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

export const PHONG_WGSL = /* wgsl */ `\
struct phongMaterialUniforms {
  unlit: u32,
  ambient: f32,
  diffuse: f32,
  shininess: f32,
  specularColor: vec3<f32>,
};

@group(3) @binding(auto) var<uniform> phongMaterial : phongMaterialUniforms;

fn lighting_getLightColor(surfaceColor: vec3<f32>, light_direction: vec3<f32>, view_direction: vec3<f32>, normal_worldspace: vec3<f32>, color: vec3<f32>) -> vec3<f32> {
  let halfway_direction: vec3<f32> = normalize(light_direction + view_direction);
  var lambertian: f32 = dot(light_direction, normal_worldspace);
  var specular: f32 = 0.0;
  if (lambertian > 0.0) {
    let specular_angle = max(dot(normal_worldspace, halfway_direction), 0.0);
    specular = pow(specular_angle, phongMaterial.shininess);
  }
  lambertian = max(lambertian, 0.0);
  return (
    lambertian * phongMaterial.diffuse * surfaceColor +
    specular * floatColors_normalize(phongMaterial.specularColor)
  ) * color;
}

fn lighting_getLightColor2(surfaceColor: vec3<f32>, cameraPosition: vec3<f32>, position_worldspace: vec3<f32>, normal_worldspace: vec3<f32>) -> vec3<f32> {
  var lightColor: vec3<f32> = surfaceColor;

  if (phongMaterial.unlit != 0u) {
    return surfaceColor;
  }

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

  let view_direction: vec3<f32> = normalize(cameraPosition - position_worldspace);
  lightColor = phongMaterial.ambient * surfaceColor * lighting.ambientColor;

  for (var i: i32 = 0; i < lighting.pointLightCount; i++) {
    let pointLight: PointLight = lighting_getPointLight(i);
    let light_position_worldspace: vec3<f32> = pointLight.position;
    let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
    let light_attenuation = getPointLightAttenuation(
      pointLight,
      distance(light_position_worldspace, position_worldspace)
    );
    lightColor += lighting_getLightColor(
      surfaceColor,
      light_direction,
      view_direction,
      normal_worldspace,
      pointLight.color / light_attenuation
    );
  }

  for (var i: i32 = 0; i < lighting.spotLightCount; i++) {
    let spotLight: SpotLight = lighting_getSpotLight(i);
    let light_position_worldspace: vec3<f32> = spotLight.position;
    let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
    let light_attenuation = getSpotLightAttenuation(spotLight, position_worldspace);
    lightColor += lighting_getLightColor(
      surfaceColor,
      light_direction,
      view_direction,
      normal_worldspace,
      spotLight.color / light_attenuation
    );
  }

  for (var i: i32 = 0; i < lighting.directionalLightCount; i++) {
    let directionalLight: DirectionalLight = lighting_getDirectionalLight(i);
    lightColor += lighting_getLightColor(surfaceColor, -directionalLight.direction, view_direction, normal_worldspace, directionalLight.color);
  }  
  
  return lightColor;
}

fn lighting_getSpecularLightColor(cameraPosition: vec3<f32>, position_worldspace: vec3<f32>, normal_worldspace: vec3<f32>) -> vec3<f32>{
  var lightColor = vec3<f32>(0, 0, 0);
  let surfaceColor = vec3<f32>(0, 0, 0);

  if (lighting.enabled != 0) {
    let view_direction = normalize(cameraPosition - position_worldspace);

    for (var i: i32 = 0; i < lighting.pointLightCount; i++) {
      let pointLight: PointLight = lighting_getPointLight(i);
      let light_position_worldspace: vec3<f32> = pointLight.position;
      let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
      let light_attenuation = getPointLightAttenuation(
        pointLight,
        distance(light_position_worldspace, position_worldspace)
      );
      lightColor += lighting_getLightColor(
        surfaceColor,
        light_direction,
        view_direction,
        normal_worldspace,
        pointLight.color / light_attenuation
      );
    }

    for (var i: i32 = 0; i < lighting.spotLightCount; i++) {
      let spotLight: SpotLight = lighting_getSpotLight(i);
      let light_position_worldspace: vec3<f32> = spotLight.position;
      let light_direction: vec3<f32> = normalize(light_position_worldspace - position_worldspace);
      let light_attenuation = getSpotLightAttenuation(spotLight, position_worldspace);
      lightColor += lighting_getLightColor(
        surfaceColor,
        light_direction,
        view_direction,
        normal_worldspace,
        spotLight.color / light_attenuation
      );
    }

    for (var i: i32 = 0; i < lighting.directionalLightCount; i++) {
        let directionalLight: DirectionalLight = lighting_getDirectionalLight(i);
        lightColor += lighting_getLightColor(surfaceColor, -directionalLight.direction, view_direction, normal_worldspace, directionalLight.color);
    }
  }
  return lightColor;
}
`;