
		str_append_c (&prompt, '[');

		char *unseen_prefix = get_unseen_prefix (ctx);
		if (unseen_prefix)
			str_append_printf (&prompt, "(%s) ", unseen_prefix);
		free (unseen_prefix);

		str_append_printf (&prompt, "%d:%s",
			buffer_get_index (ctx, buffer), buffer->name);
		if (buffer->type == BUFFER_CHANNEL && *buffer->mode)
			str_append_printf (&prompt, "(%s)", buffer->mode);

		if (buffer != ctx->global_buffer)
		{
			str_append_c (&prompt, ' ');
			str_append (&prompt, ctx->irc_nickname);
			if (*ctx->irc_user_mode)
				str_append_printf (&prompt, "(%s)", ctx->irc_user_mode);
		}

		str_append_c (&prompt, ']');
	}
	str_append (&prompt, " ");

	// After building the new prompt, replace the old one
	free (ctx->readline_prompt);

	if (!have_attributes)
		ctx->readline_prompt = xstrdup (prompt.str);
	else
	{
		// XXX: to be completely correct, we should use tputs, but we cannot
		const char *prompt_attrs = str_map_find (&ctx->config, ATTR_PROMPT);
		const char *reset_attrs  = str_map_find (&ctx->config, ATTR_RESET);
		ctx->readline_prompt = xstrdup_printf ("%c%s%c%s%c%s%c",
			RL_PROMPT_START_IGNORE, prompt_attrs, RL_PROMPT_END_IGNORE,
			prompt.str,
			RL_PROMPT_START_IGNORE, reset_attrs,  RL_PROMPT_END_IGNORE);
	}
	str_free (&prompt);

	// We need to be somehow able to initialize it
	rl_set_prompt (ctx->readline_prompt);
	if (ctx->readline_prompt_shown)
		rl_redisplay ();
}

static int
on_readline_goto_buffer (int count, int key)
{
	(void) count;

	if (!(key & 0x80))
		return 0;

	int n = (key & 0x7F) - '0';
	if (n < 0 || n > 9)
		return 0;

	// There's no zero-th buffer
	if (n == 0)
		n = 10;

	struct app_context *ctx = g_ctx;
	if (!buffer_goto (ctx, n))
		rl_ding ();
	return 0;
}

static int
on_readline_previous_buffer (int count, int key)
{
	(void) key;

	struct app_context *ctx = g_ctx;
	if (!ctx->current_buffer)
		return 0;

	struct buffer *new_buffer = ctx->current_buffer;
	while (count-- > 0)
		if (!(new_buffer = new_buffer->prev))
			new_buffer = ctx->buffers_tail;
	buffer_activate (ctx, new_buffer);
	return 0;
}

static int
on_readline_next_buffer (int count, int key)
{
	(void) key;

	struct app_context *ctx = g_ctx;
	if (!ctx->current_buffer)
		return 0;

	struct buffer *new_buffer = ctx->current_buffer;
	while (count-- > 0)
		if (!(new_buffer = new_buffer->next))
			new_buffer = ctx->buffers;
	buffer_activate (ctx, new_buffer);
	return 0;
}

static int
init_readline (void)
{
	// TODO: maybe use rl_make_bare_keymap() and start from there;
	//   our dear user could potentionally rig things up in a way that might
	//   result in some funny unspecified behaviour

	rl_add_defun ("previous-buffer", on_readline_previous_buffer, -1);
	rl_add_defun ("next-buffer", on_readline_next_buffer, -1);

	// Redefine M-0 through M-9 to switch buffers
	for (int i = 0; i <= 9; i++)
		rl_bind_key (0x80 /* this is the Meta modifier for Readline */
			| ('0' + i), on_readline_goto_buffer);

	rl_bind_keyseq ("C-p", rl_named_function ("previous-buffer"));
	rl_bind_keyseq ("C-n", rl_named_function ("next-buffer"));
	rl_bind_keyseq ("M-p", rl_named_function ("previous-history"));
	rl_bind_keyseq ("M-n", rl_named_function ("next-history"));

	return 0;
}

// --- Input handling ----------------------------------------------------------

// TODO: we will need a proper mode parser; to be shared with kike
// TODO: we alse definitely need to parse server capability messages

static void
irc_handle_ping (struct app_context *ctx, const struct irc_message *msg)
{
	if (msg->params.len)
		irc_send (ctx, "PONG :%s", msg->params.vector[0]);
	else
		irc_send (ctx, "PONG");
}

