function IsNumeric(strString){
	var strValidChars = "0123456789";
	var strChar;
	var blnResult = true;
	for (i = 0; i < strString.length && blnResult == true; i++){
		strChar = strString.charAt(i);
		if (strValidChars.indexOf(strChar) == -1)
			blnResult = false;
	}
	return blnResult;
}


var dtCh= "/";
var minYear=1900;
var maxYear=2100;

function isInteger(s){
	var i;
    for (i = 0; i < s.length; i++){
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

function stripCharsInBag(s, bag){
	var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++){
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}

function daysInFebruary (year){
	// February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 == 0) && ( (!(year % 100 == 0)) || (year % 400 == 0))) ? 29 : 28 );
}
function DaysArray(n) {
	for (var i = 1; i <= n; i++) {
		this[i] = 31
		if (i==4 || i==6 || i==9 || i==11) {this[i] = 30}
		if (i==2) {this[i] = 29}
   }
   return this
}

function isDate(dtStr){
	var daysInMonth = DaysArray(12)
	var pos1=dtStr.indexOf(dtCh)
	var pos2=dtStr.indexOf(dtCh,pos1+1)
	var strDay=dtStr.substring(0,pos1)
	var strMonth=dtStr.substring(pos1+1,pos2)
	var strYear=dtStr.substring(pos2+1)
	strYr=strYear
	if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1)
	if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1)
	for (var i = 1; i <= 3; i++) {
		if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1)
	}
	month=parseInt(strMonth)
	day=parseInt(strDay)
	year=parseInt(strYr)
	if (pos1==-1 || pos2==-1)
		return "u heeft geen datum ingegeven";
	if (strMonth.length<1 || month<1 || month>12)
		return "dit is geen geldige maand";
	if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month])
		return "dit is geen geldige dag";
	if (strYear.length != 4 || year==0 || year<minYear || year>maxYear)
		return "dit is geen geldig jaar";
	if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))==false)
		return "Please enter a valid date";
return '';
}


// ------------------------------------------------------------------------------------------------------------------------------------------------------



function checkForm(form, fields) {
	var result = true;

	fields = fields.split(',');		// split the string in pairs of the form 'field=switch'

	// initialize loop (user clicks twice, old warnings have to be cleared)
	for (element in fields)
	{
		var keyVal			= fields[element].split('=');		// split the pair in separate (element, switch)
		var formElement		= keyVal[0];
		var errorelem		= document.getElementById('error'+formElement);
		var errorelemExist	= (errorelem != null);
		if (errorelemExist)
			errorelem.innerHTML = '';
	}
	// end initialize loop

	// clear php-messages
	var phperrorelem	= document.getElementById('errors');
	if (phperrorelem != null)
		phperrorelem.innerHTML = "";

	for (element in fields)
	{
		var keyVal		= fields[element].split('=');		// split the pair in separate (element, switch)
		var formElement	= keyVal[0];
		var formSwitch	= keyVal[1];
		var errorelem	= document.getElementById('error'+formElement);
		var errorelemExist = (errorelem != null);


		if (typeof form.elements[formElement] != 'undefined')	// does the actual formelement exist?
		{
			// value
			if (formSwitch=='v')
			{
				if (form.elements[formElement].value == '')
				{
					if (errorelemExist)
						errorelem.innerHTML = 'u moet hier iets invullen';
					result = false;
				}
			}

			// length l/ l|e|g /5
			if (formSwitch.indexOf('l') == 0)
			{
				var lengthrules = formSwitch.split('/');
				if (lengthrules[1]=='l')
				{
					if (form.elements[formElement].value.length > lengthrules[2])
					{
						if (errorelemExist)
							errorelem.innerHTML = "de lengte moet minder dan "+lengthrules[2]+" zijn";
						result = false;
					}
				}
				if (lengthrules[1]=='e')
				{
					if (form.elements[formElement].value.length != lengthrules[2])
					{
						if (errorelemExist)
							errorelem.innerHTML = "de lengte moet "+lengthrules[2]+" zijn";
						result = false;
					}
				}
				if (lengthrules[1]=='g')
				{
					if (form.elements[formElement].value.length < lengthrules[2])
					{
						if (errorelemExist)
							errorelem.innerHTML = "de lengte moet groter "+lengthrules[2]+" zijn";
						result = false;
					}
				}
			}

			// numeric
			if (formSwitch=='n')
			{
				if (!IsNumeric(form.elements[formElement].value))
				{
					if (errorelemExist)	// errorelem exist (eg. div in the body)
						errorelem.innerHTML = 'dit veld mag alleen getallen bevatten';
					result = false;
				}
			}

			// email
			if (formSwitch=='e')
			{
				var match = form.elements[formElement].value.match(/^\w+([\&\-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*([,;]\s*\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*)*$/g)
//				var match = form.elements[formElement].value.match(/^(\w+(?:\.\w+)*)@((?:\w+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i)
				if (match == null)
				{
					if (errorelemExist)
						errorelem.innerHTML = 'dit is geen geldig emailadres';
					result = false;
				}
			}

			// same as s/same_as_field
			if (formSwitch.indexOf('s') == 0)
			{
				var sameasfield = formSwitch.split('/');
				if (form.elements[formElement].value != form.elements[sameasfield[1]].value)
				{
					if (errorelemExist)
						errorelem.innerHTML = "u moet twee maal hetzelfde wachtwoord invoeren";
					result = false;
				}
			}

			// date
			if (formSwitch=='d')
			{
				var returnstr = isDate(form.elements[formElement].value);
				if (returnstr.length > 0)
				{
					if (errorelemExist)
						errorelem.innerHTML = returnstr;
					result = false;
				}
			}

		} // end if (typeof form.elements[formElement] != 'undefined')
	}


	return result;
}