var DateHasChanged = false;
var CurrentNights = 0;

var fromdate = new Date();
var todate = new Date();
todate.setDate(todate.getDate() + 1);

function alterDateOrNight(src) {

	var oNights = document.forms["frmUnterkunftssuche"].elements["Nights"];
	var oDD 	= document.forms["frmUnterkunftssuche"].elements["DD"];
	var oDDt 	= document.forms["frmUnterkunftssuche"].elements["DDt"];
	var oMM 	= document.forms["frmUnterkunftssuche"].elements["MM"];
	var oMMt 	= document.forms["frmUnterkunftssuche"].elements["MMt"];
	var oYYYY 	= document.forms["frmUnterkunftssuche"].elements["YYYY"];
	var oYYYYt 	= document.forms["frmUnterkunftssuche"].elements["YYYYt"];

	var naechteAendertDatum = 0;

	var datefrom = new Date(oYYYY.value, oMM.selectedIndex, oDD.value);
	var dateto = new Date(oYYYYt.value, oMMt.selectedIndex, oDDt.value);

	var newDay;
	var newMonth;
	var newYear;
	var daydiff;

	if (src.name == 'Nights'){
		dateto.setDate(datefrom.getDate() + parseInt(oNights.value));
		oDDt.value = dateto.getDate();
		oMMt.value = dateto.getMonth()+return_MM(oMM, oMMt, dateto);
		DateHasChanged = true;
	} else {
		if ((dateto - datefrom) > 0) {
			daydiff = (dateto - datefrom)/(24*60*60*1000);
			if (daydiff==1)
				oNights.value = parseInt(daydiff, 10);
			else
				oNights.value = parseInt(daydiff, 10);

			CurrentNights = daydiff;
		} else {
		
		}
		DateHasChanged = true;

	}
	if (src.name == 'DD') {
		dateto.setDate(datefrom.getDate() + parseInt(oNights.value));
		oDDt.value = dateto.getDate();
		oMMt.value = dateto.getMonth()+return_MM(oMM, oMMt, dateto);
		DateHasChanged = true;

	}
	if (src.name == 'DDt') {
		tempdate = new Date(oYYYYt.value, oMMt.selectedIndex, oDDt.value);
		if (tempdate < datefrom) {
			oDDt.value = datefrom.getDate()+1;
			oMMt.value = datefrom.getMonth()+1;
			oYYYYt.value = datefrom.getFullYear();
			oNights.value = 1;
			DateHasChanged = true;
		}
	}

	if (src.name == 'MM') {
		tempdate = new Date(oYYYY.value, oMM.selectedIndex, oDD.value);
		tempdate.setDate(tempdate.getDate() + parseInt(oNights.value));
		oDDt.value = tempdate.getDate();
		oMMt.value = tempdate.getMonth()+1;
		oYYYYt.value = tempdate.getFullYear();
		DateHasChanged = true;
	}
	
	if (src.name == 'MMt') {
		tempdate = new Date(oYYYYt.value, oMMt.selectedIndex, oDDt.value);
		tempdate.setDate(tempdate.getDate() - parseInt(oNights.value));

		oDD.value = tempdate.getDate();
		oMM.value = tempdate.getMonth()+1;
		oYYYY.value = tempdate.getFullYear();
		DateHasChanged = true;
		if (tempdate < datefrom) {
			oDDt.value = datefrom.getDate()+1;
			oMMt.value = datefrom.getMonth()+2;
			oYYYYt.value = datefrom.getFullYear();
			oNights.value = 1;
			DateHasChanged = true;
		}
	}

	if (src.name == 'YYYY') {

	}
}

function return_MM(oMM, oMMt, dateto) {
	if (oMMt.selectedIndex > oMM.selectedIndex) {
		out = 0;
	} else {
		out = 1;
	}
	return (out);
}