static struct irc_handler
{
	char *name;
	void (*handler) (struct app_context *ctx, const struct irc_message *msg);
}
g_irc_handlers[] =
{
	// This list needs to stay sorted
	// TODO: handle as much as we can
	{ "PING", irc_handle_ping },
};

static int
irc_handler_cmp_by_name (const void *a, const void *b)
{
	const struct irc_handler *first  = a;
	const struct irc_handler *second = b;
	return strcasecmp_ascii (first->name, second->name);
}

static void
irc_process_message (const struct irc_message *msg,
	const char *raw, void *user_data)
{
	struct app_context *ctx = user_data;

	if (g_debug_mode)
	{
		struct app_readline_state state;
		if (ctx->readline_prompt_shown)
			app_readline_hide (&state);

		// TODO: ensure proper encoding
		fprintf (stderr, "[%s] ==> \"%s\"\n", "IRC", raw);

		if (ctx->readline_prompt_shown)
			app_readline_restore (&state, ctx->readline_prompt);
	}

	if (!ctx->irc_ready && (!strcasecmp (msg->command, "MODE")
		|| !strcasecmp (msg->command, "376")    // RPL_ENDOFMOTD
		|| !strcasecmp (msg->command, "422")))  // ERR_NOMOTD
	{
		// FIXME: print to the server buffer
		print_status ("successfully connected");
		ctx->irc_ready = true;

		const char *autojoin = str_map_find (&ctx->config, "autojoin");
		if (autojoin)
			irc_send (ctx, "JOIN :%s", autojoin);
	}

	struct irc_handler key = { .name = msg->command };
	struct irc_handler *handler = bsearch (&key, g_irc_handlers,
		N_ELEMENTS (g_irc_handlers), sizeof key, irc_handler_cmp_by_name);
	if (handler)
		handler->handler (ctx, msg);

	// Numerics typically have human-readable information
	unsigned long dummy;
	if (xstrtoul (&dummy, msg->command, 10))
		// TODO: ensure proper encoding
		// FIXME: print to the server buffer
		print_status ("%s", raw);
}

// --- User input handling -----------------------------------------------------

static void handle_command_help (struct app_context *, const char *);

static void
handle_command_buffer (struct app_context *ctx, const char *arguments)
{
	// TODO: parse the arguments
}

static void
handle_command_quit (struct app_context *ctx, const char *arguments)
{
	if (ctx->irc_fd != -1)
	{
		if (*arguments)
			irc_send (ctx, "QUIT :%s", arguments);
		else
			irc_send (ctx, "QUIT :%s", PROGRAM_NAME " " PROGRAM_VERSION);
	}
	initiate_quit (ctx);
}

static struct command_handler
{
	char *name;
	void (*handler) (struct app_context *ctx, const char *arguments);
	// TODO: probably also a usage string
}
g_command_handlers[] =
{
	{ "help",    handle_command_help   },
	{ "quit",    handle_command_quit   },
	{ "buffer",  handle_command_buffer },
#if 0
	{ "msg",     NULL },
	{ "query",   NULL },
	{ "notice",  NULL },
	{ "ctcp",    NULL },
	{ "me",      NULL },

	{ "join",    NULL },
	{ "part",    NULL },
	{ "cycle",   NULL },

	{ "mode",    NULL },
	{ "topic",   NULL },
	{ "kick",    NULL },
	{ "kickban", NULL },
	{ "ban",     NULL },
	{ "invite",  NULL },

	{ "list",    NULL },
	{ "names",   NULL },
	{ "who",     NULL },
	{ "whois",   NULL },

	{ "motd",    NULL },
	{ "away",    NULL },
	{ "quote",   NULL },
#endif
};

static void
handle_command_help (struct app_context *ctx, const char *arguments)
{
	// TODO: show a list of all user commands
}

static int
command_handler_cmp_by_length (const void *a, const void *b)
{
	const struct command_handler *first  = a;
	const struct command_handler *second = b;
	return strlen (first->name) - strlen (second->name);
}

static void
init_partial_matching_user_command_map (struct str_map *partial)
{
	str_map_init (partial);
	partial->key_xfrm = tolower_ascii_strxfrm;

