Responder.dart

class Responder {
  final ResponderType type;
  Call call;
  final String name;

  Responder({this.type, this.name});

  void respondToCall(Call incoming) {
    if (isBusy()) {
      throw ResponderBusyException('Responder $name of type $type is busy.');
    }
    call = incoming;
  }

  bool isBusy() {
    return this.call != null;
  }

  endCurrentCall() {
    if (this.isBusy()) {
      var temp = call;
      call = null;
      temp.endCall();
    }
  }
}