var found=false;
var now_dragging=false;
var sourcenode=0;
var Drag = {
	BIG_Z_INDEX : 10000,
	group : null,
	isDragging : false,

	makeDraggable : function(group) {
		group.handle = group;
		group.handle.group = group;

		group.minX = null;
		group.minY = null;
		group.maxX = null;
		group.maxY = null;
		group.threshold = 0;
		group.thresholdY = 0;
		group.thresholdX = 0;

		group.onDragStart = new Function();
		group.onDragEnd = new Function();
		group.onDrag = new Function();
		
		// TODO: use element.prototype.myFunc
		group.setDragHandle = Drag.setDragHandle;
		group.setDragThreshold = Drag.setDragThreshold;
		group.setDragThresholdX = Drag.setDragThresholdX;
		group.setDragThresholdY = Drag.setDragThresholdY;
		group.constrain = Drag.constrain;
		group.constrainVertical = Drag.constrainVertical;
		group.constrainHorizontal = Drag.constrainHorizontal;

		group.onmousedown = Drag.onMouseDown;
	},

	constrainVertical : function() {
		var nwOffset = Coordinates.northwestOffset(this, true);
		this.minX = nwOffset.x;
		this.maxX = nwOffset.x;
	},

	constrainHorizontal : function() {
		var nwOffset = Coordinates.northwestOffset(this, true);
		this.minY = nwOffset.y;
		this.maxY = nwOffset.y;
	},

	constrain : function(nwPosition, sePosition) {
		this.minX = nwPosition.x;
		this.minY = nwPosition.y;
		this.maxX = sePosition.x;
		this.maxY = sePosition.y;
	},

	setDragHandle : function(handle) {
		if (handle && handle != null) 
			this.handle = handle;
		else
			this.handle = this;

		this.handle.group = this;
		this.onmousedown = null;
		this.handle.onmousedown = Drag.onMouseDown;
	},

	setDragThreshold : function(threshold) {
		if (isNaN(parseInt(threshold))) return;

		this.threshold = threshold;
	},

	setDragThresholdX : function(threshold) {
		if (isNaN(parseInt(threshold))) return;

		this.thresholdX = threshold;
	},

	setDragThresholdY : function(threshold) {
		if (isNaN(parseInt(threshold))) return;

		this.thresholdY = threshold;
	},

	onMouseDown : function(event) {
		if (!lock_drag) {
		if (!found) {
		found=true;
		event = Drag.fixEvent(event);
		Drag.group = this.group;

		var group = this.group;
		var mouse = event.windowCoordinate;
		var nwOffset = Coordinates.northwestOffset(group, true);
		var nwPosition = Coordinates.northwestPosition(group);
		var sePosition = Coordinates.southeastPosition(group);
		var seOffset = Coordinates.southeastOffset(group, true);

		group.originalOpacity = group.style.opacity;
		group.originalZIndex = group.style.zIndex;
		group.initialWindowCoordinate = mouse;
		// TODO: need a better name, but don't yet understand how it
		// participates in the magic while dragging 
		group.dragCoordinate = mouse;

		Drag.showStatus(mouse, nwPosition, sePosition, nwOffset, seOffset);

		group.onDragStart(nwPosition, sePosition, nwOffset, seOffset);

		// TODO: need better constraint API
		if (group.minX != null)
			group.minMouseX = mouse.x - nwPosition.x + 
					group.minX - nwOffset.x;
		if (group.maxX != null) 
			group.maxMouseX = group.minMouseX + group.maxX - group.minX;

		if (group.minY != null)
			group.minMouseY = mouse.y - nwPosition.y + 
					group.minY - nwOffset.y;
		if (group.maxY != null) 
			group.maxMouseY = group.minMouseY + group.maxY - group.minY;

		group.mouseMin = new Coordinate(group.minMouseX, group.minMouseY);
		group.mouseMax = new Coordinate(group.maxMouseX, group.maxMouseY);

		document.onmousemove = Drag.onMouseMove;
		document.onmouseup = Drag.onMouseUp;
		}
		}

		return false;
	},

	showStatus : function(mouse, nwPosition, sePosition, nwOffset, seOffset) {
//		window.status = 
//				"mouse: " + mouse.toString() + "    " + 
//				"NW pos: " + nwPosition.toString() + "    " + 
//				"SE pos: " + sePosition.toString() + "    " + 
//				"NW offset: " + nwOffset.toString() + "    " +
//				"SE offset: " + seOffset.toString();
	},

	onMouseMove : function(event) {
		event = Drag.fixEvent(event);
		var group = Drag.group;
		var mouse = event.windowCoordinate;
		var nwOffset = Coordinates.northwestOffset(group, true);
		var nwPosition = Coordinates.northwestPosition(group);
		var sePosition = Coordinates.southeastPosition(group);
		var seOffset = Coordinates.southeastOffset(group, true);

