YUI().use("*", function(Y) {

	var UA = Y.UA,

		getClassName = Y.ClassNameManager.getClassName,

		sCheckboxFocusClass = getClassName("checkbox", "focus"),	// Create yui-checkbox-focus

		sCheckboxCheckedClass = getClassName("checkbox", "checked"),	// Create yui-checkbox-checked

		sCheckboxActiveClass = getClassName("checkbox", "active"),	// Create yui-checkbox-active

		bKeyListenersInitialized = false,

		bMouseListenersInitialized = false,

		forAttr = (UA.ie && UA.ie < 8) ? "htmlFor" : "for",

		bBlockDocumentMouseUp = false,

		bBlockClearActive = false,

		bBlockBlur = false,		

		oActiveCheckbox;			

	var initKeyListeners = function () {

		this.delegate("keydown", onCheckboxKeyDown, ".yui-checkbox");

		this.delegate("click", onCheckboxClick, ".yui-checkbox");

		this.delegate("blur", onCheckboxBlur, "input[type=checkbox]");

		bKeyListenersInitialized = true;

	};

	var initMouseListeners = function () {

		this.delegate("mouseover", onCheckboxMouseOver, ".yui-checkbox");

		this.delegate("mouseout", onCheckboxMouseOut, ".yui-checkbox-active");

		this.get("ownerDocument").on("mouseup", onDocumentMouseUp);

		bMouseListenersInitialized = true;

	};

	var getCheckbox = function (node) {

		return (node.hasClass("yui-checkbox") ? node : node.ancestor(".yui-checkbox"));

	};

	var getCheckboxForLabel = function (label) {

		var sID = label.getAttribute(forAttr),

			oInput,

			oCheckbox;

		if (sID) {

			oInput = Y.one("#" + sID);

			if (oInput) {

				oCheckbox = getCheckbox(oInput);

			}

		}

		return oCheckbox;

	};

	var updateCheckedState = function (input) {

		var oCheckbox = getCheckbox(input);

		if (input.get("checked")) {

			oCheckbox.addClass(sCheckboxCheckedClass);

		}

		else {

			oCheckbox.removeClass(sCheckboxCheckedClass);

		}

	};

	var setActiveCheckbox = function (checkbox) {

		checkbox.addClass(sCheckboxActiveClass);

		oActiveCheckbox = checkbox;

	};

	var clearActiveCheckbox = function () {

		if (oActiveCheckbox) {

			oActiveCheckbox.removeClass(sCheckboxActiveClass);

			oActiveCheckbox = null;

		}

	};

	var onCheckboxMouseOver = function (event, matchedEl) {

		if (oActiveCheckbox && oActiveCheckbox.compareTo(this)) {

			oActiveCheckbox.addClass(sCheckboxActiveClass);

		}

	};

	var onCheckboxMouseOut = function (event) {

		this.removeClass(sCheckboxActiveClass);

	};				

	var onDocumentMouseUp = function (event) {

		var oCheckbox;

		if (!bBlockDocumentMouseUp) {

			oCheckbox = getCheckbox(event.target);

			if ((oCheckbox && !oCheckbox.compareTo(oActiveCheckbox)) || !oCheckbox) {

				clearActiveCheckbox();

			}

		}

		bBlockDocumentMouseUp = false;

	};

	var onCheckboxFocus = function (event) {

		//	Remove the focus style from any checkbox that might still have it

		var oCheckbox = Y.one("#checkboxes").one(".yui-checkbox-focus");

		if (oCheckbox) {

			oCheckbox.removeClass(sCheckboxFocusClass);

		}

		//	Defer adding key-related and click event listeners until 

		//	one of the checkboxes is initially focused.

		if (!bKeyListenersInitialized) {

			initKeyListeners.call(event.container);

		}

		oCheckbox = getCheckbox(this);

		oCheckbox.addClass(sCheckboxFocusClass);

