getSource method

Implementation

@override
FutureOr<List<FileOpener>> getSource({Directory? tempDir}) async {
  final client = Client();

  final headResponse = await client.head(uri);
  String? fileName;
  DateTime? lastModified;
  if (headResponse.statusCode == HttpStatus.ok) {
    fileName = headResponse.headers['content-disposition']!
        .split('; ')
        .firstWhere(
          (element) => element.startsWith('filename='),
          orElse: () => 'filename=${uri.path.split('/').last}',
        )
        .substring(9);
    final format = DateFormat(
      "${DateFormat.ABBR_WEEKDAY}, ${DateFormat.DAY} ${DateFormat.ABBR_MONTH} ${DateFormat.YEAR} ${DateFormat.HOUR24}:${DateFormat.MINUTE}:${DateFormat.SECOND}' GMT'",
    );
    lastModified = format.parse(headResponse.headers['last-modified']!, true);
  } else {
    _logger.warning('Query URL did not accept HEAD request...');
  }

  var gtfsDirectory =
      tempDir != null ? Directory(join(tempDir.path, fileName)) : null;

  bool shouldDownload;
  if (await gtfsDirectory?.exists() ?? false) {
    final datasetDate =
        (await File(join(gtfsDirectory!.path, 'agency.txt')).stat()).modified;
    if (lastModified == null) {
      shouldDownload =
          DateTime.now().difference(datasetDate) > Duration(days: 1);
    } else {
      shouldDownload = !datasetDate.isAtSameMomentAs(lastModified);
    }
  } else {
    shouldDownload = true;
  }

  Iterable<FileOpener>? archiveFileList;

  if (!shouldDownload) {
    _logger.info('Acceptable dataset already in cache, skipping download...');
  } else {
    _logger.info('Downloading dataset...');
    final response = await MultipartRequest('GET', uri).send();

    if (fileName == null) {
      fileName = response.headers['content-disposition']!
          .split('; ')
          .firstWhere((element) => element.startsWith('filename='))
          .substring(9);
      gtfsDirectory =
          tempDir != null ? Directory(join(tempDir.path, fileName)) : null;
    }

    final archive = ZipDecoder().decodeStream(
      InputMemoryStream(await response.stream.toBytes()),
    );

    _logger.info('Finished downloading dataset.');
    if (gtfsDirectory != null) {
      extractArchiveToDiskSync(archive, gtfsDirectory.absolute.path);
      archiveFileList = gtfsDirectory
          .listSync(recursive: true)
          .whereType<File>()
          .map((e) {
            e.setLastModifiedSync(lastModified ?? DateTime.now());
            return (stream: () => e.openRead(), name: basename(e.path));
          });
    } else {
      archiveFileList = archive.map(
        (e) => (stream: () => Stream.value(e.content), name: e.name),
      );
    }
  }

  archiveFileList ??= gtfsDirectory!
      .listSync(recursive: true)
      .whereType<File>()
      .map((e) => (stream: () => e.openRead(), name: basename(e.path)));
  fileNameList = archiveFileList.map((e) => e.name).toList(growable: false);

  return archiveFileList.toList(growable: false);
}