		Drag.showStatus(mouse, nwPosition, sePosition, nwOffset, seOffset);

		if (Drag.isDragging) {
			unmarkTrack();
		}

		if (!Drag.isDragging) {
			if (group.threshold > 0) {
				var distance = group.initialWindowCoordinate.distance(
						mouse);
				if (distance < group.threshold) return true; else {
					if (userid) {
						sourcenode=group.parentNode.id;
						flowerlocked=true;
						unmarkTrack();
					} else {
						veil();document.getElementById('please_register').style.display='';
						return true;
					}
				}
			} else if (group.thresholdY > 0) {
				flowerlocked=true;
				var deltaY = Math.abs(group.initialWindowCoordinate.y - mouse.y);
				if (deltaY < group.thresholdY) return true;
			} else if (group.thresholdX > 0) {
				flowerlocked=true;
				var deltaX = Math.abs(group.initialWindowCoordinate.x - mouse.x);
				if (deltaX < group.thresholdX) return true;
			}

			Drag.isDragging = true;
			group.style["zIndex"] = Drag.BIG_Z_INDEX;
			group.style["opacity"] = 0.75;
		}

		// TODO: need better constraint API
		var adjusted = mouse.constrain(group.mouseMin, group.mouseMax);
		nwPosition = nwPosition.plus(adjusted.minus(group.dragCoordinate));
		nwPosition.reposition(group);
		group.dragCoordinate = adjusted;

		// changed to be recursive/use absolute offset for corrections
		var offsetBefore = Coordinates.northwestOffset(group, true);
		group.onDrag(nwPosition, sePosition, nwOffset, seOffset);
		var offsetAfter = Coordinates.northwestOffset(group, true);

		if (!offsetBefore.equals(offsetAfter)) {
			var errorDelta = offsetBefore.minus(offsetAfter);
			nwPosition = Coordinates.northwestPosition(group).plus(errorDelta);
			nwPosition.reposition(group);
		}

		return false;
	},

	onMouseUp : function(event) {
		found=false;
		event = Drag.fixEvent(event);
		var group = Drag.group;

		var mouse = event.windowCoordinate;
		var nwOffset = Coordinates.northwestOffset(group, true);
		var nwPosition = Coordinates.northwestPosition(group);
		var sePosition = Coordinates.southeastPosition(group);
		var seOffset = Coordinates.southeastOffset(group, true);

		document.onmousemove = null;
		document.onmouseup   = null;
		group.onDragEnd(nwPosition, sePosition, nwOffset, seOffset);

		if (Drag.isDragging) {
			// restoring zIndex before opacity avoids visual flicker in Firefox
			group.style["zIndex"] = group.originalZIndex;
			group.style["opacity"] = group.originalOpacity;
		}

		Drag.group = null;
		Drag.isDragging = false;

		return false;
	},

	fixEvent : function(event) {
		if (typeof event == 'undefined') event = window.event;
		Coordinates.fixEvent(event);

		return event;
	}
};




var lock_drag=false;

var Coordinates = {
	ORIGIN : new Coordinate(0, 0),

	northwestPosition : function(element) {
		var x = parseInt(element.style.left);
		var y = parseInt(element.style.top);

		return new Coordinate(isNaN(x) ? 0 : x, isNaN(y) ? 0 : y);
	},

	southeastPosition : function(element) {
		return Coordinates.northwestPosition(element).plus(
				new Coordinate(element.offsetWidth, element.offsetHeight));
	},

	northwestOffset : function(element, isRecursive) {
		if (element.innerHTML) {
		var offset = new Coordinate(element.offsetLeft, element.offsetTop);

		if (!isRecursive) return offset;


		var parent = element.offsetParent;
		mk=1;
		while ((parent) && (mk<200)) {
			mk++;
			offset = offset.plus(
					new Coordinate(parent.offsetLeft, parent.offsetTop));
			parent = parent.offsetParent;
		}
		return offset;
		} else {
			return(new Coordinate(0, 0));
		}
	},

	southeastOffset : function(element, isRecursive) {
		return Coordinates.northwestOffset(element, isRecursive).plus(
				new Coordinate(element.offsetWidth, element.offsetHeight));
	},

	fixEvent : function(event) {
		event.windowCoordinate = new Coordinate(event.clientX, event.clientY);
	}
};

function Coordinate(x, y) {
	this.x = x;
	this.y = y;
}

Coordinate.prototype.toString = function() {
	return "(" + this.x + "," + this.y + ")";
}

Coordinate.prototype.plus = function(that) {
	return new Coordinate(this.x + that.x, this.y + that.y);
}

