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<?php |
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/* |
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* This file is part of questocat/bank-card package. |
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* |
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* (c) questocat <[email protected]> |
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* |
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* This source file is subject to the MIT license that is bundled |
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* with this source code in the file LICENSE. |
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*/ |
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namespace Questocat\BankCard; |
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/** |
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* Luhn 算法. |
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* |
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* @see https://zh.wikipedia.org/wiki/Luhn%E7%AE%97%E6%B3%95 |
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*/ |
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class Luhn |
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{ |
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/** |
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* Verify the check digit. |
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* |
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* @param string cardNumber |
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* |
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* @return bool |
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*/ |
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public function verify($cardNumber) |
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{ |
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$originalCardNumber = $this->prepare($cardNumber); |
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$cardNumber = $this->excludeCheckDigit($originalCardNumber); |
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$luhmSum = $this->calculateLuhmSum($cardNumber); |
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$checkCode = $this->checkDigit($originalCardNumber); |
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if (0 === ($luhmSum + $checkCode) % 10) { |
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return true; |
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} |
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return false; |
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} |
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/** |
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* Calculate the check digit. |
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* |
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* @param string $number |
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* |
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* @return string |
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*/ |
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public function calculateCheckDigit($number) |
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{ |
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$luhmSum = $this->calculateLuhmSum($number); |
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return 10 - ($luhmSum % 10); |
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} |
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/** |
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* Prepare the bank card number. |
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* |
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* @param string $cardNumber |
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* |
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* @return string |
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*/ |
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protected function prepare($cardNumber) |
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{ |
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$cardNumber = str_replace(' ', '', trim($cardNumber)); |
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return $cardNumber; |
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} |
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/** |
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* Returns the check digit of card number. |
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* |
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* @param string $cardNumber |
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* |
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* @return int |
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*/ |
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protected function checkDigit($cardNumber) |
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{ |
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return substr($cardNumber, -1); |
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} |
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/** |
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* Returns the no check digit of card number. |
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* |
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* @param string $cardNumber |
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* |
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* @return string |
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*/ |
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protected function excludeCheckDigit($cardNumber) |
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{ |
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return substr($cardNumber, 0, -1); |
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} |
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/** |
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* Calculate the Luhm checksum. |
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* |
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* @param string $number |
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* |
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* @return int |
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*/ |
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protected function calculateLuhmSum($number) |
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{ |
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$len = strlen($number); |
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$luhmSum = 0; |
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$j = 1; |
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for ($i = $len - 1; $i >= 0; --$i) { |
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$k = intval($number[$i]); |
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if (1 == $j % 2) { |
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$k *= 2; |
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$k = intval($k / 10) + $k % 10; |
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} |
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$luhmSum += $k; |
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++$j; |
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} |
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return $luhmSum; |
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} |
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} |
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questocat /
bank-card
