/* --------------------------------------------------------------
 scroll_top.js 2015-09-23
 Gambio GmbH
 http://www.gambio.de
 Copyright (c) 2015 Gambio GmbH
 Released under the GNU General Public License (Version 2)
 [http://www.gnu.org/licenses/gpl-2.0.html]
 --------------------------------------------------------------
 */

/**
 * ## Scroll Top Module
 *
 * This module will display a scroll-to-top arrow on the left side of the admin menu. When the users
 * press this arrow the browser will automatically scroll to the top of the page.
 *
 * @module Compatibility/scroll_top
 */
gx.compatibility.module(
    // Module name
    'scroll_top',

    // Module dependencies
    [],

    /**  @lends module:Compatibility/scroll_top */

    function () {

        'use strict';

        // ------------------------------------------------------------------------
        // VARIABLES DEFINITION
        // ------------------------------------------------------------------------

        var module = {},
            $button;

        // ------------------------------------------------------------------------
        // EVENT HANDLER
        // ------------------------------------------------------------------------

        var _initialize = function () {
            $button = $('<div>')
                .addClass('js-scroll-top-button')
                .html('<i class="fa fa-caret-up"></i>')
                .hide()
                .appendTo('body')
                .on('click', function () {
                    $('html, body').animate({
                        scrollTop: 0
                    });
                });

            $(document).on('scroll', function () {
                var reachedMinimumScrolled = ($(document).scrollTop() > 2500),
                    reachedDocumentBottom = (
                        $(document).scrollTop() +
                        window.innerHeight === $(document).height());

                // Fade In / Out
                if (reachedMinimumScrolled) {
                    $button.fadeIn();
                } else {
                    $button.fadeOut();
                }

                // Fix poistion
                if (reachedMinimumScrolled) {
                    $button.css({
                        bottom: (reachedDocumentBottom ? '100px' : '50px')
                    });
                }
            });

            $(document).on('leftmenu:collapse', function () {
                $button.animate({
                    left: '9px'
                });
            });

            $(document).on('leftmenu:expand', function () {
                $button.animate({
                    left: '89px'
                });
            });
        };

        // ------------------------------------------------------------------------
        // INITIALIZATION
        // ------------------------------------------------------------------------

        module.init = function (done) {
            _initialize();
            done();
        };

        return module;
    });