/*
 * Ext JS Library 2.0 Copyright(c) 2006-2007, Ext JS, LLC. licensing@extjs.com
 * 
 * http://extjs.com/license
 */

/**
 * @class Ext.util.Observable Abstract base class that provides a common
 *        interface for publishing events. Subclasses are expected to to have a
 *        property "events" with all the events defined.<br>
 *        For example:
 * 
 * <pre><code>
 * Employee = function(name) {
 * 	this.name = name;
 * 	this.addEvents({
 * 				&quot;fired&quot; : true,
 * 				&quot;quit&quot; : true
 * 			});
 * }
 * Ext.extend(Employee, Ext.util.Observable);
 * </code></pre>
 */
Ext.util.Observable = function() {
	/**
	 * @cfg {Object} listeners A config object containing one or more event
	 *      handlers to be added to this object during initialization. This
	 *      should be a valid listeners config object as specified in the
	 *      {@link #addListener} example for attaching multiple handlers at
	 *      once.
	 */
	if (this.listeners) {
		this.on(this.listeners);
		delete this.listeners;
	}
};
Ext.util.Observable.prototype = {
	/**
	 * Fires the specified event with the passed parameters (minus the event
	 * name).
	 * 
	 * @param {String}
	 *            eventName
	 * @param {Object...}
	 *            args Variable number of parameters are passed to handlers
	 * @return {Boolean} returns false if any of the handlers return false
	 *         otherwise it returns true
	 */
	fireEvent : function() {
		if (this.eventsSuspended !== true) {
			var ce = this.events[arguments[0].toLowerCase()];
			if (typeof ce == "object") {
				return ce.fire.apply(ce, Array.prototype.slice.call(arguments,
								1));
			}
		}
		return true;
	},

	// private
	filterOptRe : /^(?:scope|delay|buffer|single)$/,

	/**
	 * Appends an event handler to this component
	 * 
	 * @param {String}
	 *            eventName The type of event to listen for
	 * @param {Function}
	 *            handler The method the event invokes
	 * @param {Object}
	 *            scope (optional) The scope in which to execute the handler
	 *            function. The handler function's "this" context.
	 * @param {Object}
	 *            options (optional) An object containing handler configuration
	 *            properties. This may contain any of the following properties:
	 *            <ul>
	 *            <li><b>scope</b> : Object
	 *            <p class="sub-desc">
	 *            The scope in which to execute the handler function. The
	 *            handler function's "this" context.
	 *            </p>
	 *            </li>
	 *            <li><b>delay</b> : Number
	 *            <p class="sub-desc">
	 *            The number of milliseconds to delay the invocation of the
	 *            handler after the event fires.
	 *            </p>
	 *            </li>
	 *            <li><b>single</b> : Boolean
	 *            <p class="sub-desc">
	 *            True to add a handler to handle just the next firing of the
	 *            event, and then remove itself.
	 *            </p>
	 *            </li>
	 *            <li>buffer {Number} Causes the handler to be scheduled to run
	 *            in an {@link Ext.util.DelayedTask} delayed by the specified
	 *            number of milliseconds. If the event fires again within that
	 *            time, the original handler is <em>not</em> invoked, but the
	 *            new handler is scheduled in its place.</li>
	 *            </ul>
	 *            <br>
	 *            <p>
	 *            <b>Combining Options</b><br>
	 *            Using the options argument, it is possible to combine
	 *            different types of listeners:<br>
	 *            <br>
	 *            A normalized, delayed, one-time listener that auto stops the
	 *            event and passes a custom argument (forumId)
	 * 
	 * <pre><code>
	 * el.on('click', this.onClick, this, {
	 * 			single : true,
	 * 			delay : 100,
	 * 			forumId : 4
	 * 		});
	 * </code></pre>
	 * 
	 * <p>
	 *            <b>Attaching multiple handlers in 1 call</b><br>
	 *            The method also allows for a single argument to be passed
	 *            which is a config object containing properties which specify
	 *            multiple handlers.
	 *            <p>
	 * 
	 * <pre><code>
	 * foo.on({
	 * 			'click' : {
	 * 				fn : this.onClick,
	 * 				scope : this,
	 * 				delay : 100
	 * 			},
	 * 			'mouseover' : {
	 * 				fn : this.onMouseOver,
	 * 				scope : this
	 * 			},
	 * 			'mouseout' : {
	 * 				fn : this.onMouseOut,
	 * 				scope : this
	 * 			}
	 * 		});
	 * </code></pre>
	 * 
	 * <p>
	 *            Or a shorthand syntax:<br>
	 * 
	 * <pre><code>
	 * foo.on({
	 * 			'click' : this.onClick,
	 * 			'mouseover' : this.onMouseOver,
	 * 			'mouseout' : this.onMouseOut,
	 * 			scope : this
	 * 		});
	 * </code></pre>
	 */
	addListener : function(eventName, fn, scope, o) {
		if (typeof eventName == "object") {
			o = eventName;
			for (var e in o) {
				if (this.filterOptRe.test(e)) {
					continue;
				}
				if (typeof o[e] == "function") {
					// shared options
					this.addListener(e, o[e], o.scope, o);
				} else {
					// individual options
					this.addListener(e, o[e].fn, o[e].scope, o[e]);
				}
			}
			return;
		}
		o = (!o || typeof o == "boolean") ? {} : o;
		eventName = eventName.toLowerCase();
		var ce = this.events[eventName] || true;
		if (typeof ce == "boolean") {
			ce = new Ext.util.Event(this, eventName);
			this.events[eventName] = ce;
		}
		ce.addListener(fn, scope, o);
	},

