// global instance is created here.
var dragNDrop=new mmDragHandler();
dragNDrop.extends(new Publisher());

function mmDragHandler(){
	var m_dragObject;
	var m_offsetX;
	var m_offsetY;
	var m_isDragging=false;
	var m_zIndexSave;
	var m_lastSeenNode=null;
	var m_origX=null; // Position the mouse was pushed down.
	var m_origY=null;

	document.onmousemove = onMouseMoveHandler;
	document.onmouseup = onMouseUpHandler;

	this.onMouseDownHandler=onMouseDownHandler;
	this.onMouseMoveHandler=onMouseMoveHandler;
	this.onMouseUpHandler=onMouseUpHandler;
	this.activateForObject=activateForObject;

	function activateForObject(ele) {
                ele.ondrag=function(){return false;};
                ele.onselectstart=function(){return false;};
                ele.onmousedown=onMouseDownHandler;
		// if nothing else is mentioned in the object position it in the middle of the visible area.
                if (ele.style.left=="") { 
			ele.style.left=((window.innerWidth/2) + window.scrollX) + "px"; 
		}
                if (ele.style.top=="") { 
			ele.style.top=((window.innerHeight/2) + window.scrollY) + "px"; 
		}
                ele.style.display="inline";
		this.notifySubscribers(ele,"activateDragNDrop");
	}

	function onMouseDownHandler(e) {
		if (window.event) e=window.event;
		m_dragObject = e.target;

		var dragX = parseInt(m_dragObject.style.left);
		var dragY = parseInt(m_dragObject.style.top);

		var mouseX = e.clientX;
		var mouseY = e.clientY;

		m_origX=mouseX;
		m_origY=mouseY;

		m_offsetX = mouseX - dragX;
		m_offsetY = mouseY - dragY;

		m_zIndexSave=m_dragObject.style.zIndex;
		m_dragObject.style.zIndex=5;

		m_dragObject.isDragging=true;
		m_isDragging = true;

		return(false);
	}

	function onMouseMoveHandler(e){
		if (!m_isDragging) return;
		if (window.event) e=window.event;
		
		if (e.target.id.substring(0,6)=="mmNode") {
			m_lastSeenNode=e.target; 
		}

		if ((m_origX!=e.clientX)||(m_origY!=e.clientY)) {
			dragNDrop.notifySubscribers(m_dragObject,"moving");
		}

		var newX = e.clientX - m_offsetX;
		var newY = e.clientY - m_offsetY;

		m_dragObject.style.left = newX + "px";
		m_dragObject.style.top = newY + "px";

		var addInfo=new Array();
		addInfo[0]=newX;
		addInfo[1]=newY;

		return(false);
	}

	function onMouseUpHandler(e){
		if (!m_isDragging) return;
		m_dragObject.style.zIndex=m_zIndexSave;
		m_dragObject.isDragging=false;
		m_isDragging = false;
		dragNDrop.notifySubscribers(m_dragObject,"endMoving",m_lastSeenNode);
		return(false);
	}
}