// JavaScript Document
/*
 * jQuery history plugin
 * 
 * sample page: http://www.mikage.to/jquery/jquery_history.html
 *
 * Copyright (c) 2006-2009 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.
 */


jQuery.extend({
        historyCurrentHash: undefined,
        historyCallback: undefined,
        historyIframeSrc: undefined,
        
        historyInit: function(callback, src){
                jQuery.historyCallback = callback;
                if (src) jQuery.historyIframeSrc = src;
                var current_hash = location.hash.replace(/\?.*$/, '');
                
                jQuery.historyCurrentHash = current_hash;
                // if ((jQuery.browser.msie) && (jQuery.browser.version < 8)) {
                if (jQuery.browser.msie) {
                        // To stop the callback firing twice during initilization if no hash present
                        if (jQuery.historyCurrentHash == '') {
                        jQuery.historyCurrentHash = '#';
                }
                
                        // add hidden iframe for IE
                        jQuery("body").prepend('<iframe id="jQuery_history" style="display: none;"'+
                                (jQuery.historyIframeSrc ? ' src="'+jQuery.historyIframeSrc+'"' : '')
                                +'></iframe>'
                        );
                        var ihistory = jQuery("#jQuery_history")[0];
                        var iframe = ihistory.contentWindow.document;
                        iframe.open();
                        iframe.close();
                        iframe.location.hash = current_hash;
                }
                else if (jQuery.browser.safari) {
                        // etablish back/forward stacks
                        jQuery.historyBackStack = [];
                        jQuery.historyBackStack.length = history.length;
                        jQuery.historyForwardStack = [];
                        jQuery.lastHistoryLength = history.length;
                        
                        jQuery.isFirst = true;
                }
                if(current_hash)
                        jQuery.historyCallback(current_hash.replace(/^#/, ''));
                setInterval(jQuery.historyCheck, 100);
        },
        
        historyAddHistory: function(hash) {
                // This makes the looping function do something
                jQuery.historyBackStack.push(hash);
                
                jQuery.historyForwardStack.length = 0; // clear forwardStack (true click occured)
                this.isFirst = true;
        },
        
        historyCheck: function(){
                // if ((jQuery.browser.msie) && (jQuery.browser.version < 8)) {
                if (jQuery.browser.msie) {
                        // On IE, check for location.hash of iframe
                        var ihistory = jQuery("#jQuery_history")[0];
                        var iframe = ihistory.contentDocument || ihistory.contentWindow.document;
                        var current_hash = iframe.location.hash.replace(/\?.*$/, '');
                        if(current_hash != jQuery.historyCurrentHash) {
                        
                                location.hash = current_hash;
                                jQuery.historyCurrentHash = current_hash;
                                jQuery.historyCallback(current_hash.replace(/^#/, ''));
                                
                        }
                } else if (jQuery.browser.safari) {
                        if(jQuery.lastHistoryLength == history.length && jQuery.historyBackStack.length > jQuery.lastHistoryLength) {
                                jQuery.historyBackStack.shift();
                        }
                        if (!jQuery.dontCheck) {
                                var historyDelta = history.length - jQuery.historyBackStack.length;
                                jQuery.lastHistoryLength = history.length;
                                
                                if (historyDelta) { // back or forward button has been pushed
                                        jQuery.isFirst = false;
                                        if (historyDelta < 0) { // back button has been pushed
                                                // move items to forward stack
                                                for (var i = 0; i < Math.abs(historyDelta); i++) jQuery.historyForwardStack.unshift(jQuery.historyBackStack.pop());
                                        } else { // forward button has been pushed
                                                // move items to back stack
                                                for (var i = 0; i < historyDelta; i++) jQuery.historyBackStack.push(jQuery.historyForwardStack.shift());
                                        }
                                        var cachedHash = jQuery.historyBackStack[jQuery.historyBackStack.length - 1];
                                        if (cachedHash != undefined) {
                                                jQuery.historyCurrentHash = location.hash.replace(/\?.*$/, '');
                                                jQuery.historyCallback(cachedHash);
                                        }
                                } else if (jQuery.historyBackStack[jQuery.historyBackStack.length - 1] == undefined && !jQuery.isFirst) {
                                        // back button has been pushed to beginning and URL already pointed to hash (e.g. a bookmark)
                                        // document.URL doesn't change in Safari
                                        if (location.hash) {
                                                var current_hash = location.hash;
                                                jQuery.historyCallback(location.hash.replace(/^#/, ''));
                                        } else {
                                                var current_hash = '';
                                                jQuery.historyCallback('');
                                        }
                                        jQuery.isFirst = true;
                                }
                        }
                } else {
                        // otherwise, check for location.hash
                        var current_hash = location.hash.replace(/\?.*$/, '');
                        if(current_hash != jQuery.historyCurrentHash) {
                                jQuery.historyCurrentHash = current_hash;
                                jQuery.historyCallback(current_hash.replace(/^#/, ''));
                        }
                }
        },
        historyLoad: function(hash){
                var newhash;
                hash = decodeURIComponent(hash.replace(/\?.*$/, ''));
                
                if (jQuery.browser.safari) {
                        newhash = hash;
                }
                else {
                        newhash = '#' + hash;
                        location.hash = newhash;
                }
                jQuery.historyCurrentHash = newhash;
                
                // if ((jQuery.browser.msie) && (jQuery.browser.version < 8)) {
                if (jQuery.browser.msie) {
                        var ihistory = jQuery("#jQuery_history")[0];
                        var iframe = ihistory.contentWindow.document;
                        iframe.open();
                        iframe.close();
                        iframe.location.hash = newhash;
                        jQuery.lastHistoryLength = history.length;
                        jQuery.historyCallback(hash);
                }
                else if (jQuery.browser.safari) {
                        jQuery.dontCheck = true;
                        // Manually keep track of the history values for Safari
                        this.historyAddHistory(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() {jQuery.dontCheck = false;};
                        window.setTimeout(fn, 200);
                        jQuery.historyCallback(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 {
                  jQuery.historyCallback(hash);
                }
        }
});