#pragma once

#include "tuples.h"
#include "lights.h"
#include "math.h"

struct material {
  struct tuple color;
  float ambient;
  float diffuse;
  float specular;
  float shininess;
};

inline static struct material material()
{
  return (struct material){
    color(1.0f, 1.0f, 1.0f),
    0.1f,
    0.9f,
    0.9f,
    200.0f
  };
}

inline static bool material_equal(struct material a, struct material b)
{
  return
    tuple_equal(a.color, b.color) &&
    float_equal(a.ambient, b.ambient) &&
    float_equal(a.diffuse, b.diffuse) &&
    float_equal(a.specular, b.specular) &&
    float_equal(a.shininess, b.shininess);
}

inline static struct tuple lighting(struct material material,
                                    struct light light,
                                    struct tuple point,
                                    struct tuple eyev,
                                    struct tuple normalv)
{
  struct tuple effective_color = hadmard_product(material.color, light.intensity);

  struct tuple lightv = tuple_normalize(tuple_sub(light.position, point));

  struct tuple ambient = tuple_mul(effective_color, material.ambient);

  float light_dot_normal = tuple_dot(lightv, normalv);
  struct tuple diffuse;
  struct tuple specular;
  if (light_dot_normal < 0.0f) {
    diffuse = color(0.0f, 0.0f, 0.0f); // black
    specular = color(0.0f, 0.0f, 0.0f); // black
  } else {
    diffuse = tuple_mul(effective_color, material.diffuse * light_dot_normal);

    struct tuple reflectv = tuple_reflect(tuple_neg(lightv), normalv);
    float reflect_dot_eye = tuple_dot(reflectv, eyev);
    if (reflect_dot_eye <= 0.0f) {
      specular = color(0.0f, 0.0f, 0.0f); // black
    } else {
      float factor = powf(reflect_dot_eye, material.shininess);
      specular = tuple_mul(light.intensity, material.specular * factor);
    }
  }

  return tuple_add(tuple_add(ambient, diffuse), specular);
}