msPerDay = 24 * 60 * 60 * 1000; // Number of milliseconds per day

thisYear = '2008'
nextYear = '2009'


function onArrivalChange(){

	arrdate = ArrivalDate()
	
	newdepdate = new Date(arrdate.getTime() + (msPerDay * document.reservation.triplength.value))
	
	setDeparture(newdepdate.getMonth(),newdepdate.getDate())
	
}


function onDepartureChange(){

	setTripLength()
}

function ArrivalDate(){

	ArrivalMonth = document.reservation.doa_mm.options[document.reservation.doa_mm.selectedIndex].value
	ArrivalDay = document.reservation.doa_dd.options[document.reservation.doa_dd.selectedIndex].value

	if (ArrivalMonth < 9)
		{
		useYear = nextYear
		}
	else
		{if (ArrivalMonth == 9 && ArrivalDay < 9)
			{
			useYear = nextYear
			}
		else
			{
			useYear = thisYear
			}
		}

	return (new Date(ArrivalMonth + '/' + ArrivalDay + '/' + useYear))
}

function DepartureDate(){

	DepartureMonth = document.reservation.dod_mm.options[document.reservation.dod_mm.selectedIndex].value
	DepartureDay = document.reservation.dod_dd.options[document.reservation.dod_dd.selectedIndex].value

	if (DepartureMonth < 9)
		{
		useYear = nextYear
		}
	else
		{if (DepartureMonth == 9 && DepartureDay < 10)
			{
			useYear = nextYear
			}
		else
			{
			useYear = thisYear
			}
		}

	return (new Date(DepartureMonth + '/' + DepartureDay + '/' + useYear))
}

function setDeparture(month, day){

	document.reservation.dod_mm.selectedIndex = month
	document.reservation.dod_dd.selectedIndex = day-1
}

function setTripLength(){

	arrdate = ArrivalDate()
	depdate = DepartureDate()
	
	document.reservation.triplength.value = Math.round(depdate.getTime()/ msPerDay) - Math.round(arrdate.getTime()/ msPerDay)
	
}