#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <stdint.h>
#include <inttypes.h>

#include "main.h"
#include "uring.h"
#include "config.h"
#include "server.h"
#include "rcon.h"

struct rcon {
	struct server *server;
	struct connection conn;
	struct uring_task task;
	struct uring_task_buf tbuf;
};

static void
rcon_free(struct uring_task *task)
{
	struct rcon *rcon = container_of(task, struct rcon, task);

	debug(DBG_RCON, "task %p, idle %p\n", task, rcon);
	rcon->server->rcon = NULL;
	xfree(rcon);
}

void
rcon_refdump(struct rcon *rcon)
{
	if (!rcon)
		return;

	uring_task_refdump(&rcon->task);
}

void
rcon_delete(struct cfg *cfg, struct server *server)
{
	struct rcon *rcon = server->rcon;

	if (!rcon)
		return;

	debug(DBG_RCON, "closing fd %i\n", rcon->task.fd);
	uring_task_destroy(cfg, &rcon->task);
	server->rcon = NULL;
}

static int32_t
read_int(char **pos, size_t *len)
{
	uint32_t val;
	char *p = *pos;

	if (len && *len < 4)
		return 0;

	val  = ((uint8_t)p[0] <<  0);
	val += ((uint8_t)p[1] <<  8);
	val += ((uint8_t)p[2] << 16);
	val += ((uint8_t)p[3] << 24);

	*pos += 4;
	if (len)
		*len -= 4;

	return (int32_t)val;
}

static void
write_int(char **pos, size_t *len, int32_t orig)
{
	uint32_t val = (uint32_t)orig;
	char *p = *pos;

	p[0] = (val >>  0) & 0xff;
	p[1] = (val >>  8) & 0xff;
	p[2] = (val >> 16) & 0xff;
	p[3] = (val >> 24) & 0xff;

	*pos += 4;
	if (len)
		*len += 4;
}

static void
write_str(char **pos, size_t *len, const char *str)
{
	size_t towrite = strlen(str);

	memcpy(*pos, str, towrite);
	*pos += towrite;
	if (len)
		*len += towrite;
}

static void
write_end(char **pos, size_t *len)
{
	char *p = *pos;

	p[0] = 0x00;
	p[1] = 0x00;

	*pos += 2;
	if (len)
		*len += 2;
}

enum rcon_packet_type {
	RCON_PACKET_LOGIN	= 3,
	RCON_PACKET_LOGIN_OK	= 2,
	RCON_PACKET_LOGIN_FAIL	= -1,
	RCON_PACKET_COMMAND	= 2,
	RCON_PACKET_RESPONSE	= 0,
};

static void
create_packet(struct cfg *cfg, struct rcon *rcon, int32_t reqid, enum rcon_packet_type type, const char *msg)
{
	char *pos = &rcon->tbuf.buf[4];

	/* Body */
	rcon->tbuf.len = 4;
	write_int(&pos, &rcon->tbuf.len, reqid);
	write_int(&pos, &rcon->tbuf.len, type);
	write_str(&pos, &rcon->tbuf.len, msg);
	write_end(&pos, &rcon->tbuf.len);

	/* Header (length of body) */
	pos = &rcon->tbuf.buf[0];
	write_int(&pos, NULL, rcon->tbuf.len - 4);

	debug(DBG_RCON, "created packet (reqid: %" PRIi32 ", type %" PRIi32 
	      ", len %zu, payload: %s)\n",
	      reqid, type, rcon->tbuf.len, msg);
}

static int
packet_complete(struct cfg *cfg, struct uring_task *task, int res)
{
	char *pos = task->tbuf->buf;
	size_t len = task->tbuf->len;
	int32_t plen;

	if (task->tbuf->len < 14)
		return 0;

	plen = read_int(&pos, &len);
	debug(DBG_RCON, "reply size: %zu bytes, packet size %" PRIi32 "\n",
	      task->tbuf->len, plen + 4);

	if (task->tbuf->len < plen + 4)
		return 0;
	else
		return 1;
}

static bool
rcon_read_packet(struct cfg *cfg, struct rcon *rcon, int32_t *id,
		 int32_t *type, char **rmsg)
{
	char *pos = rcon->tbuf.buf;
	size_t len = rcon->tbuf.len;
	int32_t plen;

	plen = read_int(&pos, &len);
	*id = read_int(&pos, &len);
	*type = read_int(&pos, &len);
	*rmsg = NULL;

	if (plen < 10) {
		error("invalid packet length: %" PRIi32 "\n", plen);
		return false;
	}

	if (len > 2) {
		*rmsg = pos;
		pos += len - 2;
		len = 2;
	}

	if (len < 2) {
		error("short message\n");
		return false;
	}

	if (pos[0] != '\0' || pos[1] != '\0') {
		error("invalid trailer\n");
		return false;
	}