	};

	var onCheckboxBlur = function (event) {

		if (bBlockBlur) {

			bBlockBlur = false;

			return;

		}

		var oCheckbox = getCheckbox(this);

		oCheckbox.removeClass(sCheckboxFocusClass);

		if (!bBlockClearActive && oCheckbox.compareTo(oActiveCheckbox)) {

			clearActiveCheckbox();

		}

		bBlockClearActive = false;

	};

	var onCheckboxMouseDown = function (event) {

		//	Defer adding mouse-related and click event listeners until 

		//	the user mouses down on one of the checkboxes.

		if (!bMouseListenersInitialized) {

			initMouseListeners.call(event.container);

		}

		var oCheckbox,

			oInput;

		if (this.get("nodeName").toLowerCase() === "label") {

			//	If the target of the event was the checkbox's label element, the

			//	label will dispatch a click event to the checkbox, meaning the 

			//	"onCheckboxClick" handler will be called twice.  For that reason

			//	it is necessary to block the "onDocumentMouseUp" handler from

			//	clearing the active state, so that a reference to the active  

			//	checkbox still exists the second time the "onCheckboxClick"

			//	handler is called.

			bBlockDocumentMouseUp = true;

			//	When the user clicks the label instead of the checkbox itself, 

			//	the checkbox will be blurred if it has focus.  Since the 

			//	"onCheckboxBlur" handler clears the active state it is 

			//	necessary to block the clearing of the active state when the 

			//	label is clicked instead of the checkbox itself.

			bBlockClearActive = true;

			oCheckbox = getCheckboxForLabel(this);

		}

		else {

			oCheckbox = this;

		}

		//	Need to focus the input manually for two reasons:

		//	1) 	Mousing down on a label in Webkit doesn't focus its  

		//		associated checkbox

		//	2)	By default checkboxes are focused when the user mouses 

		//		down on them.  However, since the actually checkbox is 

		//		obscurred by the two span elements that are used to 

		//		style it, the checkbox wont' receive focus as it was 

		//		never the actual target of the mousedown event.

		oInput = oCheckbox.one("input");

		//	Calling Event.preventDefault won't block the blurring of the 

		//	currently focused element in IE, so we'll use the "bBlockBlur"

		//	variable to stop the code in the blur event handler  

		//	from executing.

		bBlockBlur = (UA.ie && oInput.get("checked"));

		oInput.focus();

		setActiveCheckbox(oCheckbox);

		//	Need to call preventDefault because by default mousing down on

		//	an element will blur the element in the document that currently 

		//	has focus--in this case, the input element that was 

		//	just focused.

		event.preventDefault();

	};

	var onCheckboxClick = function (event) {

		var oInput;

		if (this.compareTo(oActiveCheckbox)) {

			oInput = this.one("input");

			if (!event.target.compareTo(oInput)) {

				//	If the click event was fired via the mouse the checked

				//	state will have to be manually updated since the input 

				//	is hidden offscreen and therefore couldn't be the 

				//	target of the click.

				oInput.set("checked", (!oInput.get("checked")));

			}

			updateCheckedState(oInput);

			clearActiveCheckbox();

		}

	};

	var onCheckboxKeyDown = function (event) {

		//	Style the checkbox as being active when the user presses the 

		//	space bar

		if (event.keyCode === 32) {

			setActiveCheckbox(this);

		}

	};

	Y.all("#checkboxes>div>span").addClass("yui-checkbox");

	//	Remove the "yui-checkboxes-loading" class used to hide the 

	//	checkboxes now that the checkboxes have been skinned.

	Y.one("#checkboxes").get("ownerDocument").get("documentElement").removeClass("yui-checkboxes-loading");

	//	Add the minimum number of event listeners needed to start, bind the 

	//	rest when needed

	Y.delegate("mousedown", onCheckboxMouseDown, "#checkboxes", ".yui-checkbox,label");

	Y.delegate("focus", onCheckboxFocus, "#checkboxes", "input[type=checkbox]");

});