// skyview dumping  gpsd client
// compile this way:
//    gcc skydump.c -o skydump -lgps
#include <gps.h>

int main(int argc, char *argv[])
{
    struct gps_data_t gps_data;
    struct satellite_t sat;
    gps_mask_t req_bits = MODE_SET | SATELLITE_SET;

    if (0 != gps_open("localhost", "2947", &gps_data)) {
        printf("Open error.  Bye, bye\n");
        return 1;
    }

    (void)gps_stream(&gps_data, WATCH_ENABLE | WATCH_JSON, NULL);

    while (gps_waiting(&gps_data, 5000000)) {
        if (-1 == gps_read(&gps_data, NULL, 0)) {
            printf("Read error.  Bye, bye\n");
            break;
        }
        if (req_bits != (req_bits & gps_data.set)) {
            // did not get valid? skyview, nothing to see here
            continue;
        }
        printf("\nsats: %d / %d\n\n",
               gps_data.satellites_used,
               gps_data.satellites_visible);
        printf("use  s# con sig frq hlt  sn  az  el\n");
        printf("=== === === === === === === === ===\n");
        for (int i=0; i < gps_data.satellites_visible; i++) {
            sat = gps_data.skyview[i];
            printf("%3s %3d %3d %3d %3d %3c %3.0f %3.0f %3.0f\n",
                   sat.used ? "y" : "n",
                   sat.svid, sat.gnssid,
                   sat.sigid, sat.freqid,
                   "?YN"[sat.health],
                   sat.ss, sat.elevation, sat.azimuth
                   );
        }
    }

    // When you are done...
    (void)gps_stream(&gps_data, WATCH_DISABLE, NULL);
    (void)gps_close(&gps_data);
    return 0;
}