<?php
/*==============================================================================

This routine checks the credit card number. The following checks are made:

1. A number has been provided
2. The number is a right length for the card
3. The number has an appropriate prefix for the card
4. The number has a valid modulus 10 number check digit if required

If the validation fails an error is reported.

The structure of credit card formats was gleaned from a variety of sources on
the web, although the best is probably on Wikepedia ("Credit card number"):

  http://en.wikipedia.org/wiki/Credit_card_number

Input parameters:
            cardnumber           number on the card
            cardname             name of card as defined in the card list below
Output parameters:
            cardnumber           number on the card
            cardname             name of card as defined in the card list below

Author:     John Gardner
Date:       4th January 2005
Updated:    26th February 2005  additional credit cards added
            1st July 2006       multiple definition of Discovery card removed
            27th Nov. 2006      Additional cards added from Wikipedia
						8th Dec 2007				Problem with Solo card definition corrected
						18th Jan 2008				Support for 18 digit Maestro cards added


if (isset($_GET['submitted'])) {
  if (checkCreditCard ($_GET['CardNumber'], $_GET['CardType'], $ccerror, $ccerrortext)) {
    $ccerrortext = 'This card has a valid format';
  }
}

==============================================================================*/


function checkCreditCard ($cardnumber, $cardname, &$errornumber, &$errortext) {
	
  // Define the cards we support. You may add additional card types.

  //  Name:      As in the selection box of the form - must be same as user's
  //  Length:    List of possible valid lengths of the card number for the card
  //  prefixes:  List of possible prefixes for the card
  //  checkdigit Boolean to say whether there is a check digit

  // Don't forget - all but the last array definition needs a comma separator!

  $cards = array (  array ('name' => 'American Express',
                          'length' => '15',
                          'prefixes' => '34,37',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Carte Blanche',
                          'length' => '14',
                          'prefixes' => '300,301,302,303,304,305,36,38',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Diners Club',
                          'length' => '14',
                          'prefixes' => '300,301,302,303,304,305,36,38',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Discover',
                          'length' => '16',
                          'prefixes' => '6011',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Enroute',
                          'length' => '15',
                          'prefixes' => '2014,2149',
                          'checkdigit' => true
                         ),
                   array ('name' => 'JCB',
                          'length' => '15,16',
                          'prefixes' => '3,1800,2131',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Maestro',
                          'length' => '16,18',
                          'prefixes' => '5020,6',
                          'checkdigit' => true
                         ),
                   array ('name' => 'MasterCard',
                          'length' => '16',
                          'prefixes' => '51,52,53,54,55',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Master Card',
                          'length' => '16',
                          'prefixes' => '51,52,53,54,55',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Solo',
                          'length' => '16,18,19',
                          'prefixes' => '6334,6767',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Switch',
                          'length' => '16,18,19',
                          'prefixes' => '4903,4905,4911,4936,564182,633110,6333,6759',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Visa',
                          'length' => '13,16',
                          'prefixes' => '4',
                          'checkdigit' => true
                         ),
                   array ('name' => 'Visa Electron',
                          'length' => '16',
                          'prefixes' => '417500,4917,4913',
                          'checkdigit' => true
                         )
                );

  $ccErrorNo = 0;

  $ccErrors [0] = "Unknown card type";
  $ccErrors [1] = "No card number provided";
  $ccErrors [2] = "Credit card number has invalid format";
  $ccErrors [3] = "Credit card number is invalid";
  $ccErrors [4] = "Credit card number is wrong length";

  // Establish card type
  $cardType = -1;
  for ($i=0; $i<sizeof($cards); $i++) {

    // See if it is this card (ignoring the case of the string)
    if (strtolower($cardname) == strtolower($cards[$i]['name'])) {
      $cardType = $i;
      break;
    }
  }

  // If card type not found, report an error
  if ($cardType == -1) {
     $errornumber = 0;
     $errortext = $ccErrors [$errornumber];
     return false;
  }

  // Ensure that the user has provided a credit card number
  if (strlen($cardnumber) == 0)  {
     $errornumber = 1;
     $errortext = $ccErrors [$errornumber];
     return false;
  }

  // Remove any spaces from the credit card number
  $cardNo = str_replace (' ', '', $cardnumber);

