//This script file contains parts of functions created by Eric Krock
//(c) 1997 Netscape Communications Corporation

//
var creditCardDelimiters = " "
var iCreditCardPrefix = "This is not a valid "
var iCreditCardSuffix = " credit card number.  Please reenter it now. "


// Notify user that contents of field theField are invalid.
// String s describes expected contents of theField.value.
// Put select theField, pu focus in it, and return false.

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


//Check if ok to continue
function checkdata(form,docin){
	if(checkCreditCard(form.cctype,form.ccnumber)){
	   alert("This is where the data would be written to a database using a cgi program or script.");
	   emptybasket(docin);
	}
}

// Get checked value from radio button.

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




// Validate credit card info.

function checkCreditCard (radio, theField){
    var cardType = getRadioButtonValue (radio)
if(cardType=="nogood"){
	alert('Please select a credit card type. ');
	return false;}
else{
    var normalizedCCN = stripCharsInBag(theField.value, creditCardDelimiters)
    if (!isCardMatch(cardType, normalizedCCN)) 
       return warnInvalid (theField, iCreditCardPrefix + cardType + iCreditCardSuffix);
    else 
    {  theField.value = normalizedCCN
       return true
    }
}
}

// Removes all characters which appear in string bag from string s.

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;
}




/*  ================================================================
    Credit card verification functions
    Originally included as Starter Application 1.0.0 in LivePayment.
    20 Feb 1997 modified by egk:
           changed naming convention to initial lowercase
                  (isMasterCard instead of IsMasterCard, etc.)
           changed isCC to isCreditCard
           retained functions named with older conventions from
                  LivePayment as stub functions for backward 
                  compatibility only
           added "AMERICANEXPRESS" as equivalent of "AMEX" 
                  for naming consistency 
    ================================================================ */


/*  ================================================================
    FUNCTION:  isCreditCard(st)
 
    INPUT:     st - a string representing a credit card number

    RETURNS:  true, if the credit card number passes the Luhn Mod-10
		    test.
	      false, otherwise
    ================================================================ */

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);

} // END FUNCTION isCreditCard()



/*  ================================================================
    FUNCTION:  isVisa()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid VISA number.
		    
	      false, otherwise

    Sample number: 4111 1111 1111 1111 (16 digits)
    ================================================================ */

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




/*  ================================================================
    FUNCTION:  isMasterCard()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid MasterCard
		    number.
		    
	      false, otherwise

    Sample number: 5500 0000 0000 0004 (16 digits)
    ================================================================ */

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;

} // END FUNCTION isMasterCard()





/*  ================================================================
    FUNCTION:  isAmericanExpress()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid American
		    Express number.
		    
	      false, otherwise

    Sample number: 340000000000009 (15 digits)
    ================================================================ */

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;

} // END FUNCTION isAmericanExpress()




/*  ================================================================
    FUNCTION:  isDinersClub()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid Diner's
		    Club number.
		    
	      false, otherwise

    Sample number: 30000000000004 (14 digits)
    ================================================================ */

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()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid Carte
		    Blanche number.
		    
	      false, otherwise
    ================================================================ */

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




/*  ================================================================
    FUNCTION:  isDiscover()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid Discover
		    card number.
		    
	      false, otherwise

    Sample number: 6011000000000004 (16 digits)
    ================================================================ */

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

} // END FUNCTION isDiscover()





/*  ================================================================
    FUNCTION:  isEnRoute()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid enRoute
		    card number.
		    
	      false, otherwise

    Sample number: 201400000000009 (15 digits)
    ================================================================ */

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



/*  ================================================================
    FUNCTION:  isJCB()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is a valid JCB
		    card number.
		    
	      false, otherwise
    ================================================================ */

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;

} // END FUNCTION isJCB()



/*  ================================================================
    FUNCTION:  isAnyCard()
 
    INPUT:     cc - a string representing a credit card number

    RETURNS:  true, if the credit card number is any valid credit
		    card number for any of the accepted card types.
		    
	      false, otherwise
    ================================================================ */

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;

} // END FUNCTION isAnyCard()



/*  ================================================================
    FUNCTION:  isCardMatch()
 
    INPUT:    cardType - a string representing the credit card type
	      cardNumber - a string representing a credit card number

    RETURNS:  true, if the credit card number is valid for the particular
	      credit card type given in "cardType".
		    
	      false, otherwise
    ================================================================ */

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;

}  // END FUNCTION CardMatch()