glastree_on_gitea

vendor/fakerphp/faker/src/Faker/Calculator/Isbn.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Faker\Calculator;
+
+/**
+ * Utility class for validating ISBN-10
+ */
+class Isbn
+{
+    /**
+     * @var string ISBN-10 validation pattern
+     */
+    public const PATTERN = '/^\d{9}[0-9X]$/';
+
+    /**
+     * ISBN-10 check digit
+     *
+     * @see http://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digits
+     *
+     * @param string $input ISBN without check-digit
+     *
+     * @throws \LengthException When wrong input length passed
+     */
+    public static function checksum(string $input): string
+    {
+        // We're calculating check digit for ISBN-10
+        // so, the length of the input should be 9
+        $length = 9;
+
+        if (strlen($input) !== $length) {
+            throw new \LengthException(sprintf('Input length should be equal to %d', $length));
+        }
+
+        $digits = str_split($input);
+        array_walk(
+            $digits,
+            static function (&$digit, $position): void {
+                $digit = (10 - $position) * $digit;
+            },
+        );
+        $result = (11 - array_sum($digits) % 11) % 11;
+
+        // 10 is replaced by X
+        return ($result < 10) ? (string) $result : 'X';
+    }
+
+    /**
+     * Checks whether the provided number is a valid ISBN-10 number
+     *
+     * @param string $isbn ISBN to check
+     */
+    public static function isValid(string $isbn): bool
+    {
+        if (!preg_match(self::PATTERN, $isbn)) {
+            return false;
+        }
+
+        return self::checksum(substr($isbn, 0, -1)) === substr($isbn, -1);
+    }
+}