/* global config, vendor, MM, Log, Module */
/* jshint unused:false */
/* jshint -W061 */


/* Magic Mirror
 * Module and File loaders.
 *
 * By Michael Teeuw http://michaelteeuw.nl
 * MIT Licensed.
 */

var Loader = (function() {

	/* Create helper valiables */

	var loadedModuleFiles = [];
	var loadedFiles = [];
	var moduleObjects = [];


	/* Private Methods */


	/* loadModules()
	 * Loops thru all modules and requests load for every module.
	 */
	var loadModules = function() {

		var moduleData = getModuleData();

		var loadNextModule = function() {
			if (moduleData.length > 0) {
				var nextModule = moduleData[0];
				loadModule(nextModule, function() {
					moduleData = moduleData.slice(1);
					loadNextModule();
				});
			} else {
				startModules();
			}
		};

		loadNextModule();		
	};

	/* startModules()
	 * Loops thru all modules and requests start for every module.
	 */
	var startModules = function() {
		for (var m in moduleObjects) {
			var module = moduleObjects[m];
			module.start();
		}

		// Notifiy core of loded modules.
		MM.modulesStarted(moduleObjects);
	};

	/* getAllModules()
	 * Retrieve list of all modules.
	 *
	 * return array - module data as configured in config 
	 */
	var getAllModules = function() {
		return config.modules;
	};

	/* getModuleData()
	 * Generate array with module information including module paths.
	 *
	 * return array - Module information.
	 */
	var getModuleData = function() {
		var modules = getAllModules();
		var moduleFiles = [];

		for (var m in modules) {
			var moduleData = modules[m];
			var module = moduleData.module;

			moduleFiles.push({
				index: m,
				identifier: 'module_' + m + '_' + module,
				name: module,
				path: config.paths.modules + '/' +  module,
				file: module + '.js',
				position: moduleData.position,
				header: moduleData.header,
				config: moduleData.config
			});


		}

		return moduleFiles;
	};


	/* loadModule(module)
	 * Load modules via ajax request and create module objects.
	 *
	 * argument callback function - Function called when done.
	 * argument module object - Information about the module we want to load.
	 */
	var loadModule = function(module, callback) {
		var url = module.path + '/' + module.file;

		var afterLoad = function() {
			var moduleObject = Module.create(module.name);
			bootstrapModule(module, moduleObject, function() {
				callback();
			});
		};

		if (loadedModuleFiles.indexOf(url) !== -1) {
			afterLoad();
		} else {
			loadFile(url, function() {
				loadedModuleFiles.push(url);
				afterLoad();
			});
		}
		
	};	

	/* bootstrapModule(module, mObj)
	 * Bootstrap modules by setting the module data and loading the scripts & styles.
	 *
	 * argument module object - Information about the module we want to load.
	 * argument mObj object - Modules instance.
	 * argument callback function - Function called when done.
	 */
	var bootstrapModule = function(module, mObj, callback) {
		Log.info('Bootstrapping module: ' + module.name);

		mObj.setData(module);

		mObj.loadScripts(function() {
			Log.log('Scripts loaded for: ' + module.name);
			mObj.loadStyles(function(){
				Log.log('Styles loaded for: ' + module.name);
				callback();
			});
		});
		

		moduleObjects.push(mObj);
	};

	/* loadFile(fileName)
	 * Load a script or stylesheet by adding it to the dom.
	 *
	 * argument fileName string - Path of the file we want to load.
	 * argument callback function - Function called when done.
	 */
	var loadFile = function(fileName, callback) {

		var extension =  fileName.slice((Math.max(0, fileName.lastIndexOf(".")) || Infinity) + 1);

		switch (extension.toLowerCase()) {
			case "js":
				Log.log('Load script: ' + fileName);

				var script = document.createElement("script");
				script.type = "text/javascript";
				script.src = fileName;
				script.onload = function() {
					if (typeof callback === 'function') {callback();}
				};

				document.getElementsByTagName("body")[0].appendChild(script);
			break;

			case "css":
				Log.log('Load stylesheet: ' + fileName);

				var stylesheet = document.createElement("link");
				stylesheet.rel = "stylesheet";
				stylesheet.type = "text/css";
				stylesheet.href = fileName;
				stylesheet.onload = function() {
					if (typeof callback === 'function') {callback();}
				};

				document.getElementsByTagName("head")[0].appendChild(stylesheet);
			break;				
		}

	};

	/* Public Methods */
	return {

		/* loadModules()
		 * Load all modules as defined in the config.
		 */
		loadModules: function() {
			loadModules();
		},

		/* loadFile()
		 * Load a file (script or stylesheet).
		 * Prevent double loading and search for files in the vendor folder.
		 *
		 * argument fileName string - Path of the file we want to load.
		 * argument module Module Object - the module that calls the loadFile function.
		 * argument callback function - Function called when done.
		 */
		loadFile: function(fileName, module, callback) {

			if (loadedFiles.indexOf(fileName.toLowerCase()) !== -1) {
				Log.log('File already loaded: ' + fileName);
				callback();
				return;
			}

			if (fileName.indexOf('http://') === 0 || fileName.indexOf('https://') === 0 || fileName.indexOf('/') !== -1) {
				// This is an absolute or relative path.
				// Load it and then return.
				loadedFiles.push(fileName.toLowerCase());
				loadFile(fileName, callback);
				return;
			}

			if (vendor[fileName] !== undefined) {
				// This file is available in the vendor folder.
				// Load it from this vendor folder.
				loadedFiles.push(fileName.toLowerCase());
				loadFile(config.paths.vendor+'/'+vendor[fileName], callback);
				return;
			}

			// File not loaded yet.
			// Load it based on the module path.
			loadedFiles.push(fileName.toLowerCase());
			loadFile(module.file(fileName), callback);
		}
	};

})();