	/**
	 * Removes a listener
	 * 
	 * @param {String}
	 *            eventName The type of event to listen for
	 * @param {Function}
	 *            handler The handler to remove
	 * @param {Object}
	 *            scope (optional) The scope (this object) for the handler
	 */
	removeListener : function(eventName, fn, scope) {
		var ce = this.events[eventName.toLowerCase()];
		if (typeof ce == "object") {
			ce.removeListener(fn, scope);
		}
	},

	/**
	 * Removes all listeners for this object
	 */
	purgeListeners : function() {
		for (var evt in this.events) {
			if (typeof this.events[evt] == "object") {
				this.events[evt].clearListeners();
			}
		}
	},

	relayEvents : function(o, events) {
		var createHandler = function(ename) {
			return function() {
				return this.fireEvent.apply(this, Ext.combine(ename,
								Array.prototype.slice.call(arguments, 0)));
			};
		};
		for (var i = 0, len = events.length; i < len; i++) {
			var ename = events[i];
			if (!this.events[ename]) {
				this.events[ename] = true;
			};
			o.on(ename, createHandler(ename), this);
		}
	},

	/**
	 * Used to define events on this Observable
	 * 
	 * @param {Object}
	 *            object The object with the events defined
	 */
	addEvents : function(o) {
		if (!this.events) {
			this.events = {};
		}
		if (typeof o == 'string') {
			for (var i = 0, a = arguments, v; v = a[i]; i++) {
				if (!this.events[a[i]]) {
					o[a[i]] = true;
				}
			}
		} else {
			Ext.applyIf(this.events, o);
		}
	},

	/**
	 * Checks to see if this object has any listeners for a specified event
	 * 
	 * @param {String}
	 *            eventName The name of the event to check for
	 * @return {Boolean} True if the event is being listened for, else false
	 */
	hasListener : function(eventName) {
		var e = this.events[eventName];
		return typeof e == "object" && e.listeners.length > 0;
	},

	/**
	 * Suspend the firing of all events. (see {@link #resumeEvents})
	 */
	suspendEvents : function() {
		this.eventsSuspended = true;
	},

	/**
	 * Resume firing events. (see {@link #suspendEvents})
	 */
	resumeEvents : function() {
		this.eventsSuspended = false;
	},

	// these are considered experimental
	// allows for easier interceptor and sequences, including cancelling and
	// overwriting the return value of the call
	// private
	getMethodEvent : function(method) {
		if (!this.methodEvents) {
			this.methodEvents = {};
		}
		var e = this.methodEvents[method];
		if (!e) {
			e = {};
			this.methodEvents[method] = e;

			e.originalFn = this[method];
			e.methodName = method;
			e.before = [];
			e.after = [];

			var returnValue, v, cancel;
			var obj = this;

			var makeCall = function(fn, scope, args) {
				if ((v = fn.apply(scope || obj, args)) !== undefined) {
					if (typeof v === 'object') {
						if (v.returnValue !== undefined) {
							returnValue = v.returnValue;
						} else {
							returnValue = v;
						}
						if (v.cancel === true) {
							cancel = true;
						}
					} else if (v === false) {
						cancel = true;
					} else {
						returnValue = v;
					}
				}
			}

			this[method] = function() {
				returnValue = v = undefined;
				cancel = false;
				var args = Array.prototype.slice.call(arguments, 0);
				for (var i = 0, len = e.before.length; i < len; i++) {
					makeCall(e.before[i].fn, e.before[i].scope, args);
					if (cancel) {
						return returnValue;
					}
				}

				if ((v = e.originalFn.apply(obj, args)) !== undefined) {
					returnValue = v;
				}

				for (var i = 0, len = e.after.length; i < len; i++) {
					makeCall(e.after[i].fn, e.after[i].scope, args);
					if (cancel) {
						return returnValue;
					}
				}
				return returnValue;
			};
		}
		return e;
	},

	// adds an "interceptor" called before the original method
	beforeMethod : function(method, fn, scope) {
		var e = this.getMethodEvent(method);
		e.before.push({
					fn : fn,
					scope : scope
				});
	},

