/*

 scrollup v1.0.0
 author: mark goodyear - http://www.markgoodyear.com
 git: https://github.com/markgoodyear/scrollup

 copyright 2013 mark goodyear
 licensed under the mit license
 http://www.opensource.org/licenses/mit-license.php

 twitter: @markgdyr

 */

;
(function ($) {

    $.scrollup = function (options) {

        // settings
        var settings = {
            scrollname: 'scrollup', // element id
            topdistance: '300', // distance from top before showing element (px)
            topspeed: 300, // speed back to top (ms)
            animation: 'fade', // fade, slide, none
            animationinspeed: 200, // animation in speed (ms)
            animationoutspeed: 200, // animation out speed (ms)
            scrolltext: 'top', // text for element
            activeoverlay: false // set css color to display scrollup active point, e.g '#00ffff'
        };

        // load settings
        if (options) {
            var settings = $.extend(settings, options);
        }

        // shorthand setting names
        var sn = '#' + settings.scrollname,
            an = settings.animation,
            os = settings.animationoutspeed,
            is = settings.animationinspeed,
            td = settings.topdistance,
            st = settings.scrolltext,
            ts = settings.topspeed,
            ao = settings.activeoverlay;

        // create element
        $('<a/>', {
            id: settings.scrollname,
            href: '#top',
            title: st,
            text: st
        }).appendto('body');

        // minium css to make the magic happen
        $(sn).css({
            'display': 'none',
            'position': 'fixed',
            'z-index': '2147483647'
        })

        // active point overlay
        if (ao) {
            $("body").append("<div id='" + settings.scrollname + "-active'></div>");
            $(sn + "-active").css({
                'position': 'absolute',
                'top': td + 'px',
                'width': '100%',
                'border-top': '1px dotted ' + ao,
                'z-index': '2147483647'
            })
        }

        // scroll funtion
        $(window).scroll(function () {

            // fade animation
            if (an === "fade") {
                $(($(window).scrolltop() > td) ? $(sn).fadein(is) : $(sn).fadeout(os));
            }

            // slideup animation
            else if (an === "slide") {
                $(($(window).scrolltop() > td) ? $(sn).slidedown(is) : $(sn).slideup(os));
            }

            // no animation
            else {
                $(($(window).scrolltop() > td) ? $(sn).show(0) : $(sn).hide(0));
            }

        });

        // back to the top
        $(sn).click(function (event) {
            $('html, body').animate({scrolltop: 0}, ts);
            return false;
        });

    }; // end scrollup function
}(jquery));