<?php declare(strict_types=1);

namespace AeonDumpManager\Service;

/**
 * Dumps are named dump_YYYY-MM-DD_HH-mm-ss.sql.gz — lexicographically sortable,
 * and the filename is the single source of truth for a dump's datetime (not
 * filesystem mtime, which can drift across copies/touches).
 */
class DumpFilenameParser
{
    private const PATTERN = '/^dump_(\d{4}-\d{2}-\d{2})_(\d{2}-\d{2}-\d{2})\.sql\.gz$/';

    public function format(\DateTimeImmutable $dateTime): string
    {
        return 'dump_' . $dateTime->format('Y-m-d_H-i-s') . '.sql.gz';
    }

    public function parse(string $filename): ?\DateTimeImmutable
    {
        if (preg_match(self::PATTERN, $filename, $matches) !== 1) {
            return null;
        }

        $dateTime = \DateTimeImmutable::createFromFormat(
            'Y-m-d_H-i-s',
            $matches[1] . '_' . $matches[2]
        );

        return $dateTime ?: null;
    }

    public function isValid(string $filename): bool
    {
        return $this->parse($filename) !== null;
    }
}