/*
* Metadata - jQuery plugin for parsing metadata from elements
*
* Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
*
* Dual licensed under the MIT and GPL licenses:
*   http://www.opensource.org/licenses/mit-license.php
*   http://www.gnu.org/licenses/gpl.html
*
* Revision: $Id: jquery.metadata.js 4187 2007-12-16 17:15:27Z joern.zaefferer $
*
*/

/**
* Sets the type of metadata to use. Metadata is encoded in JSON, and each property
* in the JSON will become a property of the element itself.
*
* There are three supported types of metadata storage:
*
*   attr:  Inside an attribute. The name parameter indicates *which* attribute.
*          
*   class: Inside the class attribute, wrapped in curly braces: { }
*   
*   elem:  Inside a child element (e.g. a script tag). The
*          name parameter indicates *which* element.
*          
* The metadata for an element is loaded the first time the element is accessed via jQuery.
*
* As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
* matched by expr, then redefine the metadata type and run another $(expr) for other elements.
* 
* @name $.metadata.setType
*
* @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("class")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from the class attribute
* 
* @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("attr", "data")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a "data" attribute
* 
* @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
* @before $.metadata.setType("elem", "script")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a nested script element
* 
* @param String type The encoding type
* @param String name The name of the attribute to be used to get metadata (optional)
* @cat Plugins/Metadata
* @descr Sets the type of encoding to be used when loading metadata for the first time
* @type undefined
* @see metadata()
*/

(function($)
{

	$.extend({
		metadata: {
			defaults: {
				type: 'class',
				name: 'metadata',
				cre: /({.*})/,
				single: 'metadata'
			},
			setType: function(type, name)
			{
				this.defaults.type = type;
				this.defaults.name = name;
			},
			get: function(elem, opts)
			{
				var settings = $.extend({}, this.defaults, opts);
				// check for empty string in single property
				if (!settings.single.length) settings.single = 'metadata';

				var data = $.data(elem, settings.single);
				// returned cached data if it already exists
				if (data) return data;

				data = "{}";

				if (settings.type == "class")
				{
					var m = settings.cre.exec(elem.className);
					if (m)
						data = m[1];
				} else if (settings.type == "elem")
				{
					if (!elem.getElementsByTagName)
						return undefined;
					var e = elem.getElementsByTagName(settings.name);
					if (e.length)
						data = $.trim(e[0].innerHTML);
				} else if (elem.getAttribute != undefined)
				{
					var attr = elem.getAttribute(settings.name);
					if (attr)
						data = attr;
				}

				if (data.indexOf('{') < 0)
					data = "{" + data + "}";

				data = eval("(" + data + ")");

				$.data(elem, settings.single, data);
				return data;
			}
		}
	});

	/**
	* Returns the metadata object for the first member of the jQuery object.
	*
	* @name metadata
	* @descr Returns element's metadata object
	* @param Object opts An object contianing settings to override the defaults
	* @type jQuery
	* @cat Plugins/Metadata
	*/
	$.fn.metadata = function(opts)
	{
		return $.metadata.get(this[0], opts);
	};

})(jQuery);