$.fn.portfolioShowcase = function () {

    function repeat(str, num) {
        return new Array( num + 1 ).join( str );
    }
  
    return this.each(function () {
        var $wrapper = $('> div', this).css('overflow', 'hidden'),
            $slider = $wrapper.find('> ul'),
            $items = $slider.find('> li'),
            $single = $items.filter(':first'),
            
            singleWidth = $single.outerWidth(), 
            visible = Math.ceil($wrapper.innerWidth() / singleWidth), // note: doesn't include padding or border
            currentPage = 1,
            pages = Math.ceil($items.length / visible);            

        // 1. Pad so that 'visible' number will always be seen, otherwise create empty items
        if (($items.length % visible) != 0) {
            $slider.append(repeat('<li class="empty" />', visible - ($items.length % visible)));
            $items = $slider.find('> li');
        }

        // 2. Top and tail the list with 'visible' number of items, top has the last section, and tail has the first
        $items.filter(':first').before($items.slice(- visible).clone().addClass('cloned'));
        $items.filter(':last').after($items.slice(0, visible).clone().addClass('cloned'));
        $items = $slider.find('> li'); // reselect
        
        // 3. Set the left position to the first 'real' item
        $wrapper.scrollLeft(singleWidth * visible);
        
        function preparePopups(currentPage) {
            var $itemsShown = $items.slice( (currentPage * visible), (currentPage + 1) * visible  );
            $itemsShown.each( function( i ) {
                $(this).hover( function() {
                        $popup = $('body').find('#'+this.id+'-popup');
                        $popup.css({ 
                            left: ($(this).offset().left - 60 - ( i * 35) ) + 'px',
                            top: Math.floor($(this).offset().top - $popup.innerHeight() - 23) + 'px', 
                            'z-index': 999 })
                            .fadeIn('300');
                    } , 
                    function() {
                        $('body').find('#'+this.id+'-popup').fadeOut('300');
                    });
                });
        }
        
        // 4. paging function
        function gotoPage(page) {
            var dir = page < currentPage ? -1 : 1,
                n = Math.abs(currentPage - page),
                left = singleWidth * dir * visible * n;
            
            $wrapper.filter(':not(:animated)').animate({
                scrollLeft : '+=' + left
            }, 500, function () {
                if (page == 0) {
                    $wrapper.scrollLeft(singleWidth * visible * pages);
                    page = pages;
                } else if (page > pages) {
                    $wrapper.scrollLeft(singleWidth * visible);
                    // reset back to start position
                    page = 1;
                } 

                currentPage = page;
                preparePopups(currentPage);
            });                
            
            return false;
        }
        
        
        $wrapper.after('<a class="arrow back"></a><a class="arrow forward"></a>');
        
        // 5. Bind to the forward and back buttons
        $('a.back', this).click(function () {
            return gotoPage(currentPage - 1);                
        });
        
        $('a.forward', this).click(function () {
            return gotoPage(currentPage + 1);
        });
        
        // create a public interface to move to a specific page
        $(this).bind('goto', function (event, page) {
            gotoPage(page);
        });

        // add popup arrow div to the bottom of each popup bubble
        $('.popup').each( function() {
            $(this).find(' > p:last').after('<div class="popup-arrow"/>');
        });
        // initialize popups on the first page
        preparePopups(currentPage);

    });  
};