	// We process them from the longest to the shortest one,
	// so that common prefixes favor shorter entries
	struct command_handler *by_length[N_ELEMENTS (g_command_handlers)];
	for (size_t i = 0; i < N_ELEMENTS (by_length); i++)
		by_length[i] = &g_command_handlers[i];
	qsort (by_length, N_ELEMENTS (by_length), sizeof *by_length,
		command_handler_cmp_by_length);

	for (size_t i = N_ELEMENTS (by_length); i--; )
	{
		char *copy = xstrdup (by_length[i]->name);
		for (size_t part = strlen (copy); part; part--)
		{
			copy[part] = '\0';
			str_map_set (partial, copy, by_length[i]);
		}
		free (copy);
	}
}

static void
process_user_command (struct app_context *ctx, char *command)
{
	// Trivially create a partial matching map
	static bool initialized = false;
	struct str_map partial;
	if (!initialized)
	{
		init_partial_matching_user_command_map (&partial);
		initialized = true;
	}

	// TODO: cut a single word (strtok_r()?)
	// TODO: if it's a number, switch to the given buffer

	struct command_handler *handler = str_map_find (&partial, command);
	if (handler)
		// FIXME: pass arguments correctly
		handler->handler (ctx, "");
}

static void
send_message_to_current_buffer (struct app_context *ctx, char *message)
{
	struct buffer *buffer = ctx->current_buffer;
	if (!buffer)
	{
		// TODO: print an error message to the global buffer
		return;
	}

	switch (buffer->type)
	{
	case BUFFER_GLOBAL:
	case BUFFER_SERVER:
		// TODO: print a message to the buffer that it's not a channel
		break;
	case BUFFER_CHANNEL:
		// TODO: send an IRC message to the channel
		break;
	case BUFFER_PM:
		// TODO: send an IRC message to the user
		break;
	}
}

static void
process_input (struct app_context *ctx, char *user_input)
{
	char *input;
	size_t len;

	if (!(input = iconv_xstrdup (ctx->term_to_utf8, user_input, -1, &len)))
		print_error ("character conversion failed for `%s'", "user input");
	else if (input[0] != '/')
		send_message_to_current_buffer (ctx, input);
	else if (input[1] == '/')
		send_message_to_current_buffer (ctx, input + 1);
	else
		process_user_command (ctx, input + 1);

	free (input);
}

// --- Supporting code (continued) ---------------------------------------------

enum irc_read_result
{
	IRC_READ_OK,                        ///< Some data were read successfully
	IRC_READ_EOF,                       ///< The server has closed connection
	IRC_READ_AGAIN,                     ///< No more data at the moment
	IRC_READ_ERROR                      ///< General connection failure
};

static enum irc_read_result
irc_fill_read_buffer_ssl (struct app_context *ctx, struct str *buf)
{
	int n_read;
start:
	n_read = SSL_read (ctx->ssl, buf->str + buf->len,
		buf->alloc - buf->len - 1 /* null byte */);

	const char *error_info = NULL;
	switch (xssl_get_error (ctx->ssl, n_read, &error_info))
	{
	case SSL_ERROR_NONE:
		buf->str[buf->len += n_read] = '\0';
		return IRC_READ_OK;
	case SSL_ERROR_ZERO_RETURN:
		return IRC_READ_EOF;
	case SSL_ERROR_WANT_READ:
		return IRC_READ_AGAIN;
	case SSL_ERROR_WANT_WRITE:
	{
		// Let it finish the handshake as we don't poll for writability;
		// any errors are to be collected by SSL_read() in the next iteration
		struct pollfd pfd = { .fd = ctx->irc_fd, .events = POLLOUT };
		soft_assert (poll (&pfd, 1, 0) > 0);
		goto start;
	}
	case XSSL_ERROR_TRY_AGAIN:
		goto start;
	default:
		print_debug ("%s: %s: %s", __func__, "SSL_read", error_info);
		return IRC_READ_ERROR;
	}
}

static enum irc_read_result
irc_fill_read_buffer (struct app_context *ctx, struct str *buf)
{
	ssize_t n_read;
start:
	n_read = recv (ctx->irc_fd, buf->str + buf->len,
		buf->alloc - buf->len - 1 /* null byte */, 0);

	if (n_read > 0)
	{
		buf->str[buf->len += n_read] = '\0';
		return IRC_READ_OK;
	}
	if (n_read == 0)
		return IRC_READ_EOF;

	if (errno == EAGAIN)
		return IRC_READ_AGAIN;
	if (errno == EINTR)
		goto start;

