'use strict';

/**
 * 0.1.1
 * Deferred load js/css file, used for ui-jq.js and Lazy Loading.
 * 
 * @ flatfull.com All Rights Reserved.
 * Author url: #user/flatfull
 */

angular.module('ui.load', [])
	.service('uiLoad', ['$document', '$q', '$timeout', function ($document, $q, $timeout) {

		var loaded = [];
		var promise = false;
		var deferred = $q.defer();

		/**
		 * Chain loads the given sources
		 * @param srcs array, script or css
		 * @returns {*} Promise that will be resolved once the sources has been loaded.
		 */
		this.load = function (srcs) {
			srcs = angular.isArray(srcs) ? srcs : srcs.split(/\s+/);
			var self = this;
			if(!promise){
				promise = deferred.promise;
			}
      angular.forEach(srcs, function(src) {
      	promise = promise.then( function(){
      		return src.indexOf('.css') >=0 ? self.loadCSS(src) : self.loadScript(src);
      	} );
      });
      deferred.resolve();
      return promise;
		}

		/**
		 * Dynamically loads the given script
		 * @param src The url of the script to load dynamically
		 * @returns {*} Promise that will be resolved once the script has been loaded.
		 */
		this.loadScript = function (src) {
			if(loaded[src]) return loaded[src].promise;

			var deferred = $q.defer();
			var script = $document[0].createElement('script');
			script.src = src;
			script.onload = function (e) {
				$timeout(function () {
					deferred.resolve(e);
				});
			};
			script.onerror = function (e) {
				$timeout(function () {
					deferred.reject(e);
				});
			};
			$document[0].body.appendChild(script);
			loaded[src] = deferred;

			return deferred.promise;
		};

		/**
		 * Dynamically loads the given CSS file
		 * @param href The url of the CSS to load dynamically
		 * @returns {*} Promise that will be resolved once the CSS file has been loaded.
		 */
		this.loadCSS = function (href) {
			if(loaded[href]) return loaded[href].promise;

			var deferred = $q.defer();
			var style = $document[0].createElement('link');
			style.rel = 'stylesheet';
			style.type = 'text/css';
			style.href = href;
			style.onload = function (e) {
				$timeout(function () {
					deferred.resolve(e);
				});
			};
			style.onerror = function (e) {
				$timeout(function () {
					deferred.reject(e);
				});
			};
			$document[0].head.appendChild(style);
			loaded[href] = deferred;

			return deferred.promise;
		};
}]);