// Sticky Plugin

// =============

// Author: Anthony Garand

// Improvements by German M. Bravo (Kronuz) and Ruud Kamphuis (ruudk)

// Improvements by Leonardo C. Daronco (daronco)

// Created: 2/14/2011

// Date: 2/12/2012

// Website: http://labs.anthonygarand.com/sticky

// Description: Makes an element on the page stick on the screen as you scroll

//              It will only set the 'top' and 'position' of your element, you

//              might need to adjust the width in some cases.

(function($) {

    var defaults = {

            topSpacing: 0,

            bottomSpacing: 0,

            className: 'is-sticky',

            wrapperClassName: 'sticky-wrapper'

        },

        $window = $(window),

        $document = $(document),

        sticked = [],

        windowHeight = $window.height(),

        scroller = function() {

            var scrollTop = $window.scrollTop(),

                documentHeight = $document.height(),

                dwh = documentHeight - windowHeight,

                extra = (scrollTop > dwh) ? dwh - scrollTop : 0;

            for (var i = 0; i < sticked.length; i++) {

                var s = sticked[i],

                    elementTop = s.stickyWrapper.offset().top,

                    etse = elementTop - s.topSpacing - extra;

                if (scrollTop <= etse) {

                    if (s.currentTop !== null) {

                        s.stickyElement

                            .css('position', '')

                            .css('top', '')

                            .removeClass(s.className);

                        s.stickyElement.parent().removeClass(s.className);

                        s.currentTop = null;

                    }

                }

                else {

                    var newTop = documentHeight - s.stickyElement.outerHeight()

                        - s.topSpacing - s.bottomSpacing - scrollTop - extra;

                    if (newTop < 0) {

                        newTop = newTop + s.topSpacing;

                    } else {

                        newTop = s.topSpacing;

                    }

                    if (s.currentTop != newTop) {

                        s.stickyElement

                            .css('position', 'fixed')

                            .css('top', newTop)

                            .addClass(s.className);

                        s.stickyElement.parent().addClass(s.className);

                        s.currentTop = newTop;

                    }

                }

            }

        },

        resizer = function() {

            windowHeight = $window.height();

        },

        methods = {

            init: function(options) {

                var o = $.extend(defaults, options);

                return this.each(function() {

                    var stickyElement = $(this);

                    stickyId = stickyElement.attr('id');

                    wrapper = $('<div></div>')

                        .attr('id', stickyId + '-sticky-wrapper')

                        .addClass(o.wrapperClassName);

                    stickyElement.wrapAll(wrapper);

                    var stickyWrapper = stickyElement.parent();

                    stickyWrapper.css('height', stickyElement.outerHeight());

                    sticked.push({

                        topSpacing: o.topSpacing,

                        bottomSpacing: o.bottomSpacing,

                        stickyElement: stickyElement,

                        currentTop: null,

                        stickyWrapper: stickyWrapper,

                        className: o.className

                    });

                });

            },

            update: scroller

        };

    // should be more efficient than using $window.scroll(scroller) and $window.resize(resizer):

    if (window.addEventListener) {

        window.addEventListener('scroll', scroller, false);

        window.addEventListener('resize', resizer, false);

    } else if (window.attachEvent) {

        window.attachEvent('onscroll', scroller);

        window.attachEvent('onresize', resizer);

    }

    $.fn.sticky = function(method) {

        if (methods[method]) {

            return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));

        } else if (typeof method === 'object' || !method ) {

            return methods.init.apply( this, arguments );

        } else {

            $.error('Method ' + method + ' does not exist on jQuery.sticky');

        }

    };

    $(function() {

        setTimeout(scroller, 0);

    });

})(jQuery);