var math = require('../../../math'),
    CONST = require('../../../const'),
    GLFramebuffer = require('pixi-gl-core').GLFramebuffer;

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

/**
 * @class
 * @memberof PIXI
 * @param gl {WebGLRenderingContext} the current WebGL drawing context
 * @param [width=0] {number} the horizontal range of the filter
 * @param [height=0] {number} the vertical range of the filter
 * @param [scaleMode=CONST.SCALE_MODES.DEFAULT] {number} See {@link PIXI.SCALE_MODES} for possible values
 * @param [resolution=CONST.RESOLUTION] {number} the current resolution
 * @param [root=false] {boolean} Whether this object is the root element or not
 */
var RenderTarget = function(gl, width, height, scaleMode, resolution, root)
{
    //TODO Resolution could go here ( eg low res blurs )

    /**
     * The current WebGL drawing context.
     *
     * @member {WebGLRenderingContext}
     */
    this.gl = gl;

    // next time to create a frame buffer and texture

    /**
     * A frame buffer
     *
     * @member {glCore.GLFramebuffer}
     */
    this.frameBuffer = null;

    /**
     * The texture
     *
     * @member {PIXI.Texture}
     */
    this.texture = null;

    /**
     * The background colour of this render target, as an array of [r,g,b,a] values
     *
     * @member {number[]}
     */
    this.clearColor = [0, 0, 0, 0];

    /**
     * The size of the object as a rectangle
     *
     * @member {PIXI.Rectangle}
     */
    this.size = new math.Rectangle(0, 0, 1, 1);

    /**
     * The current resolution
     *
     * @member {number}
     */
    this.resolution = resolution || CONST.RESOLUTION;

    /**
     * The projection matrix
     *
     * @member {PIXI.Matrix}
     */
    this.projectionMatrix = new math.Matrix();

    /**
     * The object's transform
     *
     * @member {PIXI.Matrix}
     */
    this.transform = null;

    /**
     * The frame.
     *
     * @member {PIXI.Rectangle}
     */
    this.frame = null;

    /**
     * The stencil buffer stores masking data for the render target
     *
     * @member {glCore.GLBuffer}
     */
    this.defaultFrame = new math.Rectangle();
    this.destinationFrame = null;
    this.sourceFrame = null;

    /**
     * The stencil buffer stores masking data for the render target
     *
     * @member {glCore.GLBuffer}
     */
    this.stencilBuffer = null;

    /**
     * The data structure for the stencil masks
     *
     * @member {PIXI.Graphics[]}
     */
    this.stencilMaskStack = [];

    /**
     * Stores filter data for the render target
     *
     * @member {object[]}
     */
    this.filterData = null;

    /**
     * The scale mode.
     *
     * @member {number}
     * @default PIXI.SCALE_MODES.DEFAULT
     * @see PIXI.SCALE_MODES
     */
    this.scaleMode = scaleMode || CONST.SCALE_MODES.DEFAULT;

    /**
     * Whether this object is the root element or not
     *
     * @member {boolean}
     */
    this.root = root;


    if (!this.root)
    {
        this.frameBuffer = GLFramebuffer.createRGBA(gl, 100, 100);

        if( this.scaleMode === CONST.SCALE_MODES.NEAREST)
        {
            this.frameBuffer.texture.enableNearestScaling();
        }
        else
        {
            this.frameBuffer.texture.enableLinearScaling();

        }
        /*
            A frame buffer needs a target to render to..
            create a texture and bind it attach it to the framebuffer..
         */

        // this is used by the base texture
        this.texture = this.frameBuffer.texture;
    }
    else
    {
        // make it a null framebuffer..
        this.frameBuffer = new GLFramebuffer(gl, 100, 100);
        this.frameBuffer.framebuffer = null;

    }

    this.setFrame();

    this.resize(width, height);
};

RenderTarget.prototype.constructor = RenderTarget;
module.exports = RenderTarget;

