// Copyright (c) 2009 Daniel Wachsstock
// MIT license:
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:

// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
(function($) {
	// from http://groups.google.com/group/comp.lang.javascript/msg/e04726a66face2a2 and
	// http://webreflection.blogspot.com/2008/10/big-douglas-begetobject-revisited.html
	var object = (function(F) {
		return (function(o) {
			F.prototype = o;
			return new F();
		});
	})(function() { });

	// create a widget subclass
	var OVERRIDE = /xyz/.test(function() { xyz; }) ? /\b_super\b/ : /.*/;
	$.subclassWidget = function subclass(name, base) {
		$.widget(name); // Slightly inefficient to create a widget only to discard its prototype, but it's not too bad
		name = name.split('.');
		var widget = $[name[0]][name[1]], superclass = base, superproto = superclass.prototype;


		var proto = arguments[0] = widget.prototype = object(superproto); // inherit from the superclass
		$.extend.apply(null, arguments); // and add other add-in methods to the prototype
		widget.subclass = subclass;

		// Subtle point: we want to call superclass init and destroy if they exist
		// (otherwise the user of this function would have to keep track of all that)
		for (key in proto) if (proto.hasOwnProperty(key)) switch (key) {
			case '_create':
				var create = proto._create;
				proto._create = function() {
					superproto._create.apply(this);
					create.apply(this);
				};
				break;
			case '_init':
				var init = proto._init;
				proto._init = function() {
					superproto._init.apply(this);
					init.apply(this);
				};
				break;
			case 'destroy':
				var destroy = proto.destroy;
				proto.destroy = function() {
					destroy.apply(this);
					superproto.destroy.apply(this);
				};
				break;
			case 'options':
				var options = proto.options;
				proto.options = $.extend({}, superproto.options, options);
				break;
			default:
				if ($.isFunction(proto[key]) && $.isFunction(superproto[key]) && OVERRIDE.test(proto[key])) {
					proto[key] = (function(name, fn) {
						return function() {
							var tmp = this._super;
							this._super = superproto[name];
							try { var ret = fn.apply(this, arguments); }
							finally { this._super = tmp; }
							return ret;
						};
					})(key, proto[key]);
				}
				break;
		}
	};
})(jQuery)