+function ($) {
    'use strict';
    $.fn.historyTabs = function() {
        var that = this;
        window.addEventListener('popstate', function(event) {
            if (event.state) {
                $(that).filter('[href="' + event.state.url + '"]').tab('show');
            } else {
                $(that).filter('[href="#authentication"]').tab('show');
            }
        });
        return this.each(function(index, element) {
            $(element).on('show.bs.tab', function() {
                var stateObject = {'url' : $(this).attr('href')};

                if (stateObject.url !== window.location.hash) {
                    window.history.pushState(stateObject, document.title, window.location.pathname + $(this).attr('href'));
                }
            });
            if (!window.location.hash && $(element).is('.active')) {
                // Shows the first element if there are no query parameters.
                $(element).tab('show');
            } else if ($(this).attr('href') === window.location.hash) {
                $(element).tab('show');
            }
        });
    };
}(jQuery);