#ifndef EX02_RAY_TRACER_HPP
#define EX02_RAY_TRACER_HPP

#define EX02_RAY_TRACER_VIEW_RATIO 0.5f
#define EX02_RAY_TRACER_DEFAULT_NEAR_PLANE 0.2f
#define EX02_RAY_TRACER_DEFAULT_FAR_PLANE 4.0f
#define EX02_RAY_TRACER_COLL_INCREMENT 2.0f
#define EX02_RAY_TRACER_GRAY_SPHERE_RADIUS 1.5f

#include <mutex>
#include <optional>
#include <string>
#include <tuple>
#include <vector>

#include <glm/mat4x4.hpp>
#include <glm/matrix.hpp>
#include <glm/vec3.hpp>

namespace Ex02 {
namespace RT {

  struct Pixel {
    Pixel();

    unsigned char r, g, b;
  };

  class Image {
  public:
    Image(unsigned int width, unsigned int height);

    Pixel &getPixel(unsigned int x, unsigned int y);
    const Pixel &getPixel(unsigned int x, unsigned int y) const;

    void writeToFile(const std::string &filename) const;

  private:
    unsigned int width;
    std::vector<Pixel> data;
  };

  namespace Internal {
    typedef std::optional<std::tuple<glm::vec3, glm::vec3>> RTSVisibleType;

    struct LightSource {
      LightSource();

      glm::vec3 pos;
      float falloffStart;
      float falloffEnd;
      glm::vec3 color;

      void applyLight(glm::vec3 pos, Pixel &pixelOut) const;
      void applyLight(glm::vec3 pos, Pixel &pixelOut, std::mutex *mutex) const;
    };

    struct Sphere {
      Sphere();

      glm::vec3 pos;
      float radius;

      std::optional<glm::vec3> rayToSphere(glm::vec3 rayPos,
                                           glm::vec3 rayDirUnit) const;

      RTSVisibleType rayToSphereVisible(glm::vec3 rayPos, glm::vec3 rayDirUnit,
                                        const LightSource &light) const;
    };

    // returns pos of collision
    std::optional<glm::vec3> rayToSphere(glm::vec3 rayPos, glm::vec3 rayDirUnit,
                                         glm::vec3 spherePos,
                                         float sphereRadius);

    float angleBetweenRays(glm::vec3 a, glm::vec3 b);

    float distBetweenPositions(glm::vec3 a, glm::vec3 b);

    // first vec3 is result from rayToSphere(), second is ray to light source
    RTSVisibleType rayToSphereVisible(glm::vec3 rayPos, glm::vec3 rayDirUnit,
                                      glm::vec3 spherePos, float sphereRadius,
                                      glm::vec3 lightPos);
  } // namespace Internal

  Image renderGraySphere(unsigned int outputWidth, unsigned int outputHeight,
                         unsigned int threadCount = 1);

  Image renderColorsWithSpheres(unsigned int outputWidth,
                                unsigned int outputHeight,
                                unsigned int threadCount = 1);

} // namespace RT
} // namespace Ex02

#endif