/*
Script: Namespace.js
Namespace utility

Copyright:
Copyright (c) 2009 Maxime Bouroumeau-Fuseau

License:
MIT-style license.
Version:
1.1
*/

/*jslint evil : true */
/*global Namespace, XMLHttpRequest, ActiveXObject, window, document */

var Namespace = (function() {

	var _listeners = {};
	var _includedIdentifiers = [];

	/**
	* Returns an object in an array unless the object is an array
	*
	* @param mixed obj
	* @return Array
	*/
	var _toArray = function(obj) {
		// checks if it's an array
		if (typeof (obj) == 'object' && obj.sort) {
			return obj;
		}
		return Array(obj);
	};

	/**
	* Creates an XMLHttpRequest object
	*
	* @return XMLHttpRequest
	*/
	var _createXmlHttpRequest = function() {
		var xhr;
		try { xhr = new XMLHttpRequest(); } catch (e) {
			try { xhr = new ActiveXObject("Msxml2.XMLHTTP.6.0"); } catch (e2) {
				try { xhr = new ActiveXObject("Msxml2.XMLHTTP.3.0"); } catch (e3) {
					try { xhr = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e4) {
						try { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e5) {
							throw new Error("This browser does not support XMLHttpRequest.");
						}
					}
				}
			}
		}
		return xhr;
	};

	/**
	* Checks if an http request is successful based on its status code.
	* Borrowed from dojo (http://www.dojotoolkit.org).
	*
	* @param Integer status Http status code
	* @return Boolean
	*/
	var _isHttpRequestSuccessful = function(status) {
		return (status >= 200 && status < 300) || // Boolean
status == 304 || // allow any 2XX response code
status == 1223 || // get it out of the cache
(!status && (window.location.protocol == "file:" || window.location.protocol == "chrome:")); // Internet Explorer mangled the status code
	};

	/**
	* Creates a script tag with the specified data as content
	*
	* @param String data The content of the script
	*/
	var _createScript = function(data) {
		var script = document.createElement('script');
		script.type = 'text/javascript';
		script.text = data;

		if (typeof window.execScript === "object") { // According to IE
			window.execScript(data);
		} else {
			try { // Attempt body insertion
				document.body.appendChild(script);
			} catch (e) { // Fall back on eval
				window['eval'](data);
			}
		}
	};

	/**
	* Dispatches an event
	*
	* @param String eventName
	* @param Object properties
	*/
	var _dispatchEvent = function(eventName, properties) {
		if (!_listeners[eventName]) { return; }
		properties.event = eventName;
		for (var i = 0; i < _listeners[eventName].length; i++) {
			_listeners[eventName][i](properties);
		}
	};

	/**
	* Creates an Object following the specified namespace identifier.
	*
	* @public
	* @param String identifier The namespace string
	* @param Object klasses (OPTIONAL) An object which properties will be added to the namespace
	* @return Object The most inner object
	*/
	var _namespace = function(identifier) {
		var klasses = arguments[1] || false;
		var ns = window;

		if (identifier !== '') {
			var parts = identifier.split(Namespace.separator);
			for (var i = 0; i < parts.length; i++) {
				if (!ns[parts[i]]) {
					ns[parts[i]] = {};
				}
				ns = ns[parts[i]];
			}
		}

		if (klasses) {
			for (var klass in klasses) {
				if (klasses.hasOwnProperty(klass)) {
					ns[klass] = klasses[klass];
				}
			}
		}

		_dispatchEvent('create', { 'identifier': identifier });
		return ns;
	};

	/**
	* Checks if the specified identifier is defined
	*
	* @public
	* @param String identifier The namespace string
	* @return Boolean
	*/
	_namespace.exist = function(identifier) {
		if (identifier === '') { return true; }

		var parts = identifier.split(Namespace.separator);
		var ns = window;
		for (var i = 0; i < parts.length; i++) {
			if (!ns[parts[i]]) {
				return false;
			}
			ns = ns[parts[i]];
		}

		return true;
	};

	/**
	* Maps an identifier to a uri. Is public so it can be overriden by custom scripts.
	*
	* @public
	* @param String identifier The namespace identifier
	* @return String The uri
	*/
	_namespace.mapIdentifierToUri = function(identifier) {
		var regexp = new RegExp('\\' + Namespace.separator, 'g');
		return Namespace.baseUri + identifier.replace(regexp, '/') + '.js';
	};

