/** * Returns true if and only if $value follows the Luhn algorithm (mod-10 checksum) * * @param string $value * @return boolean */ public function isValid($value) { $this->_setValue($value); if (!is_string($value)) { $this->_error(self::INVALID, $value); return false; } if (!ctype_digit($value)) { $this->_error(self::CONTENT, $value); return false; } $length = strlen($value); $types = $this->getType(); $foundp = false; $foundl = false; foreach ($types as $type) { foreach ($this->_cardType[$type] as $prefix) { if (substr($value, 0, strlen($prefix)) == $prefix) { $foundp = true; if (in_array($length, $this->_cardLength[$type])) { $foundl = true; break 2; } } } } if ($foundp == false){ $this->_error(self::PREFIX, $value); return false; } if ($foundl == false) { $this->_error(self::LENGTH, $value); return false; } $sum = 0; $weight = 2; for ($i = $length - 2; $i >= 0; $i--) { $digit = $weight * $value[$i]; $sum += floor($digit / 10) + $digit % 10; $weight = $weight % 2 + 1; } if ((10 - $sum % 10) % 10 != $value[$length - 1]) { $this->_error(self::CHECKSUM, $value); return false; } if (!empty($this->_service)) { try { $callback = new Callback($this->_service); $callback->setOptions($this->_type); if (!$callback->isValid($value)) { $this->_error(self::SERVICE, $value); return false; } } catch (\Exception $e) { $this->_error(self::SERVICEFAILURE, $value); return false; } } return true; }