/**
* jQuery.observeHashChange (Version: 1.0)
*
* http://finnlabs.github.com/jquery.observehashchange/
*
* Copyright (c) 2009, Gregor Schmidt, Finn GmbH
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
**/
(function($) {
    $.fn.hashchange = function(fn) {
        $(window).bind("jQuery.hashchange", fn);
        return this;
    };

    $.observeHashChange = function(options) {
        var opts = $.extend({}, $.observeHashChange.defaults, options);
        if (isHashChangeEventSupported()) {
            nativeVersion();
        }
        else {
            setIntervalVersion(opts);
        }
    };

    var locationHash = null;
    var functionStore = null;
    var interval = 0;

    $.observeHashChange.defaults = {
        interval: 500
    };

    function isHashChangeEventSupported() {
        return $.browser.msie && document.documentMode && document.documentMode >= 8;
    }

    function nativeVersion() {
        locationHash = document.location.hash;
        window.onhashchange = onhashchangeHandler;
    }

    function onhashchangeHandler(e, data) {
        var oldHash = locationHash;
        locationHash = document.location.hash;
        $(window).trigger("jQuery.hashchange", { before: oldHash, after: locationHash });
    }

    function setIntervalVersion(opts) {
        if (locationHash == null) {
            locationHash = document.location.hash;
        }
        if (functionStore != null) {
            clearInterval(functionStore);
        }
        if (interval != opts.interval) {
            functionStore = setInterval(checkLocationHash, opts.interval);
            interval = opts.interval;
        }
    }

    function checkLocationHash() {
        if (locationHash != document.location.hash) {
            var oldHash = locationHash;
            locationHash = document.location.hash;
            $(window).trigger("jQuery.hashchange", { before: oldHash, after: locationHash });
        }
    }

    $.observeHashChange();
})(jQuery);