/**
 * Class to handle the URL.
 **/
Vn.Hash = new Class
({
	Extends: Vn.Object

	,hash: null
	,hashMap: {}

	,initialize: function ()
	{
		this.hashChangedHandler = this.hashChanged.bind (this);
		window.addEventListener ('hashchange', this.hashChangedHandler);
		this.hashChanged ();
	}

	,destroy: function ()
	{
		this.parent ();
		window.removeEventListener ('hashchange', this.hashChangedHandler);
	}

	/**
	 * Gets the hash part of the URL.
	 *
	 * @param {string} key The variable name
	 **/
	,get: function (key)
	{
		return this.hashMap[key];
	}
	
	/**
	 * Sets the hash part of the URL, respecting the current hash variables.
	 *
	 * @param {Object} map A key-value map
	 **/
	,add: function (map)
	{
		var newMap = this.hashMap;

		for (var key in map)
			newMap[key] = map[key];
			
		this.set (newMap);
	}
	
	/**
	 * Sets the hash part of the URL.
	 *
	 * @param {Object} map A key-value map
	 **/
	,set: function (map)
	{
		for (var key in map)
		if (map[key] === null || map[key] === undefined)
			delete map[key];

		var newHash = this.make (map);

		if (newHash !== this.hash)
		{
			this.hashMap = map;
			this.putHash (newHash);
		}
	}

	/**
	 * Creates a URL with the given hash data.
	 *
	 * @param {Object} map A key-value map
	 * @param {boolean} add %true to combine with the current map, %false otherwise
	 * @return {String} The URL
	 **/
	,make: function (map, add)
	{
		var hash = '#!';
		
		if (add)
		for (var key in this.hashMap)
		if (!map[key])
			map[key] = this.hashMap[key];

		for (var key in map)
		{
			if (hash.length > 2)
				hash += '&';

			hash += key +'='+ map[key];
		}
	
		return hash;
	}
	
	,putHash: function (newHash)
	{
		location.hash = newHash;
		this.hash = location.hash;
		this.signalEmit ('changed');
	}

	,hashChanged: function ()
	{
		var newHash = location.hash;

		if (newHash === this.hash)
			return;

		this.hashMap = {};
		var kvPairs = newHash.substr(2).split ('&');

		for (var i = 0; i < kvPairs.length; i++)
		{
			var kvPair = kvPairs[i].split ('=', 2);
			
			if (kvPair[0])
				this.hashMap[kvPair[0]] = kvPair[1];
		}

		this.putHash (newHash);
	}
});