/* --------------------------------------------------------------
 scroll_to_top.js 2016-04-25
 Gambio GmbH
 http://www.gambio.de
 Copyright (c) 2016 Gambio GmbH
 Released under the GNU General Public License (Version 2)
 [http://www.gnu.org/licenses/gpl-2.0.html]
 --------------------------------------------------------------
 */

/**
 * Scroll to top functionality.
 */
gx.controllers.module('scroll_to_top', [], function () {

    'use strict';

    // ------------------------------------------------------------------------
    // VARIABLES
    // ------------------------------------------------------------------------

    /**
     * Module Selector
     *
     * @type {jQuery}
     */
    const $this = $(this);

    /**
     * Module Instance
     *
     * @type {Object}
     */
    const module = {};

    /**
     * Animation Flag
     *
     * @type {Boolean}
     */
    let onAnimation = false;

    // ------------------------------------------------------------------------
    // FUNCTIONS
    // ------------------------------------------------------------------------

    /**
     * On Window Scroll
     *
     * If the site content is large and the user has scrolled to bottom display the caret icon.
     */
    function _onWindowScroll() {
        let scrollPercentage = ($(window).scrollTop() + window.innerHeight) / $(document).outerHeight();

        if (!onAnimation && !$('#main-menu > nav > ul').hasClass('collapse')
            && scrollPercentage > 0.9 && $(document).outerHeight() > 2500) {
            $this.fadeIn();
        } else if ($this.is(':visible')) {
            $this.fadeOut();
        }
    }

    /**
     * On Icon Click
     *
     * Scroll to the top of the page whenever the user clicks on the caret icon.
     */
    function _onIconClick() {
        onAnimation = true;

        $('html, body').animate({
            scrollTop: 0
        }, 'fast', function () {
            onAnimation = false;
        });

        $this.fadeOut();
    }

    // ------------------------------------------------------------------------
    // INITIALIZE
    // ------------------------------------------------------------------------

    module.init = function (done) {
        $(window).on('scroll', _onWindowScroll);
        $this.on('click', 'i', _onIconClick);
        done();
    };

    return module;

});