//------------------------------------------------------------------------------
// kontrola tvaru emailove adresy
function wrong_mail_address(adresa){
  var re = /^[_a-zA-Z0-9\.\-]+@[_a-zA-Z0-9\.\-]+\.[a-zA-Z]{2,4}$/;
  return re.test(adresa) == 0;
}

//------------------------------------------------------------------------------
// funkce vraci element s danym ID
function getObj(id){
   if(Boolean(document.getElementById))
      return document.getElementById(id);
   else if(Boolean(document.all))
      return eval('document.all.'+id);
   else
      return eval('document.'+id);
}


//------------------------------------------------------------------------------
// prepinani obrazku
function switchPhoto(link){
    var main = getObj('main-pic');
    main.src = link.href;
    return false;
}


//------------------------------------------------------------------------------
// zobrazeni objednavkoveho fomrulare
function showForm(click){
    if(click) var vis = true;
    else try{ vis = show } catch(e){}

    if(vis){
        getObj('order-form').style.display = 'block';
        getObj('order').style.display = 'none';
        getObj('book-price').style.display = 'none';
        getObj('book-img').style.display = 'none';
    }
}

function showSub(id){
    var subs = getElementsByClassName('uroven2', 'ul');
    for(var i=0; i < subs.length; i++)
        subs[i].style.display = 'none';
    if(id) getObj('sub'+id).style.display = 'block';
}


function getElementsByClassName(className, tag, elm){
	var testClass = new RegExp("(^|\\s)" + className + "(\\s|$)");
	var tag = tag || "*";
	var elm = elm || document;
	var elements = (tag == "*" && elm.all)? elm.all : elm.getElementsByTagName(tag);
	var returnElements = [];
	var current;
	var length = elements.length;
	for(var i=0; i<length; i++){
		current = elements[i];
		if(testClass.test(current.className)){
			returnElements.push(current);
		}
	}
	return returnElements;
}