/*    Script inspired by "True Date Selector"
	Created by: Lee Hinder, lee.hinder@ntlworld.com

	Tested with Windows IE 6.0
	Tested with Linux Opera 7.21, Mozilla 1.3, Konqueror 3.1.0
*/

function daysInFebruary (year)
{
	// February has 28 days unless the year is divisible by four,
	// and if it is the turn of the century then the century year
	// must also be divisible by 400 when it has 29 days
	return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}

//function for returning how many days there are in a month including leap years
function DaysInMonth(WhichMonth, WhichYear)
{
	var DaysInMonth = 31;

	if (WhichMonth == "4" || WhichMonth == "6" || WhichMonth == "9" || WhichMonth == "11")
		DaysInMonth = 30;

	if (WhichMonth == "2")
		DaysInMonth = daysInFebruary(WhichYear);

	return DaysInMonth;
}

//function to change the available days in a months
function ChangeOptionDays(formObj, prefix)
{
	var DaysObject = eval("formObj." + prefix + "day");
	var MonthObject = eval("formObj." + prefix + "month");
	var YearObject = eval("formObj." + prefix + "year");

	if (DaysObject.selectedIndex && DaysObject.options)
	{
		// The DOM2 standard way
		// alert("The DOM2 standard way");
		var DaySelIdx = DaysObject.selectedIndex;
		var Month = parseInt(MonthObject.options[MonthObject.selectedIndex].value);
		var Year = parseInt(YearObject.options[YearObject.selectedIndex].value);
	}
	else if (DaysObject.selectedIndex && DaysObject[DaysObject.selectedIndex])
	{
		// The legacy MRBS way
		// alert("The legacy MRBS way");
		var DaySelIdx = DaysObject.selectedIndex;
		var Month = parseInt(MonthObject[MonthObject.selectedIndex].value);
		var Year = parseInt(YearObject[YearObject.selectedIndex].value);
	}
	else if (DaysObject.value)
	{
		// Opera 6 stores the selectedIndex in property 'value'.
		// alert("The Opera 6 way");
		var DaySelIdx = parseInt(DaysObject.value);
		var Month = parseInt(MonthObject.options[MonthObject.value].value);
		var Year = parseInt(YearObject.options[YearObject.value].value);
	}

	var DaysForThisSelection = DaysInMonth(Month, Year);
	var CurrentDaysInSelection = DaysObject.length;
	if (CurrentDaysInSelection > DaysForThisSelection)
	{
		for (i=0; i<(CurrentDaysInSelection-DaysForThisSelection); i++)
			DaysObject.options[DaysObject.options.length - 1] = null
	}

	if (DaysForThisSelection > CurrentDaysInSelection)
	{
		for (i=0; i<DaysForThisSelection; i++)
			DaysObject.options[i] = new Option(eval(i + 1));
	}

	if (DaysObject.selectedIndex < 0)
		DaysObject.selectedIndex = 0;

	if (DaySelIdx >= DaysForThisSelection)
		DaysObject.selectedIndex = DaysForThisSelection-1;
	else
		DaysObject.selectedIndex = DaySelIdx;
}