/* DESC: This script sends the local GPS NMEA stream to a remote UDP server.
 * Copyright (C) 2013-2015 NetModule AG, Switzerland
 */

void usage() {
	printf("usage: gps-udp-client.are <server> <port>\n");
	exit(1);
}

int gpsd_restart ()
{
    nb_syslog("Restarting GPS daemon");

    nb_config_set("gpsd.0.status=0");
    sleep(3);
    nb_config_set("gpsd.0.status=1");
    sleep(5);

    return 0;
}

int gpsd_connect ()
{
    nb_syslog("Connecting to GPS daemon");

    gpsd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (gpsd < 0) {
        nb_syslog("ERROR: Unable to open socket");
            exit(-1);
    }
    for (attempt = 0; attempt <= 5; attempt++) {
        sleep(3);

        if (connect(gpsd, "127.0.0.1", 2947) < 0) {
            nb_syslog("Could not connect to daemon");

            if (attempt == 3) {
                nb_syslog("Unable to connect, restarting daemon");
                gpsd_restart();
            }
        } else {
            break;
        }
    }
    nb_syslog("Connected to daemon, requesting NMEA");
    send(gpsd,"R=1\n");

    nb_syslog("Processing NMEA");

    return gpsd;
}

if (argc < 2) {
	usage();
}

SERVER = trim((string) argv[1]);
PORT = (int) argv[2];
gpsd = -1;

/* open UDP server socket */
server = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (server < 0) {
	nb_syslog("Unable to open socket");
	exit(-1);
}

/* process NMEA stream */
nb_syslog("Processing NMEA data");
while (1) {
    /* connect to gpsd */
    if (gpsd < 0) {
        gpsd = gpsd_connect(gpsd);
        if (gpsd < 0) {
                nb_syslog("ERROR: Unable to connect to daemon");
                sleep(5);
                continue;
        }
    }

    /* wait for client socket data  */
    rv = select(gpsd, 3);

    if (rv == -1) {
            nb_syslog("ERROR: select failed, re-connecting");
            close(gpsd);
            gpsd = -1;
            continue;
    } else if (rv == 0) {
            /* nothing received */
            continue;
    }
    data = recv(gpsd);
    len = strlen(data);

    if (len == 0) {
        nb_syslog("ERROR: no data, re-connecting");
        close(gpsd);
        gpsd = -1;
        continue;
    }

    sent = sendto(server, data, SERVER, PORT);
    if (sent != len) {
        nb_syslog("ERROR: Unable to send %d bytes to %s:%d", len, SERVER, PORT);
    }
}

if (gpsd > -1) close(gpsd);
if (server > -1) close(server);

exit(-1);