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

/**
 * @class CanvasTinter
 * @constructor
 * @static
 */
PIXI.CanvasTinter = function()
{
};

/**
 * Basically this method just needs a sprite and a color and tints the sprite with the given color.
 * 
 * @method getTintedTexture 
 * @param sprite {Sprite} the sprite to tint
 * @param color {Number} the color to use to tint the sprite with
 * @return {HTMLCanvasElement} The tinted canvas
 */
PIXI.CanvasTinter.getTintedTexture = function(sprite, color)
{
    var texture = sprite.texture;

    color = PIXI.CanvasTinter.roundColor(color);

    var stringColor = "#" + ("00000" + ( color | 0).toString(16)).substr(-6);
   
    texture.tintCache = texture.tintCache || {};

    if(texture.tintCache[stringColor]) return texture.tintCache[stringColor];

     // clone texture..
    var canvas = PIXI.CanvasTinter.canvas || document.createElement("canvas");
    
    //PIXI.CanvasTinter.tintWithPerPixel(texture, stringColor, canvas);
    PIXI.CanvasTinter.tintMethod(texture, color, canvas);

    if(PIXI.CanvasTinter.convertTintToImage)
    {
        // is this better?
        var tintImage = new Image();
        tintImage.src = canvas.toDataURL();

        texture.tintCache[stringColor] = tintImage;
    }
    else
    {
        texture.tintCache[stringColor] = canvas;
        // if we are not converting the texture to an image then we need to lose the reference to the canvas
        PIXI.CanvasTinter.canvas = null;
    }

    return canvas;
};

/**
 * Tint a texture using the "multiply" operation.
 * 
 * @method tintWithMultiply
 * @param texture {Texture} the texture to tint
 * @param color {Number} the color to use to tint the sprite with
 * @param canvas {HTMLCanvasElement} the current canvas
 */
PIXI.CanvasTinter.tintWithMultiply = function(texture, color, canvas)
{
    var context = canvas.getContext( "2d" );

    var crop = texture.crop;

    canvas.width = crop.width;
    canvas.height = crop.height;

    context.fillStyle = "#" + ("00000" + ( color | 0).toString(16)).substr(-6);
    
    context.fillRect(0, 0, crop.width, crop.height);
    
    context.globalCompositeOperation = "multiply";

    context.drawImage(texture.baseTexture.source,
                           crop.x,
                           crop.y,
                           crop.width,
                           crop.height,
                           0,
                           0,
                           crop.width,
                           crop.height);

    context.globalCompositeOperation = "destination-atop";

    context.drawImage(texture.baseTexture.source,
                           crop.x,
                           crop.y,
                           crop.width,
                           crop.height,
                           0,
                           0,
                           crop.width,
                           crop.height);
};

/**
 * Tint a texture using the "overlay" operation.
 * 
 * @method tintWithOverlay
 * @param texture {Texture} the texture to tint
 * @param color {Number} the color to use to tint the sprite with
 * @param canvas {HTMLCanvasElement} the current canvas
 */
PIXI.CanvasTinter.tintWithOverlay = function(texture, color, canvas)
{
    var context = canvas.getContext( "2d" );

    var crop = texture.crop;

    canvas.width = crop.width;
    canvas.height = crop.height;
    
    context.globalCompositeOperation = "copy";
    context.fillStyle = "#" + ("00000" + ( color | 0).toString(16)).substr(-6);
    context.fillRect(0, 0, crop.width, crop.height);

    context.globalCompositeOperation = "destination-atop";
    context.drawImage(texture.baseTexture.source,
                           crop.x,
                           crop.y,
                           crop.width,
                           crop.height,
                           0,
                           0,
                           crop.width,
                           crop.height);
    
    //context.globalCompositeOperation = "copy";
};

/**
 * Tint a texture pixel per pixel.
 * 
 * @method tintPerPixel
 * @param texture {Texture} the texture to tint
 * @param color {Number} the color to use to tint the sprite with
 * @param canvas {HTMLCanvasElement} the current canvas
 */
PIXI.CanvasTinter.tintWithPerPixel = function(texture, color, canvas)
{
    var context = canvas.getContext( "2d" );

    var crop = texture.crop;

    canvas.width = crop.width;
    canvas.height = crop.height;
  
    context.globalCompositeOperation = "copy";
    context.drawImage(texture.baseTexture.source,
                           crop.x,
                           crop.y,
                           crop.width,
                           crop.height,
                           0,
                           0,
                           crop.width,
                           crop.height);

    var rgbValues = PIXI.hex2rgb(color);
    var r = rgbValues[0], g = rgbValues[1], b = rgbValues[2];

    var pixelData = context.getImageData(0, 0, crop.width, crop.height);

    var pixels = pixelData.data;

    for (var i = 0; i < pixels.length; i += 4)
    {
        pixels[i+0] *= r;
        pixels[i+1] *= g;
        pixels[i+2] *= b;
    }

    context.putImageData(pixelData, 0, 0);
};

/**
 * Rounds the specified color according to the PIXI.CanvasTinter.cacheStepsPerColorChannel.
 * 
 * @method roundColor
 * @param color {number} the color to round, should be a hex color
 */
PIXI.CanvasTinter.roundColor = function(color)
{
    var step = PIXI.CanvasTinter.cacheStepsPerColorChannel;

    var rgbValues = PIXI.hex2rgb(color);

    rgbValues[0] = Math.min(255, (rgbValues[0] / step) * step);
    rgbValues[1] = Math.min(255, (rgbValues[1] / step) * step);
    rgbValues[2] = Math.min(255, (rgbValues[2] / step) * step);

    return PIXI.rgb2hex(rgbValues);
};

/**
 * Number of steps which will be used as a cap when rounding colors.
 *
 * @property cacheStepsPerColorChannel
 * @type Number
 */
PIXI.CanvasTinter.cacheStepsPerColorChannel = 8;

/**
 * Tint cache boolean flag.
 *
 * @property convertTintToImage
 * @type Boolean
 */
PIXI.CanvasTinter.convertTintToImage = false;

/**
 * Whether or not the Canvas BlendModes are supported, consequently the ability to tint using the multiply method.
 *
 * @property canUseMultiply
 * @type Boolean
 */
PIXI.CanvasTinter.canUseMultiply = PIXI.canUseNewCanvasBlendModes();

/**
 * The tinting method that will be used.
 * 
 * @method tintMethod
 */
PIXI.CanvasTinter.tintMethod = PIXI.CanvasTinter.canUseMultiply ? PIXI.CanvasTinter.tintWithMultiply :  PIXI.CanvasTinter.tintWithPerPixel;