var digits = '0123456789';
var lowercaseLetters = 'abcdefghijklmnopqrstuvwxyz'
var uppercaseLetters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
var whitespace = ' \t\n\r';
var decimalPointDelimiter = '.'
var phoneNumberDelimiters = '()- ';
var validUSPhoneChars = digits + phoneNumberDelimiters;
var validWorldPhoneChars = digits + phoneNumberDelimiters + '+';
var SSNDelimiters = '- ';
var validSSNChars = digits + SSNDelimiters;
var digitsInSocialSecurityNumber = 9;
var digitsInUSPhoneNumber = 10;
var ZIPCodeDelimiters = '-';
var ZIPCodeDelimeter = '-';
var validZIPCodeChars = digits + ZIPCodeDelimiters;
var digitsInZIPCode1 = 5;
var digitsInZIPCode2 = 9;
var creditCardDelimiters = ' ';
var mPrefix = 'You did not enter a value into the ';
var mSuffix = ' field. This is a required field. Please enter it now.';
var sUSLastName = 'Last Name';
var sUSFirstName = 'First Name';
var sWorldLastName = 'Family Name';
var sWorldFirstName = 'Given Name';
var sTitle = 'Title';
var sCompanyName = 'Company Name';
var sUSAddress = 'Street Address';
var sWorldAddress = 'Address';
var sCity = 'City';
var sStateCode = 'State Code';
var sWorldState = 'State, Province, or Prefecture';
var sCountry = 'Country';
var sZIPCode = 'ZIP Code';
var sWorldPostalCode = 'Postal Code';
var sPhone = 'Phone Number';
var sFax = 'Fax Number';
var sDateOfBirth = 'Date of Birth';
var sExpirationDate = 'Expiration Date';
var sEmail = 'Email';
var sSSN = 'Social Security Number';
var sCreditCardNumber = 'Credit Card Number';
var sOtherInfo = 'Other Information';
var sPassword = 'Password';
var iStateCode = 'This field must be a valid two character U.S. state abbreviation (like CA for California). Please reenter it now.';
var iZIPCode = 'This field must be a 5 or 9 digit U.S. ZIP Code (like 94043). Please reenter it now.';
var iUSPhone = 'This field must be a 10 digit U.S. phone number (like 415 555 1212). Please reenter it now.';
var iWorldPhone = 'This field must be a valid international phone number. Please reenter it now.';
var iSSN = 'This field must be a 9 digit U.S. social security number (like 123 45 6789). Please reenter it now.';
var iEmail = 'This field must be a valid email address (like foo@bar.com). Please reenter it now.';
var iCreditCardPrefix = 'This is not a valid ';
var iCreditCardSuffix = ' credit card number. (Click the link on this form to see a list of sample numbers.) Please reenter it now.';
var iDay = 'This field must be a day number between 1 and 31.  Please reenter it now.';
var iMonth = 'This field must be a month number between 1 and 12.  Please reenter it now.';
var iYear = 'This field must be a 2 or 4 digit year number.  Please reenter it now.';
var iDatePrefix = 'The Day, Month, and Year for ';
var iDateSuffix = ' do not form a valid date.  Please reenter them now.';
var pEntryPrompt = 'Please enter a ';
var pStateCode = '2 character code (like CA).';
var pZIPCode = '5 or 9 digit U.S. ZIP Code (like 94043).';
var pUSPhone = '10 digit U.S. phone number (like 415 555 1212).';
var pWorldPhone = 'international phone number.';
var pSSN = '9 digit U.S. social security number (like 123 45 6789).';
var pEmail = 'valid email address (like foo@bar.com).';
var pCreditCard = 'valid credit card number.';
var pDay = 'day number between 1 and 31.';
var pMonth = 'month number between 1 and 12.';
var pYear = '2 or 4 digit year number.';
var pPassword = 'password.';
var pPassword_Verify = 'Please enter the password again.';
var defaultEmptyOK = false;

function makeArray(n) {
//*** BUG: If I put this line in, I get two error messages:
//(1) Window.length can't be set by assignment
//(2) daysInMonth has no property indexed by 4
//If I leave it out, the code works fine.
//   this.length = 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;

var USStateCodeDelimiter = '|';
var USStateCodes = 'AL|AK|AS|AZ|AR|CA|CO|CT|DE|DC|FM|FL|GA|GU|HI|ID|IL|IN|IA|KS|KY|LA|ME|MH|MD|MA|MI|MN|MS|MO|MT|NE|NV|NH|NJ|NM|NY|NC|ND|MP|OH|OK|OR|PW|PA|PR|RI|SC|SD|TN|TX|UT|VT|VI|VA|WA|WV|WI|WY|AE|AA|AE|AE|AP'

