// TODO 2010/06/28 - Syogo Miyagawa.
// �O�D����

// Copyright (c) 2005 Thomas Fuchs (http://script.aculo.us, http://mir.aculo.us)
//           (c) 2005 Sammi Williams (http://www.oriontransfer.co.nz, sammi@oriontransfer.co.nz)
// 
// See scriptaculous.js for full license.

/*--------------------------------------------------------------------------*/

var Droppables = {

	drops:[],

	remove: function (element) {
		this.drops = this.drops.reject(function (d) { return d.element == $(element) });
	},

	add: function (element) {
		element = $(element);
		var options = Object.extend({
			greedy:true,
			hoverclass:null,
			tree:false
		}, arguments[1] || {});

		// cache containers
		if (options.containment) {
			options._containers = [];
			var containment = options.containment;
			if ((typeof containment == 'object') && (containment.constructor == Array)) {
				containment.each(function (c) { options._containers.push($(c)) });
			} else {
				options._containers.push($(containment));
			}
		}

		if (options.accept) options.accept = [options.accept].flatten();

		// fix IE
		Element.makePositioned(element);
		options.element = element;

		this.drops.push(options);
	},

	findDeepestChild: function (drops) {
		deepest = drops[0];

		for (i = 1; i < drops.length; ++i) {
			if (Element.isParent(drops[i].element, deepest.element)) {
				deepest = drops[i];
			}
		}

		return deepest;
	},

	isContained: function (element, drop) {
		var containmentNode;
		if (drop.tree) {
			containmentNode = element.treeNode; 
		} else {
			containmentNode = element.parentNode;
		}
		return drop._containers.detect(function (c) { return containmentNode == c });
	},

	isAffected: function (point, element, drop) {
		return (
			(drop.element != element)
			&& ((!drop._containers) || this.isContained(element, drop))
			&& ((!drop.accept) || (Element.classNames(element).detect(function (v) { return drop.accept.include(v) })))
			&& Position.within(drop.element, point[0], point[1])
		);
	},

	deactivate: function (drop) {
		if (drop.hoverclass) {
			Element.removeClassName(drop.element, drop.hoverclass);
		}
		this.last_active = null;
	},

	activate: function (drop) {
		if (drop.hoverclass) {
			Element.addClassName(drop.element, drop.hoverclass);
		}
		this.last_active = drop;
	},

	show: function (point, element) {
		if (!this.drops.length) return;
		var affected = [];

		if (this.last_active) this.deactivate(this.last_active);
		this.drops.each(function (drop) {
			if (Droppables.isAffected(point, element, drop)) {
				affected.push(drop);
			}
		});

		if (affected.length>0) {
			drop = Droppables.findDeepestChild(affected);
			Position.within(drop.element, point[0], point[1]);
			if (drop.onHover) {
				drop.onHover(element, drop.element, Position.overlap(drop.overlap, drop.element));
			}

			Droppables.activate(drop);
		}
	},

	fire: function (event, element) {
		if (!this.last_active) return;
		Position.prepare();

		if (this.isAffected([Event.pointerX(event), Event.pointerY(event)], element, this.last_active)) {
			if (this.last_active.onDrop) {
				this.last_active.onDrop(element, this.last_active.element, event);
			}
		}
	},

	reset: function () {
		if (this.last_active) {
			this.deactivate(this.last_active);
		}
	}
}

var Draggables = {

	drags:[],
	observers:[],

	register: function (draggable) {
		if (this.drags.length == 0) {
			this.eventMouseUp = this.endDrag.bindAsEventListener(this);
			this.eventMouseMove = this.updateDrag.bindAsEventListener(this);
			this.eventKeypress = this.keyPress.bindAsEventListener(this);