	print_debug ("%s: %s: %s", __func__, "recv", strerror (errno));
	return IRC_READ_ERROR;
}

static bool irc_connect (struct app_context *, struct error **);
static void irc_queue_reconnect (struct app_context *);

static void
irc_cancel_timers (struct app_context *ctx)
{
	poller_timer_reset (&ctx->timeout_tmr);
	poller_timer_reset (&ctx->ping_tmr);
	poller_timer_reset (&ctx->reconnect_tmr);
}

static void
on_irc_reconnect_timeout (void *user_data)
{
	struct app_context *ctx = user_data;

	struct error *e = NULL;
	if (irc_connect (ctx, &e))
		return;

	// FIXME: print to the server buffer
	print_error ("%s", e->message);
	error_free (e);
	irc_queue_reconnect (ctx);
}

static void
irc_queue_reconnect (struct app_context *ctx)
{
	hard_assert (ctx->irc_fd == -1);
	// FIXME: print to the server buffer
	print_status ("trying to reconnect in %ld seconds...",
		ctx->reconnect_delay);
	poller_timer_set (&ctx->reconnect_tmr, ctx->reconnect_delay * 1000);
}

static void
on_irc_disconnected (struct app_context *ctx)
{
	// Get rid of the dead socket and related things
	if (ctx->ssl)
	{
		SSL_free (ctx->ssl);
		ctx->ssl = NULL;
		SSL_CTX_free (ctx->ssl_ctx);
		ctx->ssl_ctx = NULL;
	}

	xclose (ctx->irc_fd);
	ctx->irc_fd = -1;
	ctx->irc_ready = false;

	ctx->irc_event.closed = true;
	poller_fd_reset (&ctx->irc_event);

	// All of our timers have lost their meaning now
	irc_cancel_timers (ctx);

	if (ctx->quitting)
		try_finish_quit (ctx);
	else if (!ctx->reconnect)
		initiate_quit (ctx);
	else
		irc_queue_reconnect (ctx);
}

static void
on_irc_ping_timeout (void *user_data)
{
	struct app_context *ctx = user_data;
	// FIXME: print to the server buffer
	print_error ("connection timeout");
	on_irc_disconnected (ctx);
}

static void
on_irc_timeout (void *user_data)
{
	// Provoke a response from the server
	struct app_context *ctx = user_data;
	irc_send (ctx, "PING :%s",
		(char *) str_map_find (&ctx->config, "nickname"));
}

static void
irc_reset_connection_timeouts (struct app_context *ctx)
{
	irc_cancel_timers (ctx);
	poller_timer_set (&ctx->timeout_tmr, 3 * 60 * 1000);
	poller_timer_set (&ctx->ping_tmr, (3 * 60 + 30) * 1000);
}

static void
on_irc_readable (const struct pollfd *fd, struct app_context *ctx)
{
	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);

	(void) set_blocking (ctx->irc_fd, false);

	struct str *buf = &ctx->read_buffer;
	enum irc_read_result (*fill_buffer)(struct app_context *, struct str *)
		= ctx->ssl
		? irc_fill_read_buffer_ssl
		: irc_fill_read_buffer;
	bool disconnected = false;
	while (true)
	{
		str_ensure_space (buf, 512);
		switch (fill_buffer (ctx, buf))
		{
		case IRC_READ_AGAIN:
			goto end;
		case IRC_READ_ERROR:
			// FIXME: print to the server buffer
			print_error ("reading from the IRC server failed");
			disconnected = true;
			goto end;
		case IRC_READ_EOF:
			// FIXME: print to the server buffer
			print_status ("the IRC server closed the connection");
			disconnected = true;
			goto end;
		case IRC_READ_OK:
			break;
		}

		if (buf->len >= (1 << 20))
		{
			// FIXME: print to the server buffer
			print_error ("the IRC server seems to spew out data frantically");
			irc_shutdown (ctx);
			goto end;
		}
	}
end:
	(void) set_blocking (ctx->irc_fd, true);
	irc_process_buffer (buf, irc_process_message, ctx);

	if (disconnected)
		on_irc_disconnected (ctx);
	else
		irc_reset_connection_timeouts (ctx);
}

static bool
irc_connect (struct app_context *ctx, struct error **e)
{
	const char *irc_host = str_map_find (&ctx->config, "irc_host");
	const char *irc_port = str_map_find (&ctx->config, "irc_port");

	const char *socks_host = str_map_find (&ctx->config, "socks_host");
	const char *socks_port = str_map_find (&ctx->config, "socks_port");
	const char *socks_username = str_map_find (&ctx->config, "socks_username");
	const char *socks_password = str_map_find (&ctx->config, "socks_password");

	const char *nickname = str_map_find (&ctx->config, "nickname");
	const char *username = str_map_find (&ctx->config, "username");
	const char *realname = str_map_find (&ctx->config, "realname");

