countCollection function

Implementation

Future<int> countCollection(
  String collectionPath, {
  List<Where> where = const [],
  List<OrderBy> orderBy = const [],
  int? limit,
  int? limitToLast,
  bool collectionGroup = false,
}) {
  final encoded = _encodeSpec(
    _querySpec(
      where: where,
      orderBy: orderBy,
      limit: limit,
      limitToLast: limitToLast,
      collectionGroup: collectionGroup,
    ),
  );

  final completer = Completer<int>();
  final receive = RawReceivePort();
  receive.handler = (Object? message) {
    receive.close();
    final bytes = message! as Uint8List;
    final seq = ByteData.sublistView(bytes).getInt64(8, Endian.host);
    if (seq < 0) {
      completer.completeError(
        FirestoreException(
          seq.toInt(),
          'count failed',
          'count $collectionPath',
        ),
      );
      return;
    }
    final value = decodeSnapshotValue(bytes);
    completer.complete(value is int ? value : 0);
  };

  final p = collectionPath.toNativeUtf8();
  final buf = calloc<Uint8>(encoded.isEmpty ? 1 : encoded.length);
  if (encoded.isNotEmpty) {
    buf.asTypedList(encoded.length).setAll(0, encoded);
  }
  final rc = fdbFsCount(
    p.cast(),
    buf,
    encoded.length,
    receive.sendPort.nativePort,
  );
  calloc
    ..free(p)
    ..free(buf);
  if (rc != 0) {
    receive.close();
    return Future.error(
      rc == -3 || rc == -4
          ? ArgumentError('this query cannot be counted as expressed')
          : StateError('count $collectionPath failed to start ($rc)'),
    );
  }
  return completer.future;
}