			Event.observe(document, "mouseup", this.eventMouseUp);
			Event.observe(document, "mousemove", this.eventMouseMove);
			Event.observe(document, "keypress", this.eventKeypress);
		}
		this.drags.push(draggable);
	},

	unregister: function (draggable) {
		this.drags = this.drags.reject(function (d) { return d == draggable });
		if (this.drags.length == 0) {
			Event.stopObserving(document, "mouseup", this.eventMouseUp);
			Event.stopObserving(document, "mousemove", this.eventMouseMove);
			Event.stopObserving(document, "keypress", this.eventKeypress);
		}
	},

	activate: function (draggable) {
		// allows keypress events if window isn't currently focused, fails for Safari
		window.focus();
		this.activeDraggable = draggable;
	},

	deactivate: function () {
		this.activeDraggable = null;
	},

	updateDrag: function (event) {
		if (!this.activeDraggable) return;
		var pointer = [Event.pointerX(event), Event.pointerY(event)];
		// Mozilla-based browsers fire successive mousemove events with
		// the same coordinates, prevent needless redrawing (moz bug?)
		if (this._lastPointer && (this._lastPointer.inspect() == pointer.inspect())) return;
		this._lastPointer = pointer;
		this.activeDraggable.updateDrag(event, pointer);
	},

	endDrag: function (event) {
		if (!this.activeDraggable) return;
		this._lastPointer = null;
		this.activeDraggable.endDrag(event);
		this.activeDraggable = null;
	},

	keyPress: function (event) {
		if (this.activeDraggable) {
			this.activeDraggable.keyPress(event);
		}
	},

	addObserver: function (observer) {
		this.observers.push(observer);
		this._cacheObserverCallbacks();
	},

	removeObserver: function (element) {
		// element instead of observer fixes mem leaks
		this.observers = this.observers.reject(function (o) { return o.element == element });
		this._cacheObserverCallbacks();
	},

	notify: function (eventName, draggable, event) {
		// 'onStart', 'onEnd', 'onDrag'
		if (this[eventName+'Count'] > 0) {
			this.observers.each(function (o) {
				if (o[eventName]) o[eventName](eventName, draggable, event);
			});
		}
	},

	_cacheObserverCallbacks: function () {
		['onStart', 'onEnd', 'onDrag'].each(function (eventName) {
			Draggables[eventName + 'Count'] = Draggables.observers.select(
				function (o) { return o[eventName]; }
			).length;
		});
	}
}

/*--------------------------------------------------------------------------*/

var Draggable = Class.create();

Draggable.prototype = {

	initialize: function (element) {

		this.offset = Array();

		var options = Object.extend({
			handle:false,
			starteffect: function (element) {
				element._opacity = Element.getOpacity(element);
				new Effect.Opacity(element, {duration:0.2, from:element._opacity, to:0.7});
			},
			reverteffect: function (element, top_offset, left_offset) {
				var dur = Math.sqrt(Math.abs(top_offset ^ 2) + Math.abs(left_offset ^ 2)) * 0.02;
				element._revert = new Effect.Move(element, {x:-left_offset, y:-top_offset, duration:dur});
			},
			endeffect: function (element) {
				var toOpacity = typeof element._opacity == 'number' ? element._opacity :1.0;
				new Effect.Opacity(element, {duration:0.2, from:0.7, to:toOpacity});
			},
			zindex:1000,
			revert:false,
			scroll:false,
			scrollSensitivity:20,
			scrollSpeed:15,
			// false, or xy or [x,y] or function (x,y){ return [x,y] }
			snap:false
		}, arguments[1] || {});

		this.element = $(element);

		if (options.handle && (typeof options.handle == 'string')) {
			var h = Element.childrenWithClassName(this.element, options.handle, true);
			if (h.length > 0) this.handle = h[0];
		}

		if (!this.handle) this.handle = $(options.handle);
		if (!this.handle) this.handle = this.element;

		if (options.scroll && !options.scroll.scrollTo && !options.scroll.outerHTML) {
			options.scroll = $(options.scroll);
		}

		// fix IE
		Element.makePositioned(this.element);

		this.delta = this.currentDelta();
		this.options = options;
		this.dragging = false;

		this.eventMouseDown = this.initDrag.bindAsEventListener(this);
		Event.observe(this.handle, "mousedown", this.eventMouseDown);

