(function($) {
	$.fn.carousel = function(o) {
		o = $.extend({ btnPrev: null, btnNext: null, btnGo: null, mouseWheel: true, auto: 3000,
			speed: 450,	easing: null, vertical: false, circular: true, visible: 2, start: 0,
			scroll: 2, beforeStart: null,	afterEnd: null
		}, o || {});

		return this.each(function() {

			var running = false, animCss = o.vertical ? "top" : "left", sizeCss = o.vertical ? "height" : "width";
			var div = $(this), ul = $("ul", div), tLi = $("li", ul), tl = tLi.size(), v = o.visible;

			if (o.circular) {
				ul.prepend(tLi.slice(tl - v - 1 + 1).clone())
              .append(tLi.slice(0, v).clone());
				o.start += v;
			}

			var li = $("li", ul), itemLength = li.size(), curr = o.start;
			div.css("visibility", "visible");

			li.css({ overflow: "hidden", float: o.vertical ? "none" : "left" });
			ul.css({ margin: "0", padding: "0", position: "relative", "list-style-type": "none", "z-index": "1" });
			div.css({ overflow: "hidden", position: "relative", "z-index": "2", left: "0px" });

			var liSize = o.vertical ? height(li) : width(li);
			var ulSize = liSize * itemLength;
			var divSize = liSize * v;

			li.css({ width: li.width(), height: li.height() });
			ul.css(sizeCss, ulSize + "px").css(animCss, -(curr * liSize));

			div.css(sizeCss, divSize + "px");

			if (o.btnPrev)
				$(o.btnPrev).click(function() {
					return go(curr - o.scroll);
				});

			if (o.btnNext)
				$(o.btnNext).click(function() {
					return go(curr + o.scroll);
				});

			if (o.btnGo)
				$.each(o.btnGo, function(i, val) {
					$(val).click(function() {
						return go(o.circular ? o.visible + i : i);
					});
				});

			if (o.mouseWheel && div.mousewheel)
				div.mousewheel(function(e, d) {
					return d > 0 ? go(curr - o.scroll) : go(curr + o.scroll);
				});

			if (o.auto)
				setInterval(function() {
					go(curr + o.scroll);
				}, o.auto + o.speed);

			function vis() {
				return li.slice(curr).slice(0, v);
			};
			
			function go(to) {
				if (!running) {

					if (o.beforeStart)
						o.beforeStart.call(this, vis());

					if (o.circular) {
						if (to <= o.start - v - 1) {
							ul.css(animCss, -((itemLength - (v * 2)) * liSize) + "px");
							curr = to == o.start - v - 1 ? itemLength - (v * 2) - 1 : itemLength - (v * 2) - o.scroll;
						} else if (to >= itemLength - v + 1) {
							ul.css(animCss, -((v) * liSize) + "px");
							curr = to == itemLength - v + 1 ? v + 1 : v + o.scroll;
						} else curr = to;
					} else {
						if (to < 0 || to > itemLength - v) return;
						else curr = to;
					}

					running = true;

					ul.animate(
                    animCss == "left" ? { left: -(curr * liSize)} : { top: -(curr * liSize) }, o.speed, o.easing,
                    function() {
                    	if (o.afterEnd)
                    		o.afterEnd.call(this, vis());
                    	running = false;
                    }
                );
					if (!o.circular) {
						$(o.btnPrev + "," + o.btnNext).removeClass("disabled");
						$((curr - o.scroll < 0 && o.btnPrev)
                        ||
                       (curr + o.scroll > itemLength - v && o.btnNext)
                        ||
                       []
                     ).addClass("disabled");
					}
				}
				return false;
			};
		});
	};

	function css(el, prop) {
		return parseInt($.css(el[0], prop)) || 0;
	};
	function width(el) {
		return el[0].offsetWidth + css(el, 'marginLeft') + css(el, 'marginRight');
	};
	function height(el) {
		return el[0].offsetHeight + css(el, 'marginTop') + css(el, 'marginBottom');
	};

})(jQuery);