class FileEncodingConstraintValidator

class FileEncodingConstraintValidator extends BaseFileConstraintValidator {
    
    /**
     * {@inheritdoc}
     */
    public function validate(mixed $value, Constraint $constraint) : void {
        
        /** @var \Drupal\file\Entity\FileInterface $file */
        $file = $this->assertValueIsFile($value);
        if (!$constraint instanceof FileEncodingConstraint) {
            throw new UnexpectedTypeException($constraint, FileEncodingConstraint::class);
        }
        $encodings = $constraint->encodings;
        $data = file_get_contents($file->getFileUri());
        foreach ($encodings as $encoding) {
            $this->validateEncoding($data, $encoding, $constraint);
        }
    }
    
    /**
     * Validates the encoding of the file.
     *
     * @param string $data
     *   The file data.
     * @param string $encoding
     *   The encoding to validate.
     * @param \Drupal\file\Plugin\Validation\Constraint\FileEncodingConstraint $constraint
     *   The constraint.
     */
    protected function validateEncoding(string $data, string $encoding, FileEncodingConstraint $constraint) : void {
        if (mb_check_encoding($data, $encoding)) {
            return;
        }
        $this->context
            ->addViolation($constraint->message, [
            '%encoding' => $encoding,
            '%detected' => mb_detect_encoding($data),
        ]);
    }

}