		Draggables.register(this);
	},

	destroy: function () {
		Event.stopObserving(this.handle, "mousedown", this.eventMouseDown);
		Draggables.unregister(this);
	},

	currentDelta: function () {
		return([
			parseInt(Element.getStyle(this.element,'left') || '0'),
			parseInt(Element.getStyle(this.element,'top') || '0')
		]);
	},

	initDrag: function (event) {
		if (Event.isLeftClick(event)) {
			// abort on form elements, fixes a Firefox issue
			var src = Event.element(event);
			if (src.tagName
				&& (src.tagName == 'INPUT'
					|| src.tagName == 'SELECT'
					|| src.tagName == 'OPTION'
					|| src.tagName == 'BUTTON'
					|| src.tagName == 'TEXTAREA')) return;

			if (this.element._revert) {
				this.element._revert.cancel();
				this.element._revert = null;
			}

			var pointer = [Event.pointerX(event), Event.pointerY(event)];
			var pos = Position.cumulativeOffset(this.element);
//			this.offset = [0,1].map(function (i) { return (pointer[i] - pos[i]) });

			this.offset[0] = pointer[0] - pos[0];
			this.offset[1] = pointer[1] - pos[1];
			
			Draggables.activate(this);
			Event.stop(event);
		}
	},

	startDrag: function (event) {
		this.dragging = true;

		if (this.options.zindex) {
			this.originalZ = parseInt(Element.getStyle(this.element, 'z-index') || 0);
			this.element.style.zIndex = this.options.zindex;
		}

		if (this.options.ghosting) {
			this._clone = this.element.cloneNode(true);
			Position.absolutize(this.element);
			this.element.parentNode.insertBefore(this._clone, this.element);
		}

		if (this.options.scroll) {
			if (this.options.scroll == window) {
				var where = this._getWindowScroll(this.options.scroll);
				this.originalScrollLeft = where.left;
				this.originalScrollTop = where.top;
			} else {
				this.originalScrollLeft = this.options.scroll.scrollLeft;
				this.originalScrollTop = this.options.scroll.scrollTop;
			}
		}

		Draggables.notify('onStart', this, event);
		if(this.options.starteffect) this.options.starteffect(this.element);
	},

	updateDrag: function (event, pointer) {
		if (!this.dragging) this.startDrag(event);

		Position.prepare();
		Droppables.show(pointer, this.element);
		Draggables.notify('onDrag', this, event);
		this.draw(pointer);

		if (this.options.change) this.options.change(this);
		
		if (this.options.scroll) {
			this.stopScrolling();
			var p;
			if (this.options.scroll == window) {
				with (this._getWindowScroll(this.options.scroll)) { p = [left, top, left+width, top+height]; }
			} else {
				p = Position.page(this.options.scroll);
				p[0] += this.options.scroll.scrollLeft;
				p[1] += this.options.scroll.scrollTop;
				p.push(p[0]+this.options.scroll.offsetWidth);
				p.push(p[1]+this.options.scroll.offsetHeight);
			}
			var speed = [0,0];
			if (pointer[0] < (p[0] + this.options.scrollSensitivity)) speed[0] = pointer[0] - (p[0] + this.options.scrollSensitivity);
			if (pointer[1] < (p[1] + this.options.scrollSensitivity)) speed[1] = pointer[1] - (p[1] + this.options.scrollSensitivity);
			if (pointer[0] > (p[2] - this.options.scrollSensitivity)) speed[0] = pointer[0] - (p[2] - this.options.scrollSensitivity);
			if (pointer[1] > (p[3] - this.options.scrollSensitivity)) speed[1] = pointer[1] - (p[3] - this.options.scrollSensitivity);
			this.startScrolling(speed);
		}

		// fix AppleWebKit rendering
		if (navigator.appVersion.indexOf('AppleWebKit') > 0) window.scrollBy(0, 0);

		Event.stop(event);
	},

	finishDrag: function (event, success) {
		this.dragging = false;

		if (this.options.ghosting) {
			Position.relativize(this.element);
			Element.remove(this._clone);
			this._clone = null;
		}

		if (success) Droppables.fire(event, this.element);
		Draggables.notify('onEnd', this, event);

		var revert = this.options.revert;
		if (revert && typeof revert == 'function') revert = revert(this.element);
		
		var d = this.currentDelta();
		if (revert && this.options.reverteffect) {
			this.options.reverteffect(this.element, d[1] - this.delta[1], d[0] - this.delta[0]);
		} else {
			this.delta = d;
		}

