var global_pos = 0;
var shown_elements = 4;
var num_of_elements = 0;
var move_increment = 45;

function setNumElements(value)
{
	num_of_elements = value;
	//alert("num_of_elements : "+num_of_elements);
}

function MoveLeft()
{
    var effect = new Fx.Style('nav_items', 'marginLeft', {
        duration: 500,
        transition: Fx.Transitions.Back.easeInOut
    });

    var left = document.getElementById("nav_items").style.marginLeft;

    if (!left)
        left = 0;

    effect.start(parseInt(left) + move_increment);

	global_pos = global_pos - 1;
	//alert(global_pos);
	checkPos();
}
function MoveRight()
{
	//alert("move right");
	
    var effect = new Fx.Style('nav_items', 'marginLeft', {
        duration: 500,
        transition:  Fx.Transitions.Back.easeInOut
    });

    var left = document.getElementById("nav_items").style.marginLeft;

	if (!left)
        left = 0;

	//alert("left : "+left);
	//alert("move_increment : "+move_increment);

    effect.start(parseInt(left) - move_increment);

	global_pos = global_pos + 1;
	//alert(global_pos);
	checkPos();
}
function checkPos()
{
	//Checks positioning and sets buttons/innerHTML to match position
	if(global_pos <= 0)
	{
		//If we're at the far left of the elements
		disableLeft();

		if(num_of_elements <= shown_elements)
			disableRight();
		else
			enableRight();
	}
	else if (global_pos >= (num_of_elements - shown_elements))
	{
		//If we're at the far right of the elements
		enableLeft();
		disableRight();
	}
	else
	{
		enableLeft();
		enableRight();
	}
}

function disableLeft()
{
	document.getElementById("btnleft").innerHTML = "<img src='/images/scroller_buttons/btn_left_disabled.gif' />";
}
function enableLeft()
{
	document.getElementById("btnleft").innerHTML = "<a href='javascript:MoveLeft();'><img src='/images/scroller_buttons/btn_left.gif' border='0' /></a>";
}
function disableRight()
{
	document.getElementById("btnright").innerHTML = "<img src='/images/scroller_buttons/btn_right_disabled.gif' />";
}
function enableRight()
{
	document.getElementById("btnright").innerHTML = "<a href='javascript:MoveRight();'><img src='/images/scroller_buttons/btn_right.gif' border='0' /></a>";
}