	// adds a "sequence" called after the original method
	afterMethod : function(method, fn, scope) {
		var e = this.getMethodEvent(method);
		e.after.push({
					fn : fn,
					scope : scope
				});
	},

	removeMethodListener : function(method, fn, scope) {
		var e = this.getMethodEvent(method);
		for (var i = 0, len = e.before.length; i < len; i++) {
			if (e.before[i].fn == fn && e.before[i].scope == scope) {
				e.before.splice(i, 1);
				return;
			}
		}
		for (var i = 0, len = e.after.length; i < len; i++) {
			if (e.after[i].fn == fn && e.after[i].scope == scope) {
				e.after.splice(i, 1);
				return;
			}
		}
	}
};
/**
 * Appends an event handler to this element (shorthand for addListener)
 * 
 * @param {String}
 *            eventName The type of event to listen for
 * @param {Function}
 *            handler The method the event invokes
 * @param {Object}
 *            scope (optional) The scope in which to execute the handler
 *            function. The handler function's "this" context.
 * @param {Object}
 *            options (optional)
 * @method
 */
Ext.util.Observable.prototype.on = Ext.util.Observable.prototype.addListener;
/**
 * Removes a listener (shorthand for removeListener)
 * 
 * @param {String}
 *            eventName The type of event to listen for
 * @param {Function}
 *            handler The handler to remove
 * @param {Object}
 *            scope (optional) The scope (this object) for the handler
 * @method
 */
Ext.util.Observable.prototype.un = Ext.util.Observable.prototype.removeListener;

/**
 * Starts capture on the specified Observable. All events will be passed to the
 * supplied function with the event name + standard signature of the event
 * <b>before</b> the event is fired. If the supplied function returns false,
 * the event will not fire.
 * 
 * @param {Observable}
 *            o The Observable to capture
 * @param {Function}
 *            fn The function to call
 * @param {Object}
 *            scope (optional) The scope (this object) for the fn
 * @static
 */
Ext.util.Observable.capture = function(o, fn, scope) {
	o.fireEvent = o.fireEvent.createInterceptor(fn, scope);
};

/**
 * Removes <b>all</b> added captures from the Observable.
 * 
 * @param {Observable}
 *            o The Observable to release
 * @static
 */
Ext.util.Observable.releaseCapture = function(o) {
	o.fireEvent = Ext.util.Observable.prototype.fireEvent;
};

(function() {

	var createBuffered = function(h, o, scope) {
		var task = new Ext.util.DelayedTask();
		return function() {
			task.delay(o.buffer, h, scope, Array.prototype.slice.call(
							arguments, 0));
		};
	};

	var createSingle = function(h, e, fn, scope) {
		return function() {
			e.removeListener(fn, scope);
			return h.apply(scope, arguments);
		};
	};

	var createDelayed = function(h, o, scope) {
		return function() {
			var args = Array.prototype.slice.call(arguments, 0);
			setTimeout(function() {
						h.apply(scope, args);
					}, o.delay || 10);
		};
	};

	Ext.util.Event = function(obj, name) {
		this.name = name;
		this.obj = obj;
		this.listeners = [];
	};

	Ext.util.Event.prototype = {
		addListener : function(fn, scope, options) {
			scope = scope || this.obj;
			if (!this.isListening(fn, scope)) {
				var l = this.createListener(fn, scope, options);
				if (!this.firing) {
					this.listeners.push(l);
				} else { // if we are currently firing this event, don't
							// disturb the listener loop
					this.listeners = this.listeners.slice(0);
					this.listeners.push(l);
				}
			}
		},

		createListener : function(fn, scope, o) {
			o = o || {};
			scope = scope || this.obj;
			var l = {
				fn : fn,
				scope : scope,
				options : o
			};
			var h = fn;
			if (o.delay) {
				h = createDelayed(h, o, scope);
			}
			if (o.single) {
				h = createSingle(h, this, fn, scope);
			}
			if (o.buffer) {
				h = createBuffered(h, o, scope);
			}
			l.fireFn = h;
			return l;
		},

		findListener : function(fn, scope) {
			scope = scope || this.obj;
			var ls = this.listeners;
			for (var i = 0, len = ls.length; i < len; i++) {
				var l = ls[i];
				if (l.fn == fn && l.scope == scope) {
					return i;
				}
			}
			return -1;
		},

		isListening : function(fn, scope) {
			return this.findListener(fn, scope) != -1;
		},

		removeListener : function(fn, scope) {
			var index;
			if ((index = this.findListener(fn, scope)) != -1) {
				if (!this.firing) {
					this.listeners.splice(index, 1);
				} else {
					this.listeners = this.listeners.slice(0);
					this.listeners.splice(index, 1);
				}
				return true;
			}
			return false;
		},

		clearListeners : function() {
			this.listeners = [];
		},

		fire : function() {
			var ls = this.listeners, scope, len = ls.length;
			if (len > 0) {
				this.firing = true;
				var args = Array.prototype.slice.call(arguments, 0);
				for (var i = 0; i < len; i++) {
					var l = ls[i];
					if (l.fireFn
							.apply(l.scope || this.obj || window, arguments) === false) {
						this.firing = false;
						return false;
					}
				}
				this.firing = false;
			}
			return true;
		}
	};
})();