		// if(this.options.zindex)
		this.element.style.zIndex = this.originalZ;

		if (this.options.endeffect) {
			this.options.endeffect(this.element);
		}

		Draggables.deactivate(this);
		Droppables.reset();
	},

	keyPress: function (event) {
		if (event.keyCode != Event.KEY_ESC) return;
		this.finishDrag(event, false);
		Event.stop(event);
	},

	endDrag: function (event) {
		if (!this.dragging) return;
		this.stopScrolling();
		this.finishDrag(event, true);
		Event.stop(event);
	},

	draw: function (point) {
		var pos = Position.cumulativeOffset(this.element);
		var d = this.currentDelta();
		pos[0] -= d[0];
		pos[1] -= d[1];

		if (this.options.scroll && (this.options.scroll != window)) {
			pos[0] -= this.options.scroll.scrollLeft - this.originalScrollLeft;
			pos[1] -= this.options.scroll.scrollTop - this.originalScrollTop;
		}
		var p = [0,1].map(function (i) {
			return (point[i] - pos[i] - this.offset[i])
		}.bind(this));
		p[0] = point[0] - pos[0] - this.offset[0];
		p[1] = point[1] - pos[1] - this.offset[1];

		if (this.options.snap) {
			if (typeof this.options.snap == 'function') {
				p = this.options.snap(p[0], p[1], this);
			} else {
				if (this.options.snap instanceof Array) {
					p = p.map(function (v, i) { return Math.round(v / this.options.snap[i]) * this.options.snap[i] }.bind(this));
				} else {
					p = p.map(function (v) { return Math.round(v / this.options.snap) * this.options.snap }.bind(this));
				}
			}
		}

		var style = this.element.style;
		if ((!this.options.constraint) || (this.options.constraint == 'horizontal')) {
			style.left = p[0] + "px";
		}
		if ((!this.options.constraint) || (this.options.constraint == 'vertical')) {
			style.top = p[1] + "px";
		}
		if (style.visibility == "hidden") {
			// fix gecko rendering
			style.visibility = "";
		}
	},

	stopScrolling: function () {
		if (this.scrollInterval) {
			clearInterval(this.scrollInterval);
			this.scrollInterval = null;
			Draggables._lastScrollPointer = null;
		}
	},

	startScrolling: function (speed) {
		this.scrollSpeed = [speed[0] * this.options.scrollSpeed,speed[1] * this.options.scrollSpeed];
		this.lastScrolled = new Date();
		this.scrollInterval = setInterval(this.scroll.bind(this), 10);
	},

	scroll: function () {
		var current = new Date();
		var delta = current - this.lastScrolled;
		this.lastScrolled = current;
		if (this.options.scroll == window) {
			with (this._getWindowScroll(this.options.scroll)) {
				if (this.scrollSpeed[0] || this.scrollSpeed[1]) {
					var d = delta / 1000;
					this.options.scroll.scrollTo(left + d*this.scrollSpeed[0], top + d*this.scrollSpeed[1]);
				}
			}
		} else {
			this.options.scroll.scrollLeft += this.scrollSpeed[0] * delta / 1000;
			this.options.scroll.scrollTop += this.scrollSpeed[1] * delta / 1000;
		}

		Position.prepare();
		Droppables.show(Draggables._lastPointer, this.element);
		Draggables.notify('onDrag', this);
		Draggables._lastScrollPointer = Draggables._lastScrollPointer || $A(Draggables._lastPointer);
		Draggables._lastScrollPointer[0] += this.scrollSpeed[0] * delta / 1000;
		Draggables._lastScrollPointer[1] += this.scrollSpeed[1] * delta / 1000;
		if (Draggables._lastScrollPointer[0] < 0) {
			Draggables._lastScrollPointer[0] = 0;
		}
		if (Draggables._lastScrollPointer[1] < 0) {
			Draggables._lastScrollPointer[1] = 0;
		}
		this.draw(Draggables._lastScrollPointer);

		if (this.options.change) {
			this.options.change(this);
		}
	},

	_getWindowScroll:function (w) {
		var T, L, W, H;
		with (w.document) {
			if (w.document.documentElement && documentElement.scrollTop) {
				T = documentElement.scrollTop;
				L = documentElement.scrollLeft;
			} else if (w.document.body) {
				T = body.scrollTop;
				L = body.scrollLeft;
			}
			if (w.innerWidth) {
				W = w.innerWidth;
				H = w.innerHeight;
			} else if (w.document.documentElement && documentElement.clientWidth) {
				W = documentElement.clientWidth;
				H = documentElement.clientHeight;
			} else {
				W = body.offsetWidth;
				H = body.offsetHeight
			}
		}
		return { top:T, left:L, width:W, height:H };
	}
}

