/* Small daemon that connects to IRC server and joins given channel
and sends whatever is written to the FIFO

Intended usage is git hook that sends commits, etc.
*/

#define _GNU_SOURCE

#include <sys/poll.h>
#include <sys/queue.h>

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include "irc.h"

#define PROGNAME "sircbot"

#if !defined(DEFAULT_PIDFILE)
#define DEFAULT_PIDFILE	"/var/run/" PROGNAME "/" PROGNAME ".pid"
#endif

struct tq_string {
	char *value;
	TAILQ_ENTRY(tq_string) entries;
};

typedef TAILQ_HEAD(tq_stringlist, tq_string) TQ_STRINGLIST;

struct sircbot_channel {
	char *name;
	char *fifo;
	int fd;
	time_t last_data_sent;
	time_t last_closetime;		/* last time we got kicked */
	TQ_STRINGLIST queue_head;	/* queue of in-data */
};


static int foreground = 0;
static int sigterm = 0;
static int flush_rate = 2;


static int write_pid(const char *file)
{
	int fd, n;
	char tmp[16];
	fd = open(file, O_CREAT | O_WRONLY, 0660);
	if (fd < 0) {
		perror(file);
		return -1;
	}
	n = snprintf(tmp, sizeof(tmp), "%d\n", getpid());
	if (write(fd, tmp, n) == n)
		n = 0;
	close(fd);
	return n;
}

int daemonize(const char *pidfile, const char *logfile)
{
	int devnull, f;
	int pid = fork();
	if (pid < 0) {
		perror("fork");
		return -1;
	}
	/* exit parent */
	if (pid > 0)
		exit(0);
	
	/* detatch to controling terminal */
	setsid();

	pid = fork();
	if (pid < 0) {
		perror("fork");
		return -1;
	}
	/* exit parent */
	if (pid > 0)
		exit(0);

	if (write_pid(pidfile) < 0)
		return -1;
		/* redirect stdin/stdout/stderr to /dev/null */
        freopen("/dev/null", "r", stdin);
        freopen(logfile, "w", stdout);
	freopen(logfile, "w", stderr);
	return 0;
}

static void log_err(const char *msg)
{
	syslog(LOG_ERR, "%s: %s", msg, strerror(errno));
}

struct tq_string *tq_stringlist_add(TQ_STRINGLIST *list, const char *data)
{
	struct tq_string *item = malloc(sizeof(struct tq_string));
	if (item == NULL) {
		log_err("malloc");
		return NULL;
	}
	if ((item->value = strdup(data)) == NULL) {
		log_err("strdup");
		return NULL;
	}
	TAILQ_INSERT_TAIL(list, item, entries);
	return item;
}
	
int init_fifo(struct sircbot_channel *chan)
{
	unlink(chan->fifo);
	if (mkfifo(chan->fifo, 0666) < 0)
		return -1;
	chan->fd = open(chan->fifo, O_RDONLY | O_NONBLOCK);
	if (chan->fd < 0)
		return -1;
	return 0;
}

int close_fifo(struct sircbot_channel *chan, time_t closetime)
{
	close(chan->fd);
	chan->fd = -1;
	chan->last_closetime = closetime;
	return unlink(chan->fifo);
}


int join_channel(struct sircbot_channel *chan, int numchan, char *name)
{
	int i;
	for (i = 0; i < numchan; i++) {
		if (strcmp(chan[i].name, name) == 0)
			return init_fifo(&chan[i]);
	}
	return 0;
}

int kick_channel(struct sircbot_channel *chan, int numchan, char *name)
{
	int i;
	time_t now = time(NULL);
	printf("got kicked from %s\n", name);
	for (i = 0; i < numchan; i++) {
		if (strcmp(chan[i].name, name) == 0)
			return close_fifo(&chan[i], now);
	}
	return 0;
}

int run_hooks(char *user, char *rcpt, char* data)
{
	int pid = fork();
	int status;
	char dir[PATH_MAX];
	if (pid < 0) {
		log_err("fork");
		return -1;
	}
	if (pid == 0) {
		/* detatch to controling terminal */
		setsid();

		pid = fork();
		if (pid < 0) {
			perror("fork");
			exit(1);
		}
		/* exit parent */
		if (pid > 0)
			exit(0);
		
		snprintf(dir, sizeof(dir), "/etc/" PROGNAME ".d/%s", rcpt);
		printf("DEBUG: running scripts in %s\n", dir);
		execlp("/bin/run-parts", "/bin/run-parts", "-a", user, 
			   "-a", data, "-a", rcpt, dir, NULL);
		log_err("run-parts");
		exit(1);
	}
	wait(&status);
	return 0;
}

