"use strict";

var Program     = require('./Program');
var Shader      = require('./Shader');
var Texture     = require('./Texture');
var Script      = require('./Script');
var WebGLCanvas = require('./WebGLCanvas');

var Class       = require('uclass');

var vertexShaderScript = Script.createFromSource("x-shader/x-vertex", `
  attribute vec3 aVertexPosition;
  attribute vec2 aTextureCoord;
  uniform mat4 uMVMatrix;
  uniform mat4 uPMatrix;
  varying highp vec2 vTextureCoord;
  void main(void) {
    gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
    vTextureCoord = aTextureCoord;
  }
`);


var fragmentShaderScript = Script.createFromSource("x-shader/x-fragment", `
  precision highp float;
  varying highp vec2 vTextureCoord;
  uniform sampler2D YTexture;
  uniform sampler2D UTexture;
  uniform sampler2D VTexture;
  const mat4 YUV2RGB = mat4
  (
   1.1643828125, 0, 1.59602734375, -.87078515625,
   1.1643828125, -.39176171875, -.81296875, .52959375,
   1.1643828125, 2.017234375, 0, -1.081390625,
   0, 0, 0, 1
  );

  void main(void) {
   gl_FragColor = vec4( texture2D(YTexture,  vTextureCoord).x, texture2D(UTexture, vTextureCoord).x, texture2D(VTexture, vTextureCoord).x, 1) * YUV2RGB;
  }
`);




var YUVWebGLCanvas = new Class({
  Extends  : WebGLCanvas,
  Binds : ['decode'],

  initialize : function(canvas, size) {
    YUVWebGLCanvas.parent.initialize.call(this, canvas, size);
  },

  onInitShaders: function() {
    this.program = new Program(this.gl);
    this.program.attach(new Shader(this.gl, vertexShaderScript));
    this.program.attach(new Shader(this.gl, fragmentShaderScript));
    this.program.link();
    this.program.use();
    this.vertexPositionAttribute = this.program.getAttributeLocation("aVertexPosition");
    this.gl.enableVertexAttribArray(this.vertexPositionAttribute);
    this.textureCoordAttribute = this.program.getAttributeLocation("aTextureCoord");;
    this.gl.enableVertexAttribArray(this.textureCoordAttribute);
  },

  onInitTextures: function () {
    console.log("creatingTextures: size: " + this.size);
    this.YTexture = new Texture(this.gl, this.size);
    this.UTexture = new Texture(this.gl, this.size.getHalfSize());
    this.VTexture = new Texture(this.gl, this.size.getHalfSize());
  },

  onInitSceneTextures: function () {
    this.YTexture.bind(0, this.program, "YTexture");
    this.UTexture.bind(1, this.program, "UTexture");
    this.VTexture.bind(2, this.program, "VTexture");
  },

  fillYUVTextures: function(y, u, v) {
    this.YTexture.fill(y);
    this.UTexture.fill(u);
    this.VTexture.fill(v);
  },

  decode: function(buffer, width, height) {

    if (!buffer)
      return;

    var lumaSize = width * height;
    var chromaSize = lumaSize >> 2;

    this.YTexture.fill(buffer.subarray(0, lumaSize));
    this.UTexture.fill(buffer.subarray(lumaSize, lumaSize + chromaSize));
    this.VTexture.fill(buffer.subarray(lumaSize + chromaSize, lumaSize + 2 * chromaSize));
    this.drawScene();
  },

  toString: function() {
    return "YUVCanvas Size: " + this.size;
  }
});





module.exports = YUVWebGLCanvas;