/*--------------------------------------------------------------------------*/

var SortableObserver = Class.create();

SortableObserver.prototype = {

	initialize: function (element, observer) {
		this.element = $(element);
		this.observer = observer;
		this.lastValue = Sortable.serialize(this.element);
	},

	onStart: function () {
		this.lastValue = Sortable.serialize(this.element);
	},

	onEnd: function () {
		Sortable.unmark();
		if (this.lastValue != Sortable.serialize(this.element)) {
			this.observer(this.element)
		}
	}
}

var Sortable = {

	sortables:{},

	_findRootElement: function (element) {
		while (element.tagName != "BODY") {
			if (element.id && Sortable.sortables[element.id]) return element;
			element = element.parentNode;
		}
	},

	options: function (element) {
		element = Sortable._findRootElement($(element));
		if (!element) return;
		return Sortable.sortables[element.id];
	},

	destroy: function (element){
		var s = Sortable.options(element);

		if (s) {
			Draggables.removeObserver(s.element);
			s.droppables.each(function (d){ Droppables.remove(d) });
			s.draggables.invoke('destroy');

			delete Sortable.sortables[s.element.id];
		}
	},

	create: function (element) {
		element = $(element);
		var options = Object.extend({ 
			element:element,
			// assumes li children, override with tag:'tagname'
			tag:'li',
			dropOnEmpty:false,
			tree:false,
			treeTag:'ul',
			// one of 'vertical', 'horizontal'
			overlap:'vertical',
			// one of 'vertical', 'horizontal', false
			constraint:'vertical',
			// also takes array of elements (or id's); or false
			containment:element,
			// or a CSS class
			handle:false,
			only:false,
			hoverclass:null,
			ghosting:false,
			scroll:false,
			scrollSensitivity:20,
			scrollSpeed:15,
			format:/^[^_]*_(.*)$/,
			onChange:Prototype.emptyFunction,
			onUpdate:Prototype.emptyFunction
		}, arguments[1] || {});

		// clear any old sortable with same element
		this.destroy(element);

		// build options for the draggables
		var options_for_draggable = {
			revert:true,
			scroll:options.scroll,
			scrollSpeed:options.scrollSpeed,
			scrollSensitivity:options.scrollSensitivity,
			ghosting:options.ghosting,
			constraint:options.constraint,
			handle:options.handle
		};

		if (options.starteffect) {
			options_for_draggable.starteffect = options.starteffect;
		}

		if (options.reverteffect) {
			options_for_draggable.reverteffect = options.reverteffect;
		}
		else {
			if (options.ghosting) {
				options_for_draggable.reverteffect = function (element) { element.style.top = 0; element.style.left = 0; };
			}
		}

		if (options.endeffect) {
			options_for_draggable.endeffect = options.endeffect;
		}

		if (options.zindex) {
			options_for_draggable.zindex = options.zindex;
		}

		// build options for the droppables	
		var options_for_droppable = {
			overlap:options.overlap,
			containment:options.containment,
			tree:options.tree,
			hoverclass:options.hoverclass,
			onHover:Sortable.onHover
			//greedy:!options.dropOnEmpty
		}

		var options_for_tree = {
			onHover:Sortable.onEmptyHover,
			overlap:options.overlap,
			containment:options.containment,
			hoverclass: options.hoverclass
		}

		// fix for gecko engine
		Element.cleanWhitespace(element); 

		options.draggables = [];
		options.droppables = [];

		// drop on empty handling
		if (options.dropOnEmpty || options.tree) {
			Droppables.add(element, options_for_tree);
			options.droppables.push(element);
		}

		(this.findElements(element, options) || []).each(function (e) {
			// handles are per-draggable
			var handle = options.handle ? Element.childrenWithClassName(e, options.handle)[0] : e;
			options.draggables.push(new Draggable(e, Object.extend(options_for_draggable, { handle:handle })));
			Droppables.add(e, options_for_droppable);
			if(options.tree) e.treeNode = element;
			options.droppables.push(e);
		});

		if (options.tree) {
			(Sortable.findTreeElements(element, options) || []).each(function (e) {
				Droppables.add(e, options_for_tree);
				e.treeNode = element;
				options.droppables.push(e);
			});
		}

