#include <stdio.h>
#include <math.h>

#define PI 3.141592653589793

struct angle {
  int degres;
  int minutes;
  int secondes;
  char dir;
};

struct positionGPS {
  struct angle latitude;
  struct angle longitude;
};

double convertirVersDoubleEnRadian(struct angle a) {
  double ang = (a.degres + a.minutes / 60.0 + a.secondes / 3600.0)*PI/180.0;
  if ((a.dir == 'O') || (a.dir == 'S')) {
    ang = -ang;
  }
  return ang;
}

double calculerDistanceOrthodromique(struct positionGPS p1, struct positionGPS p2) {
  double lat1 = convertirVersDoubleEnRadian(p1.latitude);
  double lat2 = convertirVersDoubleEnRadian(p2.latitude);
  double lon1 = convertirVersDoubleEnRadian(p1.longitude);
  double lon2 = convertirVersDoubleEnRadian(p2.longitude);
  double dist = 6378.0 * acos(sin(lat1) * sin(lat2) + cos(lat1) * cos(lat2) * cos(lon2 - lon1));
  return dist;
}

void afficherAngle(struct angle a) {
  printf("[%03d:%02d:%02d:%c]", a.degres, a.minutes, a.secondes, a.dir);
}

void afficherPositionGPS(struct positionGPS p) {
  printf("[");
  afficherAngle(p.latitude);
  printf("-");
  afficherAngle(p.longitude);
  printf("]");
}

int main(void) {
  struct positionGPS p1 = { {47,14,16,'N'},{6,1,27,'E'} };     // Besancon
  struct positionGPS p2 = { {17,32,6,'S'},{149,34,11,'O'} };   // Papeete
  printf("La distance entre\n");
  afficherPositionGPS(p1);
  printf("\net\n");
  afficherPositionGPS(p2);
  printf("\nest %lf km.\n", calculerDistanceOrthodromique(p1, p2));
  return 0;
}