/*
 * Ext JS Library 2.0 Copyright(c) 2006-2007, Ext JS, LLC. licensing@extjs.com
 * 
 * http://extjs.com/license
 */

/**
 * @class Ext.dd.Registry Provides easy access to all drag drop components that
 *        are registered on a page. Items can be retrieved either directly by
 *        DOM node id, or by passing in the drag drop event that occurred and
 *        looking up the event target.
 * @singleton
 */
Ext.dd.Registry = function() {
	var elements = {};
	var handles = {};
	var autoIdSeed = 0;

	var getId = function(el, autogen) {
		if (typeof el == "string") {
			return el;
		}
		var id = el.id;
		if (!id && autogen !== false) {
			id = "extdd-" + (++autoIdSeed);
			el.id = id;
		}
		return id;
	};

	return {
		/**
		 * Resgister a drag drop element
		 * 
		 * @param {String/HTMLElement)
		 *            element The id or DOM node to register
		 * @param {Object}
		 *            data (optional) An custom data object that will be passed
		 *            between the elements that are involved in drag drop
		 *            operations. You can populate this object with any
		 *            arbitrary properties that your own code knows how to
		 *            interpret, plus there are some specific properties known
		 *            to the Registry that should be populated in the data
		 *            object (if applicable):
		 * 
		 * <pre>
		 * Value      Description
		 * <br />
		 * ---------  ------------------------------------------
		 * <br />
		 * handles    Array of DOM nodes that trigger dragging
		 * <br />
		 * for the element being registered
		 * <br />
		 * isHandle
		 * True if the element passed in triggers
		 * <br />
		 * 		       dragging itself, else false
		 * 		
		 * </pre>
		 */
		register : function(el, data) {
			data = data || {};
			if (typeof el == "string") {
				el = document.getElementById(el);
			}
			data.ddel = el;
			elements[getId(el)] = data;
			if (data.isHandle !== false) {
				handles[data.ddel.id] = data;
			}
			if (data.handles) {
				var hs = data.handles;
				for (var i = 0, len = hs.length; i < len; i++) {
					handles[getId(hs[i])] = data;
				}
			}
		},

		/**
		 * Unregister a drag drop element
		 * 
		 * @param {String/HTMLElement)
		 *            element The id or DOM node to unregister
		 */
		unregister : function(el) {
			var id = getId(el, false);
			var data = elements[id];
			if (data) {
				delete elements[id];
				if (data.handles) {
					var hs = data.handles;
					for (var i = 0, len = hs.length; i < len; i++) {
						delete handles[getId(hs[i], false)];
					}
				}
			}
		},

		/**
		 * Returns the handle registered for a DOM Node by id
		 * 
		 * @param {String/HTMLElement}
		 *            id The DOM node or id to look up
		 * @return {Object} handle The custom handle data
		 */
		getHandle : function(id) {
			if (typeof id != "string") { // must be element?
				id = id.id;
			}
			return handles[id];
		},

		/**
		 * Returns the handle that is registered for the DOM node that is the
		 * target of the event
		 * 
		 * @param {Event}
		 *            e The event
		 * @return {Object} handle The custom handle data
		 */
		getHandleFromEvent : function(e) {
			var t = Ext.lib.Event.getTarget(e);
			return t ? handles[t.id] : null;
		},

		/**
		 * Returns a custom data object that is registered for a DOM node by id
		 * 
		 * @param {String/HTMLElement}
		 *            id The DOM node or id to look up
		 * @return {Object} data The custom data
		 */
		getTarget : function(id) {
			if (typeof id != "string") { // must be element?
				id = id.id;
			}
			return elements[id];
		},

		/**
		 * Returns a custom data object that is registered for the DOM node that
		 * is the target of the event
		 * 
		 * @param {Event}
		 *            e The event
		 * @return {Object} data The custom data
		 */
		getTargetFromEvent : function(e) {
			var t = Ext.lib.Event.getTarget(e);
			return t ? elements[t.id] || handles[t.id] : null;
		}
	};
}();