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

PIXI.TextureCache = {};
PIXI.FrameCache = {};

PIXI.TextureCacheIdGenerator = 0;

/**
 * A texture stores the information that represents an image or part of an image. It cannot be added
 * to the display list directly. Instead use it as the texture for a PIXI.Sprite. If no frame is provided then the whole image is used.
 *
 * @class Texture
 * @uses EventTarget
 * @constructor
 * @param baseTexture {BaseTexture} The base texture source to create the texture from
 * @param frame {Rectangle} The rectangle frame of the texture to show
 * @param [crop] {Rectangle} The area of original texture 
 * @param [trim] {Rectangle} Trimmed texture rectangle
 */
PIXI.Texture = function(baseTexture, frame, crop, trim)
{
    /**
     * Does this Texture have any frame data assigned to it?
     *
     * @property noFrame
     * @type Boolean
     */
    this.noFrame = false;

    if (!frame)
    {
        this.noFrame = true;
        frame = new PIXI.Rectangle(0,0,1,1);
    }

    if (baseTexture instanceof PIXI.Texture)
    {
        baseTexture = baseTexture.baseTexture;
    }

    /**
     * The base texture that this texture uses.
     *
     * @property baseTexture
     * @type BaseTexture
     */
    this.baseTexture = baseTexture;

    /**
     * The frame specifies the region of the base texture that this texture uses
     *
     * @property frame
     * @type Rectangle
     */
    this.frame = frame;

    /**
     * The texture trim data.
     *
     * @property trim
     * @type Rectangle
     */
    this.trim = trim;

    /**
     * This will let the renderer know if the texture is valid. If it's not then it cannot be rendered.
     *
     * @property valid
     * @type Boolean
     */
    this.valid = false;

    /**
     * This will let a renderer know that a texture has been updated (used mainly for webGL uv updates)
     *
     * @property requiresUpdate
     * @type Boolean
     */
    this.requiresUpdate = false;

    /**
     * The WebGL UV data cache.
     *
     * @property _uvs
     * @type Object
     * @private
     */
    this._uvs = null;

    /**
     * The width of the Texture in pixels.
     *
     * @property width
     * @type Number
     */
    this.width = 0;

    /**
     * The height of the Texture in pixels.
     *
     * @property height
     * @type Number
     */
    this.height = 0;

    /**
     * This is the area of the BaseTexture image to actually copy to the Canvas / WebGL when rendering,
     * irrespective of the actual frame size or placement (which can be influenced by trimmed texture atlases)
     *
     * @property crop
     * @type Rectangle
     */
    this.crop = crop || new PIXI.Rectangle(0, 0, 1, 1);

    if (baseTexture.hasLoaded)
    {
        if (this.noFrame) frame = new PIXI.Rectangle(0, 0, baseTexture.width, baseTexture.height);
        this.setFrame(frame);
    }
    else
    {
        baseTexture.addEventListener('loaded', this.onBaseTextureLoaded.bind(this));
    }
};

PIXI.Texture.prototype.constructor = PIXI.Texture;
PIXI.EventTarget.mixin(PIXI.Texture.prototype);

/**
 * Called when the base texture is loaded
 *
 * @method onBaseTextureLoaded
 * @private
 */
PIXI.Texture.prototype.onBaseTextureLoaded = function()
{
    var baseTexture = this.baseTexture;
    baseTexture.removeEventListener('loaded', this.onLoaded);

    if (this.noFrame) this.frame = new PIXI.Rectangle(0, 0, baseTexture.width, baseTexture.height);

    this.setFrame(this.frame);

    this.dispatchEvent( { type: 'update', content: this } );
};

/**
 * Destroys this texture
 *
 * @method destroy
 * @param destroyBase {Boolean} Whether to destroy the base texture as well
 */
PIXI.Texture.prototype.destroy = function(destroyBase)
{
    if (destroyBase) this.baseTexture.destroy();

    this.valid = false;
};

