// BASIC DATA VALIDATION FUNCTIONS:
// isEmail (s [,eok])
// isUSPhoneNumber (s [,eok])
// isInteger (s [,eok])
// isYear (s [,eok])
// isMonth (s [,eok])

// CREDIT CARD DATA VALIDATION FUNCTIONS
//
// isCreditCard (st)
// isVisa (cc)
// isMasterCard (cc)
// isAmericanExpress (cc)
// isCardMatch (Type, Number)

// VARIABLE DECLARATIONS
var digits = "0123456789";
var defaultEmptyOK = false
var digitsInUSPhoneNumber = 10;

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;
}

// BOI, followed by one or more characters, followed by @,
// followed by one or more characters, followed by .,
// followed by one or more characters, followed by EOI.
var reEmail = /^.+\@.+\..+$/

// BOI, followed by one or more digits, followed by EOI.
var reInteger = /^\d+$/

// s is an abbreviation for "string"
var sEmail = "Email"
var sPhone = "Phone Number"
var sFax = "Fax Number"
var sExpirationDate = "Expiration Date"
var sCreditCardNumber = "Credit Card Number"

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

function isEmail (s)

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

    else {
       return reEmail.test(s)
    }
}

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 isInteger (s)

{   var i;

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

    return reInteger.test(s)
}

function isYear (s)
{   if (isEmpty(s))
       if (isMonth.arguments.length == 1) return defaultEmptyOK;
       else return (isMonth.arguments[1] == true);
    return isIntegerInRange (s, 0, 99);
}

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 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 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--;
  }

  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 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;

}