var DATE_DEFAULT_SEP	 = ".";

var DATE_SPLIT			 = /[\-\/\.\,\*\+\ ]/;

var VALID_DATE_CHARS     = VALID_NUMBERS + "-/.,*+ ";



var VALID_DATE_PATTERNS  = new Array();



initDateInputChecks();



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

// Return true if string s is a valid year

function isYear (s, required) {

    if (! required && isWhiteSpace(s)) return true;



    if (! isInteger(s, true)) return false;



    if (s > 99 && s < 1000) return false; // 3-stellig

    if (s < 1 || s > 9999) return false;



    return true;

}



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

// erzeugt 4-stelliges Jahr aufgrund der Eingabe

function getYear (s) {

    if (s >= 1 && s <= 99) return 2000 + Number (s);

    return s;

}



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

// Return true if string s is a valid Month

function isMonth (s, required) {

    if (! required && isWhiteSpace(s)) return true;



    if (! isInteger(s, true)) return false;



    if (s < 1 || s > 12) return false;



    return true;

}



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

// Return true if string s is a valid Month

function isDay (s, required) {

    if (! required && isWhiteSpace(s)) return true;



    if (! isInteger(s, true)) return false;



    if (s < 1 || s > 31) return false;



    return true;

}



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

function isDate(year,month,day) {



    var daysInMonth = new Array();

    daysInMonth[1] = 31;

    daysInMonth[2] = 29;   // must programmatically check this

    daysInMonth[3] = 31;

    daysInMonth[4] = 30;

    daysInMonth[5] = 31;

    daysInMonth[6] = 30;

    daysInMonth[7] = 31;

    daysInMonth[8] = 31;

    daysInMonth[9] = 30;

    daysInMonth[10] = 31;

    daysInMonth[11] = 30;

    daysInMonth[12] = 31;



    if (! isYear(year,true)) {

        return false;

    }



    if (! isMonth(month,true)) {

        return false;

    }



    if (! isDay(day,true)) {

        return false;

    }



    var intYear = parseInt(year, 10);

    var intMonth = parseInt(month, 10);

    var intDay = parseInt(day, 10);

    // catch invalid days, except for February



    if (intDay > daysInMonth[intMonth]) return false;



    if ((intMonth == 2) && (intDay > daysInFebruary(intYear))) return false;



    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 );

    }



    return true;



}



function initDateInputChecks() {

	VALID_DATE_PATTERNS[0] = /^\d\d?[\-\/\.\,\*\+\ ]+\d\d?[\-\/\.\,\*\+\ ]+\d\d?$/;

	VALID_DATE_PATTERNS[1] = /^\d\d?[\-\/\.\,\*\+\ ]+\d\d?[\-\/\.\,\*\+\ ]+\d\d\d\d$/;

	VALID_DATE_PATTERNS[2] = /^\d\d\d\d\d\d$/;

	VALID_DATE_PATTERNS[3] = /^\d\d\d\d\d\d\d\d$/;

}



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

// Datum Eingabecheck

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

function date_onKeyPress(keyEvent) {

	if (isNavigator() == false) keyEvent = getIEEvent();;

	var field = getEventField(keyEvent);

	if (isEnterKey(keyEvent)) {

		if (field.value.length == 0) return true;

		if (date_isValid(field) == false) {

			field.blur();

			return false;

		}

		date_format(field);

		return true;

	}

	if (isValidKey(keyEvent, VALID_DATE_CHARS) == false) return false;

	return true;

}



function date_onBlur(field) {

	if (field.value.length == 0) return;



	if (date_isValid(field) == false) {

                nbalert(msgDateError);

		field.value = "";

		field.focus();

		return;

	}

	date_format(field);

}



function date_format(field) {

	var parts = date_getParts(field);

	field.value = fillWithNull(parts[0],2) + DATE_DEFAULT_SEP +

	              fillWithNull(parts[1],2) + DATE_DEFAULT_SEP + parts[2];

}



function date_isValid(field) {

	if (field.value.length == 0) return true;

	if (hasValidPattern(field, VALID_DATE_PATTERNS)==false) return false;

	var parts = date_getParts(field);

	return isDate(parts[2], parts[1], parts[0]);

}



function date_getParts(field) {

	var value = field.value;

	var parts;

	if (DATE_SPLIT.test(value))

		parts = value.split(DATE_SPLIT);

	else {

		parts = new Array();

		parts[0] = value.substring(0,2);

		parts[1] = value.substring(2,4);

		parts[2] = value.substring(4);

	}

	if (parts[2].length < 4) {

		if(parts[2] > 20) {

			parts[2] = "19" + parts[2];

		} else {

			parts[2] = "20" + parts[2];

		}

	}

	return parts;

}