#include "geod_interface.h"
#include "proj.h"
#include "proj_internal.h"

void geod_ini(void) { geod_init(&GlobalGeodesic, geod_a, geod_f); }

void geod_pre(void) {
    double lat1 = phi1 / DEG_TO_RAD, lon1 = lam1 / DEG_TO_RAD,
           azi1 = al12 / DEG_TO_RAD;
    geod_lineinit(&GlobalGeodesicLine, &GlobalGeodesic, lat1, lon1, azi1, 0U);
}

void geod_for(void) {
    double s12 = geod_S, lat2, lon2, azi2;
    geod_position(&GlobalGeodesicLine, s12, &lat2, &lon2, &azi2);
    azi2 += azi2 >= 0 ? -180 : 180; /* Compute back azimuth */
    phi2 = lat2 * DEG_TO_RAD;
    lam2 = lon2 * DEG_TO_RAD;
    al21 = azi2 * DEG_TO_RAD;
}

void geod_inv(void) {
    double lat1 = phi1 / DEG_TO_RAD, lon1 = lam1 / DEG_TO_RAD,
           lat2 = phi2 / DEG_TO_RAD, lon2 = lam2 / DEG_TO_RAD, azi1, azi2, s12;
    geod_inverse(&GlobalGeodesic, lat1, lon1, lat2, lon2, &s12, &azi1, &azi2);
    /* Compute back azimuth
     * map +/-0 -> -/+180; +/-180 -> -/+0
     * this depends on abs(azi2) <= 180 */
    azi2 = copysign(azi2 + copysign(180.0, -azi2), -azi2);
    al12 = azi1 * DEG_TO_RAD;
    al21 = azi2 * DEG_TO_RAD;
    geod_S = s12;
}