  // Check that the number is numeric and of the right sort of length.
  if (!preg_match('/^[0-9]{13,19}$/',$cardNo))  {
     $errornumber = 2;
     $errortext = $ccErrors [$errornumber];
     return false;
  }

  // Now check the modulus 10 check digit - if required
  if ($cards[$cardType]['checkdigit']) {
    $checksum = 0;                                  // running checksum total
    $mychar = "";                                   // next char to process
    $j = 1;                                         // takes value of 1 or 2

    // Process each digit one by one starting at the right
    for ($i = strlen($cardNo) - 1; $i >= 0; $i--) {

      // Extract the next digit and multiply by 1 or 2 on alternative digits.
      $calc = $cardNo{$i} * $j;

      // If the result is in two digits add 1 to the checksum total
      if ($calc > 9) {
        $checksum = $checksum + 1;
        $calc = $calc - 10;
      }

      // Add the units element to the checksum total
      $checksum = $checksum + $calc;

      // Switch the value of j
      if ($j ==1) {$j = 2;} else {$j = 1;};
    }

    // All done - if checksum is divisible by 10, it is a valid modulus 10.
    // If not, report an error.
    if ($checksum % 10 != 0) {
     $errornumber = 3;
     $errortext = $ccErrors [$errornumber];
     return false;
    }
  }

  // The following are the card-specific checks we undertake.

  // Load an array with the valid prefixes for this card
  $prefix = explode(',',$cards[$cardType]['prefixes']);

  // Now see if any of them match what we have in the card number
  $PrefixValid = false;
  for ($i=0; $i<sizeof($prefix); $i++) {
    $exp = '/^' . $prefix[$i] . '/';
    
    if (preg_match($exp,$cardNo)) {
      $PrefixValid = true;
      break;
    }
  }

  // If it isn't a valid prefix there's no point at looking at the length
  if (!$PrefixValid) {
     $errornumber = 3;
     $errortext = $ccErrors [$errornumber];
     return false;
  }

  // See if the length is valid for this card
  $LengthValid = false;
  $lengths = explode(',',$cards[$cardType]['length']);
  for ($j=0; $j<sizeof($lengths); $j++) {
    if (strlen($cardNo) == $lengths[$j]) {
      $LengthValid = true;
      break;
    }
  }

  // See if all is OK by seeing if the length was valid.
  if (!$LengthValid) {
     $errornumber = 4;
     $errortext = $ccErrors [$errornumber];
     return false;
  };

  // The credit card is in the required format.
  return true;
}
/*============================================================================*/


/**
 * Validates a card expiry date.  Finds the midnight on first day of the following
 * month and ensures that is greater than the current time (cards expire at the
 * end of the printed month).  Assumes basic sanity checks have already been performed
 * on month/year (i.e. length, numeric, etc).
 *
 * @param integer The expiry month shown on the card.
 * @param integer The expiry year printed on the card.
 * @return boolean Returns true if the card is still valid, false if it has expired.
 */
function cardExpiryValid($month,$year) {
	if($year != ' ')
	{
	 	$expiry_date = mktime ( 0, 0, 0, ($month + 1), 1, $year );
	 	return ($expiry_date > time ());
	}
}

/**
* Truncates a card number retaining only the first 4 and the last 4 digits.  It then returns the truncated form.
*
* @param string The card number to truncate.
* @return string The truncated card number.
*/
function truncate_card($card_num) {
    #$padsize = (strlen($card_num) < 7 ? 0 : strlen($card_num) - 7);
    #return substr($card_num, 0, 4) . str_repeat('X', $padsize). substr($card_num, -3);
    $padsize = (strlen($card_num) < 7 ? 0 : strlen($card_num) - 4);
    return str_repeat('X', $padsize). substr($card_num,- 4);
}

/**
* Strips all non-numerics from the card number.
*
* @param string The card number to clean up.
* @return string The stripped down card number.
*/
function card_number_clean($number) {
    return ereg_replace("[^0-9]", "", $number);
}
/**
* checking numeric from the card number.
*
* @param string The card number for numeric checking.
* @return string true or false.
 */
function is_number($card_number)
{
	return preg_match('/^\d+$/',$card_number);
}

?>