/**
* History/Remote - jQuery plugin for enabling history support and bookmarking
* @requires jQuery v1.0.3
*
* http://stilbuero.de/jquery/history/
*
* Copyright (c) 2006 Klaus Hartl (stilbuero.de)
* Dual licensed under the MIT and GPL licenses:
* http://www.opensource.org/licenses/mit-license.php
* http://www.gnu.org/licenses/gpl.html
*
* Version: 0.2.3
* -> minor fixes performed by Chris van de Steeg
*/

(function($) { // block scope

    /**
    * Initialize the history manager. Subsequent calls will not result in additional history state change 
    * listeners. Should be called soonest when the DOM is ready, because in IE an iframe needs to be added
    * to the body to enable history support.
    *
    * @example $.ajaxHistory.initialize();
    *
    * @param Function callback A single function that will be executed in case there is no fragment
    *                          identifier in the URL, for example after navigating back to the initial
    *                          state. Use to restore such an initial application state.
    *                          Optional. If specified it will overwrite the default action of 
    *                          emptying all containers that are used to load content into.
    * @type undefined
    *
    * @name $.ajaxHistory.initialize()
    * @cat Plugins/History
    * @author Klaus Hartl/klaus.hartl@stilbuero.de
    */
    $.ajaxHistory = new function() {

        var RESET_EVENT = 'historyReset';

        var _currentHash = location.hash;
        var _intervalId = null;
        var _observeHistory; // define outside if/else required by Opera

        this.update = function() { }; // empty function body for graceful degradation

        // create custom event for state reset
        var _defaultReset = function() {
            $('.remote-output').empty();
        };
        $(document).bind(RESET_EVENT, _defaultReset);

        // TODO fix for Safari 3
        // if ($.browser.msie)
        // else if hash != _currentHash
        // else check history length

        if ($.browser.msie) {

            var _historyIframe, initialized = false; // for IE

            // add hidden iframe
            $(function() {
                _historyIframe = $('<iframe style="display: none;"></iframe>').appendTo(document.body).get(0);
                var iframe = _historyIframe.contentWindow.document;
                // create initial history entry
                iframe.open();
                iframe.close();
                if (_currentHash && _currentHash != '#') {
                    iframe.location.hash = _currentHash.replace('#', '');
                }
            });

            this.update = function(hash) {
                _currentHash = hash;
                var iframe = _historyIframe.contentWindow.document;
                iframe.open();
                iframe.close();
                iframe.location.hash = hash.replace('#', '');
            };

            _observeHistory = function() {
                var iframe = _historyIframe.contentWindow.document;
                var iframeHash = iframe.location.hash;
                if (iframeHash != _currentHash) {
                    _currentHash = iframeHash;
                    if (iframeHash && iframeHash != '#') {
                        // order does matter, set location.hash after triggering the click...
                        $('a[@href$="' + iframeHash + '"]').click();
                        location.hash = iframeHash;
                    } else if (initialized) {
                        location.hash = '';
                        $(document).trigger(RESET_EVENT);
                    }
                }
                initialized = true;
            };

        } else if ($.browser.mozilla || $.browser.opera) {

            this.update = function(hash) {
                _currentHash = hash;
            };

            _observeHistory = function() {
                if (location.hash) {
                    if (_currentHash != location.hash) {
                        _currentHash = location.hash;
                        $('a[@href$="' + encodeURI(_currentHash) + '"]').click();
                    }
                } else if (_currentHash) {
                    _currentHash = '';
                    $(document).trigger(RESET_EVENT);
                }
            };

        } else if ($.browser.safari) {

            var _backStack, _forwardStack, _addHistory; // for Safari

            // etablish back/forward stacks
            $(function() {
                _backStack = [];
                _backStack.length = history.length;
                _forwardStack = [];

            });
            var isFirst = false, initialized = false;
            _addHistory = function(hash) {
                _backStack.push(hash);
                _forwardStack.length = 0; // clear forwardStack (true click occured)
                isFirst = false;
            };

            this.update = function(hash) {
                _currentHash = hash;
                _addHistory(_currentHash);
            };

