fullcalendar/src/common/Model.js

var Model = Class.extend(EmitterMixin, ListenerMixin, {

	_props: null,
	_watchers: null,
	_globalWatchArgs: null,

	constructor: function() {
		this._watchers = {};
		this._props = {};
		this.applyGlobalWatchers();
		this.constructed();
	},

	// useful for monkeypatching. TODO: BaseClass?
	constructed: function() {
	},

	applyGlobalWatchers: function() {
		var argSets = this._globalWatchArgs || [];
		var i;

		for (i = 0; i < argSets.length; i++) {
			this.watch.apply(this, argSets[i]);
		}
	},

	has: function(name) {
		return name in this._props;
	},

	get: function(name) {
		if (name === undefined) {
			return this._props;
		}

		return this._props[name];
	},

	set: function(name, val) {
		var newProps;

		if (typeof name === 'string') {
			newProps = {};
			newProps[name] = val === undefined ? null : val;
		}
		else {
			newProps = name;
		}

		this.setProps(newProps);
	},

	reset: function(newProps) {
		var oldProps = this._props;
		var changeset = {}; // will have undefined's to signal unsets
		var name;

		for (name in oldProps) {
			changeset[name] = undefined;
		}

		for (name in newProps) {
			changeset[name] = newProps[name];
		}

		this.setProps(changeset);
	},

	unset: function(name) { // accepts a string or array of strings
		var newProps = {};
		var names;
		var i;

		if (typeof name === 'string') {
			names = [ name ];
		}
		else {
			names = name;
		}

		for (i = 0; i < names.length; i++) {
			newProps[names[i]] = undefined;
		}

		this.setProps(newProps);
	},

	setProps: function(newProps) {
		var changedProps = {};
		var changedCnt = 0;
		var name, val;

		for (name in newProps) {
			val = newProps[name];

			// a change in value?
			// if an object, don't check equality, because might have been mutated internally.
			// TODO: eventually enforce immutability.
			if (
				typeof val === 'object' ||
				val !== this._props[name]
			) {
				changedProps[name] = val;
				changedCnt++;
			}
		}

		if (changedCnt) {

			this.trigger('before:batchChange', changedProps);

			for (name in changedProps) {
				val = changedProps[name];

				this.trigger('before:change', name, val);
				this.trigger('before:change:' + name, val);
			}

			for (name in changedProps) {
				val = changedProps[name];

				if (val === undefined) {
					delete this._props[name];
				}
				else {
					this._props[name] = val;
				}

				this.trigger('change:' + name, val);
				this.trigger('change', name, val);
			}

			this.trigger('batchChange', changedProps);
		}
	},

	watch: function(name, depList, startFunc, stopFunc) {
		var _this = this;

		this.unwatch(name);

		this._watchers[name] = this._watchDeps(depList, function(deps) {
			var res = startFunc.call(_this, deps);

			if (res && res.then) {
				_this.unset(name); // put in an unset state while resolving
				res.then(function(val) {
					_this.set(name, val);
				});
			}
			else {
				_this.set(name, res);
			}
		}, function(deps) {
			_this.unset(name);

			if (stopFunc) {
				stopFunc.call(_this, deps);
			}
		});
	},

	unwatch: function(name) {
		var watcher = this._watchers[name];

		if (watcher) {
			delete this._watchers[name];
			watcher.teardown();
		}
	},

	_watchDeps: function(depList, startFunc, stopFunc) {
		var _this = this;
		var queuedChangeCnt = 0;
		var depCnt = depList.length;
		var satisfyCnt = 0;
		var values = {}; // what's passed as the `deps` arguments
		var bindTuples = []; // array of [ eventName, handlerFunc ] arrays
		var isCallingStop = false;

		function onBeforeDepChange(depName, val, isOptional) {
			queuedChangeCnt++;
			if (queuedChangeCnt === 1) { // first change to cause a "stop" ?
				if (satisfyCnt === depCnt) { // all deps previously satisfied?
					isCallingStop = true;
					stopFunc(values);
					isCallingStop = false;
				}
			}
		}

		function onDepChange(depName, val, isOptional) {

			if (val === undefined) { // unsetting a value?

				// required dependency that was previously set?
				if (!isOptional && values[depName] !== undefined) {
					satisfyCnt--;
				}

				delete values[depName];
			}
			else { // setting a value?

				// required dependency that was previously unset?
				if (!isOptional && values[depName] === undefined) {
					satisfyCnt++;
				}

				values[depName] = val;
			}

			queuedChangeCnt--;
			if (!queuedChangeCnt) { // last change to cause a "start"?

				// now finally satisfied or satisfied all along?
				if (satisfyCnt === depCnt) {

					// if the stopFunc initiated another value change, ignore it.
					// it will be processed by another change event anyway.
					if (!isCallingStop) {
						startFunc(values);
					}
				}
			}
		}

		// intercept for .on() that remembers handlers
		function bind(eventName, handler) {
			_this.on(eventName, handler);
			bindTuples.push([ eventName, handler ]);
		}

		// listen to dependency changes
		depList.forEach(function(depName) {
			var isOptional = false;

			if (depName.charAt(0) === '?') { // TODO: more DRY
				depName = depName.substring(1);
				isOptional = true;
			}

			bind('before:change:' + depName, function(val) {
				onBeforeDepChange(depName, val, isOptional);
			});

			bind('change:' + depName, function(val) {
				onDepChange(depName, val, isOptional);
			});
		});

		// process current dependency values
		depList.forEach(function(depName) {
			var isOptional = false;

			if (depName.charAt(0) === '?') { // TODO: more DRY
				depName = depName.substring(1);
				isOptional = true;
			}

			if (_this.has(depName)) {
				values[depName] = _this.get(depName);
				satisfyCnt++;
			}
			else if (isOptional) {
				satisfyCnt++;
			}
		});

		// initially satisfied
		if (satisfyCnt === depCnt) {
			startFunc(values);
		}

		return {
			teardown: function() {
				// remove all handlers
				for (var i = 0; i < bindTuples.length; i++) {
					_this.off(bindTuples[i][0], bindTuples[i][1]);
				}
				bindTuples = null;

				// was satisfied, so call stopFunc
				if (satisfyCnt === depCnt) {
					stopFunc();
				}
			},
			flash: function() {
				if (satisfyCnt === depCnt) {
					stopFunc();
					startFunc(values);
				}
			}
		};
	},

	flash: function(name) {
		var watcher = this._watchers[name];

		if (watcher) {
			watcher.flash();
		}
	}

});


Model.watch = function(/* same arguments as this.watch() */) {
	// creates new array every time, to not mess with subclass prototypes
	// TODO: make more efficient
	this.prototype._globalWatchArgs = (this.prototype._globalWatchArgs || []).concat(arguments);
};


FC.Model = Model;