import '../../../users/data/models/user_response.dart';

class SettingsUserCache {
  UserResponse? _cachedUser;
  Future<UserResponse>? _inflight;
  int _generation = 0;

  UserResponse? get cachedUser => _cachedUser;

  Future<UserResponse> getOrLoad(Future<UserResponse> Function() loader) {
    final cached = _cachedUser;
    if (cached != null) {
      return Future<UserResponse>.value(cached);
    }

    final inflight = _inflight;
    if (inflight != null) {
      return inflight;
    }

    final generation = _generation;
    late final Future<UserResponse> request;
    request = loader()
        .then((user) {
          if (generation == _generation) {
            _cachedUser = user;
          }
          return user;
        })
        .whenComplete(() {
          if (identical(_inflight, request)) {
            _inflight = null;
          }
        });

    _inflight = request;
    return request;
  }

  void set(UserResponse user) {
    _cachedUser = user;
  }

  void invalidate() {
    _generation += 1;
    _cachedUser = null;
    _inflight = null;
  }
}