            _observeHistory = function() {
                var historyDelta = history.length - _backStack.length;
                if (historyDelta) { // back or forward button has been pushed
                    isFirst = false;
                    if (historyDelta < 0) { // back button has been pushed
                        // move items to forward stack
                        for (var i = 0; i < Math.abs(historyDelta); i++) _forwardStack.unshift(_backStack.pop());
                    } else { // forward button has been pushed
                        // move items to back stack
                        for (var i = 0; i < historyDelta; i++) _backStack.push(_forwardStack.shift());
                    }
                    var cachedHash = _backStack[_backStack.length - 1];
                    if (!initialized || cachedHash != _currentHash) {
                        $('a[@href$="' + cachedHash + '"]').click();
                        _currentHash = location.hash;
                    }
                } else if (_backStack[_backStack.length - 1] == undefined && !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) {
                        $('a[@href$="' + '#' + document.URL.split('#')[1] + '"]').click();
                    } else if (initialized) {
                        $(document).trigger(RESET_EVENT);
                    }
                    isFirst = true;
                }
                initialized = true;
            };

        }

        this.initialize = function(callback) {
            // custom callback to reset app state (no hash in url)
            if (typeof callback == 'function') {
                $(document).unbind(RESET_EVENT, _defaultReset).bind(RESET_EVENT, callback);
            }
            // look for hash in current URL (not Safari)
            if (location.hash && typeof _addHistory == 'undefined') {
                $('a[@href$="' + location.hash + '"]').trigger('click');
            }
            // start observer
            if (_observeHistory && _intervalId == null) {
                _intervalId = setInterval(_observeHistory, 200); // Safari needs at least 200 ms
            }
        };

    };

    /**
    * Implement Ajax driven links in a completely unobtrusive and accessible manner (also known as "Hijax")
    * with support for the browser's back/forward navigation buttons and bookmarking.
    *
    * The link's href attribute gets altered to a fragment identifier, such as "#remote-1", so that the browser's
    * URL gets updated on each click, whereas the former value of that attribute is used to load content via
    * XmlHttpRequest from and update the specified element. If no target element is found, a new div element will be
    * created and appended to the body to load the content into. The link informs the history manager of the 
    * state change on click and adds an entry to the browser's history.
    *
    * jQuery's Ajax implementation adds a custom request header of the form "X-Requested-With: XmlHttpRequest"
    * to any Ajax request so that the called page can distinguish between a standard and an Ajax (XmlHttpRequest)
    * request.
    *
    * @example $('a.remote').remote('#output');
    * @before <a class="remote" href="/path/to/content.html">Update</a>
    * @result <a class="remote" href="#remote-1">Update</a>
    * @desc Alter a link of the class "remote" to an Ajax-enhanced link and let it load content from
    *       "/path/to/content.html" via XmlHttpRequest into an element with the id "output".
    * @example $('a.remote').remote('#output', {hashPrefix: 'chapter'});
    * @before <a class="remote" href="/path/to/content.html">Update</a>
    * @result <a class="remote" href="#chapter-1">Update</a>
    * @desc Alter a link of the class "remote" to an Ajax-enhanced link and let it load content from
    *       "/path/to/content.html" via XmlHttpRequest into an element with the id "output".
    *
    * @param String expr A string containing a CSS selector or basic XPath specifying the element to load
    *                    content into via XmlHttpRequest.
    * @param Object settings An object literal containing key/value pairs to provide optional settings.
    * @option String hashPrefix A String that is used for constructing the hash the link's href attribute
    *                           gets altered to, such as "#remote-1". Default value: "remote-".
    * @param Function callback A single function that will be executed when the request is complete. 
    * @type jQuery
    *
    * @name remote
    * @cat Plugins/Remote
    * @author Klaus Hartl/klaus.hartl@stilbuero.de
    */