int handle_response(struct irc_session *sess, char *user, char *cmd, char *data,
		    struct sircbot_channel *chan, int numchan)
{
	printf("DEBUG: handling response: user=%s, cmd=%s, data=%s\n",
		   user, cmd, data);

	if (strncmp(cmd, "PING", 4) == 0) {
		return irc_send(sess, "PONG", data);
	} else if (strncmp(cmd, "PONG", 4) == 0) {
		sess->last_pong = time(NULL);
	} else if (strncmp(cmd, "JOIN", 4) == 0 &&
		   strncmp(user, sess->nick, strlen(sess->nick)) == 0) {
		return join_channel(chan, numchan, data);
	} else if (strncmp(cmd, "KICK", 4) == 0) {
		char *p = strchr(data, ' ');
		if (p)
			*p = '\0';
		return kick_channel(chan, numchan, data);
	} else if (strncmp(cmd, "PRIVMSG", 7) == 0) {
		char *p = strchr(data, ' ');
		if (p) {
			*p++ = '\0';
			if (*p == ':')
				p++;
		}
		return run_hooks(user, data, p);
	}
	return 0;
}

int parse_line(struct irc_session *sess, char *line, 
	       struct sircbot_channel *chan, int numchan)
{
	char *user = NULL, *p, *cmd, *data = NULL;
	printf("DEBUG: parsing: '%s'\n", line);

	if (line[0] == ':') {
		user = &line[1];
		p = strchr(user, ' ');
		if (p == NULL)
			return -1;
		*p++ = '\0';
		cmd = p;
		if ((p = strchr(user, '!')))
			*p = '\0';
	} else
		cmd = line;
	p = strchr(cmd, ' ');
	if (p) {
		*p++ = '\0';
		data = p;
		if (*data == ':')
			data++;
	}
//	printf("DEBUG: user='%s', cmd='%s', data='%s'\n", user, cmd, data);
	handle_response(sess, user, cmd, data, chan, numchan);
	return 0;
}

int parse_irc_data(char *buf, struct sircbot_channel *chan, int numchan,
		   struct irc_session *sess)
{
	char *p = buf;
	while ((p = strsep(&buf, "\n")) != NULL) {
		char *c = strchr(p, '\r');
		if (c != NULL)
			*c = '\0';
		if (*p != '\0')
			parse_line(sess, p, chan, numchan);
	}
	return 0;
}

/* init pollfd strucs */
static void irc_reset_pollfds(struct irc_session *sess, struct pollfd *fds,
			      struct sircbot_channel *chan, int numchan)
{
	int i;
	/* first pollfd struc is the irc session */
	fds[0].fd = sess->fd;
	fds[0].events = POLLIN;
	fds[0].revents = 0;
	/* rest is channel fifos */
	for (i = 1; i < numchan + 1; i++) {
		fds[i].fd = chan[i-1].fd;
		fds[i].events = POLLIN;
		fds[i].revents = 0;
	}
}

static int send_fifo_queue(struct irc_session *sess,
			   struct sircbot_channel *chan, time_t now)
{
	int r;
	struct tq_string *item = TAILQ_FIRST(&chan->queue_head);
	if (item == NULL || (now - chan->last_data_sent) < flush_rate)
		return 0;	/* nothing in queue, or too early to send */

	r = irc_send_chan(sess, chan->name, item->value);
	chan->last_data_sent = now;
	/* remove from FIFO queue */
	TAILQ_REMOVE(&chan->queue_head, item, entries);
	free(item->value);
	free(item);
	return r;
}
static int irc_loop(struct irc_session *sess, struct sircbot_channel *chan,
		    int numchan)
{
	int i, r, joined = 0;
	char buf[4096];
	struct pollfd fds[numchan + 1];
	sigset_t sigmask;
	struct timespec tv;
	time_t now, last_ping;

	sigemptyset(&sigmask);
	sigaddset(&sigmask, SIGTERM);
	tv.tv_sec = 1;
	tv.tv_nsec = 0;
	while (!sigterm) {
		now = time(NULL);
		/* wait atleast 5 secs before we join a channel */
		for (i = 0; i < numchan; i++)
			if ((now - chan[i].last_closetime) > 5 
			     && chan[i].fd < 0) {
				printf("DEBUG: joining %s\n", chan[i].name);
				chan[i].last_closetime = now;
				irc_send(sess, "JOIN", chan[i].name);
			}


		irc_reset_pollfds(sess, fds, chan, numchan);
		r = ppoll(fds, numchan+1, &tv, &sigmask);
//		r = poll(fds, numchan+1, 120000);
		if (r < 0) {
			log_err("ppoll");
			return -1;
		}
		now = time(NULL);

