// 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);