<?php

declare(strict_types=1);

namespace App\BusProNet\Model;

use League\Flysystem\FilesystemException;
use League\Flysystem\FilesystemOperator;

final readonly class XmlExportInfo
{
    private const INFO_FILENAME = 'uebertragung.info';
    private const TIMESTAMP_FORMAT = 'd.m.Y H:i:s';

    public function __construct(
        public \DateTimeImmutable $lastTransfer,
        public int $fileCount,
    ) {
    }

    public static function getFilename(): string
    {
        return self::INFO_FILENAME;
    }

    /**
     * Reads the marker from a storage, or null when it is missing or unreadable.
     *
     * A marker caught mid-sync or truncated is treated as absent rather than as an error:
     * callers only ever want to know which export they are looking at, and "unknown" is
     * an answer they can act on.
     */
    public static function fromStorage(FilesystemOperator $storage): ?self
    {
        try {
            if (false === $storage->fileExists(self::INFO_FILENAME)) {
                return null;
            }

            return self::fromString($storage->read(self::INFO_FILENAME));
        } catch (FilesystemException|\InvalidArgumentException) {
            return null;
        }
    }

    public static function fromString(string $content): self
    {
        $content = mb_convert_encoding($content, 'UTF-8', 'Windows-1252');
        $lines = array_filter(array_map('trim', explode("\n", $content)));

        if (count($lines) < 3) {
            throw new \InvalidArgumentException('Invalid uebertragung.info format: expected at least 3 lines');
        }

        $timestamp = \DateTimeImmutable::createFromFormat(self::TIMESTAMP_FORMAT, $lines[0]);
        if (false === $timestamp) {
            throw new \InvalidArgumentException(sprintf('Invalid timestamp format in uebertragung.info: expected "%s", got "%s"', self::TIMESTAMP_FORMAT, $lines[0]));
        }

        if (1 !== preg_match('/(\d+)/', $lines[2], $matches)) {
            throw new \InvalidArgumentException(sprintf('Could not extract file count from: "%s"', $lines[2]));
        }

        return new self($timestamp, (int) $matches[1]);
    }

    public function isNewerThan(self $other): bool
    {
        return $this->lastTransfer > $other->lastTransfer;
    }
}