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

#include "gps/gps_visibility.h"

static void expect_near(double actual, double expected, double tolerance)
{
	assert(fabs(actual - expected) <= tolerance);
}

int main(void)
{
	const double earth_radius_m = 6378137.0;
	const double receiver[3] = {earth_radius_m, 0.0, 0.0};
	double elevation = 0.0;

	const double zenith_satellite[3] = {26560000.0, 0.0, 0.0};
	assert(gps_visibility_elevation_deg(
		receiver, 0.0, 0.0, zenith_satellite, &elevation));
	expect_near(elevation, 90.0, 1.0e-9);

	const double opposite_hemisphere_satellite[3] =
		{-26560000.0, 0.0, 0.0};
	assert(gps_visibility_elevation_deg(
		receiver, 0.0, 0.0,
		opposite_hemisphere_satellite, &elevation));
	expect_near(elevation, -90.0, 1.0e-9);

	const double horizon_satellite[3] =
		{earth_radius_m, 26560000.0, 0.0};
	assert(gps_visibility_elevation_deg(
		receiver, 0.0, 0.0, horizon_satellite, &elevation));
	expect_near(elevation, 0.0, 1.0e-9);

	assert(!gps_visibility_elevation_deg(
		receiver, 100.0, 0.0, zenith_satellite, &elevation));
	puts("gps visibility geometry tests passed");
	return 0;
}