	/**
	* Loads a remote script atfer mapping the identifier to an uri
	*
	* @param String identifier The namespace identifier
	* @param Function successCallback When set, the file will be loaded asynchronously. Will be called when the file is loaded
	* @param Function errorCallback Callback to be called when an error occurs
	* @return Boolean Success of failure when loading synchronously
	*/
	var _loadScript = function(identifier) {
		var successCallback = arguments[1];
		var errorCallback = arguments[2];
		var async = typeof successCallback === "function";
		var uri = _namespace.mapIdentifierToUri(identifier);
		var event = { 'identifier': identifier, 'uri': uri, 'async': async, 'callback': successCallback };

		var xhr = _createXmlHttpRequest();
		xhr.open("GET", uri, async);

		if (async) {
			xhr.onreadystatechange = function() {
				if (xhr.readyState == 4) {
					if (_isHttpRequestSuccessful(xhr.status || 0)) {
						_createScript(xhr.responseText);
						_dispatchEvent('include', event);
						successCallback();
						return;
					}
					event.status = xhr.status;
					_dispatchEvent('includeError', event);
					if (typeof errorCallback === "function") {
						errorCallback();
					}
				}
			};
		}

		xhr.send(null);

		if (!async) {
			if (_isHttpRequestSuccessful(xhr.status || 0)) {
				_createScript(xhr.responseText);
				_dispatchEvent('include', event);
				return true;
			}
			event.status = xhr.status;
			_dispatchEvent('includeError', event);
			return false;
		}
	};

	/**
	* Includes a remote javascript file identified by the specified namespace string. The identifier
	* must point to a class. Separators in the string will be converted to slashes and the .js extension will be appended.
	*
	* @public
	* @param String identifier The namespace string
	* @param Function callback (OPTIONAL) A function to call when the remote script has been included
	*/
	_namespace.include = function(identifier) {
		var successCallback = arguments[1] || false;
		var errorCallback = arguments[2] || false;

		// checks if the identifier is not already included
		if (_includedIdentifiers[identifier]) {
			if (typeof successCallback === "function") { successCallback(); }
			return true;
		}

		if (successCallback) {
			_loadScript(identifier, function() {
				_includedIdentifiers[identifier] = true;
				successCallback();
			}, errorCallback);
		} else {
			if (_loadScript(identifier)) {
				_includedIdentifiers[identifier] = true;
				return true;
			}
			return false;
		}
	};

	/**
	* Imports properties from the specified namespace to the global space (ie. under window)
	*
	* The identifier string can contain the * wildcard character as its last segment (eg: com.test.*)
	* which will import all properties from the namespace.
	*
	* If not, the targeted namespace will be imported (ie. if com.test is imported, the test object
	* will now be global). If the targeted object is not found, it will be included using include().
	*
	* @public
	* @param String identifier The namespace string
	* @param Function callback (OPTIONAL) A function to call when the process is completed (including the include() if used)
	* @param Boolean autoInclude (OPTIONAL) Whether to automatically auto include the targeted object is not found. Default is Namespace.autoInclude
	*/
	_namespace.use = function(identifier) {
		var identifiers = _toArray(identifier);
		var callback = arguments[1] || false;
		var autoInclude = arguments.length > 2 ? arguments[2] : Namespace.autoInclude;
		var event = { 'identifier': identifier };
		var parts, target, ns;

		for (var i = 0; i < identifiers.length; i++) {
			identifier = identifiers[i];

			parts = identifier.split(Namespace.separator);
			target = parts.pop();
			ns = _namespace(parts.join(Namespace.separator));

			if (target == '*') {
				// imports all objects from the identifier, can't use include() in that case
				for (var objectName in ns) {
					if (ns.hasOwnProperty(objectName)) {
						window[objectName] = ns[objectName];
					}
				}
			} else {
				// imports only one object
				if (ns[target]) {
					// the object exists, import it
					window[target] = ns[target];
				} else {
					// the object does not exist
					if (autoInclude) {
						// try to auto include it
						if (callback) {
							_namespace.include(identifier, function() {
								window[target] = ns[target];

								if (i + 1 < identifiers.length) {
									// we continue to unpack the rest from here
									_namespace.unpack(identifiers.slice(i + 1), callback, autoInclude);
								} else {
									// no more identifiers to unpack
									_dispatchEvent('use', event);
									if (typeof callback === "function") {
										callback();
									}
								}
							});
							return;
						} else {
							_namespace.include(identifier);
							window[target] = ns[target];
						}
					}
				}
			}

