/* GPS/AIS client extractor, forwad to gpsd via UDP
 *
 * (C) 2013 by Harald Welte <laforge@gnumonks.org>
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */ 

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <syslog.h>
#include <stdint.h>
#include <netdb.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>

#include <netinet/in.h>

#include <libgsmd/libgsmd.h>
#include <libgsmd/event.h>
#include <gsmd/usock.h>
#include <gsmd/ts0705.h>
#include <common/linux_list.h>

#ifndef __GSMD__
#define __GSMD__
#include <gsmd/talloc.h>
#undef __GSMD__
#endif

static int out_fd = -1;
static FILE *outf;

static int celllog_main(struct lgsm_handle *lgsmh)
{
	int rc;
	char buf[8192+1];
	fd_set readset;
	int gsm_fd = lgsm_fd(lgsmh);

	fcntl(gsm_fd, F_SETFD, O_NONBLOCK);
	FD_ZERO(&readset);

	while (1) {
		fd_set readset;
		FD_SET(gsm_fd, &readset);

		rc = select(gsm_fd+1, &readset, NULL, NULL, NULL);
		if (rc < 0)
			break;

		if (FD_ISSET(gsm_fd, &readset)) {
			/* we've received something on the gsmd socket, pass it
			 * on to the library */
			rc = read(gsm_fd, buf, sizeof(buf));
			if (rc <= 0) {
				syslog(LOG_ERR, "ERROR reading from gsm_fd\n");
				break;
			}
			rc = lgsm_handle_packet(lgsmh, buf, rc);
			if (rc < 0)
				syslog(LOG_ERR, "ERROR processing packet: %d(%s)\n", rc, strerror(-rc));
		}
		fflush(outf);
	}
	return 0;
}

static int gps_handler(struct lgsm_handle *lh, int evt, struct gsmd_evt_auxdata *aux)
{
	int rc;

	rc = fprintf(outf, "%s\r\n", aux->data);
	if (rc < 0) {
		syslog(LOG_ERR, "error %d during fprintf() on socket, aborting\n", rc);
		exit(3);
	}

	return 0;
}


/* more or less a copy form libosmocore, we could simply make this a
 * dependency... */
static int out_sock_init(uint16_t family, uint16_t type, uint8_t proto,
			 const char *host, uint16_t port)
{
	int fd = -1, rc;
	struct addrinfo hints, *result, *rp;
	char portbuf[16];

	sprintf(portbuf, "%u", port);
	memset(&hints, 0, sizeof(struct addrinfo));
	hints.ai_family = family;

	rc = getaddrinfo(host, portbuf, &hints, &result);
	if (rc != 0) {
		syslog(LOG_ERR, "Error during getaddrinfo(%s:%d)\n",
			host, port);
		return -EINVAL;
	}

	for (rp = result; rp != NULL; rp = rp->ai_next) {

		fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
		if (fd < 0)
			continue;

		rc = connect(fd, rp->ai_addr, rp->ai_addrlen);
		if (rc != -1 || (rc == -1 && errno == EINPROGRESS))
			break;

		close(fd);
	}
	freeaddrinfo(result);

	if (rp == NULL) {
		syslog(LOG_ERR, "unable to connect socket\n");
		return -ENODEV;
	}

	return fd;
}

int main(int argc, char **argv)
{
	static struct lgsm_handle *lgsmh;
	char *host;
	int port;
	int rc;

	printf("gps_fwd - (C) 2013 by Harald Welte <laforge@gnumonks.org>.\n"
		"This program is Free Software and has ABSOLUTELY NO WARRANTY\n\n");

	if (argc < 3) {
		fprintf(stderr, "You have to specify the remote hostname + port\n");
		exit(2);
	}

	host = argv[1];
	port = atoi(argv[2]);

	openlog("gps_fwd", 0, LOG_LOCAL0);

	lgsmh = lgsm_init(LGSMD_DEVICE_GSMD);
	if (!lgsmh) {
		fprintf(stderr, "Can't connect to gsmd\n");
		exit(1);
	}

	lgsm_evt_handler_register(lgsmh, GSMD_EVT_GPS, &gps_handler);
	lgsm_evt_handler_register(lgsmh, GSMD_EVT_AIS, &gps_handler);

	out_fd = out_sock_init(AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, host, port);
	if (out_fd < 0)
		exit(1);

	outf = fdopen(out_fd, "w");

	celllog_main(lgsmh);

	exit(0);
}