/*
 * 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 <ctype.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>

#include <err.h>


static struct Oper opers[OPERS_MAX];
size_t opers_c;

static int names(struct Message *msg, struct Peer *peer);

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

	/* 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, msg->command), 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 (cp = msg->params[0]; *cp; ++cp)
		ensure(
			*cp != '\a' && *cp != ',' && *cp != ':',
			reply(peer, 403, msg->params[0]),
			0
		);

	for (i = 0; i < peer->channels_c; ++i)
		ensure(strcmp(channels[i].name, msg->params[0]), (void)0, 0);

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

		if (channel_join(&channels[i], peer))
			reply(peer, 471);
		else
			names(&namesmsg, peer);
		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);
	names(&namesmsg, 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
names(struct Message *msg, struct Peer *peer)
{
	static char buf[MESSAGE_MAX];
	size_t i, j;

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

		memset(buf, 0, sizeof(buf));
		for (j = 0; j < peer->channels[i]->users_c; ++j)
		{
			strlcat(buf, peer->channels[i]->users[j]->nick, sizeof(buf));
			if (strlen(buf) >= MESSAGE_MAX - 4*PEER_NICK_MAX)
			{
				reply(peer, 353, peer->channels[i]->name, buf);
				memset(buf, 0, sizeof(buf));
			} else
			{
				strlcat(buf, " ", sizeof(buf));
			}
		}
		if (*buf)
			reply(peer, 353, peer->channels[i]->name, buf);
	}

	reply(peer, 366, msg->params[0] ? msg->params[0] : "*");
	return 0;
}

static int
nick(struct Message *msg, struct Peer *peer)
{
	size_t i;
	char *cp;

	ensure(msg->params[0] && *msg->params[0], reply(peer, 431), 0);
	ensure(!(peer->modes & RESTRICTED), reply(peer, 484), 0);

	cp = msg->params[0];
	ensure(
		isupper(*cp) || islower(*cp)
		|| 0x5b <= *cp && *cp <= 0x60
		|| 0x7b <= *cp && *cp <= 0x7d,
		reply(peer, 432, msg->params[0]),
		0
	);
	for (++cp; *cp; ++cp)
		ensure(
			isupper(*cp) || islower(*cp) || isdigit(*cp)
			|| 0x5b <= *cp && *cp <= 0x60
			|| 0x7b <= *cp && *cp <= 0x7d
			|| *cp == '-',
			reply(peer, 432, msg->params[0]),
			0
		);

	for (i = 0; i < peers_c; ++i)
		if (peers[i].fd != peer->fd)
			ensure(
				strcmp(peers[i].nick, msg->params[0]),
				reply(peer, 433, msg->params[0]),
				0
			);

	if (peer->type)
		announce(
			peer,
			":%s!%s@%s NICK %s",
			getnick(peer),
			peer->user,
			peer->host,
			msg->params[0]
		);

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

	return 0;
}

static int
oper(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, msg->command), 0);
	ensure(msg->params[1] && *msg->params[1], reply(peer, 464), 0);

	for (i = 0; i < opers_c; ++i)
		if (!strcmp(opers[i].nick, msg->params[0]))
			break;
	ensure(i != opers_c && !strcmp(opers[i].pass, msg->params[1]), reply(peer, 464), 0);

	peer->modes |= OPER;
	reply(peer, 381);

	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, msg->command), 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
ping(struct Message *msg, struct Peer *peer)
{
	ensure(msg->params[0] && *msg->params[0], reply(peer, 409), 0);

	writef(
		peer->fd,
		":%s PONG :%s",
		hostname,
		msg->params[0]
	);

	return 0;
}

static int
pong(struct Message *msg, struct Peer *peer)
{
	ensure(msg->params[0] && *msg->params[0], reply(peer, 409), 0);

	peer->ping = 0;

	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 %s %s :%s",
					peer->nick,
					peer->user,
					peer->host,
					*msg->command == 'p'
						? "PRIVMSG"
						: "NOTICE",
					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 %s %s :%s",
				peer->nick,
				peer->user,
				peer->host,
				*msg->command == 'p'
					? "PRIVMSG"
					: "NOTICE",
				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)
{
	strlcpy(peer->quit, msg->params[0] ? msg->params[0] : "Client Quit", PEER_QUIT_MAX);

	return 1;
}

static int
setcreation(struct Message *msg, struct Peer *peer)
{
	ensure(peer->type == CONFIG, reply(peer, 481, "You're not a config file"), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 461, msg->command), 0);

	strlcpy(creation, msg->params[0], sizeof(creation));

	return 0;
}

static int
setinfo(struct Message *msg, struct Peer *peer)
{
	ensure(peer->type == CONFIG, reply(peer, 481, "You're not a config file"), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 461, msg->command), 0);

	strlcpy(info, msg->params[0], sizeof(info));

	return 0;
}

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

	ensure(peer->type == CONFIG, reply(peer, 481, "You're not a config file"), 0);
	ensure(msg->params[0] && *msg->params[0], reply(peer, 461, msg->command), 0);
	ensure(msg->params[1], reply(peer, 461, msg->command), 0);
	ensure(
		!*msg->params[1] || *msg->params[1] && opers_c < OPERS_MAX,
		reply(peer, 420, msg->params[0]),
		0
	);

	for (i = 0; i < opers_c; ++i)
		if (!strcmp(opers[i].nick, msg->params[0]))
			break;

	if (*msg->params[1])
	{
		++opers_c;
		strlcpy(opers[i].nick, msg->params[0], sizeof(opers->pass));
		strlcpy(opers[i].pass, msg->params[1], sizeof(opers->pass));
	}
	else if (i < PEERS_MAX)
	{
		opers[i] = opers[--opers_c];
	}

	return 0;
}

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

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

	for (cp = msg->params[0]; *cp; ++cp)
		if (*cp == '@')
		{
			*cp = 0;
			break;
		}

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

	return 0;
}

static int
whois(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, 431), 0);

	for (i = 0; i < peers_c; ++i)
		if (!strcmp(msg->params[0], peers[i].nick))
			break;
	ensure(i != peers_c, reply(peer, 401, msg->params[0]), 0);

	reply(
		peer,
		311,
		peers[i].nick,
		peers[i].user,
		peers[i].host,
		peers[i].real
	);
	reply(
		peer,
		312,
		peers[i].nick,
		hostname,
		info
	);
	if (peers[i].modes & OPER)
		reply(
			peer,
			313,
			peers[i].nick
		);
	reply(peer, 318, peers[i].nick);

	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 },
	{ "names", names },
	{ "nick", nick },
	{ "notice", privmsg },
	{ "oper", oper },
	{ "part", part },
	{ "ping", ping },
	{ "pong", pong },
	{ "privmsg", privmsg },
	{ "quit", quit },
	{ "setcreation", setcreation },
	{ "setinfo", setinfo },
	{ "setoper", setoper },
	{ "user", user },
	{ "whois", whois },
};

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;
}