/**
 * This object is a hovering data cell which flys between two existing data cells
 * and copys the value from the source data cell to the target data cell.
 */

var MOVE_INTERVAL = 17;
var DEFAULT_STEP = 2;

/**
 * Constructor
 * source - Source DataCell
 * target - Target DataCell
 * srcLeft - Absolute left coordinate of the source data cell
 * srcTop - Absolute top coordinate of the source data cell
 * trgtLeft - Absolute left coordinate of the target data cell
 * trgtTop - Absolute top coordinate of the target data cell
 * width - Width of the flying data cell
 * height - Height of the flying data cell
 * highlight - Defines whether the flying cell is highlighted or not
 * speed - Speed of the flying cell (values between 1 to 5)
 */
function FlyingData(source, target, srcLeft, srcTop, trgtLeft, trgtTop,
					width, height, highlight, speed) {
	var d0 = document.createElement("DIV");
	d0.style.position = "absolute";
	d0.style.left = srcLeft - 1;
	d0.style.top = srcTop - 1;
	
	d0.style.width = target.itemDiv.offsetWidth; //width;
	d0.style.height = target.itemDiv.offsetHeight; //height;
	
	d0.style.borderStyle = "Solid";
	d0.style.borderWidth = "1px";
	d0.style.borderColor = "#000000";
	d0.style.fontFamily = "Arial";
	d0.style.lineHeight = parseInt(height) + "px";
	d0.style.fontSize = CELL_FONT_SIZE;
	d0.style.textAlign = "center";
	d0.style.fontWeight = "Bolder";
	d0.style.display = "none";
	if (!highlight) 
		d0.style.backgroundColor = "#FFFF00";//CELL_COLOR;
	else
		d0.style.backgroundColor = CELL_HIGHLIGHT;	
	document.body.appendChild(d0);
	
	d0.innerHTML = source.getStringValue();
	
	var that = this;
	
	/**
	 * Private function
	 * Starts the fly
	 */
	function flyTo(x, y) {
		var sx = Math.abs(getAbsLeft(d0) - x);
		var sy = Math.abs(getAbsTop(d0) - y);
		var xStep = DEFAULT_STEP + speed * 2;
		var yStep = Math.round(xStep * (sy/sx));
		var slowX = (xStep > yStep * 2);
		var slowY = (yStep > xStep * 2);
		if (yStep < 1) yStep = 1;
		setTimeout(function() { moveX(d0, x - 1, xStep, slowX); }, 2);
		setTimeout(function() { moveY(d0, y - 1, yStep, slowY); }, 1);
		var interval = MOVE_INTERVAL;
		
		/**
		 * Moves the cell on X axis
		 */
		function moveX(obj, x, moveStep, slow) {
			var pLeft = parseInt(obj.style.left);
			if (pLeft < x) {
				obj.style.left = pLeft + moveStep;
			}
			else {
				obj.style.left = pLeft - moveStep;
			}
			if (parseInt(obj.style.left) < x - moveStep || parseInt(obj.style.left) > x + moveStep) 
				setTimeout(function() {
					moveX(obj, x, moveStep);
				}, interval * (slow ? 2 : 1));
			else {
				obj.style.left = x;
				upSemaphore();
			}					
		}

		/**
		 * Moves the cell on Y axis
		 */
		function moveY(obj, y, moveStep, slow) {
			var pTop = parseInt(obj.style.top);
			if (pTop < y) {
				obj.style.top = pTop + moveStep;
			}
			else {
				obj.style.top = pTop - moveStep;
			}
			if (parseInt(obj.style.top) < y - moveStep || parseInt(obj.style.top) > y + moveStep) {
				setTimeout(function() {
					moveY(obj, y, moveStep);
				}, interval * (slow ? 2 : 1));
			}
			else {
				obj.style.top = y;
				upSemaphore();
			}					
		}
		
		/**
		 * A semaphore-like data structure, used to signal when both X and Y axes move are done.
		 */
		var semaphore = -2;
		var available = true;
		
		function upSemaphore() {
			if (!available) { 
				setTimeout(upSemaphore, 1);
				return;
			}
			available = false;
			semaphore++;
			if (semaphore == 0) ready();
			available = true;
		}
	}

	var onReadyFunc;

	/**
	 * Setting up the operation of this object and initiates the fly
	 * onReady - a reference to a function to be called when done
	 */
	this.fly = function(onReady) {
		d0.style.display = "block";
		onReadyFunc = onReady;
		flyTo(trgtLeft, trgtTop);
	}
	
	/**
	 * Finalizes the operation of this object, disposes HTML DOM objects and calls 
	 * the onReady function.
	 */
	function ready() {
		function _ready() {
			document.body.removeChild(d0);
			d0 = null;
			onReadyFunc();
		}
		setTimeout(_ready, 700 * (1.0 / speed));
	}
}