/*
 * Copyright (c) 2026 Nakidai Perumenei <nakidai at disroot dot org>
 *
 * Permission to use, copy, modify, and 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.
 */

#include "ircd.h"

#include <stddef.h>
#include <stdio.h>
#include <string.h>

#include <err.h>


static int
join(struct Message *msg, struct Peer *peer)
{
	size_t i, j;

	/* TODO: support comma separated list of channels, keys */
	ensure(peer->type, reply(peer, 451), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 461), 0);
	ensure(peer->channels_c != lengthof(peer->channels), reply(peer, 405, msg->params[0]), 0)
	ensure(*msg->params[0] == '#', reply(peer, 403, msg->params[0]), 0);

	for (i = 0; i < channels_c; ++i)
	{
		if (strcmp(channels[i].name, msg->params[0]))
			continue;

		for (j = 0; j < channels[i].users_c; ++j)
			ensure(
				strcmp(channels[i].users[j]->nick, peer->nick),
				(void)0,
				0
			);

		ensure(!channel_join(&channels[i], peer), reply(peer, 471), 0);
		return 0;
	}

	channels[channels_c] = (struct Channel){0};
	strlcpy(channels[channels_c].name, msg->params[0], sizeof(channels->name));
	channel_join(&channels[channels_c++], peer);
	return 0;
}

static int
mode(struct Message *msg, struct Peer *peer)
{
	int set = 1, m;

	ensure(peer->type, reply(peer, 451), 0);
	ensure(msg->params[0] && msg->params[0], reply(peer, 431), 0);
	ensure(msg->params[1] && msg->params[1], reply(peer, 221), 0);

	switch (*msg->params[1])
	{
	case '-':
		set = !set;
	case '+':
		++msg->params[1];
	default:
	{
		for (; *msg->params[1]; ++msg->params[1])
		{
			m = user_mode(*msg->params[1]);
			if (!m)
			{
				reply(peer, 501, msg->params[1]);
				continue;
			}

			if (m & AWAY)
				continue;

			if (set && !(m & (OPER | LOCALOPER)))
				peer->modes |= m;
			else if (!(m & RESTRICTED))
				peer->modes &= ~m;
		}
	}
	}

	return 0;
}

static int
nick(struct Message *msg, struct Peer *peer)
{
	ensure(msg->params[0] && msg->params[0], reply(peer, 431), 0);
	ensure(!(peer->modes & RESTRICTED), reply(peer, 484), 0);

	user_reg(peer, msg->params[0], NULL, NULL, NULL);

	return 0;
}

static int
part(struct Message *msg, struct Peer *peer)
{
	size_t i;

	ensure(peer->type, reply(peer, 451), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 461), 0);

	for (i = 0; i < peer->channels_c; ++i)
		if (!strcmp(peer->channels[i]->name, msg->params[0]))
			break;
	ensure(i != peer->channels_c, reply(peer, 442, msg->params[0]), 0)

	writechanf(
		0,
		peer->channels[i],
		":%s!%s@%s PART %s :%s",
		getnick(peer),
		peer->user,
		peer->host,
		msg->params[0],
		msg->params[1] ? msg->params[1] : getnick(peer)
	);
	channel_exit(peer->channels[i], peer);
	return 0;
}

static int
privmsg(struct Message *msg, struct Peer *peer)
{
	size_t i;

	ensure(peer->type, reply(peer, 451), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 411), 0);
	ensure(msg->params[1] && *msg->params[1], reply(peer, 412), 0);

	/* TODO: implement channels */
	ensure(!strchr("!+&", *msg->params[0]), writef(
		peer->fd,
		":%s 421 %s :Channels are not supported yet",
		hostname,
		getnick(peer)
	), 0);

	/* TODO: implement server-to-server communication */
	switch (*msg->params[0])
	{
	case '#':
	{
		for (i = 0; i < channels_c; ++i)
			if (!strcmp(channels[i].name, msg->params[0]))
			{
				writechanf(
					peer,
					&channels[i],
					":%s!%s@%s PRIVMSG %s :%s",
					peer->nick,
					peer->user,
					peer->host,
					msg->params[0],
					msg->params[1]
				);
				break;
			}
		ensure(i != channels_c, reply(peer, 401, msg->params[0]), 0);
	} break;
	default:
	{
		for (i = 0; i < peers_c; ++i)
		{
			if (peers[i].type != CLIENT || strcmp(peers[i].nick, msg->params[0]))
				continue;

			writef(
				peers[i].fd,
				":%s!%s@%s PRIVMSG %s :%s",
				peer->nick,
				peer->user,
				peer->host,
				msg->params[0],
				msg->params[1]
			);
			break;
		}
		ensure(i != peers_c, reply(peer, 401, msg->params[0]), 0);
	} break;
	}
	return 0;
}

static int
quit(struct Message *msg, struct Peer *peer)
{
	size_t i, j;

	ensure(peer->type, (void)0, 1)

	writef(
		peer->fd,
		":%s!%s@%s QUIT :%s",
		getnick(peer),
		peer->user,
		peer->host,
		msg->params[0] ? msg->params[0] : "Client Quit"
	);

	for (i = 0; i < peer->channels_c; ++i)
	{
		channel_exit(peer->channels[i], peer);
		for (j = 0; j < peer->channels[i]->users_c; ++j)
			peer->channels[i]->users[j]->flags |= ANNOUNCE;
	}

	for (i = 0; i < peers_c; ++i)
		if (peers[i].flags & ANNOUNCE)
		{
			writef(
				peers[i].fd,
				":%s!%s@%s QUIT :%s",
				getnick(peer),
				peer->user,
				peer->host,
				msg->params[0] ? msg->params[0] : "Client Quit"
			);
			peers[i].flags &= ~ANNOUNCE;
		}

	return 1;
}

static int
user(struct Message *msg, struct Peer *peer)
{
	size_t i;

	ensure(!peer->type, reply(peer, 462), 0);
	for (i = 0; i < 4; ++i)
		ensure(msg->params[i] && *msg->params[i], reply(peer, 461), 0);

	user_reg(peer, NULL, msg->params[0], msg->params[3], msg->params[1]);

	return 0;
}

static int
default_handler(struct Message *msg, struct Peer *peer)
{
	ensure(peer->type, (void)0, 0);

	reply(peer, 421, msg->command);
	return 0;
}

static struct Handler {
	const char *name;
	Handler *handler;
} handlers[] =
{
	{ "join", join },
	{ "mode", mode },
	{ "nick", nick },
	{ "part", part },
	{ "privmsg", privmsg },
	{ "quit", quit },
	{ "user", user },
};

Handler *
find(const char *command)
{
	struct Handler *l, *m, *r;
	int res;

	l = handlers;
	r = handlers + lengthof(handlers) - 1;
	while (l <= r)
	{
		m = l + (r - l) / 2;
		res = strcmp(command, m->name);
		if (res > 0)
			l = ++m;
		else if (res < 0)
			r = --m;
		else
			return m->handler;
	}

	return default_handler;
}