#include "light/light.h"
#include "scene/scene.h"
#include "shader/phongshader.h"

PhongShader::PhongShader(Color const &diffuseColor, float diffuseCoefficient, Color const &specularColor,
                         float specularCoefficient, float shininessExponent)
        : diffuseColor(diffuseColor), diffuseCoefficient(diffuseCoefficient), specularColor(specularColor),
          specularCoefficient(specularCoefficient), shininessExponent(shininessExponent) {}

Color PhongShader::shade(Scene const &scene, Ray const &ray) const {
    Color fragmentColor;


    for (auto &light: scene.lights()) {
        auto illum = light->illuminate(scene, ray);

        Vector3d reflection = illum.direction - 2 * dotProduct(illum.direction, ray.normal) * ray.normal;
        Color diffuse = diffuseCoefficient * dotProduct(illum.direction, -ray.normal) * diffuseColor;
        Color specular = specularCoefficient * specularColor
                * std::pow(dotProduct(ray.direction, -reflection), shininessExponent);
        fragmentColor += illum.color * diffuse + illum.color * specular;
    }

    return fragmentColor;
}