/*
 * 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 <stdarg.h>

#include <err.h>


#define ARG(n) const char *n = va_arg(ap, const char *)
#define M1(x, ...)
#define M2(x, ...) ARG(x); M1(__VA_ARGS__)
#define M3(x, ...) ARG(x); M2(__VA_ARGS__)
#define M4(x, ...) ARG(x); M3(__VA_ARGS__)
#define M5(x, ...) ARG(x); M4(__VA_ARGS__)
#define M6(x, ...) ARG(x); M5(__VA_ARGS__)
#define M7(x, ...) ARG(x); M6(__VA_ARGS__)
#define GET_M(_0,_1,_2,_3,_4,_5,_6,_7,NAME,...) NAME
#define ARGS(_0, ...) GET_M(_0,__VA_ARGS__,M7,M6,M5,M4,M3,M2,M1,M0,)(__VA_ARGS__,)

/*
 * REPLY macro allows to write less boilerplate for each IRC reply
 * For example,
 * | REPLY(401, WRITE(
 * | 	":%s 401 %s %s :No such nick/channel",
 * | 	hostname,
 * | 	getnick(peer),
 * | 	name
 * | ), name, _);
 * is unrolled into
 * | {
 * | 	const char *name = va_arg(ap, const char *);
 * | 	return WRITE(
 * | 		":%s 401 %s %s :No such nick/channel",
 * | 		hostname,
 * | 		getnick(peer),
 * | 		name
 * | 	);
 * | }
 *
 * Note the `_' argument, it's present as C doesn't support empty __VA_ARGS__
 */
#define REPLY(n, action, ...) case n: { ARGS(,__VA_ARGS__); return action; }


static int
vreply(const struct Peer *peer, int number, va_list ap)
{
	switch (number)
	{
#define WRITE(...) writef(peer->fd, __VA_ARGS__)
	REPLY(1, WRITE(
		":%s 001 %s Welcome to the Internet Relay Network %s!%s@%s",
		hostname,
		getnick(peer),
		getnick(peer),
		peer->user,
		peer->host
	), _);
	REPLY(401, WRITE(
		":%s 401 %s %s :No such nick/channel",
		hostname,
		getnick(peer),
		name
	), name, _);
	REPLY(403, WRITE(
		":%s 403 %s %s :No such channel",
		hostname,
		getnick(peer),
		channel
	), channel, _);
	REPLY(405, WRITE(
		":%s 405 %s %s :You have joined too many channels",
		hostname,
		getnick(peer),
		channel
	), channel, _);
	REPLY(411, WRITE(
		":%s 411 %s :No recipient given (PRIVMSG)",
		hostname,
		getnick(peer)
	), _);
	REPLY(412, WRITE(
		":%s 412 %s :No text to send",
		hostname,
		getnick(peer)
	), _);
	REPLY(421, WRITE(
		":%s 421 %s %s :Unknown command",
		hostname,
		getnick(peer),
		command
	), command, _);
	REPLY(431, WRITE(
		":%s 431 %s :No nickname given",
		hostname,
		getnick(peer)
	), _);
	REPLY(442, WRITE(
		":%s 442 %s %s :You're not on that channel",
		hostname,
		getnick(peer),
		channel
	), channel, _);
	REPLY(451, WRITE(
		":%s 451 %s :You have not registered",
		hostname,
		getnick(peer)
	), _);
	REPLY(461, WRITE(
		":%s 461 %s %s :Not enough parameters",
		hostname,
		getnick(peer),
		command
	), command, _);
	REPLY(462, WRITE(
		":%s 462 %s :Unauthorized command (already registered)",
		hostname,
		getnick(peer)
	), _);
	REPLY(471, WRITE(
		":%s 471 %s %s :Cannot join channel (+l)",
		hostname,
		getnick(peer),
		channel
	), channel, _);
	default: warn("unknown reply: %d", number); WRITE(
		":%s 421 %s err :Reply %d is not implemented yet",
		hostname,
		getnick(peer),
		number
	);
	}
}

int
reply(const struct Peer *peer, int number, ...)
{
	va_list args;
	int ret;

	va_start(args, number);
	ret = vreply(peer, number, args);
	va_end(args);

	return ret;
}