improve nif validator

src/Validator/Constraints/SpanishNifValidator.php

@@ -11,6 +11,18 @@
 
 class SpanishNifValidator extends ConstraintValidator
 {
+    // Valid first letters for a legal entity NIF
+    private const string VALID_FIRST_LETTERS = 'ABCDEFGHJNPQRSUVW';
+
+    // First letters requiring a letter as control character
+    private const array LETTER_CONTROL = ['P', 'Q', 'R', 'S', 'W', 'N'];
+
+    // First letters requiring a digit as control character
+    private const array DIGIT_CONTROL = ['A', 'B', 'E', 'H'];
+
+    // Mapping from control digit to control letter: J=0, A=1, B=2 ... I=9
+    private const string CONTROL_LETTERS = 'JABCDEFGHI';
+
     public function validate(mixed $value, Constraint $constraint): void
     {
         if (!$constraint instanceof SpanishNif) {
@@ -25,11 +37,56 @@ public function validate(mixed $value, Constraint $constraint): void
             throw new UnexpectedValueException($value, 'string');
         }
 
-        if (1 !== preg_match('/^[A-Z][A-Z0-9]{8}$/', $value)) {
+        if (!$this->isValid($value)) {
             $this->context->buildViolation($constraint::MESSAGE)
                 ->setParameter('{{ value }}', $this->formatValue($value))
                 ->setCode($constraint::WRONG_FORMAT_ERROR)
                 ->addViolation();
         }
     }
+
+    private function isValid(string $value): bool
+    {
+        // Strict format: known first letter + 7 digits + 1 control character
+        if (
+            1 !== preg_match('/^([' . self::VALID_FIRST_LETTERS . '])(\d{7})([0-9A-Z])$/', $value, $matches)
+        ) {
+            return false;
+        }
+
+        [, $firstLetter, $digits, $control] = $matches;
+
+        $expectedDigit = $this->computeControlDigit($digits);
+        $expectedLetter = self::CONTROL_LETTERS[$expectedDigit];
+
+        if (in_array($firstLetter, self::LETTER_CONTROL, true)) {
+            return $control === $expectedLetter;
+        }
+
+        if (in_array($firstLetter, self::DIGIT_CONTROL, true)) {
+            return $control === (string)$expectedDigit;
+        }
+
+        // Other first letters accept either a digit or a letter
+        return $control === (string)$expectedDigit || $control === $expectedLetter;
+    }
+
+    private function computeControlDigit(string $digits): int
+    {
+        // Sum digits at even positions (0-based indexes 1, 3, 5)
+        $evenSum = (int)$digits[1] + (int)$digits[3] + (int)$digits[5];
+
+        // For each odd position (0-based indexes 0, 2, 4, 6):
+        // multiply by 2, then add the resulting digits together
+        $oddSum = 0;
+        foreach ([0, 2, 4, 6] as $i) {
+            $val = (int)$digits[$i] * 2;
+            $oddSum += $val >= 10 ? intdiv($val, 10) + ($val % 10) : $val;
+        }
+
+        $total = $evenSum + $oddSum;
+        $units = $total % 10;
+
+        return $units !== 0 ? 10 - $units : 0;
+    }
 }

tests/Validator/Constraints/SpanishNifValidatorTest.php

@@ -29,24 +29,24 @@ public static function providerValidValues(): iterable
     {
         yield 'null value' => [null];
         yield 'empty string' => [''];
-        yield 'valid NIF with digit suffix' => ['A12345678'];
-        yield 'valid NIF with letter suffix' => ['B1234567C'];
-        yield 'valid NIF all zeros' => ['Z00000000'];
-        yield 'valid NIF mixed alphanumeric suffix' => ['H1234567A'];
+        yield 'type A with digit control' => ['A58818501']; // Wikipedia example
+        yield 'type A with digit control (Adyen)' => ['A39000013']; // Adyen docs example
+        yield 'type P with letter control' => ['P2813200I']; // Ayuntamiento de Madrid
     }
 
     public static function providerInvalidValues(): iterable
     {
-        $expectedMessage = SpanishNif::MESSAGE;
         $code = SpanishNif::WRONG_FORMAT_ERROR;
-
-        yield 'too short' => ['A1234567', $code, $expectedMessage];
-        yield 'too long' => ['A1234567890', $code, $expectedMessage];
-        yield 'starts with digit' => ['112345678', $code, $expectedMessage];
-        yield 'starts with lowercase' => ['a12345678', $code, $expectedMessage];
-        yield 'contains lowercase' => ['A1234567b', $code, $expectedMessage];
-        yield 'contains special characters' => ['A1234-678', $code, $expectedMessage];
-        yield 'contains spaces' => ['A1234 678', $code, $expectedMessage];
-        yield 'single letter' => ['A', $code, $expectedMessage];
+        $message = SpanishNif::MESSAGE;
+
+        yield 'too short' => ['A1234567', $code, $message];
+        yield 'too long' => ['A1234567890', $code, $message];
+        yield 'starts with digit' => ['112345678', $code, $message];
+        yield 'starts with lowercase' => ['a12345678', $code, $message];
+        yield 'invalid first letter' => ['Z12345678A', $code, $message];
+        yield 'wrong control digit' => ['A58818502', $code, $message];
+        yield 'wrong control letter' => ['P2813200Z', $code, $message];
+        yield 'contains special character' => ['A1234-678', $code, $message];
+        yield 'contains space' => ['A1234 678', $code, $message];
     }
 }