function addDays(date, dayAdd) {
	millisec = dayAdd * 86400000;
	newTime = date.getTime() + millisec;
	return new Date(newTime);
}
function diffDays(date1, date2) {
	//diff = Math.floor((date2.getTime() - date1.getTime())/86400000);
	diff = Math.round((date2.getTime() - date1.getTime())/86400000);
	return diff;
}
		
function setNumberNight() {
	var sDayVal  = Number(document.getElementById('gi')[document.getElementById('gi').selectedIndex].value);
	var sYearVal = Number(document.getElementById('ai')[document.getElementById('ai').selectedIndex].value);
	var sMonthVal= Number(document.getElementById('mi')[document.getElementById('mi').selectedIndex].value);
	var dataStart =  new Date(sYearVal,sMonthVal-1,sDayVal,12,0,0);

	var sDayVal  = Number(document.getElementById('gf')[document.getElementById('gf').selectedIndex].value);
	var sYearVal = Number(document.getElementById('af')[document.getElementById('af').selectedIndex].value);
	var sMonthVal= Number(document.getElementById('mf')[document.getElementById('mf').selectedIndex].value);
	var dataEnd = new Date(sYearVal,sMonthVal-1,sDayVal,12,0,0);
	
	if (dataStart<dataEnd) {
		  document.getElementById('days').value = diffDays(dataStart, dataEnd);
      document.getElementById('giorni').value  = diffDays(dataStart, dataEnd);
	} else {
      document.getElementById('days').value = 2;
      document.getElementById('giorni').value  = 2;
	 	  setEndNight();
	}
	return true;
}

function setEndNight() {
	if (isNaN(Number (document.getElementById('days').value)) ) {
			document.getElementById('days').value=2;
			document.getElementById('giorni').value=2;
	}
		var dataEnd =  new Date();
	  var sDayVal  = Number(document.getElementById('gi')[document.getElementById('gi').selectedIndex].value);
	  var sYearVal = Number(document.getElementById('ai')[document.getElementById('ai').selectedIndex].value);
	  var sMonthVal= Number(document.getElementById('mi')[document.getElementById('mi').selectedIndex].value);
		var dataStart = new Date(sYearVal,sMonthVal-1,sDayVal,12,0,0);
	  oggi = new Date();
	  var sYearini = oggi.getFullYear();
		
		dataEnd = addDays(dataStart, Number(document.getElementById('days').value));
		document.getElementById('gf').options[""+dataEnd.getDate()-1].selected = true;
		document.getElementById('mf').options[""+dataEnd.getMonth()].selected = true;
		document.getElementById('af').options[""+(dataEnd.getFullYear()-sYearini)].selected = true;

	return true;
}