var HashListener = require('./hash-listener');

/**
 * Class to handle the URL.
 */
module.exports =  {
	 path: null
	,_hash: null
	,_hashMap: {}
	,_listener: null

	,initialize: function() {
		this.$ = this._hasMap;
		this._listener = new HashListener();
	
		this._hashChangedHandler = this._hashChanged.bind(this);
		window.addEventListener('hashchange', this._hashChangedHandler);
		this._hashChanged();
	}

	,destroy: function() {
		window.removeEventListener('hashchange', this._hashChangedHandler);
	}
	
	,getListener: function() {
		return this._listener;
	}

	/**
	 * Gets the hash part of the URL.
	 *
	 * @param {string} key The variable name
	 */
	,get: function(key) {
		return this._hashMap[key];
	}

	/**
	 * Unsets a hash key.
	 *
	 * @param {string} key The variable name
	 */
	,unset: function(key) {
		this.add({[key]: undefined});
	}
	
	/**
	 * 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) {
		if (map)
		for (var key in map)
		if (map[key] === null || map[key] === undefined)
			delete map[key];

		var newHash = this.make(map);

		if (!map)
			map = {};

		if (newHash !== this._hash) {
			this._hashMap = map;
			this.$ = map;
			this._hash = newHash;
			
			this._blockChanged = true;
			location.hash = newHash;
			this._blockChanged = false;

			this._listener.changed();
		}
	}

	/**
	 * 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 && map)
		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 += encodeURIComponent(key) +'='+ encodeURIComponent(map[key]);
		}
	
		return hash;
	}

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

		if (this._blockChanged || newHash === this._hash)
			return;

		var newMap = hashMap = {};
		var kvPairs = newHash.substring(2).split('&');

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

		this._hashMap = newMap;
		this.$ = newMap;
		this._hash = newHash;
		this._listener.changed();
	}
};