Coordinate.prototype.minus = function(that) {
	return new Coordinate(this.x - that.x, this.y - that.y);
}

Coordinate.prototype.distance = function(that) {
	var deltaX = this.x - that.x;
	var deltaY = this.y - that.y;

	return Math.sqrt(Math.pow(deltaX, 2) + Math.pow(deltaY, 2));
}

Coordinate.prototype.max = function(that) {
	var x = Math.max(this.x, that.x);
	var y = Math.max(this.y, that.y);
	return new Coordinate(x, y);
}

Coordinate.prototype.constrain = function(min, max) {
	if (min.x > max.x || min.y > max.y) return this;

	var x = this.x;
	var y = this.y;

	if (min.x != null) x = Math.max(x, min.x);
	if (max.x != null) x = Math.min(x, max.x);
	if (min.y != null) y = Math.max(y, min.y);
	if (max.y != null) y = Math.min(y, max.y);

	return new Coordinate(x, y);
}

Coordinate.prototype.reposition = function(element) {
	element.style["top"] = this.y + "px";
	element.style["left"] = this.x + "px";
}

Coordinate.prototype.equals = function(that) {
	if (this == that) return true;
	if (!that || that == null) return false;

	return this.x == that.x && this.y == that.y;
}

// returns true of this point is inside specified box
Coordinate.prototype.inside = function(northwest, southeast) {
	if (northwest) {
		if ((this.x >= northwest.x) && (this.x <= southeast.x) &&
			(this.y >= northwest.y) && (this.y <= southeast.y)) {
			return true;
		}
	}
	return false;
}

/**********************************************************
 Adapted from the sortable lists example by Tim Taylor
 http://tool-man.org/examples/sorting.html
 **********************************************************/

var DragDrop = {
	firstContainer : null,
	lastContainer : null,
	
	makeListContainer : function(list) {
		lock_drag=true;

		// each container becomes a linked list node
		if (this.firstContainer == null) {
			this.firstContainer = this.lastContainer = list;
			list.previousContainer = null;
			list.nextContainer = null;
		} else {
			list.previousContainer = this.lastContainer;
			list.nextContainer = null;
			this.lastContainer.nextContainer = list;
			this.lastContainer = list;
		}
		
		list.onDragOver = new Function();
		list.onDragOut = new Function();

	    	var items = list.getElementsByTagName( "li" );
    	
		for (var i = 0; i < items.length; i++) {
			DragDrop.makeItemDragable(items[i]);
		}
		lock_drag=false;
	},

	makeItemDragable : function(item) {
		Drag.makeDraggable(item);
		if (userid) {
			item.setDragThreshold(5);
		} else {
			item.setDragThreshold(40);
		}
		
		item.isOutside = false;
		
		item.onDragStart = DragDrop.onDragStart;
		item.onDrag = DragDrop.onDrag;
		item.onDragEnd = DragDrop.onDragEnd;
	},

	onDragStart : function(nwPosition, sePosition, nwOffset, seOffset) {
		if (!lock_drag) {
		now_dragging=true;
		// update all container bounds, since they may have changed
		// on a previous drag
		//
		// could be more smart about when to do this
		var container = DragDrop.firstContainer;
		mk=1;
		while ((container != null) && (mk<200)) {
			mk++;
			container.northwest = Coordinates.northwestOffset( container, true );
			container.southeast = Coordinates.southeastOffset( container, true );
			container = container.nextContainer;
		}
		
		// item starts out over current parent
		this.parentNode.onDragOver();
		}
	},

	onDrag : function(nwPosition, sePosition, nwOffset, seOffset) {
		if (!lock_drag) {
		// check if we were nowhere
		if (this.isOutside) {
			// check each container to see if in its bounds
			var container = DragDrop.firstContainer;
			mk=1;
			while ((container != null) && (mk<200)) {
				mk++;
				if (nwOffset.inside( container.northwest, container.southeast ) ||
					seOffset.inside( container.northwest, container.southeast )) {
					// we're inside this one
					container.onDragOver();
					this.isOutside = false;
					
					var tempParent = this.parentNode;
					tempParent.removeChild( this );
					container.appendChild( this );
					tempParent.parentNode.removeChild( tempParent );
					break;
				}
				container = container.nextContainer;
			}
			// we're still not inside the bounds of any container
			if (this.isOutside)
				return;
		
		// check if we're outside our parent's bounds
		} else {
		if (!(nwOffset.inside( this.parentNode.northwest, this.parentNode.southeast ) ||
			seOffset.inside( this.parentNode.northwest, this.parentNode.southeast ))) {
			
			this.isOutside = true;
			
