Response? _fileRangeResponse()

in lib/src/static_handler.dart [214:258]

• 38 lines of code
• 12 McCabe index (conditional complexity)

Response? _fileRangeResponse(
    Request request, File file, Map<String, Object> headers) {
  final range = request.headers[HttpHeaders.rangeHeader];
  if (range == null) return null;
  final matches = RegExp(r'^bytes=(\d*)\-(\d*)$').firstMatch(range);
  // Ignore ranges other than bytes
  if (matches == null) return null;

  final actualLength = file.lengthSync();
  final startMatch = matches[1]!;
  final endMatch = matches[2]!;
  if (startMatch.isEmpty && endMatch.isEmpty) return null;

  int start; // First byte position - inclusive.
  int end; // Last byte position - inclusive.
  if (startMatch.isEmpty) {
    start = actualLength - int.parse(endMatch);
    if (start < 0) start = 0;
    end = actualLength - 1;
  } else {
    start = int.parse(startMatch);
    end = endMatch.isEmpty ? actualLength - 1 : int.parse(endMatch);
  }

  // If the range is syntactically invalid the Range header
  // MUST be ignored (RFC 2616 section 14.35.1).
  if (start > end) return null;

  if (end >= actualLength) {
    end = actualLength - 1;
  }
  if (start >= actualLength) {
    return Response(
      HttpStatus.requestedRangeNotSatisfiable,
      headers: headers,
    );
  }
  return Response(
    HttpStatus.partialContent,
    body: request.method == 'HEAD' ? null : file.openRead(start, end + 1),
    headers: headers
      ..[HttpHeaders.contentLengthHeader] = (end - start + 1).toString()
      ..[HttpHeaders.contentRangeHeader] = 'bytes $start-$end/$actualLength',
  );
}