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

PIXI.glContexts = []; // this is where we store the webGL contexts for easy access.

/**
 * the WebGLRenderer draws the stage and all its content onto a webGL enabled canvas. This renderer
 * should be used for browsers that support webGL. This Render works by automatically managing webGLBatch's.
 * 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=0 {Number} the width of the canvas view
 * @param height=0 {Number} the height of the canvas view
 * @param view {HTMLCanvasElement} the canvas to use as a view, optional
 * @param transparent=false {Boolean} If the render view is transparent, default false
 * @param antialias=false {Boolean} sets antialias (only applicable in chrome at the moment)
 *
 */
PIXI.WebGLRenderer = function(width, height, view, transparent, antialias)
{
    if(!PIXI.defaultRenderer)PIXI.defaultRenderer = this;

    this.type = PIXI.WEBGL_RENDERER;

    // do a catch.. only 1 webGL renderer..
    /**
     * Whether the render view is transparent
     *
     * @property transparent
     * @type Boolean
     */
    this.transparent = !!transparent;

    /**
     * The width of the canvas view
     *
     * @property width
     * @type Number
     * @default 800
     */
    this.width = width || 800;

    /**
     * The height of the canvas view
     *
     * @property height
     * @type Number
     * @default 600
     */
    this.height = height || 600;

    /**
     * The canvas element that everything is drawn to
     *
     * @property view
     * @type HTMLCanvasElement
     */
    this.view = view || document.createElement( 'canvas' );
    this.view.width = this.width;
    this.view.height = this.height;

    // deal with losing context..
    this.contextLost = this.handleContextLost.bind(this);
    this.contextRestoredLost = this.handleContextRestored.bind(this);
    
    this.view.addEventListener('webglcontextlost', this.contextLost, false);
    this.view.addEventListener('webglcontextrestored', this.contextRestoredLost, false);

    this.options = {
        alpha: this.transparent,
        antialias:!!antialias, // SPEED UP??
        premultipliedAlpha:!!transparent,
        stencil:true
    };

    //try 'experimental-webgl'
    try {
        this.gl = this.view.getContext('experimental-webgl',  this.options);
    } catch (e) {
        //try 'webgl'
        try {
            this.gl = this.view.getContext('webgl',  this.options);
        } catch (e2) {
            // fail, not able to get a context
            throw new Error(' This browser does not support webGL. Try using the canvas renderer' + this);
        }
    }

    var gl = this.gl;
    this.glContextId = gl.id = PIXI.WebGLRenderer.glContextId ++;

    PIXI.glContexts[this.glContextId] = gl;

    if(!PIXI.blendModesWebGL)
    {
        PIXI.blendModesWebGL = [];

        PIXI.blendModesWebGL[PIXI.blendModes.NORMAL]        = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.ADD]           = [gl.SRC_ALPHA, gl.DST_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.MULTIPLY]      = [gl.DST_COLOR, gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.SCREEN]        = [gl.SRC_ALPHA, gl.ONE];
        PIXI.blendModesWebGL[PIXI.blendModes.OVERLAY]       = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.DARKEN]        = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.LIGHTEN]       = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.COLOR_DODGE]   = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.COLOR_BURN]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.HARD_LIGHT]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.SOFT_LIGHT]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.DIFFERENCE]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.EXCLUSION]     = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.HUE]           = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.SATURATION]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.COLOR]         = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
        PIXI.blendModesWebGL[PIXI.blendModes.LUMINOSITY]    = [gl.ONE,       gl.ONE_MINUS_SRC_ALPHA];
    }




    this.projection = new PIXI.Point();
    this.projection.x =  this.width/2;
    this.projection.y =  -this.height/2;

    this.offset = new PIXI.Point(0, 0);

    this.resize(this.width, this.height);
    this.contextLost = false;

    // time to create the render managers! each one focuses on managine a state in webGL
    this.shaderManager = new PIXI.WebGLShaderManager(gl);                   // deals with managing the shader programs and their attribs
    this.spriteBatch = new PIXI.WebGLSpriteBatch(gl);                       // manages the rendering of sprites
    this.maskManager = new PIXI.WebGLMaskManager(gl);                       // manages the masks using the stencil buffer
    this.filterManager = new PIXI.WebGLFilterManager(gl, this.transparent); // manages the filters

    this.renderSession = {};
    this.renderSession.gl = this.gl;
    this.renderSession.drawCount = 0;
    this.renderSession.shaderManager = this.shaderManager;
    this.renderSession.maskManager = this.maskManager;
    this.renderSession.filterManager = this.filterManager;
    this.renderSession.spriteBatch = this.spriteBatch;
    this.renderSession.renderer = this;

    gl.useProgram(this.shaderManager.defaultShader.program);

    gl.disable(gl.DEPTH_TEST);
    gl.disable(gl.CULL_FACE);

    gl.enable(gl.BLEND);
    gl.colorMask(true, true, true, this.transparent);
};