/**
 * Clears the filter texture.
 *
 * @param [clearColor=this.clearColor] {number[]} Array of [r,g,b,a] to clear the framebuffer
 */
RenderTarget.prototype.clear = function(clearColor)
{
    var cc = clearColor || this.clearColor;
    this.frameBuffer.clear(cc[0],cc[1],cc[2],cc[3]);//r,g,b,a);
};

/**
 * Binds the stencil buffer.
 *
 */
RenderTarget.prototype.attachStencilBuffer = function()
{
    //TODO check if stencil is done?
    /**
     * The stencil buffer is used for masking in pixi
     * lets create one and then add attach it to the framebuffer..
     */
    if (!this.root)
    {
        this.frameBuffer.enableStencil();
    }
};

RenderTarget.prototype.setFrame = function(destinationFrame, sourceFrame)
{
    this.destinationFrame = destinationFrame || this.destinationFrame || this.defaultFrame;
    this.sourceFrame = sourceFrame || this.sourceFrame || destinationFrame;
};

/**
 * Binds the buffers and initialises the viewport.
 *
 */
RenderTarget.prototype.activate = function()
{
    //TOOD refactor usage of frame..
    var gl = this.gl;

    // make surethe texture is unbound!
    this.frameBuffer.bind();

    this.calculateProjection( this.destinationFrame, this.sourceFrame );

    if(this.transform)
    {
        this.projectionMatrix.append(this.transform);
    }

    //TODO add a check as them may be the same!
    if(this.destinationFrame !== this.sourceFrame)
    {

        gl.enable(gl.SCISSOR_TEST);
        gl.scissor(this.destinationFrame.x | 0,this.destinationFrame.y | 0, (this.destinationFrame.width * this.resolution) | 0, (this.destinationFrame.height* this.resolution) | 0);
    }
    else
    {
        gl.disable(gl.SCISSOR_TEST);
    }


    // TODO - does not need to be updated all the time??
    gl.viewport(this.destinationFrame.x | 0,this.destinationFrame.y | 0, (this.destinationFrame.width * this.resolution) | 0, (this.destinationFrame.height * this.resolution)|0);


};


/**
 * Updates the projection matrix based on a projection frame (which is a rectangle)
 *
 */
RenderTarget.prototype.calculateProjection = function (destinationFrame, sourceFrame)
{
    var pm = this.projectionMatrix;

    sourceFrame = sourceFrame || destinationFrame;

    pm.identity();

    // TODO: make dest scale source
    if (!this.root)
    {
        pm.a = 1 / destinationFrame.width*2;
        pm.d = 1 / destinationFrame.height*2;

        pm.tx = -1 - sourceFrame.x * pm.a;
        pm.ty = -1 - sourceFrame.y * pm.d;
    }
    else
    {
        pm.a = 1 / destinationFrame.width*2;
        pm.d = -1 / destinationFrame.height*2;

        pm.tx = -1 - sourceFrame.x * pm.a;
        pm.ty = 1 - sourceFrame.y * pm.d;
    }
};


/**
 * Resizes the texture to the specified width and height
 *
 * @param width {Number} the new width of the texture
 * @param height {Number} the new height of the texture
 */
RenderTarget.prototype.resize = function (width, height)
{
    width = width | 0;
    height = height | 0;

    if (this.size.width === width && this.size.height === height)
    {
        return;
    }

    this.size.width = width;
    this.size.height = height;

    this.defaultFrame.width = width;
    this.defaultFrame.height = height;


    this.frameBuffer.resize(width * this.resolution, height * this.resolution);

    var projectionFrame = this.frame || this.size;

    this.calculateProjection( projectionFrame );
};

/**
 * Destroys the render target.
 *
 */
RenderTarget.prototype.destroy = function ()
{
    this.frameBuffer.destroy();

    this.frameBuffer = null;
    this.texture = null;
};