    /**
    * Implement Ajax driven links in a completely unobtrusive and accessible manner (also known as "Hijax")
    * with support for the browser's back/forward navigation buttons and bookmarking.
    *
    * The link's href attribute gets altered to a fragment identifier, such as "#remote-1", so that the browser's
    * URL gets updated on each click, whereas the former value of that attribute is used to load content via
    * XmlHttpRequest from and update the specified element. If no target element is found, a new div element will be
    * created and appended to the body to load the content into. The link informs the history manager of the 
    * state change on click and adds an entry to the browser's history.
    *
    * jQuery's Ajax implementation adds a custom request header of the form "X-Requested-With: XmlHttpRequest"
    * to any Ajax request so that the called page can distinguish between a standard and an Ajax (XmlHttpRequest)
    * request.
    *
    * @example $('a.remote').remote( $('#output > div')[0] );
    * @before <a class="remote" href="/path/to/content.html">Update</a>
    * @result <a class="remote" href="#remote-1">Update</a>
    * @desc Alter a link of the class "remote" to an Ajax-enhanced link and let it load content from
    *       "/path/to/content.html" via XmlHttpRequest into an element with the id "output".
    * @example $('a.remote').remote('#output', {hashPrefix: 'chapter'});
    * @before <a class="remote" href="/path/to/content.html">Update</a>
    * @result <a class="remote" href="#chapter-1">Update</a>
    * @desc Alter a link of the class "remote" to an Ajax-enhanced link and let it load content from
    *       "/path/to/content.html" via XmlHttpRequest into an element with the id "output".
    *
    * @param Element elem A DOM element to load content into via XmlHttpRequest.
    * @param Object settings An object literal containing key/value pairs to provide optional settings.
    * @option String hashPrefix A String that is used for constructing the hash the link's href attribute
    *                           gets altered to, such as "#remote-1". Default value: "remote-".
    * @param Function callback A single function that will be executed when the request is complete. 
    * @type jQuery
    *
    * @name remote
    * @cat Plugins/Remote
    * @author Klaus Hartl/klaus.hartl@stilbuero.de
    */
    $.fn.remote = function(output, settings, callback) {

        callback = callback || function() { };
        if (typeof settings == 'function') { // shift arguments
            callback = settings;
        }

        settings = $.extend({
            hashPrefix: 'remote-'
        }, settings || {});

        var target = $(output).size() && $(output) || $('<div></div>').appendTo('body');
        target.addClass('remote-output');

        return this.each(function(i) {
            var href = this.href, hash = '#' + (this.title && this.title.replace(/\s/g, '_') || settings.hashPrefix + (i + 1)),
            a = this;
            this.href = hash;
            $(this).click(function(e) {
                // lock target to prevent double loading in Firefox
                if (!target['locked']) {
                    // add to history only if true click occured, not a triggered click
                    if (e.clientX) {
                        $.ajaxHistory.update(hash);
                    }
                    target.load(href, function() {
                        target['locked'] = null;
                        callback.apply(a);
                    });
                }
            });
        });

    };

    /**
    * Provides the ability to use the back/forward navigation buttons in a DHTML application.
    * A change of the application state is reflected by a change of the URL fragment identifier.
    *
    * The link's href attribute needs to point to a fragment identifier within the same resource,
    * although that fragment id does not need to exist. On click the link changes the URL fragment
    * identifier, informs the history manager of the state change and adds an entry to the browser's
    * history.
    *
    * @param Function callback A single function that will be executed as the click handler of the 
    *                          matched element. It will be executed on click (adding an entry to 
    *                          the history) as well as in case the history manager needs to trigger 
    *                          it depending on the value of the URL fragment identifier, e.g. if its 
    *                          current value matches the href attribute of the matched element.
    *                           
    * @type jQuery
    *
    * @name history
    * @cat Plugins/History
    * @author Klaus Hartl/klaus.hartl@stilbuero.de
    */
    $.fn.history = function(callback) {
        return this.click(function(e) {
            // add to history only if true click occured, not a triggered click
            if (e.clientX) {
                $.ajaxHistory.update(this.hash);
            }
            typeof callback == 'function' && callback.apply(this);
        });
    };

})(jQuery);

/*
var logger;
$(function() {
logger = $('<div style="position: fixed; top: 0; overflow: hidden; border: 1px solid; padding: 3px; width: 120px; height: 150px; background: #fff; color: red;"></div>').appendTo(document.body);
});
function log(m) {    
logger.prepend(m + '<br />');
};
*/