	// We have a default value for these
	hard_assert (irc_port && socks_port);

	// These are filled automatically if needed
	hard_assert (nickname && username && realname);

	// TODO: again, get rid of `struct error' in here.  The question is: how
	//   do we tell our caller that he should not try to reconnect?
	if (!irc_host)
	{
		error_set (e, "no hostname specified in configuration");
		return false;
	}

	bool use_ssl;
	if (!irc_get_boolean_from_config (ctx, "ssl", &use_ssl, e))
		return false;

	if (socks_host)
	{
		char *address = format_host_port_pair (irc_host, irc_port);
		char *socks_address = format_host_port_pair (socks_host, socks_port);
		// FIXME: print to the server buffer
		print_status ("connecting to %s via %s...", address, socks_address);
		free (socks_address);
		free (address);

		struct error *error = NULL;
		int fd = socks_connect (socks_host, socks_port, irc_host, irc_port,
			socks_username, socks_password, &error);
		if (fd == -1)
		{
			error_set (e, "%s: %s", "SOCKS connection failed", error->message);
			error_free (error);
			return false;
		}
		ctx->irc_fd = fd;
	}
	else if (!irc_establish_connection (ctx, irc_host, irc_port, e))
		return false;

	if (use_ssl && !irc_initialize_ssl (ctx, e))
	{
		xclose (ctx->irc_fd);
		ctx->irc_fd = -1;
		return false;
	}
	// FIXME: print to the server buffer
	print_status ("connection established");

	poller_fd_init (&ctx->irc_event, &ctx->poller, ctx->irc_fd);
	ctx->irc_event.dispatcher = (poller_fd_fn) on_irc_readable;
	ctx->irc_event.user_data = ctx;

	poller_fd_set (&ctx->irc_event, POLLIN);
	irc_reset_connection_timeouts (ctx);

	irc_send (ctx, "NICK %s", nickname);
	irc_send (ctx, "USER %s 8 * :%s", username, realname);
	return true;
}

// --- I/O event handlers ------------------------------------------------------

static void
on_signal_pipe_readable (const struct pollfd *fd, struct app_context *ctx)
{
	char dummy;
	(void) read (fd->fd, &dummy, 1);

	if (g_termination_requested && !ctx->quitting)
	{
		// There may be a timer set to reconnect to the server
		irc_cancel_timers (ctx);

		if (ctx->irc_fd != -1)
			irc_send (ctx, "QUIT :Terminated by signal");
		initiate_quit (ctx);
	}

	if (g_winch_received)
	{
		// 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 ();
		rl_get_screen_size (&ctx->lines, &ctx->columns);
	}
}

static void
on_tty_readable (const struct pollfd *fd, struct app_context *ctx)
{
	(void) ctx;

	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);

	rl_callback_read_char ();
}

static void
on_readline_input (char *line)
{
	// Otherwise the prompt is shown at all times
	g_ctx->readline_prompt_shown = false;

	if (line)
	{
		if (*line)
			add_history (line);

		process_input (g_ctx, line);
		free (line);
	}

	g_ctx->readline_prompt_shown = true;
}

// --- Configuration loading ---------------------------------------------------

static bool
read_hexa_escape (const char **cursor, struct str *output)
{
	int i;
	char c, code = 0;

	for (i = 0; i < 2; i++)
	{
		c = tolower (*(*cursor));
		if (c >= '0' && c <= '9')
			code = (code << 4) | (c - '0');
		else if (c >= 'a' && c <= 'f')
			code = (code << 4) | (c - 'a' + 10);
		else
			break;

