#include "haversine.h"
#include "aliases.h"
#include "point_types.h"
#include <math.h>

#define PI 3.14159265358979323845
#define SQUARE(X) ((X) * (X))

f64 radians(f64 degrees);

f64 haversine_of_degrees(const PointPair &pair, f64 radius) {
  f64 x0 = pair.p1.x;
  f64 y0 = pair.p1.y;
  f64 x1 = pair.p2.x;
  f64 y1 = pair.p2.y;

  f64 dy = radians(y1 - y0);
  f64 dx = radians(x1 - x0);
  y0 = radians(y0);
  y1 = radians(y1);

  f64 root_term =
      SQUARE(sin(dy / 2.0)) + cos(y0) * cos(y1) * SQUARE(sin(dx / 2.0));

  f64 result = 2.0 * radius * asin(sqrt(root_term));

  return result;
}

f64 radians(f64 degrees) { return (degrees * PI) / 180.0; }