(function($) {

	var dropShadowZindex = 1;  //z-index counter

	$.fn.dropShadow = function(options) {
		// Default options
		var opt = $.extend({
			left: 4,
			top: 4,
			blur: 2,
			opacity: 1,
			color: "black",
			swap: false
		}, options);
		var jShadows = $([]);  //empty jQuery collection

		// Loop through original elements
		this.not(".dropShadow").each(function() {
			var jthis = $(this);
			var shadows = [];
			var blur = (opt.blur <= 0) ? 0 : opt.blur;
			var opacity = (blur == 0) ? opt.opacity : opt.opacity / (blur * 8);
			var zOriginal = (opt.swap) ? dropShadowZindex : dropShadowZindex + 1;
			var zShadow = (opt.swap) ? dropShadowZindex + 1 : dropShadowZindex;

			// Create ID for shadow
			var shadowId;
			if (this.id) {
				shadowId = this.id + "_dropShadow";
			}
			else {
				shadowId = "ds" + (1 + Math.floor(9999 * Math.random()));
			}

			// Modify original element
			$.data(this, "shadowId", shadowId); //store id in expando
			$.data(this, "shadowOptions", options); //store options in expando
			jthis
        .attr("shadowId", shadowId)
        .css("zIndex", zOriginal);
			if (jthis.css("position") != "absolute") {
				jthis.css({
					position: "relative",
					zoom: 1 //for IE layout
				});
			}

			// Create first shadow layer
			bgColor = jthis.css("backgroundColor");
			if (bgColor == "rgba(0, 0, 0, 0)") bgColor = "transparent";  //Safari
			if (bgColor != "transparent" || jthis.css("backgroundImage") != "none"
          || this.nodeName == "SELECT"
          || this.nodeName == "INPUT"
          || this.nodeName == "TEXTAREA") {
				shadows[0] = $("<div></div>")
          .css("background", opt.color);
			}
			else {
				shadows[0] = jthis
          .clone()
          .removeAttr("id")
          .removeAttr("name")
          .removeAttr("shadowId")
          .css("color", opt.color);
			}
			if (opacity < 1) {
				shadows[0]
					.addClass("dropShadow")
					.css({
						height: jthis.outerHeight(),
						left: blur,
						opacity: opacity,
						position: "absolute",
						top: blur,
						width: jthis.outerWidth(),
						zIndex: zShadow
					});
				} else {
				shadows[0]
					.addClass("dropShadow")
					.css({
						height: jthis.outerHeight(),
						left: blur,
						position: "absolute",
						top: blur,
						width: jthis.outerWidth(),
						zIndex: zShadow
					});
			}

			// Create other shadow layers
			var layers = (8 * blur) + 1;
			for (i = 1; i < layers; i++) {
				shadows[i] = shadows[0].clone();
			}

			// Position layers
			var i = 1;
			var j = blur;
			while (j > 0) {
				shadows[i].css({ left: j * 2, top: 0 });           //top
				shadows[i + 1].css({ left: j * 4, top: j * 2 });   //right
				shadows[i + 2].css({ left: j * 2, top: j * 4 });   //bottom
				shadows[i + 3].css({ left: 0, top: j * 2 });       //left
				shadows[i + 4].css({ left: j * 3, top: j });       //top-right
				shadows[i + 5].css({ left: j * 3, top: j * 3 });   //bottom-right
				shadows[i + 6].css({ left: j, top: j * 3 });       //bottom-left
				shadows[i + 7].css({ left: j, top: j });           //top-left
				i += 8;
				j--;
			}

			// Create container
			var divShadow = $("<div></div>")
        .attr("id", shadowId)
        .addClass("dropShadow")
        .css({
        	left: jthis.position().left + opt.left - blur,
        	marginTop: jthis.css("marginTop"),
        	marginRight: jthis.css("marginRight"),
        	marginBottom: jthis.css("marginBottom"),
        	marginLeft: jthis.css("marginLeft"),
        	position: "absolute",
        	top: jthis.position().top + opt.top - blur,
        	zIndex: zShadow
        });

			// Add layers to container  
			for (i = 0; i < layers; i++) {
				divShadow.append(shadows[i]);
			}

			// Add container to DOM
			jthis.after(divShadow);

			// Add shadow to return set
			jShadows = jShadows.add(divShadow);

			// Re-align shadow on window resize
			$(window).resize(function() {
				try {
					divShadow.css({
						left: jthis.position().left + opt.left - blur,
						top: jthis.position().top + opt.top - blur
					});
				}
				catch (e) { }
			});

			// Increment z-index counter
			dropShadowZindex += 2;

		});  //end each

		return this.pushStack(jShadows);
	};


	$.fn.redrawShadow = function() {
		// Remove existing shadows
		this.removeShadow();

		// Draw new shadows
		return this.each(function() {
			var shadowOptions = $.data(this, "shadowOptions");
			$(this).dropShadow(shadowOptions);
		});
	};


	$.fn.removeShadow = function() {
		return this.each(function() {
			var shadowId = $(this).shadowId();
			$("div#" + shadowId).remove();
		});
	};


	$.fn.shadowId = function() {
		return $.data(this[0], "shadowId");
	};


	$(function() {
		// Suppress printing of shadows
		var noPrint = "<style type='text/css' media='print'>";
		noPrint += ".dropShadow{visibility:hidden;}</style>";
		$("head").append(noPrint);
	});

})(jQuery);