		// keep reference
		this.sortables[element.id] = options;

		// for onupdate
		Draggables.addObserver(new SortableObserver(element, options.onUpdate));

	},

	// return all suitable-for-sortable elements in a guaranteed order
	findElements: function (element, options) {
		return Element.findChildren(element, options.only, options.tree ? true : false, options.tag);
	},

	findTreeElements: function (element, options) {
		return Element.findChildren(element, options.only, options.tree ? true : false, options.treeTag);
	},

	onHover: function (element, dropon, overlap) {
		if (Element.isParent(dropon, element)) return;

		if (overlap > .33 && overlap < .66 && Sortable.options(dropon).tree) {
			return;
		} else if(overlap > 0.5) {
			Sortable.mark(dropon, 'before');
			if (dropon.previousSibling != element) {
				var oldParentNode = element.parentNode;
				// fix gecko rendering
				element.style.visibility = "hidden";
				dropon.parentNode.insertBefore(element, dropon);
				if (dropon.parentNode != oldParentNode) {
					Sortable.options(oldParentNode).onChange(element);
				}
				Sortable.options(dropon.parentNode).onChange(element);
			}
		} else {
			Sortable.mark(dropon, 'after');
			var nextElement = dropon.nextSibling || null;
			if (nextElement != element) {
				var oldParentNode = element.parentNode;
				// fix gecko rendering
				element.style.visibility = "hidden";
				dropon.parentNode.insertBefore(element, nextElement);
				if (dropon.parentNode != oldParentNode) {
					Sortable.options(oldParentNode).onChange(element);
				}
				Sortable.options(dropon.parentNode).onChange(element);
			}
		}
	},

	onEmptyHover: function (element, dropon, overlap) {
		var oldParentNode = element.parentNode;
		var droponOptions = Sortable.options(dropon);

		if (!Element.isParent(dropon, element)) {
			var index;

			var children = Sortable.findElements(dropon, {tag:droponOptions.tag});
			var child = null;

			if (children) {
				var offset = Element.offsetSize(dropon, droponOptions.overlap) * (1.0 - overlap);

				for (index = 0; index < children.length; index += 1) {
					if (offset - Element.offsetSize (children[index], droponOptions.overlap) >= 0) {
						offset -= Element.offsetSize (children[index], droponOptions.overlap);
					} else if (offset - (Element.offsetSize (children[index], droponOptions.overlap) / 2) >= 0) {
						child = index + 1 < children.length ? children[index + 1] : null;
						break;
					} else {
						child = children[index];
						break;
					}
				}
			}

			dropon.insertBefore(element, child);

			Sortable.options(oldParentNode).onChange(element);
			droponOptions.onChange(element);
		}
	},

	unmark: function () {
		if (Sortable._marker) Element.hide(Sortable._marker);
	},

	mark: function (dropon, position) {
		// mark on ghosting only
		var sortable = Sortable.options(dropon.parentNode);
		if (sortable && !sortable.ghosting) return; 

		if (!Sortable._marker) {
			Sortable._marker = $('dropmarker') || document.createElement('DIV');
			Element.hide(Sortable._marker);
			Element.addClassName(Sortable._marker, 'dropmarker');
			Sortable._marker.style.position = 'absolute';
			document.getElementsByTagName("body").item(0).appendChild(Sortable._marker);
		}
		var offsets = Position.cumulativeOffset(dropon);
		Sortable._marker.style.left = offsets[0] + 'px';
		Sortable._marker.style.top = offsets[1] + 'px';

		if (position=='after') {
			if (sortable.overlap == 'horizontal') {
				Sortable._marker.style.left = (offsets[0] + dropon.clientWidth) + 'px';
			}
			else {
				Sortable._marker.style.top = (offsets[1] + dropon.clientHeight) + 'px';
			}
		}

