#include "NightSky.h"

#include "Color.h"
#include "Vector3.h"
#include "Geometry.h"
#include "SoftwareRenderer.h"
#include "SurfaceMaterial.h"

#define WORLD_SCALING 0.05
#define MOON_DISTANCE 384403.0
#define MOON_DISTANCE_SCALED (MOON_DISTANCE / WORLD_SCALING)
#define MOON_RADIUS 1737.4
#define MOON_RADIUS_SCALED (MOON_RADIUS / WORLD_SCALING)

NightSky::NightSky(SoftwareRenderer* renderer):
    renderer(renderer)
{
}

NightSky::~NightSky()
{
}

void NightSky::update()
{
}

const Color NightSky::getColor(double altitude, const Vector3 &direction)
{
    Color result(0.01, 0.012, 0.03);

    Vector3 location(0.0, altitude, 0.0);

    // Get stars

    // Get moon
    Vector3 moon_direction = Vector3(0.9, 0.5, -0.6).normalize();
    if (moon_direction.dotProduct(direction) >= 0)
    {
        Vector3 moon_position = moon_direction.scale(MOON_DISTANCE_SCALED);
        double moon_radius = MOON_RADIUS_SCALED * 5.0;
        Vector3 hit1, hit2;
        int hits = Geometry::rayIntersectSphere(location, direction, moon_position, moon_radius, &hit1, &hit2);
        if (hits > 1)
        {
            double dist = hit2.sub(hit1).getNorm() / moon_radius; // distance between intersection points (relative to radius)

            Vector3 nearest = (hit1.sub(location).getNorm() > hit2.sub(location).getNorm()) ? hit2 : hit1;
            SurfaceMaterial moon_material(Color(3.0, 3.0, 3.0, 1.0));
            moon_material.validate();

            Color moon_color = renderer->applyLightingToSurface(nearest, nearest.sub(moon_position).normalize(), moon_material);
            if (dist <= 0.05)
            {
                moon_color.a *= 1.0 - dist / 0.05;
            }
            result.mask(moon_color);
        }
    }


    return result;

}