dojo.provide("dojo.Stateful");

dojo.declare("dojo.Stateful", null, {
	// summary:
	//		Base class for objects that provide named properties with optional getter/setter
	//		control and the ability to watch for property changes
	// example:
	//	|	var obj = new dojo.Stateful();
	//	|	obj.watch("foo", function(){
	//	|		console.log("foo changed to " + this.get("foo"));
	//	|	});
	//	|	obj.set("foo","bar");
	postscript: function(mixin){
		if(mixin){
			dojo.mixin(this, mixin);
		}
	},
	
	get: function(/*String*/name){
		// summary:
		//		Get a property on a Stateful instance.
		//	name:
		//		The property to get.
		// description:
		//		Get a named property on a Stateful object. The property may
		//		potentially be retrieved via a getter method in subclasses. In the base class
		// 		this just retrieves the object's property. 
		// 		For example:
		//	|	stateful = new dojo.Stateful({foo: 3});
		//	|	stateful.get("foo") // returns 3
		//	|	stateful.foo // returns 3
		
		return this[name];
	},
	set: function(/*String*/name, /*Object*/value){
		// summary:
		//		Set a property on a Stateful instance
		//	name:
		//		The property to set. 
		//	value:
		//		The value to set in the property.
		// description:
		//		Sets named properties on a stateful object and notifies any watchers of 
		// 		the property. A programmatic setter may be defined in subclasses.
		// 		For example:
		//	|	stateful = new dojo.Stateful();
		//	|	stateful.watch(function(name, oldValue, value){
		//	|		// this will be called on the set below
		//	|	}
		//	|	stateful.set(foo, 5);
		//
		//	set() may also be called with a hash of name/value pairs, ex:
		//	|	myObj.set({
		//	|		foo: "Howdy",
		//	|		bar: 3
		//	|	})
		//	This is equivalent to calling set(foo, "Howdy") and set(bar, 3)
		if(typeof name === "object"){
			for(var x in name){
				this.set(x, name[x]); 
			}
			return this;
		}
		var oldValue = this[name];
		this[name] = value;
		if(this._watchCallbacks){
			this._watchCallbacks(name, oldValue, value);
		}
		return this;
	},
	watch: function(/*String?*/name, /*Function*/callback){
		// summary:
		//		Watches a property for changes
		//	name:
		//		Indicates the property to watch. This is optional (the callback may be the 
		// 		only parameter), and if omitted, all the properties will be watched
		// returns:
		//		An object handle for the watch. The unwatch method of this object 
		// 		can be used to discontinue watching this property:
		//		|	var watchHandle = obj.watch("foo", callback);
		//		|	watchHandle.unwatch(); // callback won't be called now
		//	callback:
		//		The function to execute when the property changes. This will be called after
		//		the property has been changed. The callback will be called with the |this|
		//		set to the instance, the first argument as the name of the property, the 
		// 		second argument as the old value and the third argument as the new value.
		
		var callbacks = this._watchCallbacks;
		if(!callbacks){
			var self = this;
			callbacks = this._watchCallbacks = function(name, oldValue, value, ignoreCatchall){
				var notify = function(propertyCallbacks){
					for(var i = 0, l = propertyCallbacks && propertyCallbacks.length; i < l; i++){
						try{
							propertyCallbacks[i].call(self, name, oldValue, value);
						}catch(e){
							console.error(e);
						}
					}
				};
				notify(callbacks[name]);
				if(!ignoreCatchall){
					notify(callbacks["*"]); // the catch-all
				}
			}; // we use a function instead of an object so it will be ignored by JSON conversion
		}
		if(!callback && typeof name === "function"){
			callback = name;
			name = "*";
		}
		var propertyCallbacks = callbacks[name];
		if(typeof propertyCallbacks !== "object"){
			propertyCallbacks = callbacks[name] = [];
		}
		propertyCallbacks.push(callback);
		return {
			unwatch: function(){
				propertyCallbacks.splice(dojo.indexOf(propertyCallbacks, callback), 1);
			}
		};
	}
	
});