// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import {glsl} from '../../../lib/glsl-utils/highlight';

export const PHONG_VS = glsl`\
uniform phongMaterialUniforms {
  uniform float ambient;
  uniform float diffuse;
  uniform float shininess;
  uniform vec3  specularColor;
} material;
`;

export const PHONG_FS = glsl`\
uniform phongMaterialUniforms {
  uniform float ambient;
  uniform float diffuse;
  uniform float shininess;
  uniform vec3  specularColor;
} material;

vec3 lighting_getLightColor(vec3 surfaceColor, vec3 light_direction, vec3 view_direction, vec3 normal_worldspace, vec3 color) {
  vec3 halfway_direction = normalize(light_direction + view_direction);
  float lambertian = dot(light_direction, normal_worldspace);
  float specular = 0.0;
  if (lambertian > 0.0) {
    float specular_angle = max(dot(normal_worldspace, halfway_direction), 0.0);
    specular = pow(specular_angle, material.shininess);
  }
  lambertian = max(lambertian, 0.0);
  return (lambertian * material.diffuse * surfaceColor + specular * material.specularColor) * color;
}

vec3 lighting_getLightColor(vec3 surfaceColor, vec3 cameraPosition, vec3 position_worldspace, vec3 normal_worldspace) {
  vec3 lightColor = surfaceColor;

  if (lighting.enabled == 0) {
    return lightColor;
  }

  vec3 view_direction = normalize(cameraPosition - position_worldspace);
  lightColor = material.ambient * surfaceColor * lighting.ambientColor;

  for (int i = 0; i < lighting.pointLightCount; i++) {
    PointLight pointLight = lighting_getPointLight(i);
    vec3 light_position_worldspace = pointLight.position;
    vec3 light_direction = normalize(light_position_worldspace - position_worldspace);
    float light_attenuation = getPointLightAttenuation(pointLight, distance(light_position_worldspace, position_worldspace));
    lightColor += lighting_getLightColor(surfaceColor, light_direction, view_direction, normal_worldspace, pointLight.color / light_attenuation);
  }

  int totalLights = min(MAX_LIGHTS, lighting.pointLightCount + lighting.directionalLightCount);
  for (int i = lighting.pointLightCount; i < totalLights; i++) {
    DirectionalLight directionalLight = lighting_getDirectionalLight(i);
    lightColor += lighting_getLightColor(surfaceColor, -directionalLight.direction, view_direction, normal_worldspace, directionalLight.color);
  }
  
  return lightColor;
}

`;