		(*cursor)++;
	}

	if (!i)
		return false;

	str_append_c (output, code);
	return true;
}

static bool
read_octal_escape (const char **cursor, struct str *output)
{
	int i;
	char c, code = 0;

	for (i = 0; i < 3; i++)
	{
		c = *(*cursor);
		if (c < '0' || c > '7')
			break;

		code = (code << 3) | (c - '0');
		(*cursor)++;
	}

	if (!i)
		return false;

	str_append_c (output, code);
	return true;
}

static bool
read_string_escape_sequence (const char **cursor,
	struct str *output, struct error **e)
{
	int c;
	switch ((c = *(*cursor)++))
	{
	case '?':  str_append_c (output, '?');  break;
	case '"':  str_append_c (output, '"');  break;
	case '\\': str_append_c (output, '\\'); break;
	case 'a':  str_append_c (output, '\a'); break;
	case 'b':  str_append_c (output, '\b'); break;
	case 'f':  str_append_c (output, '\f'); break;
	case 'n':  str_append_c (output, '\n'); break;
	case 'r':  str_append_c (output, '\r'); break;
	case 't':  str_append_c (output, '\t'); break;
	case 'v':  str_append_c (output, '\v'); break;

	case 'e':
	case 'E':
		str_append_c (output, '\x1b');
		break;

	case 'x':
	case 'X':
		if (!read_hexa_escape (cursor, output))
			FAIL ("invalid hexadecimal escape");
		break;

	case '\0':
		FAIL ("premature end of escape sequence");

	default:
		(*cursor)--;
		if (!read_octal_escape (cursor, output))
			FAIL ("unknown escape sequence");
	}
	return true;
}

static bool
unescape_string (const char *s, struct str *output, struct error **e)
{
	int c;
	while ((c = *s++))
	{
		if (c != '\\')
			str_append_c (output, c);
		else if (!read_string_escape_sequence (&s, output, e))
			return false;
	}
	return true;
}

static bool
autofill_user_info (struct app_context *ctx, struct error **e)
{
	const char *nickname = str_map_find (&ctx->config, "nickname");
	const char *username = str_map_find (&ctx->config, "username");
	const char *realname = str_map_find (&ctx->config, "realname");

	if (nickname && username && realname)
		return true;

	// TODO: read POSIX user info and fill the configuration if needed
	struct passwd *pwd = getpwuid (geteuid ());
	if (!pwd)
		FAIL ("cannot retrieve user information: %s", strerror (errno));

	if (!nickname)
		str_map_set (&ctx->config, "nickname", xstrdup (pwd->pw_name));
	if (!username)
		str_map_set (&ctx->config, "username", xstrdup (pwd->pw_name));

	// Not all systems have the GECOS field but the vast majority does
	if (!realname)
	{
		char *gecos = pwd->pw_gecos;

		// The first comma, if any, ends the user's real name
		char *comma = strchr (gecos, ',');
		if (comma)
			*comma = '\0';

		str_map_set (&ctx->config, "username", xstrdup (gecos));
	}

	return true;
}

static bool
unescape_config (struct str_map *input, struct str_map *output, struct error **e)
{
	struct error *error = NULL;
	struct str_map_iter iter;
	str_map_iter_init (&iter, input);
	while (str_map_iter_next (&iter))
	{
		struct str value;
		str_init (&value);
		if (!unescape_string (iter.link->data, &value, &error))
		{
			error_set (e, "error reading configuration: %s: %s",
				iter.link->key, error->message);
			error_free (error);
			return false;
		}

		str_map_set (output, iter.link->key, str_steal (&value));
	}
	return true;
}

static bool
load_config (struct app_context *ctx, struct error **e)
{
	// TODO: employ a better configuration file format, so that we don't have
	//   to do this convoluted post-processing anymore.

	struct str_map map;
	str_map_init (&map);
	map.free = free;

	bool success = read_config_file (&map, e) &&
		unescape_config (&map, &ctx->config, e) &&
		autofill_user_info (ctx, e);
	str_map_free (&map);
	if (!success)
		return false;

	if (!irc_get_boolean_from_config (ctx,
		"reconnect", &ctx->reconnect, e)
	 || !irc_get_boolean_from_config (ctx,
		"isolate_buffers", &ctx->isolate_buffers, e))
		return false;

	const char *delay_str = str_map_find (&ctx->config, "reconnect_delay");
	hard_assert (delay_str != NULL);  // We have a default value for this
	if (!xstrtoul (&ctx->reconnect_delay, delay_str, 10))
	{
		error_set (e, "invalid configuration value for `%s'",
			"reconnect_delay");
		return false;
	}
	return true;
}

