import { CompareFunction, CullMode, Engine, Material, Shader, TextureCube, Vector4 } from "oasis-engine";

export class ARSkyMaterial extends Material {
  constructor(engine: Engine) {
    const vertexSource = `
        attribute vec3 POSITION;

        uniform mat4 u_mvpNoscale;
        varying vec3 v_cubeUV;

        void main() {
            v_cubeUV = vec3(-POSITION.x, POSITION.y, POSITION.z );
            gl_Position = u_mvpNoscale * vec4( POSITION, 1.0 );
            gl_Position.z = gl_Position.w;
        }
    `;

    const fragSource = `
    uniform samplerCube u_cube; 
    varying vec3 v_cubeUV;
    uniform vec4 u_cubeDecodeParam;
    vec4 RGBMToLinear(vec4 value, float maxRange ) {
        return vec4( value.rgb * value.a * maxRange, 1.0 );
    }
    
    vec4 linearToGamma(vec4 linearIn){
        return vec4( pow(linearIn.rgb, vec3(1.0 / 2.2)), linearIn.a);
    }
    void main (void) {
        vec4 textureColor = textureCube( u_cube, v_cubeUV );

        if (u_cubeDecodeParam.x > 0.0){
           textureColor = RGBMToLinear(textureColor, u_cubeDecodeParam.y);
           textureColor = linearToGamma(textureColor);
        }
    
        gl_FragColor = textureColor;
    }
    `;
    const shader = Shader.create("ARSkyMaterial", vertexSource, fragSource);
    super(engine, shader);

    this.renderState.rasterState.cullMode = CullMode.Off;
    this.renderState.depthState.compareFunction = CompareFunction.LessEqual;
    this.shaderData.setVector4("u_cubeDecodeParam", this._decodeParam);
  }

  private _decodeParam: Vector4 = new Vector4(0, 5, 0, 0);

  /**
   * Whether to decode from texture with RGBM format.
   */
  get textureDecodeRGBM(): boolean {
    return Boolean(this._decodeParam.x);
  }

  set textureDecodeRGBM(value: boolean) {
    this._decodeParam.x = Number(value);
  }

  /**
   * RGBM decode factor, default 5.0.
   */
  get RGBMDecodeFactor(): number {
    return this._decodeParam.y;
  }

  set RGBMDecodeFactor(value: number) {
    this._decodeParam.y = value;
  }

  /**
   * Texture cube map of the sky box material.
   */
  get textureCubeMap(): TextureCube {
    return this.shaderData.getTexture("u_cube") as TextureCube;
  }

  set textureCubeMap(v: TextureCube) {
    this.shaderData.setTexture("u_cube", v);
  }
}