	debug(DBG_RCON, "response - len: %" PRIi32 ", id: %" PRIi32
	      ", type: %" PRIi32 ", msg: %s\n",
	      plen, *id, *type, *rmsg);

	return true;
}

static void
rcon_stop_reply(struct cfg *cfg, struct uring_task *task, int res)
{
	struct rcon *rcon = container_of(task, struct rcon, task);
	int32_t id;
	int32_t type;
	char *msg;

	if (task->dead) {
		debug(DBG_RCON, "task dead\n");
		return;
	}

	if (res < 0) {
		debug(DBG_RCON, "res: %i\n", res);
		goto out;
	}

	debug(DBG_RCON, "packet complete\n");
	rcon_read_packet(cfg, rcon, &id, &type, &msg);

	if (id != 2) {
		error("rcon stop cmd failed - unexpected reply id (%" PRIi32 ")\n", id);
		goto out;
	} else if (type != RCON_PACKET_RESPONSE) {
		error("rcon stop cmd failed - unexpected reply type (%" PRIi32 ")\n", type);
		goto out;
	}

	verbose("rcon stop cmd successful (%s)\n", msg);

out:
	uring_task_put(cfg, &rcon->task);
}

static void
rcon_stop_sent(struct cfg *cfg, struct uring_task *task, int res)
{
	struct rcon *rcon = container_of(task, struct rcon, task);

	if (task->dead) {
		debug(DBG_RCON, "task dead\n");
		return;
	}

	if (res < 0) {
		debug(DBG_RCON, "res: %i\n", res);
		uring_task_put(cfg, &rcon->task);
		return;
	}

	debug(DBG_RCON, "stop cmd sent\n");
	uring_tbuf_read_until(cfg, &rcon->task, packet_complete, rcon_stop_reply);
}

static void
rcon_login_reply(struct cfg *cfg, struct uring_task *task, int res)
{
	struct rcon *rcon = container_of(task, struct rcon, task);
	int32_t id;
	int32_t type;
	char *msg;

	if (task->dead) {
		debug(DBG_RCON, "task dead\n");
		return;
	}

	if (res < 0) {
		debug(DBG_RCON, "res: %i\n", res);
		goto out;
	}

	debug(DBG_RCON, "packet complete\n");
	rcon_read_packet(cfg, rcon, &id, &type, &msg);

	if (id != 1) {
		error("rcon login failed - unexpected reply id (%" PRIi32 ")\n", id);
		goto out;
	} else if (type == RCON_PACKET_LOGIN_FAIL) {
		error("rcon login failed - incorrect password\n");
		goto out;
	} else if (type != RCON_PACKET_LOGIN_OK) {
		error("rcon login failed - unexpected reply type (%" PRIi32 ")\n", type);
		goto out;
	}

	debug(DBG_RCON, "rcon login successful\n");
	create_packet(cfg, rcon, 2, RCON_PACKET_COMMAND, "stop");
	uring_tbuf_write(cfg, &rcon->task, rcon_stop_sent);
	return;

out:
	uring_task_put(cfg, &rcon->task);
}

static void
rcon_login_sent(struct cfg *cfg, struct uring_task *task, int res)
{
	struct rcon *rcon = container_of(task, struct rcon, task);

	if (task->dead) {
		debug(DBG_RCON, "task dead\n");
		return;
	}

	if (res < 0) {
		debug(DBG_RCON, "res: %i\n", res);
		uring_task_put(cfg, &rcon->task);
		return;
	}

	debug(DBG_RCON, "login sent\n");
	uring_tbuf_read_until(cfg, &rcon->task, packet_complete, rcon_login_reply);
}

static void
rcon_connected_cb(struct cfg *cfg, struct connection *conn, bool connected)
{
	struct rcon *rcon = container_of(conn, struct rcon, conn);

	if (!connected) {
		error("rcon connection to remote server (%s) failed\n",
		      rcon->server->name);
		return;
	}

	create_packet(cfg, rcon, 1, RCON_PACKET_LOGIN, rcon->server->rcon_password);
	uring_tbuf_write(cfg, &rcon->task, rcon_login_sent);
}

void
rcon_init(struct cfg *cfg, struct server *server)
{
	struct rcon *rcon;

	if (!server)
		return;

	if (list_empty(&server->rcons) || !server->rcon_password)
		return;

	rcon = zmalloc(sizeof(*rcon));
	if (!rcon)
		perrordie("malloc");

	uring_task_init(&rcon->task, "rcon", &server->task, rcon_free);
	uring_task_set_buf(&rcon->task, &rcon->tbuf);
	rcon->server = server;
	server->rcon = rcon;

	connect_any(cfg, &rcon->task, &server->rcons, &rcon->conn, rcon_connected_cb);
}