/*
 * jQuery history plugin
 *
 * Copyright (c) 2006 Taku Sano (Mikage Sawatari)
 * Licensed under the MIT License:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Modified by Lincoln Cooper to add Safari support and only call the callback once during initialization
 * for msie when no initial hash supplied.
 * API rewrite by Lauris Bukšis-Haberkorns
 */

(function($) {

function History()
{
	this._curHash = '';
	this._callback = function(hash){};
};

$.extend(History.prototype, {

	init: function(callback) {
		this._callback = callback;
		this._curHash = location.hash;

		if($.browser.msie) {
			// To stop the callback firing twice during initilization if no hash present
			if (this._curHash == '') {
				this._curHash = '#';
			}

			// add hidden iframe for IE
			$("body").prepend('<iframe id="jQuery_history" style="display: none;"></iframe>');
			var iframe = $("#jQuery_history")[0].contentWindow.document;
			iframe.open();
			iframe.close();
			iframe.location.hash = this._curHash;
		}
		else if ($.browser.safari) {
			// etablish back/forward stacks
			this._historyBackStack = [];
			this._historyBackStack.length = history.length;
			this._historyForwardStack = [];
			this._isFirst = true;
			this._dontCheck = false;
		}
		this._callback(this._curHash.replace(/^#/, ''));
		setInterval(this._check, 100);
	},

	add: function(hash) {
		// This makes the looping function do something
		this._historyBackStack.push(hash);
		
		this._historyForwardStack.length = 0; // clear forwardStack (true click occured)
		this._isFirst = true;
	},
	
	_check: function() {
		if($.browser.msie) {
			// On IE, check for location.hash of iframe
			var ihistory = $("#jQuery_history")[0];
			var iframe = ihistory.contentDocument || ihistory.contentWindow.document;
			var current_hash = iframe.location.hash;
			if(current_hash != $.history._curHash) {
			
				location.hash = current_hash;
				$.history._curHash = current_hash;
				$.history._callback(current_hash.replace(/^#/, ''));
				
			}
		} else if ($.browser.safari) {
			if (!$.history._dontCheck) {
				var historyDelta = history.length - $.history._historyBackStack.length;
				
				if (historyDelta) { // back or forward button has been pushed
					$.history._isFirst = false;
					if (historyDelta < 0) { // back button has been pushed
						// move items to forward stack
						for (var i = 0; i < Math.abs(historyDelta); i++) $.history._historyForwardStack.unshift($.history._historyBackStack.pop());
					} else { // forward button has been pushed
						// move items to back stack
						for (var i = 0; i < historyDelta; i++) $.history._historyBackStack.push($.history._historyForwardStack.shift());
					}
					var cachedHash = $.history._historyBackStack[$.history._historyBackStack.length - 1];
					if (cachedHash != undefined) {
						$.history._curHash = location.hash;
						$.history._callback(cachedHash);
					}
				} else if ($.history._historyBackStack[$.history._historyBackStack.length - 1] == undefined && !$.history._isFirst) {
					// back button has been pushed to beginning and URL already pointed to hash (e.g. a bookmark)
					// document.URL doesn't change in Safari
					if (document.URL.indexOf('#') >= 0) {
						$.history._callback(document.URL.split('#')[1]);
					} else {
						$.history._callback('');
					}
					$.history._isFirst = true;
				}
			}
		} else {
			// otherwise, check for location.hash
			var current_hash = location.hash;
			if(current_hash != $.history._curHash) {
				$.history._curHash = current_hash;
				$.history._callback(current_hash.replace(/^#/, ''));
			}
		}
	},

	load: function(hash) {
		var newhash;
		
		if ($.browser.safari) {
			newhash = hash;
		} else {
			newhash = '#' + hash;
			location.hash = newhash;
		}
		this._curHash = newhash;
		
		if ($.browser.msie) {
			var ihistory = $("#jQuery_history")[0]; // TODO: need contentDocument?
			var iframe = ihistory.contentWindow.document;
			iframe.open();
			iframe.close();
			iframe.location.hash = newhash;
			this._callback(hash);
		}
		else if ($.browser.safari) {
			this._dontCheck = true;
			// Manually keep track of the history values for Safari
			this.add(hash);
			
			// Wait a while before allowing checking so that Safari has time to update the "history" object
			// correctly (otherwise the check loop would detect a false change in hash).
			var fn = function() {$.history._dontCheck = false;};
			window.setTimeout(fn, 200);
			this._callback(hash);
			// N.B. "location.hash=" must be the last line of code for Safari as execution stops afterwards.
			//      By explicitly using the "location.hash" command (instead of using a variable set to "location.hash") the
			//      URL in the browser and the "history" object are both updated correctly.
			location.hash = newhash;
		}
		else {
		  this._callback(hash);
		}
	}
});

$(document).ready(function() {
	$.history = new History(); // singleton instance
});

})(jQuery);
