/**
 * @author Mat Groves http://matgroves.com/ @Doormat23
 */

PIXI._defaultFrame = new PIXI.Rectangle(0,0,1,1);

// an instance of the gl context..
// only one at the moment :/
PIXI.gl;

/**
 * the WebGLRenderer is draws the stage and all its content onto a webGL enabled canvas. This renderer should be used for browsers support webGL. This Render works by automatically managing webGLBatchs. So no need for Sprite Batch's or Sprite Cloud's
 * Dont forget to add the view to your DOM or you will not see anything :)
 * @class WebGLRenderer
 * @constructor
 * @param width {Number} the width of the canvas view
 * @default 0
 * @param height {Number} the height of the canvas view
 * @default 0
 * @param view {Canvas} the canvas to use as a view, optional
 * @param transparent {Boolean} the transparency of the render view, default false
 * @default false
 * 
 */
PIXI.WebGLRenderer = function(width, height, view, transparent)
{
	// do a catch.. only 1 webGL renderer..

	//console.log(transparent)
	this.transparent = !!transparent;
	
	this.width = width || 800;
	this.height = height || 600;
	
	this.view = view || document.createElement( 'canvas' ); 
    this.view.width = this.width;
	this.view.height = this.height;  
	
	// deal with losing context..	
    var scope = this;
	this.view.addEventListener('webglcontextlost', function(event) { scope.handleContextLost(event); }, false)
	this.view.addEventListener('webglcontextrestored', function(event) { scope.handleContextRestored(event); }, false)

	this.batchs = [];
	
	try 
 	{
        PIXI.gl = this.gl = this.view.getContext("experimental-webgl",  {  	
    		 alpha: this.transparent,
    		 antialias:false, // SPEED UP??
    		 premultipliedAlpha:true
        });
    } 
    catch (e) 
    {
    	throw new Error(" This browser does not support webGL. Try using the canvas renderer" + this);
    }
    
    this.initShaders();
    
    
    var gl = this.gl;
    PIXI.WebGLRenderer.gl = gl;
    
    this.batch = new PIXI.WebGLBatch(gl);
   	gl.disable(gl.DEPTH_TEST);
   	gl.disable(gl.CULL_FACE);
    gl.enable(gl.BLEND);
    gl.colorMask(true, true, true, this.transparent); 
    
    this.projectionMatrix =  PIXI.mat4.create();
    this.resize(this.width, this.height);
    this.contextLost = false;
    
    this.stageRenderGroup = new PIXI.WebGLRenderGroup(this.gl);
}

// constructor
PIXI.WebGLRenderer.constructor = PIXI.WebGLRenderer;

/**
 * @private 
 */
PIXI.WebGLRenderer.getBatch = function()
{
	if(PIXI._batchs.length == 0)
	{
		return new PIXI.WebGLBatch(PIXI.WebGLRenderer.gl);
	}
	else
	{
		return PIXI._batchs.pop();
	}
}

/**
 * @private
 */
PIXI.WebGLRenderer.returnBatch = function(batch)
{
	batch.clean();	
	PIXI._batchs.push(batch);
}


/**
 * @private
 */
PIXI.WebGLRenderer.prototype.initShaders = function() 
{
	var gl = this.gl;
	var fragmentShader = PIXI.CompileFragmentShader(gl, PIXI.shaderFragmentSrc);
	var vertexShader = PIXI.CompileVertexShader(gl, PIXI.shaderVertexSrc);
	
	PIXI.shaderProgram = gl.createProgram();
	
	var shaderProgram = PIXI.shaderProgram;
	
    gl.attachShader(shaderProgram, vertexShader);
    gl.attachShader(shaderProgram, fragmentShader);
    gl.linkProgram(shaderProgram);

    if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
        alert("Could not initialise shaders");
    }

    gl.useProgram(shaderProgram);

    shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
    gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

    shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
    gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);
	
	shaderProgram.colorAttribute = gl.getAttribLocation(shaderProgram, "aColor");
    gl.enableVertexAttribArray(shaderProgram.colorAttribute);


    shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
    shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
}


/**
 * Renders the stage to its webGL view
 * @method render
 * @param stage {Stage} the PIXI.Stage element to be rendered
 */
PIXI.WebGLRenderer.prototype.render = function(stage)
{
	if(this.contextLost)return;
	
	
	// if rendering a new stage clear the batchs..
	if(this.__stage !== stage)
	{
		// TODO make this work
		// dont think this is needed any more?
		//if(this.__stage)this.checkVisibility(this.__stage, false)
		
		this.__stage = stage;
		this.stageRenderGroup.setRenderable(stage);
	}
	
	// TODO not needed now... 
	// update children if need be
	// best to remove first!
	/*for (var i=0; i < stage.__childrenRemoved.length; i++)
	{
		var group = stage.__childrenRemoved[i].__renderGroup
		if(group)group.removeDisplayObject(stage.__childrenRemoved[i]);
	}*/

