var Drag =
{

obj : null,

init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
{
	o.onmousedown = Drag.start;
	o.hmode = bSwapHorzRef ? false : true ;
	o.vmode = bSwapVertRef ? false : true ;
	o.root = oRoot && oRoot != null ? oRoot : o ;
	if (o.hmode  && isNaN(parseInt(o.root.style.left))) o.root.style.left = "0px";
	if (o.vmode  && isNaN(parseInt(o.root.style.top))) o.root.style.top = "0px";
	if (!o.hmode && isNaN(parseInt(o.root.style.right))) o.root.style.right = "0px";
	if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";	
	o.minX = typeof minX != 'undefined' ? minX : null;
	o.minY = typeof minY != 'undefined' ? minY : null;
	o.maxX = typeof maxX != 'undefined' ? maxX : null;
	o.maxY = typeof maxY != 'undefined' ? maxY : null;
	o.xMapper = fXMapper ? fXMapper : null;
	o.yMapper = fYMapper ? fYMapper : null;
	o.root.onDragStart = new Function();
	o.root.onDragEnd = new Function();
	o.root.onDrag = new Function();
},

start : function(e)
{
	var o = Drag.obj = this;
	e = Drag.fixE(e);
	var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);
	var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right);
	o.lastMouseX = e.clientX;
	o.lastMouseY = e.clientY;
	o.root.onDragStart(o.lastMouseX,o.lastMouseY);
	if (o.hmode)
	{
		if (o.minX != null) o.minMouseX = e.clientX - x + o.minX;
		if (o.maxX != null) o.maxMouseX = o.minMouseX + o.maxX - o.minX;
	}
	else
	{
		if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
		if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
	}
	if (o.vmode)
	{
		if (o.minY != null) o.minMouseY = e.clientY - y + o.minY;
		if (o.maxY != null) o.maxMouseY = o.minMouseY + o.maxY - o.minY;
	}
	else
	{
		if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
		if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
	}
	document.onmousemove = Drag.drag;
	document.onmouseup = Drag.end;
	return false;
},

drag : function(e)
{
	e = Drag.fixE(e);
	var o = Drag.obj;	
	var ey = e.clientY;
	var ex = e.clientX;
	var y = parseInt(o.vmode ? o.root.style.top : o.root.style.bottom);
	var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right);
	var nx, ny;
	if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
	if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
	if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
	if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);
	nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
	ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));	
	if (o.xMapper) nx = o.xMapper(y)
	else if (o.yMapper) ny = o.yMapper(x)
	Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
	Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
	Drag.obj.lastMouseX = ex;
	Drag.obj.lastMouseY = ey;
	Drag.obj.root.onDrag(ex,ey);
	return false;
},

end : function()
{
	document.onmousemove = null;
	document.onmouseup = null;
	Drag.obj.root.onDragEnd(Drag.obj.lastMouseX,Drag.obj.lastMouseY);
	Drag.obj = null;
},

fixE : function(e)
{
	if (typeof e == 'undefined') e = window.event;
	if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
	if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
	return e;
}

};

var doneDragDrop = false;

function computeRealPosition(obj)
{
	var par = obj.parentNode;
	var npar = par;
	var xx = 0;
	var yy = 0;
	var ww = par.offsetWidth;
	var hh = par.offsetHeight;
	var steps = 0;
	while (par != null && steps < 100)
	{
		++steps;
		xx += par.offsetLeft - par.scrollLeft;
		yy += par.offsetTop - par.scrollTop;
		par = par.offsetParent;
	}
	npar.realX = xx;
	npar.realY = yy;
	npar.realWidth = ww;
	npar.realHeight = hh;
}

function findDropElement(x,y)
{
	var drops = document.getElementsByName("drop");
	for (i = 0; i < drops.length; ++i)
	{
		computeRealPosition(drops.item(i));
	}
	for (i = 0; i < drops.length; ++i)
	{
		var par = drops.item(i).parentNode;
		if (par.realX <= x && par.realY <= y && x - par.realX <= par.realWidth && y - par.realY <= par.realHeight) return par;
	}
	return null;
}

var curDrop = null;

function onDragStart(x,y)
{
	curDrop = null;
	Drag.obj.copyIndex = Drag.obj.style.zIndex;
	Drag.obj.style.zIndex = 10000;
}

function onDrag(x,y)
{
	var drop = findDropElement(x,y);
	if (drop == curDrop) return;
	if (curDrop != null)
	{
		curDrop.style.border = '';
		curDrop.style.margin = '2px';
	}
	curDrop = drop;
	if (curDrop != null)
	{
		curDrop.style.margin = '';
		curDrop.style.border = '2px dotted #ff0000';
	}
}

function onDragEnd(x,y)
{
	var dragId = Drag.obj.id;
	computeRealPosition(Drag.obj);
	var drop = findDropElement(x,y);
	if (drop == null) immediateEvent(true,dragId,'ondrop',null,true);
	else
	{
		drop.style.border = '';
		drop.style.margin = '2px';
		var dropId = drop.id;
		immediateEvent(true,dragId,'ondrop',drop.id+':'+ (x - drop.realX) + ':' + (y - drop.realY),true);
	}
	curDrop = null;
	Drag.obj.style.zIndex = Drag.obj.copyIndex;
}

function doDragDrop()
{
	var drags = document.getElementsByName("drag");
	for (i = 0; i < drags.length; ++i)
	{
		var par = drags.item(i).parentNode;
		Drag.init(par);
		par.onDragStart = onDragStart;
		par.onDrag = onDrag;
		par.onDragEnd = onDragEnd;
	}
}