/*
 * 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 Bukðis-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;" src="javascript:void(0);"></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 (location.hash.indexOf('#') >= 0) {
                                                $.history._callback(location.hash.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(/^#/, ''));
                        }
                }
        },

        isKonqueror: function() {
                return /KHTML|Konqueror/.test(navigator.userAgent);
        },

        load: function(hash) {
                var newhash;

                if ($.browser.safari) {
                        newhash = hash;
                } else {
                        newhash = (this.isKonqueror() ? '' : '#') + 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);