#pragma once

#include "materials.h"
#include "shapes.h"
#include "lights.h"
#include "patterns.h"

inline static struct tuple lighting(struct material material,
                                    struct shape const * const object,
                                    struct light light,
                                    struct tuple point,
                                    struct tuple eyev,
                                    struct tuple normalv,
                                    bool in_shadow)
{
  struct tuple color;
  if (material.has_pattern) {
    color = pattern_at_object(material.pattern, object->transform, point);
  } else {
    color = material.color;
  }
  struct tuple effective_color = hadmard_product(color, light.intensity);

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

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

  if (in_shadow) {
    return ambient;
  }

  float light_dot_normal = tuple_dot(lightv, normalv);
  if (light_dot_normal < 0.0f) {
    return ambient;
  } else {
    struct tuple 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) {
      return tuple_add(ambient, diffuse);
    } else {
      float factor = powf(reflect_dot_eye, material.shininess);
      struct tuple specular = tuple_mul(light.intensity, material.specular * factor);
      return tuple_add(tuple_add(ambient, diffuse), specular);
    }
  }
}