#include <gps.h>
#include <stdio.h>
#include <string.h>

int main (int argc, char **argv) {
  int status, used, visible;
  struct gps_data_t gpsdata;
  #define OID_VISIBLE ".1.3.6.1.2.1.25.1.31"
  #define OID_USED ".1.3.6.1.2.1.25.1.32"
  #define OID_SNR_AVG ".1.3.6.1.2.1.25.1.33"

  if ((argc > 2) && (strcmp ("-g", argv[1]) == 0))
  {
    status = gps_open (GPSD_SHARED_MEMORY, DEFAULT_GPSD_PORT, &gpsdata);
    status = gps_read (&gpsdata);
    used  = gpsdata.satellites_used;
    visible = gpsdata.satellites_visible;
    int i; double snr_total=0;
    for(i=0;i<=used;i++) {
        if (gpsdata.skyview[i].used> 0 && gpsdata.skyview[i].ss > 1) {
//            printf("i: %d, P:%d, ss: %f\n", i, gpsdata.PRN[i], gpsdata.ss[i]);
            snr_total+=gpsdata.skyview[i].ss;
        }
    }
    gps_close (&gpsdata);
    double snr_avg = 0.0;
    if (used > 0) {
        snr_avg = snr_total / used;
    }
    if (strcmp (OID_VISIBLE, argv[2]) == 0) {
      printf (OID_VISIBLE);
      printf ("\n");
      printf ("gauge\n");
      printf ("%d\n", visible);
    }
    if (strcmp (OID_USED, argv[2]) == 0) {
      printf (OID_USED);
      printf ("\n");
      printf ("gauge\n");
      printf ("%d\n", used);
    }
    if (strcmp (OID_SNR_AVG, argv[2]) == 0) {
      printf (OID_SNR_AVG);
      printf ("\n");
      printf ("gauge\n");
      printf ("%lf\n", snr_avg);
    }
  }
  return 0;
}