	// update any textures	
	PIXI.WebGLRenderer.updateTextures();
		
	// recursivly loop through all items!
	//this.checkVisibility(stage, true);
	
	// update the scene graph	
	stage.updateTransform();
	
	var gl = this.gl;
	
	// -- Does this need to be set every frame? -- //
	gl.colorMask(true, true, true, this.transparent); 
	gl.viewport(0, 0, this.width, this.height);	
	
	// set the correct matrix..	
   // gl.uniformMatrix4fv(this.shaderProgram.mvMatrixUniform, false, this.projectionMatrix);
   
   	gl.bindFramebuffer(gl.FRAMEBUFFER, null);
		
	gl.clearColor(stage.backgroundColorSplit[0],stage.backgroundColorSplit[1],stage.backgroundColorSplit[2], this.transparent);     
	gl.clear(gl.COLOR_BUFFER_BIT);


	this.stageRenderGroup.backgroundColor = stage.backgroundColorSplit;
	this.stageRenderGroup.render(this.projectionMatrix);
	
	// interaction
	// run interaction!
	if(stage.interactive)
	{
		//need to add some events!
		if(!stage._interactiveEventsAdded)
		{
			stage._interactiveEventsAdded = true;
			stage.interactionManager.setTarget(this);
		}
	}
	
	// after rendering lets confirm all frames that have been uodated..
	if(PIXI.Texture.frameUpdates.length > 0)
	{
		for (var i=0; i < PIXI.Texture.frameUpdates.length; i++) 
		{
		  	PIXI.Texture.frameUpdates[i].updateFrame = false;
		};
		
		PIXI.Texture.frameUpdates = [];
	}
}

/**
 * @private
 */

PIXI.WebGLRenderer.updateTextures = function()
{
	for (var i=0; i < PIXI.texturesToUpdate.length; i++) this.updateTexture(PIXI.texturesToUpdate[i]);
	for (var i=0; i < PIXI.texturesToDestroy.length; i++) this.destroyTexture(PIXI.texturesToDestroy[i]);
	PIXI.texturesToUpdate = [];
	PIXI.texturesToDestroy = [];
}

PIXI.WebGLRenderer.updateTexture = function(texture)
{
	var gl = PIXI.gl;
	
	if(!texture._glTexture)
	{
		texture._glTexture = gl.createTexture();
	}
	
	if(texture.hasLoaded)
	{
		gl.bindTexture(gl.TEXTURE_2D, texture._glTexture);
	 	gl.pixelStorei(gl.UNPACK_PREMULTIPLY_ALPHA_WEBGL, true);
	 	
		gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.source);
		gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
		gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
		
		// reguler...
		
		if(!texture._powerOf2)
		{
			gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
			gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
		}
		else
		{
			gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
			gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);
		}
		
		gl.bindTexture(gl.TEXTURE_2D, null);
	}
	
}

PIXI.WebGLRenderer.prototype.destroyTexture = function(texture)
{
	var gl = this.gl;
	
	if(texture._glTexture)
	{
		texture._glTexture = gl.createTexture();
		gl.deleteTexture(gl.TEXTURE_2D, texture._glTexture);
	}
}

/**
 * resizes the webGL view to the specified width and height
 * @method resize
 * @param width {Number} the new width of the webGL view
 * @param height {Number} the new height of the webGL view
 */
PIXI.WebGLRenderer.prototype.resize = function(width, height)
{
	this.width = width;
	this.height = height;
	
	this.view.width = width;
	this.view.height = height;
	
	this.gl.viewport(0, 0, this.width, this.height);	
	
	var projectionMatrix = this.projectionMatrix;
	
	projectionMatrix[0] = 2/this.width;
	projectionMatrix[5] = -2/this.height;
	projectionMatrix[12] = -1;
	projectionMatrix[13] = 1;
}

/**
 * @private
 */
PIXI.WebGLRenderer.prototype.handleContextLost = function(event)
{
	event.preventDefault();
	this.contextLost = true;
}

/**
 * @private
 */
PIXI.WebGLRenderer.prototype.handleContextRestored = function(event)
{
	this.gl = this.view.getContext("experimental-webgl",  {  	
		alpha: true
    });
        
	this.initShaders();	
	
	for(var key in PIXI.TextureCache) 
	{
        	var texture = PIXI.TextureCache[key].baseTexture;
        	texture._glTexture = null;
        	PIXI.WebGLRenderer.updateTexture(texture);
	};
	
	for (var i=0; i <  this.batchs.length; i++) 
	{
		this.batchs[i].restoreLostContext(this.gl)//
		this.batchs[i].dirty = true;
	};
	
	PIXI._restoreBatchs(this.gl);
	
	this.contextLost = false;
}

