var Cards = new makeArray(4);
Cards[0] = new CardType("MasterCard", "51,52,53,54,55", "16");
var MasterCard = Cards[0];
Cards[1] = new CardType("VisaCard", "4", "13,16");
var VisaCard = Cards[1];
Cards[2] = new CardType("AmExCard", "34,37", "15");
var AmExCard = Cards[2];
var LuhnCheckSum = Cards[3] = new CardType();

function CheckCardNumber(form) {
  var tmpyear;
  if (form.CardNumber.value.length == 0) {
    //alert("Please key in Card Number.");
    form.CardNumber.focus();
    return false;
  }
  if (form.ExpYear.value.length == 0) {
    //alert("Please key in Expiry Year.");
    form.ExpYear.focus();
    return false;
  }
  if (form.ExpYear.value > 96)
    tmpyear = form.ExpYear.value;
  else if (form.ExpYear.value < 21)
    tmpyear = form.ExpYear.value;
  else {
    //alert("bad year");
    return false;
  }
  tmpmonth = form.ExpMon.value;
  if (!(new CardType()).isExpiryDate(tmpyear, tmpmonth)) {
    //alert("A data de validade do cartão já expirou!");
    return false;
  }
  card = form.CardType.options[form.CardType.selectedIndex].value;
  var retval = eval(card + ".checkCardNumber(\"" + form.CardNumber.value +
        "\", " + tmpyear + ", " + tmpmonth + ");");

  cardname = "";
  if (retval)
	return true;
  else {
    // The cardnumber has the valid luhn checksum, but we want to know which
    // cardtype it belongs to.
    for (var n = 0; n < Cards.size; n++) {
      if (Cards[n].checkCardNumber(form.CardNumber.value, tmpyear, tmpmonth)) {
        cardname = Cards[n].getCardType();
        break;
      }
    }
    if (cardname.length > 0) {
      //alert("This's " + cardname + " number, not " + card + " number.");
	  return false;
    }
    else {
      //alert("This's not a card number.");
	  return false;
    }
  }
}
function CardType() {
  var n;
  var argv = CardType.arguments;
  var argc = CardType.arguments.length;

  this.objname = "object CardType";

  var tmpcardtype = (argc > 0) ? argv[0] : "CardObject";
  var tmprules = (argc > 1) ? argv[1] : "0,1,2,3,4,5,6,7,8,9";
  var tmplen = (argc > 2) ? argv[2] : "13,14,15,16,19";

  this.setCardNumber = setCardNumber;

  this.setCardType = setCardType;

  this.setLen = setLen;

  this.setRules = setRules;

  this.setExpiryDate = setExpiryDate;

  this.setCardType(tmpcardtype);
  this.setLen(tmplen);
  this.setRules(tmprules);
  if (argc > 4)
    this.setExpiryDate(argv[3], argv[4]);
  this.checkCardNumber = checkCardNumber;
  this.getExpiryDate = getExpiryDate;
  this.getCardType = getCardType;
  this.isCardNumber = isCardNumber;
  this.isExpiryDate = isExpiryDate;
  this.luhnCheck = luhnCheck;
  return this;
}
function checkCardNumber() {
  var argv = checkCardNumber.arguments;
  var argc = checkCardNumber.arguments.length;
  var cardnumber = (argc > 0) ? argv[0] : this.cardnumber;
  var year = (argc > 1) ? argv[1] : this.year;
  var month = (argc > 2) ? argv[2] : this.month;

  this.setCardNumber(cardnumber);
  this.setExpiryDate(year, month);

  if (!this.isCardNumber())
    return false;

  if (!this.isExpiryDate())
    return false;

  return true;
}
function getCardType() {
  return this.cardtype;
}

function getExpiryDate() {
  return this.month + "/" + this.year;
}
function isCardNumber() {
  var argv = isCardNumber.arguments;
  var argc = isCardNumber.arguments.length;
  var cardnumber = (argc > 0) ? argv[0] : this.cardnumber;

  if (!this.luhnCheck())
    return false;

  for (var n = 0; n < this.len.size; n++)
    if (cardnumber.toString().length == this.len[n]) {
      for (var m = 0; m < this.rules.size; m++) {
        var headdigit = cardnumber.substring(0, this.rules[m].toString().length);
        if (headdigit == this.rules[m])
          return true;
      }
      return false;
    }
  return false;
}
function isExpiryDate() {
  var argv = isExpiryDate.arguments;
  var argc = isExpiryDate.arguments.length;

  year = argc > 0 ? argv[0] : this.year;
  month = argc > 1 ? argv[1] : this.month;

  if (!isNum(year+""))
    return false;
  if (!isNum(month+""))
    return false;
  today = new Date();
  expiry = new Date(year, month);
  if (today.getTime() > expiry.getTime())
    return false;
  else
    return true;
}

function isNum(argvalue) {
  argvalue = argvalue.toString();

  if (argvalue.length == 0)
    return false;

  for (var n = 0; n < argvalue.length; n++)
    if (argvalue.substring(n, n+1) < "0" || argvalue.substring(n, n+1) > "9")
      return false;
  return true;
}
function luhnCheck() {
  var argv = luhnCheck.arguments;
  var argc = luhnCheck.arguments.length;

  var CardNumber = argc > 0 ? argv[0] : this.cardnumber;

  if (! isNum(CardNumber)) {
    return false;
  }

  var no_digit = CardNumber.length;
  var oddoeven = no_digit & 1;
  var sum = 0;

  for (var count = 0; count < no_digit; count++) {
    var digit = parseInt(CardNumber.charAt(count));
    if (!((count & 1) ^ oddoeven)) {
      digit *= 2;
      if (digit > 9)
	digit -= 9;
    }
    sum += digit;
  }
  if (sum % 10 == 0)
    return true;
  else
    return false;
}
function makeArray(size) {
  this.size = size;
  return this;
}
function setCardNumber(cardnumber) {
  this.cardnumber = cardnumber;
  return this;
}
function setCardType(cardtype) {
  this.cardtype = cardtype;
  return this;
}
function setExpiryDate(year, month) {
  this.year = year;
  this.month = month;
  return this;
}
function setLen(len) {

  if (len.length == 0 || len == null)
    len = "13,14,15,16,19";

  var tmplen = len;
  n = 1;
  while (tmplen.indexOf(",") != -1) {
    tmplen = tmplen.substring(tmplen.indexOf(",") + 1, tmplen.length);
    n++;
  }
  this.len = new makeArray(n);
  n = 0;
  while (len.indexOf(",") != -1) {
    var tmpstr = len.substring(0, len.indexOf(","));
    this.len[n] = tmpstr;
    len = len.substring(len.indexOf(",") + 1, len.length);
    n++;
  }
  this.len[n] = len;

  return this;
}

function setRules(rules) {

  if (rules.length == 0 || rules == null)
    rules = "0,1,2,3,4,5,6,7,8,9";
  
  var tmprules = rules;
  n = 1;
  while (tmprules.indexOf(",") != -1) {
    tmprules = tmprules.substring(tmprules.indexOf(",") + 1, tmprules.length);
    n++;
  }
  this.rules = new makeArray(n);
  n = 0;
  while (rules.indexOf(",") != -1) {
    var tmpstr = rules.substring(0, rules.indexOf(","));
    this.rules[n] = tmpstr;
    rules = rules.substring(rules.indexOf(",") + 1, rules.length);
    n++;
  }
  this.rules[n] = rules;

  return this;
}