var hasShown = false;

function init() {
	// Drop-Down-Liste der Abreisebox sichern und löschen
	TOPTS = new Array();
  form = document.forms['fname'];
  antElem = form.elements[ant];
  abtElem = form.elements[abt];
  anmjElem = form.elements[anmj];
  abmjElem = form.elements[abmj];
  msgabElem = document.getElementById(msgabid)
	for(var i = abmjElem.length-1;i>=0;i--) {
	  TOPTS[i] = abmjElem.options[i];
		abmjElem.options[i] = null;
	}

  document.forms['fname'].elements[anmj].onchange = function() {
    updateAbreiseBox();
    nextYearWarning();
  }
  updateAbreiseBox();
}

function nextYearWarning() {
  var date = new Date();
  var aktMon = date.getMonth();
  var aktJahr = date.getFullYear();

	var value = anmjElem.options[anmjElem.selectedIndex].value.split("x");
	var monat = value[0];
	var jahr  = value[1];
	if(!hasShown && monat > aktMon && jahr > aktJahr || monat <= aktMon && jahr > aktJahr+1) {
    msgabElem.style.display = "block";
	} else {
	  msgabElem.style.display = "none";
	}
}

function clearMsgBox() {
  msgabElem.style.display = "none";
  hasShown = true;
}

function updateAbreiseBox() {
  if(anmjElem.value == "x") { // Kein Anreisedatum gewählt
	  abmjElem.options[0] = new Option("Anreisetag wählen...", "x", false, true);
	  abmjElem.options[0].style.backgroundColor="#FF0000";
  } else {                    // Monat bekannt -> Abreisebox belegen
    var offset = anmjElem.selectedIndex;
    abmjElem.options[0] = TOPTS[0];
    for(var i=0; i < MAXMON; i = i+1) {
      abmjElem.options[i+1] = TOPTS[offset + i];
    }
  }
}