(function() {

    app.ui.createImageScroller = function(params) {
        var yCenter = 160;
        var xCenter = 160;
        var scrollCenter = {x:xCenter,y:yCenter};
        var scrollDuration = 100;
        var centerThreshold = 20;

        var imageScroller = Ti.UI.createView({
            height:params.height,
            width:960,
            backgroundColor:params.backgroundColor,
            center:{x:xCenter,y:yCenter}
        });

        var index = 0;
        var imageViews = [];
        var images = [];
        for (var i = 0; i < 3; i++) {
            var imageView = Ti.UI.createImageView({
                defaultImage:params.loadingImage,
                height:params.height,
                width:320,
                left:(i * 320)
            });
            imageViews.push(imageView);
            imageScroller.add(imageView);
        }

        var dif = 0;
        imageScroller.addEventListener('touchstart', function(e) {
            dif = e.globalPoint.x - imageScroller.center.x;
        });

        imageScroller.addEventListener('touchmove', function(e) {
            imageScroller.setCenter({x:e.globalPoint.x - dif,y:yCenter});
        });

        imageScroller.addEventListener('touchend', function(e) {
            if (imageScroller.center.x < (xCenter - centerThreshold) && canNext()) {
                imageScroller.next();
            } else if (imageScroller.center.x > (xCenter + centerThreshold) && canPrevious()) {
                imageScroller.previous();
            } else {
                imageScroller.animate({center:scrollCenter,duration:scrollDuration});
            }
        });

        imageScroller.goto = function(imageIndex) {
            if (imageIndex < images.length) {
                index = imageIndex;
                updateImages();
                fireScrollEvent();
            }
        }

        function updateImages() {
            updateCurrent();
            updateNext();
            updatePrevious();
        }

        function canNext() {
            return (index + 1) < images.length;
        }

        function canPrevious() {
            return index - 1 >= 0;
        }

        function updateCurrent() {
            imageViews[1].image = images[index].url;
            images[index].hasViewed = true;
        }

        function updateNext() {
            imageViews[2].image = canNext() ? (images[index + 1].hasViewed ? images[index + 1].url : params.loadingImage) : null;
        }

        function updatePrevious() {
            imageViews[0].image = canPrevious() ? (images[index - 1].hasViewed ? images[index - 1].url : params.loadingImage) : null;
        }

        function fireScrollEvent() {
            imageScroller.fireEvent('scroll', {index:index});
        }

        imageScroller.next = function() {
            if (canNext()) {
                imageScroller.animate({center:{x:-160,y:yCenter},duration:scrollDuration}, function() {
                    imageViews[2].left = 320;
                    imageScroller.center = scrollCenter;
                    imageViews[1].left = 0;
                    imageViews[0].left = 640;
                    imageViews = [imageViews[1],imageViews[2],imageViews[0]];
                    imageScroller.goto(index + 1);
                });
            }
        }

        imageScroller.previous = function() {
            if (canPrevious()) {
                imageScroller.animate({center:{x:480,y:yCenter},duration:scrollDuration}, function() {
                    imageViews[0].left = 320;
                    imageScroller.center = scrollCenter;
                    imageViews[1].left = 640;
                    imageViews[2].left = 0;
                    imageViews = [imageViews[2],imageViews[0],imageViews[1]];
                    imageScroller.goto(index - 1);
                });
            }
        }

        imageScroller.appendUrls = function(urls) {
            for (var i = 0,count = urls.length; i < count; i++) {
                images.push({url:urls[i],hasViewed:false});
            }
        };

        imageScroller.updateUrls = function(urls) {
            images = [];
            imageScroller.appendUrls(urls);
            updateImages();
        };

        imageScroller.count = function() {
            return images.length;
        }

        return imageScroller;
    }

})();