var DDSPEED = 5;
var DDTIMER = 15;

// main function to handle the mouse events //
function ddMenu(id,d){
  var h = document.getElementById(id + '-ddheader');
  var a = document.getElementById(id + '2');
  var c = document.getElementById(id + '-ddcontent'); 
  clearInterval(c.timer);
  if(d == 1){
  	if(id=='five') {
  	a.style.backgroundImage = "url(../images/nase-produkty-bg-hov.png)";
  	a.style.backgroundColor= '#808080';
  }
    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)},50);
	if(id=='five') a.style.backgroundImage = "url(../images/nase-produkty-bg.png)";
	a.style.backgroundColor= '';
  }
}

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

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id){
  var h = document.getElementById(id + '-ddheader');
  var a = document.getElementById(id + '2');
  var c = document.getElementById(id + '-ddcontent');
  if(id=='five') {
  	a.style.backgroundImage = "url(../images/nase-produkty-bg-hov.png)";
  	a.style.backgroundColor= '#808080';
  }
  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 checkform ( form )
{
  if (form.poptavka.value == "") {
    alert( "Vyplňte prosím váš požadavek." );
    form.poptavka.focus();
    return false ;
  }
  if (form.jmeno.value == "") {
    alert( "Vyplňte prosím vaše jméno." );
    form.jmeno.focus();
    return false ;
  }
  if (form.adresa.value == "") {
    alert( "Vyplňte prosím vaší adresu." );
    form.adresa.focus();
    return false ;
  }
  if (form.mesto.value == "") {
    alert( "Vyplňte prosím vaše město." );
    form.mesto.focus();
    return false ;
  }
  if (form.psc.value == "") {
    alert( "Vyplňte prosím vaše PSČ." );
    form.psc.focus();
    return false ;
  }

  if (form.email.value == "") {
    alert( "Vyplňte prosím vaší e-mailovou adresu." );
    form.email.focus();
    return false ;
  }

  if (form.telefon.value == "") {
    alert( "Vyplňte prosím vaše telefonní číslo." );
    form.telefon.focus();
    return false ;
  }
  if (form.spam.value != 30) {
    alert( "Vyplňte prosím kontrolní kód." );
    form.spam.focus();
    return false ;
  }
  return true ;
}