#include <iostream>

#include "depthoffieldshader.h"


DOFShader::DOFShader(SimpleScene& _scene, Color const &_diffuseColor, int _numSamples, float _aperture, float _focalDistance, float _focalLength, PerspectiveCamera& _camera) : scene(_scene), diffuseColor(_diffuseColor), numSamples(_numSamples), aperture(_aperture),
focalDistance(_focalDistance), focalLength(_focalLength), camera(_camera) {}

std::random_device DOFShader::rd;
std::mt19937 DOFShader::gen(DOFShader::rd());

Color DOFShader::shade(Scene const &scene, Ray const &ray) const {
    Color color;

    // Accumulate the light over all light sources
    for (const auto &light : scene.lights()) {
        Light::Illumination const illum = light->illuminate(scene, ray);
        Color const diffuse = this->diffuseColor * std::max(dotProduct(-illum.direction, ray.normal), 0.0f);
        // Add the sample color to the final color
        color += diffuse * sample(ray, illum);
    }

    return color;
}

Color DOFShader::sample(Ray ray, Light::Illumination const &illum) const {

    std::uniform_real_distribution<float> dis(-1.0, 1.0);

    // calculate the point of focus
    Vector3d focusPoint = ray.origin + ray.direction * focalDistance;

    // create a random point on the aperture
    Vector3d rnd = Vector3d(dis(gen), dis(gen), 0);
    Vector3d offset = aperture * (rnd.x * camera.getRightDirection() + rnd.y * camera.getUpDirection());

    // create the new ray with the offset point
    Vector3d dofRayStart = camera.getPosition() + offset;
    Vector3d dofRayDir = normalized(focusPoint - (camera.getPosition() + offset));

    Ray dofRay = Ray(dofRayStart, dofRayDir);

    // trace the new ray and sample the color

    Color tracedColor = scene.traceRay(dofRay);
    return tracedColor;
}