// --- Main program ------------------------------------------------------------

static void
init_poller_events (struct app_context *ctx)
{
	poller_timer_init (&ctx->timeout_tmr, &ctx->poller);
	ctx->timeout_tmr.dispatcher = on_irc_timeout;
	ctx->timeout_tmr.user_data = ctx;

	poller_timer_init (&ctx->ping_tmr, &ctx->poller);
	ctx->ping_tmr.dispatcher = on_irc_ping_timeout;
	ctx->ping_tmr.user_data = ctx;

	poller_timer_init (&ctx->reconnect_tmr, &ctx->poller);
	ctx->reconnect_tmr.dispatcher = on_irc_reconnect_timeout;
	ctx->reconnect_tmr.user_data = ctx;

	poller_fd_init (&ctx->signal_event, &ctx->poller, g_signal_pipe[0]);
	ctx->signal_event.dispatcher = (poller_fd_fn) on_signal_pipe_readable;
	ctx->signal_event.user_data = &ctx;
	poller_fd_set (&ctx->signal_event, POLLIN);

	poller_fd_init (&ctx->tty_event, &ctx->poller, STDIN_FILENO);
	ctx->tty_event.dispatcher = (poller_fd_fn) on_tty_readable;
	ctx->tty_event.user_data = &ctx;
	poller_fd_set (&ctx->tty_event, POLLIN);
}

int
main (int argc, char *argv[])
{
	static const struct opt opts[] =
	{
		{ 'd', "debug", NULL, 0, "run in debug mode" },
		{ 'h', "help", NULL, 0, "display this help and exit" },
		{ 'V', "version", NULL, 0, "output version information and exit" },
		{ 'w', "write-default-cfg", "FILENAME",
		  OPT_OPTIONAL_ARG | OPT_LONG_ONLY,
		  "write a default configuration file and exit" },
		{ 0, NULL, NULL, 0, NULL }
	};

	struct opt_handler oh;
	opt_handler_init (&oh, argc, argv, opts, NULL, "Experimental IRC client.");

	int c;
	while ((c = opt_handler_get (&oh)) != -1)
	switch (c)
	{
	case 'd':
		g_debug_mode = true;
		break;
	case 'h':
		opt_handler_usage (&oh, stdout);
		exit (EXIT_SUCCESS);
	case 'V':
		printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
		exit (EXIT_SUCCESS);
	case 'w':
		call_write_default_config (optarg, g_config_table);
		exit (EXIT_SUCCESS);
	default:
		print_error ("wrong options");
		opt_handler_usage (&oh, stderr);
		exit (EXIT_FAILURE);
	}

	opt_handler_free (&oh);

	struct app_context ctx;
	print_status (PROGRAM_NAME " " PROGRAM_VERSION " starting");
	app_context_init (&ctx);
	g_ctx = &ctx;

	// We only need to convert to and from the terminal encoding
	setlocale (LC_CTYPE, "");

	SSL_library_init ();
	atexit (EVP_cleanup);
	SSL_load_error_strings ();
	atexit (ERR_free_strings);

	using_history ();
	// This can cause memory leaks, or maybe even a segfault.  Funny, eh?
	stifle_history (HISTORY_LIMIT);

	setup_signal_handlers ();

	init_colors (&ctx);
	init_poller_events (&ctx);
	init_buffers (&ctx);
	ctx.current_buffer = ctx.global_buffer;
	refresh_prompt (&ctx);

	// TODO: connect asynchronously (first step towards multiple servers)
	// TODO: print load_config() errors to the global buffer,
	//   switch buffers and print irc_connect() errors to the server buffer?
	struct error *e = NULL;
	if (!load_config (&ctx, &e)
	 || !irc_connect (&ctx, &e))
	{
		// FIXME: print to the global buffer
		print_error ("%s", e->message);
		error_free (e);
		exit (EXIT_FAILURE);
	}

	rl_startup_hook = init_readline;
	rl_catch_sigwinch = false;
	rl_callback_handler_install (ctx.readline_prompt, on_readline_input);
	rl_get_screen_size (&ctx.lines, &ctx.columns);
	ctx.readline_prompt_shown = true;

	ctx.polling = true;
	while (ctx.polling)
		poller_run (&ctx.poller);

	if (ctx.readline_prompt_shown)
		rl_callback_handler_remove ();
	putchar ('\n');

	app_context_free (&ctx);
	free_terminal ();
	return EXIT_SUCCESS;
}