var scroll_div;
var container_div;
var targets;

var scroll_count = 0;
var inprog = false;

function setElements () {
	scroll_div = document.getElementById("newsItems");
	container_div = document.getElementById("newsBox");
	targets = scroll_div.getElementsByTagName("div");
}

function scrollDown () {
	if (inprog == false) {
		setElements();
		if (scroll_count < (targets.length-1)) {
			var tY = -(Element.getHeight(targets[scroll_count]));
			function complete (obj) {
				scroll_count++;
				inprog = false;
			}
			new Effect.Move(scroll_div, {x: 0, y: tY, mode: 'relative', afterFinish:complete, duration: 0.5});
			inprog = true;
			document.getElementById("upBtn").style.visibility = "visible";
			if (scroll_count == (targets.length-2)) {
				document.getElementById("downBtn").style.visibility = "hidden";
			} else {
				document.getElementById("downBtn").style.visibility = "visible";	
			}
		}
	}
}

function scrollUp () {
	if (inprog == false) {
		setElements();
		if (scroll_count > 0) {
			scroll_count--;
			var tY = (Element.getHeight(targets[scroll_count]));
			function complete (obj) {
				inprog = false;
			}
			new Effect.Move(scroll_div, {x: 0, y: tY, mode: 'relative', afterFinish:complete, duration: 0.5});
			inprog = true;
			document.getElementById("downBtn").style.visibility = "visible";
			if (scroll_count == 0) {
				document.getElementById("upBtn").style.visibility = "hidden";
			} else {
				document.getElementById("upBtn").style.visibility = "visible";
			}
		}
	}
}