/*
 * 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.
 *
 * Modified by Jonathan Bingham to work in IE8 with XHTML and HTML5 using onhashchange.
 */
jQuery.extend({
    historyCurrentHash: undefined,
    historyCallback: undefined,
    historyIframeSrc: undefined,
    historyCurrentQueryString: undefined,

    stopHistory: false,

    historyInit: function(callback, src) {
        jQuery.historyCallback = callback;
        if (src) jQuery.historyIframeSrc = src;
        var current_hash = location.hash.replace(/\?.*$/, '');
        var current_qstr = "";
        if (!$.browser.msie || ($.browser.msie && $.browser.version >= 7)) {
            if (location.hash.indexOf("?") > 0) {
                current_qstr = location.hash.replace(/.*\?$/, '')
                current_qstr = current_qstr.replace(current_hash, "").replace("?", "");
            }
        } else
            current_qstr = location.search.replace("\?", "");




        jQuery.historyCurrentHash = current_hash;

        jQuery.historyCurrentQueryString = current_qstr;

        if (jQuery.browser.msie && jQuery.browser.version >= 8 && ('onhashchange' in document.body)) {
            document.body.onhashchange = function() {
                jQuery.historyCheck();
            };
        }
        else 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 + (current_qstr == "" ? "" : "?" + current_qstr);
        }
        else if (jQuery.browser.safari) {
            // etablish back/forward stacks
            jQuery.historyBackQStrStack = [];
            jQuery.historyBackStack = [];
            jQuery.historyBackStack.length = jQuery.historyBackQStrStack.length = history.length;
            jQuery.historyForwardStack = [];
            jQuery.historyForwardQStrStack = [];
            jQuery.lastHistoryLength = history.length;

            jQuery.isFirst = true;
        }
        if (current_hash) {
            jQuery.historyCallback(current_hash.replace(/^#/, ''), jQuery.historyCurrentQueryString);
        }
        setInterval(jQuery.historyCheck, 100);
    },

    historyAddHistory: function(hash, qstr) {
        if (jQuery.stopHistory) return;
        // This makes the looping function do something
        jQuery.historyBackStack.push(hash);

        jQuery.historyBackQStrStack.push(qstr);

        jQuery.historyForwardStack.length = 0; // clear forwardStack (true click occured)
        this.isFirst = true;
    },

    historyCheck: function() {
        if (jQuery.stopHistory && $.browser.safari) return;
        if ((jQuery.browser.msie) && !(jQuery.browser.version >= 8 && 'onhashchange' in document.body)) {
            //if (jQuery.browser.msie) {
            // On IE, check for location.hash of iframe
            var ihistory = jQuery("#jQuery_history")[0];
            var iframe = ihistory.contentDocument || ihistory.contentWindow.document;
            var current_hash = iframe.location.hash.replace(/\?.*$/, '');

            var current_qstr = "";

            if (!$.browser.msie || ($.browser.msie && $.browser.version >= 7)) {
                if (iframe.location.hash.indexOf("?") > 0) {
                    current_qstr = iframe.location.hash.replace(/.*\?$/, '')
                    current_qstr = current_qstr.replace(current_hash, "").replace("?", "");
                }
            } else
                current_qstr = location.search.replace("\?", "");


            if (current_hash != jQuery.historyCurrentHash || current_qstr != jQuery.historyCurrentQueryString) {

                jQuery.historyCurrentQueryString = current_qstr;

                location.hash = current_hash + (jQuery.historyCurrentQueryString != "" ? "?" + jQuery.historyCurrentQueryString : "");
                jQuery.historyCurrentHash = current_hash;
                jQuery.historyCallback(current_hash.replace(/^#/, ''), jQuery.historyCurrentQueryString);

            }
        } else if (jQuery.browser.safari) {
            if (jQuery.lastHistoryLength == history.length && jQuery.historyBackStack.length > jQuery.lastHistoryLength) {
                jQuery.historyBackStack.shift();
                jQuery.historyBackQStrStack.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());
                            jQuery.historyForwardQStrStack.unshift(jQuery.historyBackQStrStack.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());
                            jQuery.historyBackQStrStack.push(jQuery.historyForwardQStrStack.shift());
                        }
                    }
                    var cachedHash = jQuery.historyBackStack[jQuery.historyBackStack.length - 1];
                    if (cachedHash != undefined) {
                        cachedQStr = jQuery.historyBackQStrStack[jQuery.historyBackQStrStack.length - 1];
                        if (cachedQStr != undefined) {
                            jQuery.historyCurrentQueryString = location.hash.replace(/.*\?/, '');
                        }
                        jQuery.historyCurrentHash = location.hash.replace(/\?.*$/, '');
                        jQuery.historyCallback(cachedHash, cachedQStr);
                    }
                } else if (jQuery.historyBackStack[jQuery.historyBackStack.length - 1] == undefined && !jQuery.isFirst) {
                    // back button has been pushed to beginning and URL already pointed to hash (e.g. a bookmark)
                    // document.URL doesn't change in Safari
                    if (location.hash) {
                        var current_hash = location.hash;
                        var qstr = (location.hash.indexOf("?") < 0) ? undefined : location.hash.substring(location.hash.indexOf("?") + 1)
                        jQuery.historyCallback(location.hash.replace(/^#/, '').replace(/\?.*$/), qstr);
                    } else {
                        var current_hash = '';
                        jQuery.historyCallback('', undefined);
                    }
                    jQuery.isFirst = true;
                }
            }
        } else {
            // otherwise, check for location.hash
            var current_hash = location.hash.replace(/\?.*$/, '');
            var current_qstr = "";
            if (location.hash.indexOf("?") > 0) {
                current_qstr = location.hash.replace(/.*\?$/, '')
                current_qstr = current_qstr.replace(current_hash, "").replace("?", "");
            }
            if (current_hash != jQuery.historyCurrentHash || current_qstr != jQuery.historyCurrentQueryString) {
                jQuery.historyCurrentHash = current_hash;
                jQuery.historyCurrentQueryString = current_qstr;
            }
        }
    },
    historyLoad: function(hash) {
        var newhash;
        var qstr = hash.indexOf("?") < 0 ? undefined : hash.replace(/.*\?/, '');
        hash = decodeURIComponent(hash.replace(/\?.*$/, ''));

        if (jQuery.browser.safari) {
            newhash = hash;
        }
        else {
            newhash = '#' + hash;
            location.hash = newhash + (qstr != undefined ? "?" + qstr : "");
        }
        jQuery.historyCurrentHash = newhash;
        jQuery.historyCurrentQueryString = qstr;

        if ((jQuery.browser.msie) && !(jQuery.browser.version >= 8 && 'onhashchange' in document.body)) {
            //if (jQuery.browser.msie) {
            var ihistory = jQuery("#jQuery_history")[0];
            var iframe = ihistory.contentWindow.document;
            iframe.open();
            iframe.close();
            iframe.location.hash = newhash + (qstr != "" ? "?" + qstr : "");
            jQuery.lastHistoryLength = history.length;
            jQuery.historyCallback(hash, qstr);
        }
        else if (jQuery.browser.safari) {
            jQuery.dontCheck = true;
            jQuery.stopHistory = false;
            // Manually keep track of the history values for Safari
            this.historyAddHistory(hash, qstr);

            // 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, qstr);
            // 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 + (qstr != undefined ? "?" + qstr : "");
        }
        else {
            jQuery.historyCallback(hash, qstr);
        }
    }
});