// dateValidation.js 
// Set of JavaScript functions for validating a date in an HTML form.
// R.Krishnasankar - added and modified code from fValidation.js

// m - abbreviation for "missing"
var mPrefix = "You did not enter a value into the "
var mSuffix = " field. This is a required field. Please enter it now."

// i - abbreviation for "invalid"
var iDatePrefix = "The Day, Month, and Year for "
var iDateSuffix = " do not form a valid date.  Please reenter them now."

// Global variable defaultEmptyOK defines default return value 
var defaultEmptyOK = false


function makeArray(n)
{
   for (var i = 1; i <= n; i++)
   {
      this[i] = 0
   } 
   return this
}

var daysInMonth = makeArray(12);

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;


function isEmpty(s)
{   return ((s == null) || (s.length == 0))
}


function isDigit (c)
{   return ((c >= "0") && (c <= "9"))
}


function isInteger (s)
{
	var i;

    if (isEmpty(s)) 
       if (isInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isInteger.arguments[1] == true);

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character is number.
        var c = s.charAt(i);


        if (!isDigit(c)) return false;
    }

    return true;
}


function isSignedInteger (s)
{
	if (isEmpty(s)) 
       if (isSignedInteger.arguments.length == 1) return defaultEmptyOK;
       else return (isSignedInteger.arguments[1] == true);

    else {
        var startPos = 0;

        var secondArg = defaultEmptyOK;


        if (isSignedInteger.arguments.length > 1)
            secondArg = isSignedInteger.arguments[1];

        // skip leading + or -
        if ( (s.charAt(0) == "-") || (s.charAt(0) == "+") )
           startPos = 1;    
        return (isInteger(s.substring(startPos, s.length), secondArg))
    }
}


function isNonnegativeInteger (s)
{
	var secondArg = defaultEmptyOK;

    if (isNonnegativeInteger.arguments.length > 1)
        secondArg = isNonnegativeInteger.arguments[1];

    return (isSignedInteger(s, secondArg)
         && ( (isEmpty(s) && secondArg)  || (parseInt (s,10) >= 0) ) );
}


function isYear (s)
{
	if (isEmpty(s)) 
	{
       if (isYear.arguments.length == 1)
			return defaultEmptyOK;
       else
		return (isYear.arguments[1] == true);
	}
    if (!isNonnegativeInteger(s))
		return false;
//    return ((s.length == 2) || (s.length == 4));
	return (s.length == 4);
}



function isIntegerInRange (s, a, b)
{
	if (isEmpty(s)) 
       if (isIntegerInRange.arguments.length == 1) return defaultEmptyOK;
       else return (isIntegerInRange.arguments[1] == true);

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

    var num = parseInt (s,10);
    return ((num >= a) && (num <= b));
}


function isMonth (s)
{
	if (isEmpty(s)) 
       if (isMonth.arguments.length == 1) return defaultEmptyOK;
           else  return (isMonth.arguments[1] == true);
return isIntegerInRange (s, 1, 12);
}


function isDay (s)
{   if (isEmpty(s)) 
       if (isDay.arguments.length == 1) return defaultEmptyOK;
       else return (isDay.arguments[1] == true);   
    return isIntegerInRange (s, 1, 31);
}


function daysInFebruary (year)
{
    return ( (year % 4 == 0) &&( !(year % 100 == 0) || (year % 400 == 0) ) ? 29 : 28 );
}


function isDate (year, month, day)
{
    if (! (isYear(year, false) && isMonth(month, false) && isDay(day, false)))
		returnfalse;

//  Use the parseInt() function with the radix paramater 
//  with 10 (decimal) otherwise assumes octal.. !?
//  V. Mukundan
    var intYear = parseInt(year,10);

    var intMonth = parseInt(month,10);

    var intDay = parseInt(day,10);


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

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

    return true;
}


// added and modified code - Krishnasankar
function checkDate (yearField, monthField, dayField, labelString, OKtoOmitDay)
{
    if (checkDate.arguments.length == 4)
		OKtoOmitDay = false;
    if (!isYear(yearField))
	{
		alert ('Please enter a valid year in the ' + labelString + ' field.');
		return false;
	}
    if (!isMonth(monthField))
	{
		alert ('Please enter a valid month in the ' + labelString + ' field.');
		return (false);
	}
    if ( (OKtoOmitDay == true) && isEmpty(dayField) )
		return true;
    else if (!isDay(dayField)) 
	{
		alert ('Please enter a valid day in the ' + labelString + ' field.');
		return false;
	}
    if ( isDate(yearField, monthField, dayField))
       return true;

	// error message
    alert (iDatePrefix + labelString + iDateSuffix)
    return false;
}


// Krishnasankar
function validateDate (givenDate, labelString)
{
	var i;
	var yearField, monthField, dayField;
	var validDate;

	dateElements = givenDate.value.split('/');
	if (dateElements.length < 3)
	{
		alert ('Please enter day, month and year for the "'
					+ labelString + '" field.');
		givenDate.select();
		givenDate.focus();
		return (false);
	}

	validDate = checkDate (dateElements [2], dateElements [1], dateElements [0],
							labelString);
	if ( !validDate)
	{
		givenDate.select();
		givenDate.focus();
		return false;
	}

	return true;
}