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

/**
 * Renders the stage to its webGL view
 *
 * @method render
 * @param stage {Stage} the Stage element to be rendered
 */
PIXI.WebGLRenderer.prototype.render = function(stage)
{
    if(this.contextLost)return;


    // if rendering a new stage clear the batches..
    if(this.__stage !== stage)
    {
        if(stage.interactive)stage.interactionManager.removeEvents();

        // TODO make this work
        // dont think this is needed any more?
        this.__stage = stage;
    }

    // update any textures this includes uvs and uploading them to the gpu
    PIXI.WebGLRenderer.updateTextures();

    // update the scene graph
    stage.updateTransform();


    // interaction
    if(stage._interactive)
    {
        //need to add some events!
        if(!stage._interactiveEventsAdded)
        {
            stage._interactiveEventsAdded = true;
            stage.interactionManager.setTarget(this);
        }
    }
    
    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);

    // make sure we are bound to the main frame buffer
    gl.bindFramebuffer(gl.FRAMEBUFFER, null);

    if(this.transparent)
    {
        gl.clearColor(0, 0, 0, 0);
    }
    else
    {
        gl.clearColor(stage.backgroundColorSplit[0],stage.backgroundColorSplit[1],stage.backgroundColorSplit[2], 1);
    }


    gl.clear(gl.COLOR_BUFFER_BIT);

    this.renderDisplayObject( stage, this.projection );

    // interaction
    if(stage.interactive)
    {
        //need to add some events!
        if(!stage._interactiveEventsAdded)
        {
            stage._interactiveEventsAdded = true;
            stage.interactionManager.setTarget(this);
        }
    }
    else
    {
        if(stage._interactiveEventsAdded)
        {
            stage._interactiveEventsAdded = false;
            stage.interactionManager.setTarget(this);
        }
    }

    /*
    //can simulate context loss in Chrome like so:
     this.view.onmousedown = function(ev) {
     console.dir(this.gl.getSupportedExtensions());
        var ext = (
            gl.getExtension("WEBGL_scompressed_texture_s3tc")
       // gl.getExtension("WEBGL_compressed_texture_s3tc") ||
       // gl.getExtension("MOZ_WEBGL_compressed_texture_s3tc") ||
       // gl.getExtension("WEBKIT_WEBGL_compressed_texture_s3tc")
     );
     console.dir(ext);
     var loseCtx = this.gl.getExtension("WEBGL_lose_context");
      console.log("killing context");
      loseCtx.loseContext();
     setTimeout(function() {
          console.log("restoring context...");
          loseCtx.restoreContext();
      }.bind(this), 1000);
     }.bind(this);
     */
};

/**
 * Renders a display Object
 *
 * @method renderDIsplayObject
 * @param displayObject {DisplayObject} The DisplayObject to render
 * @param projection {Point} The projection
 * @param buffer {Array} a standard WebGL buffer 
 */
PIXI.WebGLRenderer.prototype.renderDisplayObject = function(displayObject, projection, buffer)
{
    // reset the render session data..
    this.renderSession.drawCount = 0;
    this.renderSession.currentBlendMode = 9999;

    this.renderSession.projection = projection;
    this.renderSession.offset = this.offset;

    // start the sprite batch
    this.spriteBatch.begin(this.renderSession);

    // start the filter manager
    this.filterManager.begin(this.renderSession, buffer);

    // render the scene!
    displayObject._renderWebGL(this.renderSession);

    // finish the sprite batch
    this.spriteBatch.end();
};

/**
 * Updates the textures loaded into this webgl renderer
 *
 * @static
 * @method updateTextures
 * @private
 */
PIXI.WebGLRenderer.updateTextures = function()
{
    var i = 0;

    //TODO break this out into a texture manager...
    //for (i = 0; i < PIXI.texturesToUpdate.length; i++)
    //    PIXI.WebGLRenderer.updateTexture(PIXI.texturesToUpdate[i]);


    for (i=0; i < PIXI.Texture.frameUpdates.length; i++)
        PIXI.WebGLRenderer.updateTextureFrame(PIXI.Texture.frameUpdates[i]);

    for (i = 0; i < PIXI.texturesToDestroy.length; i++)
        PIXI.WebGLRenderer.destroyTexture(PIXI.texturesToDestroy[i]);

    PIXI.texturesToUpdate.length = 0;
    PIXI.texturesToDestroy.length = 0;
    PIXI.Texture.frameUpdates.length = 0;
};

/**
 * Destroys a loaded webgl texture
 *
 * @method destroyTexture
 * @param texture {Texture} The texture to update
 * @private
 */
PIXI.WebGLRenderer.destroyTexture = function(texture)
{
    //TODO break this out into a texture manager...