		Element.show(Sortable._marker);
	},

	_tree: function (element, options, parent) {
		var children = Sortable.findElements(element, options) || [];

		for (var i = 0; i < children.length; ++i) {
			var match = children[i].id.match(options.format);

			if (!match) continue;

			var child = {
				id: encodeURIComponent(match ? match[1] : null),
				element:element,
				parent:parent,
				children:new Array,
				position:parent.children.length,
				container: Sortable._findChildrenElement(children[i], options.treeTag.toUpperCase())
			}

			/* Get the element containing the children and recurse over it */
			if (child.container) {
				this._tree(child.container, options, child);
			}

			parent.children.push (child);
		}

		return parent;
	},

	/*
	 * Finds the first element of the given tag type within a parent element.
	 * Used for finding the first LI[ST] within a L[IST]I[TEM].
	*/
	_findChildrenElement: function (element, containerTag) {
		if (element && element.hasChildNodes) {
			for (var i = 0; i < element.childNodes.length; ++i) {
				if (element.childNodes[i].tagName == containerTag) {
					return element.childNodes[i];
				}
			}
		}

		return null;
	},

	tree: function (element) {
		element = $(element);
		var sortableOptions = this.options(element);
		var options = Object.extend({
			tag:sortableOptions.tag,
			treeTag:sortableOptions.treeTag,
			only:sortableOptions.only,
			name:element.id,
			format:sortableOptions.format
		}, arguments[1] || {});

		var root = {
			id:null,
			parent:null,
			children:new Array,
			container:element,
			position:0
		}

		return Sortable._tree (element, options, root);
	},

	/* Construct a [i] index for a particular node */
	_constructIndex: function (node) {
		var index = '';
		do {
			if (node.id) index = '[' + node.position + ']' + index;
		} while ((node = node.parent) != null);
		return index;
	},

	sequence: function (element) {
		element = $(element);
		var options = Object.extend(this.options(element), arguments[1] || {});
		
		return $(this.findElements(element, options) || []).map(function (item) {
			return item.id.match(options.format) ? item.id.match(options.format)[1] : '';
		});
	},

	setSequence: function (element, new_sequence) {
		element = $(element);
		var options = Object.extend(this.options(element), arguments[2] || {});

		var nodeMap = {};
		this.findElements(element, options).each(function (n) {
			if (n.id.match(options.format)) {
				nodeMap[n.id.match(options.format)[1]] = [n, n.parentNode];
			}
			n.parentNode.removeChild(n);
		});

		new_sequence.each(function (ident) {
			var n = nodeMap[ident];
			if (n) {
				n[1].appendChild(n[0]);
				delete nodeMap[ident];
			}
		});
	},

	serialize: function (element) {
		element = $(element);
		var options = Object.extend(Sortable.options(element), arguments[1] || {});
		var name = encodeURIComponent((arguments[1] && arguments[1].name) ? arguments[1].name : element.id);

		if (options.tree) {
			return Sortable.tree(element, arguments[1]).children.map(function (item) {
				return [name + Sortable._constructIndex(item) + "=" + encodeURIComponent(item.id)].concat(item.children.map(arguments.callee));
			}).flatten().join('&');
		} else {
			return Sortable.sequence(element, arguments[1]).map(function (item) {
				return name + "[]=" + encodeURIComponent(item);
			}).join('&');
		}
	}
}

/* Returns true if child is contained within element */
Element.isParent = function (child, element) {

	if (!child.parentNode || child == element) return false;

	if (child.parentNode == element) return true;

	return Element.isParent(child.parentNode, element);
}

Element.findChildren = function (element, only, recursive, tagName) {

	if (!element.hasChildNodes()) return null;
	tagName = tagName.toUpperCase();
	if (only) only = [only].flatten();
	var elements = [];
	$A(element.childNodes).each(function (e) {
		if (e.tagName && e.tagName.toUpperCase() == tagName && (!only || (Element.classNames(e).detect(function (v) { return only.include(v) })))) {
			elements.push(e);
		}
		if (recursive) {
			var grandchildren = Element.findChildren(e, only, recursive, tagName);
			if(grandchildren) elements.push(grandchildren);
		}
	});

	return (elements.length > 0 ? elements.flatten() : []);
}

Element.offsetSize = function (element, type) {

	if (type == 'vertical' || type == 'height') {
		return element.offsetHeight;
	}
	else {
		return element.offsetWidth;
	}
}