getSnapshots method

Future<List<Snapshot>> getSnapshots(Mirror mirror)

Get list of available snapshots from a mirror.

CoMaps CDN doesn't provide directory listings, so we dynamically probe versions based on the current date (going back 90 days). Results are sorted by date, newest first.

Implementation

Future<List<utils.Snapshot>> getSnapshots(Mirror mirror) async {
  final snapshots = <utils.Snapshot>[];
  final candidates = generateCandidateVersions();

  // Probe candidate versions until we find one
  for (final version in candidates) {
    final testUrl = utils.MirrorService.buildDownloadUrl(
      mirror.baseUrl, version, 'countries.txt');
    try {
      final response = await _client
          .head(Uri.parse(testUrl))
          .timeout(const Duration(seconds: 3));
      if (response.statusCode == 200) {
        snapshots.add(utils.Snapshot(version: version));
        // Found one, we can stop or continue to find more
        // For now, just find the first (latest) one to be efficient
        break;
      }
    } catch (e) {
      // Skip unavailable snapshots
    }
  }

  // Sort by date, newest first
  snapshots.sort((a, b) => b.date.compareTo(a.date));
  return snapshots;
}