    for (var i = texture._glTextures.length - 1; i >= 0; i--)
    {
        var glTexture = texture._glTextures[i];
        var gl = PIXI.glContexts[i];

        if(gl && glTexture)
        {
            gl.deleteTexture(glTexture);
        }
    }

    texture._glTextures.length = 0;
};

/**
 *
 * @method updateTextureFrame
 * @param texture {Texture} The texture to update the frame from
 * @private
 */
PIXI.WebGLRenderer.updateTextureFrame = function(texture)
{
    texture.updateFrame = false;

    // now set the uvs. Figured that the uv data sits with a texture rather than a sprite.
    // so uv data is stored on the texture itself
    texture._updateWebGLuvs();
};

/**
 * 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);

    this.projection.x =  this.width/2;
    this.projection.y =  -this.height/2;
};

/**
 * Creates a WebGL texture
 *
 * @method createWebGLTexture
 * @param texture {Texture} the texture to render
 * @param gl {webglContext} the WebGL context
 * @static
 */
PIXI.createWebGLTexture = function(texture, gl)
{


    if(texture.hasLoaded)
    {
        texture._glTextures[gl.id] = gl.createTexture();

        gl.bindTexture(gl.TEXTURE_2D, texture._glTextures[gl.id]);
        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, texture.scaleMode === PIXI.scaleModes.LINEAR ? gl.LINEAR : gl.NEAREST);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, texture.scaleMode === PIXI.scaleModes.LINEAR ? gl.LINEAR : gl.NEAREST);

        // 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);
    }

    return  texture._glTextures[gl.id];
};

/**
 * Updates a WebGL texture
 *
 * @method updateWebGLTexture
 * @param texture {Texture} the texture to update
 * @param gl {webglContext} the WebGL context
 * @private
 */
PIXI.updateWebGLTexture = function(texture, gl)
{
    if( texture._glTextures[gl.id] )
    {
        gl.bindTexture(gl.TEXTURE_2D, texture._glTextures[gl.id]);
        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, texture.scaleMode === PIXI.scaleModes.LINEAR ? gl.LINEAR : gl.NEAREST);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, texture.scaleMode === PIXI.scaleModes.LINEAR ? gl.LINEAR : gl.NEAREST);

        // 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);
    }
    
};

/**
 * Handles a lost webgl context
 *
 * @method handleContextLost
 * @param event {Event}
 * @private
 */
PIXI.WebGLRenderer.prototype.handleContextLost = function(event)
{
    event.preventDefault();
    this.contextLost = true;
};

/**
 * Handles a restored webgl context
 *
 * @method handleContextRestored
 * @param event {Event}
 * @private
 */
PIXI.WebGLRenderer.prototype.handleContextRestored = function()
{

    //try 'experimental-webgl'
    try {
        this.gl = this.view.getContext('experimental-webgl',  this.options);
    } catch (e) {
        //try 'webgl'
        try {
            this.gl = this.view.getContext('webgl',  this.options);
        } catch (e2) {
            // fail, not able to get a context
            throw new Error(' This browser does not support webGL. Try using the canvas renderer' + this);
        }
    }

    var gl = this.gl;
    gl.id = PIXI.WebGLRenderer.glContextId ++;



    // need to set the context...
    this.shaderManager.setContext(gl);
    this.spriteBatch.setContext(gl);
    this.maskManager.setContext(gl);
    this.filterManager.setContext(gl);


    this.renderSession.gl = this.gl;

    gl.disable(gl.DEPTH_TEST);
    gl.disable(gl.CULL_FACE);

    gl.enable(gl.BLEND);
    gl.colorMask(true, true, true, this.transparent);

    this.gl.viewport(0, 0, this.width, this.height);

    for(var key in PIXI.TextureCache)
    {
        var texture = PIXI.TextureCache[key].baseTexture;
        texture._glTextures = [];
    }

    /**
     * Whether the context was lost 
     * @property contextLost
     * @type Boolean
     */
    this.contextLost = false;

};

/**
 * Removes everything from the renderer (event listeners, spritebatch, etc...)
 *
 * @method destroy
 */
PIXI.WebGLRenderer.prototype.destroy = function()
{

    // deal with losing context..
    
    // remove listeners
    this.view.removeEventListener('webglcontextlost', this.contextLost);
    this.view.removeEventListener('webglcontextrestored', this.contextRestoredLost);

    PIXI.glContexts[this.glContextId] = null;

    this.projection = null;
    this.offset = null;

    // time to create the render managers! each one focuses on managine a state in webGL
    this.shaderManager.destroy();
    this.spriteBatch.destroy();
    this.maskManager.destroy();
    this.filterManager.destroy();

    this.shaderManager = null;
    this.spriteBatch = null;
    this.maskManager = null;
    this.filterManager = null;
    
    this.gl = null;
    //
    this.renderSession = null;
};


PIXI.WebGLRenderer.glContextId = 0;
