/*
 * ImageLoader
 * Visit http://createjs.com/ for documentation, updates and examples.
 *
 *
 * Copyright (c) 2012 gskinner.com, inc.
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

// namespace:
this.createjs = this.createjs || {};

(function () {
	"use strict";

	// constructor
	/**
	 * A loader for image files.
	 * @class ImageLoader
	 * @param {LoadItem|Object} loadItem
	 * @param {Boolean} preferXHR
	 * @extends AbstractLoader
	 * @constructor
	 */
	function ImageLoader (loadItem, preferXHR) {
		this.AbstractLoader_constructor(loadItem, preferXHR, createjs.Types.IMAGE);

		// public properties
		this.resultFormatter = this._formatResult;

		// protected properties
		this._tagSrcAttribute = "src";

		// Check if the preload item is already a tag.
		if (createjs.DomUtils.isImageTag(loadItem)) {
			this._tag = loadItem;
		} else if (createjs.DomUtils.isImageTag(loadItem.src)) {
			this._tag = loadItem.src;
		} else if (createjs.DomUtils.isImageTag(loadItem.tag)) {
			this._tag = loadItem.tag;
		}

		if (this._tag != null) {
			this._preferXHR = false;
		} else {
			this._tag = createjs.Elements.img();
		}

		this.on("initialize", this._updateXHR, this);
	};

	var p = createjs.extend(ImageLoader, createjs.AbstractLoader);
	var s = ImageLoader;

	// static methods
	/**
	 * Determines if the loader can load a specific item. This loader can only load items that are of type
	 * {{#crossLink "Types/IMAGE:property"}}{{/crossLink}}.
	 * @method canLoadItem
	 * @param {LoadItem|Object} item The LoadItem that a LoadQueue is trying to load.
	 * @returns {Boolean} Whether the loader can load the item.
	 * @static
	 */
	s.canLoadItem = function (item) {
		return item.type == createjs.Types.IMAGE;
	};

	// public methods
	p.load = function () {
		if (this._tag.src != "" && this._tag.complete) {
			this._request._handleTagComplete();
			this._sendComplete();
			return;
		}

		var crossOrigin = this._item.crossOrigin;
		if (crossOrigin == true) { crossOrigin = "Anonymous"; }
		if (crossOrigin != null && !createjs.URLUtils.isLocal(this._item)) {
			this._tag.crossOrigin = crossOrigin;
		}

		this.AbstractLoader_load();
	};

	// protected methods
	/**
	 * Before the item loads, set its mimeType and responseType.
	 * @property _updateXHR
	 * @param {Event} event
	 * @private
	 */
	p._updateXHR = function (event) {
		event.loader.mimeType = 'text/plain; charset=x-user-defined-binary';

		// Only exists for XHR
		if (event.loader.setResponseType) {
			event.loader.setResponseType("blob");
		}
	};

	/**
	 * The result formatter for Image files.
	 * @method _formatResult
	 * @param {AbstractLoader} loader
	 * @returns {HTMLImageElement}
	 * @private
	 */
	p._formatResult = function (loader) {
		return this._formatImage;
	};

	/**
	 * The asynchronous image formatter function. This is required because images have
	 * a short delay before they are ready.
	 * @method _formatImage
	 * @param {Function} successCallback The method to call when the result has finished formatting
	 * @param {Function} errorCallback The method to call if an error occurs during formatting
	 * @private
	 */
	p._formatImage = function (successCallback, errorCallback) {
		var tag = this._tag;
		var URL = window.URL || window.webkitURL;

		if (!this._preferXHR) {

			//document.body.removeChild(tag);
		} else if (URL) {
			var objURL = URL.createObjectURL(this.getResult(true));
			tag.src = objURL;

			tag.addEventListener("load", this._cleanUpURL, false);
			tag.addEventListener("error", this._cleanUpURL, false);
		} else {
			tag.src = this._item.src;
		}

		if (tag.complete) {
			successCallback(tag);
		} else {
            tag.onload = createjs.proxy(function() {
                successCallback(this._tag);
                tag.onload = tag.onerror = null;
            }, this);

            tag.onerror = createjs.proxy(function(event) {
                errorCallback(new createjs.ErrorEvent('IMAGE_FORMAT', null, event));
                tag.onload = tag.onerror = null;
            }, this);
		}
	};

	/**
	 * Clean up the ObjectURL, the tag is done with it. Note that this function is run
	 * as an event listener without a proxy/closure, as it doesn't require it - so do not
	 * include any functionality that requires scope without changing it.
	 * @method _cleanUpURL
	 * @param event
	 * @private
	 */
	p._cleanUpURL = function (event) {
		var URL = window.URL || window.webkitURL;
		URL.revokeObjectURL(event.target.src);
	};

	createjs.ImageLoader = createjs.promote(ImageLoader, "AbstractLoader");

}());