			// check if we're inside a new container's bounds
			var container = DragDrop.firstContainer;
			mk=1;
			while ((container != null) && (mk<200)) {
				mk++;
				if (nwOffset.inside( container.northwest, container.southeast ) ||
					seOffset.inside( container.northwest, container.southeast )) {
					// we're inside this one
					this.parentNode.onDragOut();
					container.onDragOver();
					this.isOutside = false;
					this.parentNode.removeChild( this );
					container.appendChild( this );
					break;
				}
				container = container.nextContainer;
			}

			// if we're not in any container now, make a temporary clone of
			// the previous container node and add it to the document
			if (this.isOutside) {
				var tempParent = this.parentNode.cloneNode( false );
				this.parentNode.removeChild( this );
				tempParent.appendChild( this );

				if (document.getElementById('playlist')) {
					dlis=document.getElementById('playlist').getElementsByTagName('li');
					if (!dlis) {
						document.getElementById( "playlist" ).appendChild( tempParent );
					} else {
						if (!dlis.length) {
							document.getElementById( "playlist" ).appendChild( tempParent );
						} else {
							document.getElementById( "playlist_followup" ).appendChild( tempParent );
						}
					}
				}
				return;
			}
		} else {
			var container = DragDrop.firstContainer;
			deepestOne=this.parentNode;
			k=0;
			mk=1;
			while ((container != null) && (mk<200)) {
				mk++;
				if (nwOffset.inside( container.northwest, container.southeast ) ||
					seOffset.inside( container.northwest, container.southeast )) {
					if (container==this.parentNode) k=0;
					deepestOne=container;
					k++;
				}
				container = container.nextContainer;
			}
			status=k;
			if (k>1 && (deepestOne.parentNode!=this)) {
				this.isOutside=false;
				this.parentNode.onDragOut();
				deepestOne.onDragOver();
				this.parentNode.removeChild(this);
				deepestOne.appendChild(this);
			}
		}
		}
		
		var parent = this.parentNode;

		var item = this;
		var next = DragUtils.nextItem(item);
		var mk = 1;
		while ((next != null && this.offsetTop >= next.offsetTop - 2) && (mk<200)) {
			mk++;
			var item = next;
			var next = DragUtils.nextItem(item);
		}
		if (this != item) {
			DragUtils.swap(this, next);
			return;
		}

		var item = this;
		var previous = DragUtils.previousItem(item);
		var mk = 1;
		while ((previous != null && this.offsetTop <= previous.offsetTop + 2) && (mk<200)) {
			mk++;
			var item = previous;
			var previous = DragUtils.previousItem(item);
		}
		if (this != item) {
			DragUtils.swap(this, item);
			return;
		}
		}
	},

	onDragEnd : function(nwPosition, sePosition, nwOffset, seOffset) {
		if (!lock_drag) {
		if (this.isOutside) {
			var tempParent = this.parentNode;
			this.parentNode.removeChild(this);
			tempParent.parentNode.removeChild( tempParent );


			if (document.getElementById('playlist')) {
				dlis=document.getElementById('playlist').getElementsByTagName('li');
				if (!dlis) {
					sourcenode=0;
				} else {
					if (!dlis.length) sourcenode=0;
				}
			}

//			document.getElementById('playlist').appendChild(this);
			if (sourcenode) {
				document.getElementById(sourcenode).appendChild(this);
				DragDrop.makeListContainer(document.getElementById(sourcenode));
				if (sourcenode=="playlist") {
					addControls(document.getElementById(sourcenode));
				} else {
					removeControls(document.getElementById(sourcenode));
				}
			} else {
				document.getElementById('playlist').appendChild(this);
			}

			now_dragging=false;
			this.parentNode.onDragOut();
			this.style["top"] = "0px";
			this.style["left"] = "0px";
			generatePlaylist(cur_playlist);
			return;
		}
		now_dragging=false;
		this.parentNode.onDragOut();
		this.style["top"] = "0px";
		this.style["left"] = "0px";

/*##################################################
##   Здесь можно поставить обработчик изменений   ##
##################################################*/

	}
	}
};

var DragUtils = {
	swap : function(item1, item2) {
		var parent = item1.parentNode;
		parent.removeChild(item1);
		parent.insertBefore(item1, item2);

		item1.style["top"] = "0px";
		item1.style["left"] = "0px";
	},

	nextItem : function(item) {
		var sibling = item.nextSibling;
		while (sibling != null) {
			if (sibling.nodeName == item.nodeName) return sibling;
			sibling = sibling.nextSibling;
		}
		return null;
	},

	previousItem : function(item) {
		var sibling = item.previousSibling;
		while (sibling != null) {
			if (sibling.nodeName == item.nodeName) return sibling;
			sibling = sibling.previousSibling;
		}
		return null;
	}		
};