firestore_service.dart

/* import略 */

String documentIdFromCurrentDate() => DateTime.now().toIso8601String();

/*
...略...
*/

class FirestoreService {
  FirestoreService({@required this.uid})
    // 1
      : assert(uid != null, 'Cannot create FirestoreDatabase with null uid');
  final String uid;

  final _service = FirebaseFirestore.instance;

  // 2
  static Future<void> createUser(FirAuth.UserCredential userCredential) async {
    FirAuth.User user = userCredential.user;
    String email = user.email;
    String displayName = user.email.split('@')[0];
    await FirebaseFirestore.instance.collection('/users/').doc(user.uid).set({
      'description': null,
      'displayName': displayName,
      'email': email,
      'imageUrl': null,
      'numFollowers': 0,
      'numFollowing': 0
    });
  }

  // 3
  Stream<User> userStream({ String uid }) {
    if (uid == null) {
      uid = this.uid;
    }
    return _service.collection('/users/').doc(uid).snapshots().map((snapshot) => User.fromMap(snapshot.id, snapshot.data()));
  }

  /* 
  ...中略...
  */

  // 5
  Stream<List<Room>> roomsStream() {
    return _service.collection('rooms').snapshots().map((snapshot) => snapshot.docs.map((doc) => Room.fromMap(doc.data(), doc.id)).toList());
  }

  // 6
  Stream<RoomDetailViewModel> roomStream({ AgoraService agoraService, Room room, User currentUser }) {
    return _service.doc('/rooms/${room.identifier}').snapshots()
        .map((snapshot) => Room.fromMap(snapshot.data(), snapshot.id))
        .map((room) => RoomDetailViewModel(room: room, currentUser: currentUser, database: this, agora: agoraService));
  }

  // 7
  Stream<SpeakerTileViewModel> participantStream({ User user }) {
    return _service.doc('/users/${user.identifier}').snapshots()
        .map((snapshot) => User.fromMap(snapshot.id, snapshot.data()))
        .map((speaker) => SpeakerTileViewModel(speaker: speaker));
  }

  /*
  ...略...
  */
}