var DDSPEED = 10;
var DDTIMER = 15;

// main function to handle the mouse events //
function ddMenu(id,d)
{
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  clearInterval(c.timer);
  if(d == 1)
  {
    clearTimeout(h.timer);
    if(c.maxh && c.maxh <= c.offsetHeight)
    {
    	return;
    }
    else if(!c.maxh)
    {
      c.style.display = 'block';
      c.style.height = 'auto';
      c.maxh = c.offsetHeight;
      c.style.height = '0px';
    }
    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
  }
  else
  {
    h.timer = setTimeout(function(){ddCollapse(c)},250);
  }
}

// collapse the menu //
function ddCollapse(c)
{
  c.timer = setInterval( function() {ddSlide(c,-1)},DDTIMER);
  setTimeout(function(){setHeightToZero(c)},400)
}

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id)
{
  var h = document.getElementById(id + '-ddheader');
  var c = document.getElementById(id + '-ddcontent');
  clearTimeout(h.timer);
  clearInterval(c.timer);
  if(c.offsetHeight < c.maxh)
  {
    c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
  }
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlide(c,d)
{
  var currh = c.offsetHeight;
  var dist;
  if(d == 1)
  {
    dist = (Math.round((c.maxh - currh) / DDSPEED));
  }else
  {
    dist = (Math.round(currh / DDSPEED));
  }
  if(dist <= 1 && d == 1)
  {
    dist = 1;
  }
  c.style.height = currh + (dist * d) + 'px';
  c.style.opacity = currh / c.maxh;
  c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
  if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1))
  {
    clearInterval(c.timer);
  }
}

function setHeightToZero(c)
{
	c.style.height='0px';	
}