/**
 * Specifies the region of the baseTexture that this texture will use.
 *
 * @method setFrame
 * @param frame {Rectangle} The frame of the texture to set it to
 */
PIXI.Texture.prototype.setFrame = function(frame)
{
    this.noFrame = false;

    this.frame = frame;
    this.width = frame.width;
    this.height = frame.height;

    this.crop.x = frame.x;
    this.crop.y = frame.y;
    this.crop.width = frame.width;
    this.crop.height = frame.height;

    if (!this.trim && (frame.x + frame.width > this.baseTexture.width || frame.y + frame.height > this.baseTexture.height))
    {
        throw new Error('Texture Error: frame does not fit inside the base Texture dimensions ' + this);
    }

    this.valid = frame && frame.width && frame.height && this.baseTexture.source && this.baseTexture.hasLoaded;

    if (this.trim)
    {
        this.width = this.trim.width;
        this.height = this.trim.height;
        this.frame.width = this.trim.width;
        this.frame.height = this.trim.height;
    }
    
    if (this.valid) this._updateUvs();

};

/**
 * Updates the internal WebGL UV cache.
 *
 * @method _updateUvs
 * @private
 */
PIXI.Texture.prototype._updateUvs = function()
{
    if(!this._uvs)this._uvs = new PIXI.TextureUvs();

    var frame = this.crop;
    var tw = this.baseTexture.width;
    var th = this.baseTexture.height;
    
    this._uvs.x0 = frame.x / tw;
    this._uvs.y0 = frame.y / th;

    this._uvs.x1 = (frame.x + frame.width) / tw;
    this._uvs.y1 = frame.y / th;

    this._uvs.x2 = (frame.x + frame.width) / tw;
    this._uvs.y2 = (frame.y + frame.height) / th;

    this._uvs.x3 = frame.x / tw;
    this._uvs.y3 = (frame.y + frame.height) / th;
};

/**
 * Helper function that creates a Texture object from the given image url.
 * If the image is not in the texture cache it will be  created and loaded.
 *
 * @static
 * @method fromImage
 * @param imageUrl {String} The image url of the texture
 * @param crossorigin {Boolean} Whether requests should be treated as crossorigin
 * @param scaleMode {Number} Should be one of the PIXI.scaleMode consts
 * @return Texture
 */
PIXI.Texture.fromImage = function(imageUrl, crossorigin, scaleMode)
{
    var texture = PIXI.TextureCache[imageUrl];

    if(!texture)
    {
        texture = new PIXI.Texture(PIXI.BaseTexture.fromImage(imageUrl, crossorigin, scaleMode));
        PIXI.TextureCache[imageUrl] = texture;
    }

    return texture;
};

/**
 * Helper function that returns a Texture objected based on the given frame id.
 * If the frame id is not in the texture cache an error will be thrown.
 *
 * @static
 * @method fromFrame
 * @param frameId {String} The frame id of the texture
 * @return Texture
 */
PIXI.Texture.fromFrame = function(frameId)
{
    var texture = PIXI.TextureCache[frameId];
    if(!texture) throw new Error('The frameId "' + frameId + '" does not exist in the texture cache ');
    return texture;
};

/**
 * Helper function that creates a new a Texture based on the given canvas element.
 *
 * @static
 * @method fromCanvas
 * @param canvas {Canvas} The canvas element source of the texture
 * @param scaleMode {Number} Should be one of the PIXI.scaleMode consts
 * @return Texture
 */
PIXI.Texture.fromCanvas = function(canvas, scaleMode)
{
    var baseTexture = PIXI.BaseTexture.fromCanvas(canvas, scaleMode);

    return new PIXI.Texture( baseTexture );

};

/**
 * Adds a texture to the global PIXI.TextureCache. This cache is shared across the whole PIXI object.
 *
 * @static
 * @method addTextureToCache
 * @param texture {Texture} The Texture to add to the cache.
 * @param id {String} The id that the texture will be stored against.
 */
PIXI.Texture.addTextureToCache = function(texture, id)
{
    PIXI.TextureCache[id] = texture;
};

/**
 * Remove a texture from the global PIXI.TextureCache.
 *
 * @static
 * @method removeTextureFromCache
 * @param id {String} The id of the texture to be removed
 * @return {Texture} The texture that was removed
 */
PIXI.Texture.removeTextureFromCache = function(id)
{
    var texture = PIXI.TextureCache[id];
    delete PIXI.TextureCache[id];
    delete PIXI.BaseTextureCache[id];
    return texture;
};

PIXI.TextureUvs = function()
{
    this.x0 = 0;
    this.y0 = 0;

    this.x1 = 0;
    this.y1 = 0;

    this.x2 = 0;
    this.y2 = 0;

    this.x3 = 0;
    this.y3 = 0;
};

PIXI.Texture.emptyTexture = new PIXI.Texture(new PIXI.BaseTexture());