<?php declare(strict_types=1);

final class DocumentFormatValidator
{
    private function validatePrefix(Filename $filename, DocumentFormat $format): void
    {
        $detectedPrefix = $this->detectPrefix($filename);

        if ($format->requiresPrefix()) {
            if ($detectedPrefix === null) {
                throw new DomainException('Missing prefix.');
            }

            if (!in_array($detectedPrefix->toString(), $format->prefixes, true)) {
                throw new DomainException('Invalid prefix.');
            }
        } else {
            if ($detectedPrefix !== null) {
                throw new DomainException('Non required prefix detected.');
            }
        }
    }