getComet function

Future<Comet?> getComet({ int? offset, })

Implementation

Future<Comet?> getComet({int? offset}) async {
  if (_cometUserChannel != null) {

    //Initialize of continue the offset.
    if (offset == null) {
      offset = _cometOffset;
    }

    Http.Response? response = await _clientGetRes(_cometUserChannel!.cometServer, queryParameters: { 'offset': offset.toString() });
    if (response != null) {
      String body = response.body;
      //Try substring the json.
      String headStr = 'CometChannel.scriptCallback(';
      String tailStr = ');';
      String jsonStr =
      body.substring(headStr.length, body.length - tailStr.length);
      dynamic jsonObject = json.decode(jsonStr);
      if (jsonObject != null) {
        Comet comet = Comet.fromJson(jsonObject);
        if (comet.newOffset != null) {
          //Check how we should update the comet offset.
          if (comet.newOffset == -1) {
            //Waiting for data to be posted. Don't update the offset.

          } else if (comet.newOffset == -3) {
            //Your offset is wrong and you need to resync your data.
            _cometOffset = 0;
          } else {
            //Update the offset.
            _cometOffset = comet.newOffset;
          }
        }
        return comet;
      } else {
        print('Oops! getComet decode json failed?');
        return null;
      }
    } else {
      print('Oops! getComet null response or body?');
      return null;
    }
  } else {
    print(
        'Oops! cometUserChannel is null! Try realtimeGetUserChannel() first to cache a UserChannel!');
    return null;
  }
}