// Copyright (C) 2022 WYATT GROUP
// Please see the AUTHORS file for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

import 'dart:async';

import 'package:wyatt_architecture/wyatt_architecture.dart';

/// Usecase observers
mixin Observer<Parameters, ReturnType> {
  /// Called before usecase is runned.
  /// Useful to check the preconditions
  FutureOr<void> onStart(Parameters? params) {}

  /// Called when error occures during main scenario
  /// Useful to run alternative scenario
  FutureOr<void> onError(AppException? error) {}
}

/// Specific observer for classic usecase
mixin AsyncObserver<ReturnType> {
  /// Called when usecase is completed
  FutureOr<void> onComplete(ReturnType? data) {}
}

/// Specific observer for stream case usecase
mixin StreamObserver<ReturnType> {
  /// Replaces the data event handler of this subscription.
  void onDone() {}

  /// Replaces the done event handler of this subscription.
  void onData(ReturnType? data) {}
}