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

function isWhitespace (s)
{
   var i;

    // Is s empty?
    if (isEmpty(s)) return true;

    // Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    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++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }

    return returnString;
}

function stripCharsNotInBag (s, bag)
{
   var i;
    var returnString = '';

    // Search through string's characters one by one.
    // If character is in bag, append to returnString.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (bag.indexOf(c) != -1) returnString += c;
    }

    return returnString;
}

function stripWhitespace (s)
{
   return stripCharsInBag (s, whitespace)
}

function charInString (c, s)
{
   for (i = 0; i < s.length; i++)
    {   if (s.charAt(i) == c) return true;
    }
    return false
}

function stripInitialWhitespace (s)
{
   var i = 0;

    while ((i < s.length) && charInString (s.charAt(i), whitespace))
       i++;
    
    return s.substring (i, s.length);
}

function isLetter (c)
{
   return ( ((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z')) )
}

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

function isLetterOrDigit (c)
{
   return (isLetter(c) || isDigit(c))
}

function isInteger (s)
{
   var i;

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

    // Search through string's characters one by one
    // until we find a non-numeric character.
    // When we do, return false; if we don't, return true.

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

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

    // All characters are numbers.
    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 isPositiveInteger (s)
{
   var secondArg = defaultEmptyOK;

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

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a positive, not negative, number

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

function isNonnegativeInteger (s)
{
   var secondArg = defaultEmptyOK;

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

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a number >= 0

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

function isNegativeInteger (s)
{
   var secondArg = defaultEmptyOK;

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

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a negative, not positive, number

    return (isSignedInteger(s, secondArg)
         && ( (isEmpty(s) && secondArg)  || (parseInt (s) < 0) ) );
}

function isNonpositiveInteger (s)
{
   var secondArg = defaultEmptyOK;

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

    // The next line is a bit byzantine.  What it means is:
    // a) s must be a signed integer, AND
    // b) one of the following must be true:
    //    i)  s is empty and we are supposed to return true for
    //        empty strings
    //    ii) this is a number <= 0

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

function isFloat (s)
{
   var i;
    var seenDecimalPoint = false;

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

    if (s == decimalPointDelimiter) return false;

    // Search through string's characters one by one
    // until we find a non-numeric character.
    // When we do, return false; if we don't, return true.

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

        if ((c == decimalPointDelimiter) && !seenDecimalPoint) seenDecimalPoint = true;
        else if (!isDigit(c)) return false;
    }

    // All characters are numbers.
    return true;
}

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

    else {
        var startPos = 0;
        var secondArg = defaultEmptyOK;

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

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

function isAlphabetic (s)
{
   var i;

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

    // Search through string's characters one by one
    // until we find a non-alphabetic character.
    // When we do, return false; if we don't, return true.

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

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

    // All characters are letters.
    return true;
}

function isAlphanumeric (s)
{
   var i;

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

    // Search through string's characters one by one
    // until we find a non-alphanumeric character.
    // When we do, return false; if we don't, return true.

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

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

    // All characters are numbers or letters.
    return true;
}

function reformat (s)
{
   var arg;
    var sPos = 0;
    var resultString = '';

    for (var i = 1; i < reformat.arguments.length; i++) {
       arg = reformat.arguments[i];
       if (i % 2 == 1) resultString += arg;
       else {
           resultString += s.substring(sPos, sPos + arg);
           sPos += arg;
       }
    }
    return resultString;
}

function isSSN (s)
{
   if (isEmpty(s)) 
       if (isSSN.arguments.length == 1) return defaultEmptyOK;
       else return (isSSN.arguments[1] == true);
    return (isInteger(s) && s.length == digitsInSocialSecurityNumber)
}

function isUSPhoneNumber (s)
{
   if (isEmpty(s)) 
       if (isUSPhoneNumber.arguments.length == 1) return defaultEmptyOK;
       else return (isUSPhoneNumber.arguments[1] == true);
    return (isInteger(s) && s.length == digitsInUSPhoneNumber)
}

