// set arrays for number of days in months
var aLong_days = new Array("(Day)","1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31");
var aShort_days = new Array("(Day)","1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","");
var aFeb_days = new Array("(Day)","1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","","");

function swapOptions(nMonth)
{
	var array_name = ""
	var numbers_select = window.document.date_form.day
	if (nMonth == "2") {
		array_name = eval(aFeb_days);
		} 
	else {
		if (nMonth == "4" || nMonth == "6" || nMonth == "9" || nMonth == "11") {
			array_name = eval(aShort_days);	
			} 
		else {
		array_name = eval(aLong_days);
		}
	}
	setOptionText(window.document.date_form.day, array_name);	
}

function setOptionText(the_select, the_array)
{
	for (loop=0; loop < the_select.options.length; loop++) 	
	{
		the_select.options[loop].text = the_array[loop]; 	
	}
}

function checkFields() 
{
	missinginfo = "";
	nMonth = document.date_form.month.value;
	nDay = document.date_form.day.value;
	nYear = document.date_form.years.value;
	
	//Check value of month
	if (eval(nMonth) == 0) {
		missinginfo += "\n     -  Month";
	}
	//Check value of day
	if (eval(nDay) == 0 ) {
		missinginfo += "\n     -  Day";
	}
	//Check short months
	if ((nMonth == "4" || nMonth == "6" || nMonth == "9" || nMonth == "11") && eval(nDay) > 30) {
		missinginfo += "\n     -  Day";
	}
	//Check February
	if (nMonth == "2") {
		//Leap Year calculations
		if (eval(nDay) > 28) {
			if (eval(nDay) > 29) {
				missinginfo += "\n     -  Day";
			}
			else { //nDay == 29
				if (eval(nYear) % 4 != 0) {
					missinginfo += "\n     -  Day";
				}
				else { //Year is divisible by 4
					if (eval(nYear) % 100 == 0 && eval(nYear) % 400 != 0) {
							missinginfo += "\n     -  Day";
					}
				}
			}	
	 	} 
	}

	//Check value of year
	if (nYear == "0") {
		missinginfo += "\n     -  Year";
	}
	//Out put error message
	if (missinginfo != "") {
		missinginfo ="You forgot to fill in a field\n" +
		"Please select a :\n" +
		missinginfo + "\n_____________________________" +
		"\nPlease re-enter and submit again!";
	
		alert(missinginfo);
		return false;
	}
	else return true;
}