		}

		// all identifiers have been unpacked
		_dispatchEvent('use', event);
		if (typeof callback === "function") { callback(); }
	};

	/**
	* Binds the include() and unpack() method to a specified identifier
	*
	* @public
	* @param String identifier The namespace identifier
	* @return Object
	*/
	_namespace.from = function(identifier) {
		return {
			/**
			* Includes the identifier specified in from()
			*
			* @see Namespace.include()
			*/
			include: function() {
				var callback = arguments[0] || false;
				_namespace.include(identifier, callback);
			},
			/**
			* Includes the identifier specified in from() and unpack
			* the specified indentifier in _identifier
			*
			* @see Namespace.use()
			*/
			use: function(_identifier) {
				var callback = arguments[1] || false;
				if (_identifier.charAt(0) == '.') {
					_identifier = identifier + _identifier;
				}

				if (callback) {
					_namespace.include(identifier, function() {
						_namespace.use(_identifier, callback, false);
					});
				} else {
					_namespace.include(identifier);
					_namespace.use(_identifier, callback, false);
				}
			}
		};
	};

	/**
	* Registers a namespace so it won't be included
	*
	* Idea and code submitted by Nathan Smith (http://github.com/smith)
	*
	* @param String|Array identifier
	*/
	_namespace.provide = function(identifier) {
		var identifiers = _toArray(identifier);

		for (var i = 0; i < identifiers.length; i++) {
			if (!(identifier in _includedIdentifiers)) {
				_dispatchEvent('provide', { 'identifier': identifier });
				_includedIdentifiers[identifier] = true;
			}
		}
	};

	/**
	* Registers a function to be called when the specified event is dispatched
	*
	* @param String eventName
	* @param Function callback
	*/
	_namespace.addEventListener = function(eventName, callback) {
		if (!_listeners[eventName]) { _listeners[eventName] = []; }
		_listeners[eventName].push(callback);
	};

	/**
	* Unregisters an event listener
	*
	* @param String eventName
	* @param Function callback
	*/
	_namespace.removeEventListener = function(eventName, callback) {
		if (!_listeners[eventName]) { return; }
		for (var i = 0; i < _listeners[eventName].length; i++) {
			if (_listeners[eventName][i] == callback) {
				delete _listeners[eventName][i];
				return;
			}
		}
	};

	/**
	* Adds methods to javascript native's object
	* Inspired by http://thinkweb2.com/projects/prototype/namespacing-made-easy/
	*
	* @public
	*/
	_namespace.registerNativeExtensions = function() {
		/**
		* @see Namespace()
		*/
		String.prototype.namespace = function() {
			var klasses = arguments[0] || {};
			return _namespace(this.valueOf(), klasses);
		};
		/**
		* @see Namespace.include()
		*/
		String.prototype.include = function() {
			var callback = arguments[0] || false;
			return _namespace.include(this.valueOf(), callback);
		};
		/**
		* @see Namespace.use()
		*/
		String.prototype.use = function() {
			var callback = arguments[0] || false;
			return _namespace.use(this.valueOf(), callback);
		};
		/**
		* @see Namespace.from()
		*/
		String.prototype.from = function() {
			return _namespace.from(this.valueOf());
		};
		/**
		* @see Namespace.provide()
		* Idea and code submitted by Nathan Smith (http://github.com/smith)
		*/
		String.prototype.provide = function() {
			return _namespace.provide(this.valueOf());
		};
		/**
		* @see Namespace.use()
		*/
		Array.prototype.use = function() {
			var callback = arguments[0] || false;
			return _namespace.use(this, callback);
		};
		/**
		* @see Namespace.provide()
		*/
		Array.prototype.provide = function() {
			return _namespace.provide(this);
		};
	};

	return _namespace;
})();

/**
* Namespace segment separator
*
* @var String
*/
Namespace.separator = '.';

/**
* Base uri when using Namespace.include()
* Must end with a slash
*
* @var String
*/
Namespace.baseUri = './';

/**
* Whether to automatically call Namespace.include() when Namespace.import()
* does not find the targeted object.
*
* @var Boolean
*/
Namespace.autoInclude = true;