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

function isZIPCode (s)
{
  if (isEmpty(s)) 
       if (isZIPCode.arguments.length == 1) return defaultEmptyOK;
       else return (isZIPCode.arguments[1] == true);
   return (isInteger(s) && 
            ((s.length == digitsInZIPCode1) ||
             (s.length == digitsInZIPCode2)))
}

function isStateCode(s)
{
   if (isEmpty(s)) 
       if (isStateCode.arguments.length == 1) return defaultEmptyOK;
       else return (isStateCode.arguments[1] == true);
    return ( (USStateCodes.indexOf(s) != -1) &&
             (s.indexOf(USStateCodeDelimiter) == -1) )
}

function isEmail (s)
{
   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
   
    // is s whitespace?
    if (isWhitespace(s)) return false;
    
    // there must be >= 1 character before @, so we
    // start looking at character position 1 
    // (i.e. second character)
    var i = 1;
    var sLength = s.length;

    // look for @
    while ((i < sLength) && (s.charAt(i) != '@'))
    { i++
    }

    if ((i >= sLength) || (s.charAt(i) != '@')) return false;
    else i += 2;

    // look for .
    while ((i < sLength) && (s.charAt(i) != '.'))
    { i++
    }

    // there must be at least one character after the .
    if ((i >= sLength - 1) || (s.charAt(i) != '.')) return false;
    else return true;
}

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));
}

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

    // Catch non-integer strings to avoid creating a NaN below,
    // which isn't available on JavaScript 1.0 for Windows.
    if (!isInteger(s, false)) return false;

    // Now, explicitly change the type to integer via parseInt
    // so that the comparison code below will work both on 
    // JavaScript 1.2 (which typechecks in equality comparisons)
    // and JavaScript 1.1 and before (which doesn't).
    var num = parseInt (s);
    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)
{
   // 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 isDate (year, month, day)
{
   // catch invalid years (not 2- or 4-digit) and invalid months and days.
    if (! (isYear(year, false) && isMonth(month, false) && isDay(day, false))) return false;

    // Explicitly change type to integer to make code work in both
    // JavaScript 1.1 and JavaScript 1.2.
    var intYear = parseInt(year);
    var intMonth = parseInt(month);
    var intDay = parseInt(day);

    // catch invalid days, except for February
    if (intDay > daysInMonth[intMonth]) return false; 

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

    return true;
}

function prompt (s)
{
   window.status = s
}

function promptEntry (s)
{
   window.status = pEntryPrompt + s
}

function warnEmpty (theField, s)
{
   theField.focus()
    alert(mPrefix + s + mSuffix)
    return false
}

function warnInvalid (theField, s)
{
   theField.focus()
    theField.select()
    alert(s)
    return false
}

function checkString (theField, s, emptyOK)
{
   // Next line is needed on NN3 to avoid "undefined is not a number" error
    // in equality comparison below.
    if (checkString.arguments.length == 2) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (isWhitespace(theField.value)) 
       return warnEmpty (theField, s);
    else return true;
}

function checkStateCode (theField, emptyOK)
{
   if (checkStateCode.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  theField.value = theField.value.toUpperCase();
       if (!isStateCode(theField.value, false)) 
          return warnInvalid (theField, iStateCode);
       else return true;
    }
}

function reformatZIPCode (ZIPString)
{
   if (ZIPString.length == 5) return ZIPString;
    else return (reformat (ZIPString, '', 5, '-', 4));
}

function checkZIPCode (theField, emptyOK)
{
   if (checkZIPCode.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    { var normalizedZIP = stripCharsInBag(theField.value, ZIPCodeDelimiters)
      if (!isZIPCode(normalizedZIP, false)) 
         return warnInvalid (theField, iZIPCode);
      else 
      {  // if you don't want to insert a hyphen, comment next line out
         theField.value = reformatZIPCode(normalizedZIP)
         return true;
      }
    }
}



// takes USPhone, a string of 10 digits
// and reformats as (123) 456-789

function reformatUSPhone (USPhone)
{
   return (reformat (USPhone, '(', 3, ') ', 3, '-', 4))
}

function checkUSPhone (theField, emptyOK)
{
   if (checkUSPhone.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  var normalizedPhone = stripCharsInBag(theField.value, phoneNumberDelimiters)
       if (!isUSPhoneNumber(normalizedPhone, false)) 
          return warnInvalid (theField, iUSPhone);
       else 
       {  // if you don't want to reformat as (123) 456-789, comment next line out
          theField.value = reformatUSPhone(normalizedPhone)
          return true;
       }
    }
}

function checkInternationalPhone (theField, emptyOK)
{
   if (checkInternationalPhone.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  if (!isInternationalPhoneNumber(theField.value, false)) 
          return warnInvalid (theField, iWorldPhone);
       else return true;
    }
}

