/*
---

name: Element.defineCustomEvent

description: Allows to create custom events based on other custom events.

authors: Christoph Pojer (@cpojer)

license: MIT-style license.

requires: [Core/Element.Event]

provides: Element.defineCustomEvent

...
*/

(function(){

[Element, Window, Document].invoke('implement', {hasEvent: function(event){
	var events = this.retrieve('events'),
		list = (events && events[event]) ? events[event].values : null;
	if (list){
		var i = list.length;
		while (i--) if (i in list){
			return true;
		}
	}
	return false;
}});

var wrap = function(custom, method, extended){
	method = custom[method];
	extended = custom[extended];

	return function(fn, name){
		if (extended && !this.hasEvent(name)) extended.call(this, fn, name);
		if (method) method.call(this, fn, name);
	};
};

var inherit = function(custom, base, method){
	return function(fn, name){
		base[method].call(this, fn, name);
		custom[method].call(this, fn, name);
	};
};

var events = Element.Events;

Element.defineCustomEvent = function(name, custom){
	var base = events[custom.base];

	custom.onAdd = wrap(custom, 'onAdd', 'onSetup');
	custom.onRemove = wrap(custom, 'onRemove', 'onTeardown');

	events[name] = base ? Object.append({}, custom, {

		base: base.base,

		condition: function(event, name){
			return (!base.condition || base.condition.call(this, event, name)) &&
				(!custom.condition || custom.condition.call(this, event, name));
		},

		onAdd: inherit(custom, base, 'onAdd'),
		onRemove: inherit(custom, base, 'onRemove')

	}) : custom;

	return this;
};

Element.enableCustomEvents = function(){
  Object.each(events, function(event, name){
    if (event.onEnable) event.onEnable.call(event, name);
  });
};

Element.disableCustomEvents = function(){
  Object.each(events, function(event, name){
    if (event.onDisable) event.onDisable.call(event, name);
  });
};

})();