		/* send a ping every 2 min */
		if ((now - last_ping) > 120) {
			irc_send_ping(sess);
			last_ping = now;
		}

		for (i = 0; i < numchan + 1; i++) {
			int j;
			
			/* send data in queue for this fifo */
			if (i != 0 && 
			    send_fifo_queue(sess, &chan[i-1], now) < 0)
				goto ret_err;
			
			if (fds[i].revents & POLLHUP) {
				if (i == 0)
					/* server hang up on us */
					return 0;

				/* one of the fifos closed due to
				   writer process exit. We just
				   reopen it assuming we are still
				   joined the channel */
				close_fifo(&chan[i-1],
					   chan[i-1].last_closetime);
				init_fifo(&chan[i-1]);
				continue;
			}

			if (fds[i].revents & POLLERR)
				goto ret_err;

			if (!(fds[i].revents & POLLIN))
				continue; /* no data available for read */

			printf("DEBUG: data available from fds[%i]\n", i);
			r = read(fds[i].fd, buf, sizeof(buf)-1);
			if (r < 0)
				goto ret_err;
			if (r == 0)
				continue;
				
			printf("DEBUG: read %i bytes\n", r);

			buf[r] = '\0';
			if (i == 0) {
				/* data was from IRC server */
				printf("DEBUG: data from server: %s\n", buf);
				parse_irc_data(buf, chan, numchan, sess);
				continue;
			}
			
			/* data was from fifos */
			printf("DEBUG: data from fifo %s: %s\n", chan[i-1].name, buf);
			tq_stringlist_add(&chan[i-1].queue_head, buf);
		}
	}
	return 0;

ret_err:
	log_err(sess->server);
	return -1;
}

void sighandler(int signal)
{
	switch (signal) {
	case SIGTERM:
		sigterm = 1;
		break;
	}
}

static void usage_exit(int exitcode)
{
	printf("sircbot " VERSION "\nusage: sircbot [-f] [-n nick] [-r flushrate] [-s server] [-p port] CHANNEL\n");
	exit(exitcode);
}

int main(int argc, char *argv[])
{
	const char *pidfile = DEFAULT_PIDFILE;
	const char *server = "irc.freenode.org";
	const char *nick = "sircbot";
	const char *user = "sircbot";
	const char *group = "sircbot";
	const char *pass = NULL;
	const char *logfile = "/dev/null";
	struct sircbot_channel *chan;
	int i, c, port = 6667;

	while ((c = getopt(argc, argv, "fl:n:p:P:r:s:")) != -1) {
		switch (c) {
		case 'f':
			foreground = 1;
			break;
		case 'l':
			logfile = optarg;
			break;
		case 'n':
			nick = optarg;
			break;
		case 'P':
			pass = optarg;
			break;
		case 'p':
			port = atoi(optarg);
			break;
		case 'r':
			flush_rate = atoi(optarg);
			break;
		case 's':
			server = optarg;
			break;
		default:
			usage_exit(1);
		}
	}

	argv += optind;
	argc -= optind;
	if (argc <= 0)
		usage_exit(1);

	/* init channel strucs */
	chan = malloc(argc * sizeof(struct sircbot_channel));
	if (chan == NULL)
		err(1, "malloc");
	for (i = 0; i < argc; i++) {
		chan[i].fd = -1;
		chan[i].name = strdup(argv[i]);
		chan[i].last_closetime = 0;
		asprintf(&chan[i].fifo, "/var/run/sircbot/%s", argv[i]);
		unlink(chan[i].fifo);
		TAILQ_INIT(&chan[i].queue_head);
	}

	/* daemonize */
	if (!foreground) {
		if (daemonize(pidfile, logfile) < 0)
			return 1;
	}
	signal(SIGTERM, sighandler);
	openlog("sircbot",0, LOG_DAEMON);

	while (1) {
		struct irc_session *s = irc_connect(server, port, nick, pass);
		char buf[256];

		if (s == NULL) {
			log_err(server);
			sleep(10);
			continue;
		}
		
		irc_loop(s, chan, argc);
		irc_close(s, "bye");
		/* reset fifos */
		for (i = 0; i < argc; i++) 
			close_fifo(&chan[i], 0);
		if (sigterm)
			break;
		sleep(10);
	}
	unlink(pidfile);
	return 0;
}