function checkEmail (theField, emptyOK)
{
   if (checkEmail.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else if (!isEmail(theField.value, false)) 
       return warnInvalid (theField, iEmail);
    else return true;
}

function reformatSSN (SSN)
{
   return (reformat (SSN, '', 3, '-', 2, '-', 4))
}

function checkSSN (theField, emptyOK)
{
   if (checkSSN.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    else
    {  var normalizedSSN = stripCharsInBag(theField.value, SSNDelimiters)
       if (!isSSN(normalizedSSN, false)) 
          return warnInvalid (theField, iSSN);
       else 
       {  // if you don't want to reformats as 123-456-7890, comment next line out
          theField.value = reformatSSN(normalizedSSN)
          return true;
       }
    }
}

function checkYear (theField, emptyOK)
{
   if (checkYear.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (!isYear(theField.value, false)) 
       return warnInvalid (theField, iYear);
    else return true;
}

function checkMonth (theField, emptyOK)
{
   if (checkMonth.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (!isMonth(theField.value, false)) 
       return warnInvalid (theField, iMonth);
    else return true;
}

function checkDay (theField, emptyOK)
{
   if (checkDay.arguments.length == 1) emptyOK = defaultEmptyOK;
    if ((emptyOK == true) && (isEmpty(theField.value))) return true;
    if (!isDay(theField.value, false)) 
       return warnInvalid (theField, iDay);
    else return true;
}

function checkDate (yearField, monthField, dayField, labelString, OKtoOmitDay)
{
   // Next line is needed on NN3 to avoid "undefined is not a number" error
    // in equality comparison below.
    if (checkDate.arguments.length == 4) OKtoOmitDay = false;
    if (!isYear(yearField.value)) return warnInvalid (yearField, iYear);
    if (!isMonth(monthField.value)) return warnInvalid (monthField, iMonth);
    if ( (OKtoOmitDay == true) && isEmpty(dayField.value) ) return true;
    else if (!isDay(dayField.value)) 
       return warnInvalid (dayField, iDay);
    if (isDate (yearField.value, monthField.value, dayField.value))
       return true;
    alert (iDatePrefix + labelString + iDateSuffix)
    return false
}

function getRadioButtonValue (radio)
{
   for (var i = 0; i < radio.length; i++)
    {   if (radio[i].checked) { break }
    }
    return radio[i].value
}

function checkCreditCard (radio, theField)
{
   var cardType = getRadioButtonValue (radio)
    var normalizedCCN = stripCharsInBag(theField.value, creditCardDelimiters)
    if (!isCardMatch(cardType, normalizedCCN)) 
       return warnInvalid (theField, iCreditCardPrefix + cardType + iCreditCardSuffix);
    else 
    {  theField.value = normalizedCCN
       return true
    }
}

function isCreditCard(st)
{
  // Encoding only works on cards with less than 19 digits
  if (st.length > 19)
    return (false);

  sum = 0; mul = 1; l = st.length;
  for (i = 0; i < l; i++) {
    digit = st.substring(l-i-1,l-i);
    tproduct = parseInt(digit ,10)*mul;
    if (tproduct >= 10)
      sum += (tproduct % 10) + 1;
    else
      sum += tproduct;
    if (mul == 1)
      mul++;
    else
      mul--;
  }
// Uncomment the following line to help create credit card numbers
// 1. Create a dummy number with a 0 as the last digit
// 2. Examine the sum written out
// 3. Replace the last digit with the difference between the sum and
//    the next multiple of 10.

//  document.writeln('<BR>Sum      = ',sum,'<BR>');
//  alert('Sum      = ' + sum);

  if ((sum % 10) == 0)
    return (true);
  else
    return (false);

}

function isVisa(cc)
{
  if (((cc.length == 16) || (cc.length == 13)) &&
      (cc.substring(0,1) == 4))
    return isCreditCard(cc);
  return false;
}

function isMasterCard(cc)
{
  firstdig = cc.substring(0,1);
  seconddig = cc.substring(1,2);
  if ((cc.length == 16) && (firstdig == 5) &&
      ((seconddig >= 1) && (seconddig <= 5)))
    return isCreditCard(cc);
  return false;

}

function isAmericanExpress(cc)
{
  firstdig = cc.substring(0,1);
  seconddig = cc.substring(1,2);
  if ((cc.length == 15) && (firstdig == 3) &&
      ((seconddig == 4) || (seconddig == 7)))
    return isCreditCard(cc);
  return false;

}

function isDinersClub(cc)
{
  firstdig = cc.substring(0,1);
  seconddig = cc.substring(1,2);
  if ((cc.length == 14) && (firstdig == 3) &&
      ((seconddig == 0) || (seconddig == 6) || (seconddig == 8)))
    return isCreditCard(cc);
  return false;
}

function isCarteBlanche(cc)
{
  return isDinersClub(cc);
}

function isDiscover(cc)
{
  first4digs = cc.substring(0,4);
  if ((cc.length == 16) && (first4digs == '6011'))
    return isCreditCard(cc);
  return false;

} // END FUNCTION isDiscover()


function isEnRoute(cc)
{
  first4digs = cc.substring(0,4);
  if ((cc.length == 15) &&
      ((first4digs == '2014') ||
       (first4digs == '2149')))
    return isCreditCard(cc);
  return false;
}

function isJCB(cc)
{
  first4digs = cc.substring(0,4);
  if ((cc.length == 16) &&
      ((first4digs == '3088') ||
       (first4digs == '3096') ||
       (first4digs == '3112') ||
       (first4digs == '3158') ||
       (first4digs == '3337') ||
       (first4digs == '3528')))
    return isCreditCard(cc);
  return false;

}

function isAnyCard(cc)
{
  if (!isCreditCard(cc))
    return false;
  if (!isMasterCard(cc) && !isVisa(cc) && !isAmericanExpress(cc) && !isDinersClub(cc) &&
      !isDiscover(cc) && !isEnRoute(cc) && !isJCB(cc)) {
    return false;
  }
  return true;

}

function isCardMatch (cardType, cardNumber)
{

	cardType = cardType.toUpperCase();
	var doesMatch = true;

	if ((cardType == 'VISA') && (!isVisa(cardNumber)))
		doesMatch = false;
	if ((cardType == 'MASTERCARD') && (!isMasterCard(cardNumber)))
		doesMatch = false;
	if ( ( (cardType == 'AMERICANEXPRESS') || (cardType == 'AMEX') )
                && (!isAmericanExpress(cardNumber))) doesMatch = false;
	if ((cardType == 'DISCOVER') && (!isDiscover(cardNumber)))
		doesMatch = false;
	if ((cardType == 'JCB') && (!isJCB(cardNumber)))
		doesMatch = false;
	if ((cardType == 'DINERS') && (!isDinersClub(cardNumber)))
		doesMatch = false;
	if ((cardType == 'CARTEBLANCHE') && (!isCarteBlanche(cardNumber)))
		doesMatch = false;
	if ((cardType == 'ENROUTE') && (!isEnRoute(cardNumber)))
		doesMatch = false;
	return doesMatch;

}

/*  ================================================================
    The below stub functions are retained for backward compatibility
    with the original LivePayment code so that it should be possible
    in principle to swap in this new module as a replacement for the  
    older module without breaking existing code.  (There are no
    guarantees, of course, but it should work.)

    When writing new code, do not use these stub functions; use the
    functions defined above.
    ================================================================ */

function IsCC (st) {
    return isCreditCard(st);
}

function IsVisa (cc)  {
  return isVisa(cc);
}

function IsVISA (cc)  {
  return isVisa(cc);
}

function IsMasterCard (cc)  {
  return isMasterCard(cc);
}

function IsMastercard (cc)  {
  return isMasterCard(cc);
}

function IsMC (cc)  {
  return isMasterCard(cc);
}

function IsAmericanExpress (cc)  {
  return isAmericanExpress(cc);
}

function IsAmEx (cc)  {
  return isAmericanExpress(cc);
}

function IsDinersClub (cc)  {
  return isDinersClub(cc);
}

function IsDC (cc)  {
  return isDinersClub(cc);
}

function IsDiners (cc)  {
  return isDinersClub(cc);
}

function IsCarteBlanche (cc)  {
  return isCarteBlanche(cc);
}

function IsCB (cc)  {
  return isCarteBlanche(cc);
}

function IsDiscover (cc)  {
  return isDiscover(cc);
}

function IsEnRoute (cc)  {
  return isEnRoute(cc);
}

function IsenRoute (cc)  {
  return isEnRoute(cc);
}

function IsJCB (cc)  {
  return isJCB(cc);
}

function IsAnyCard(cc)  {
  return isAnyCard(cc);
}

function IsCardMatch (cardType, cardNumber)  {
  return isCardMatch (cardType, cardNumber);
}