Bnb.java

package com.mywonderfulbnb.bnb.definition

final class Bnb implements ReadOnlyBnb {
  private BnbId bnbId;
  private OwnerId ownerId;
  private Name name;
  private Rooms rooms;

  public Bnb(BnbId bnbId, OwnerId ownerId, Name name, Rooms rooms) {
    this.bnbId = bnbId;
    this.ownerId = ownerId;
    this.name = name;
    this.rooms = rooms;
  }
  
  public void addRoomByName(RoomName roomName) {
    // check if room with that name already exists, then...
    room = new Room(roomName);
    rooms = rooms.add(room);
  }
  
  public BnbId getBnbId() {
    return bnbId;
  }
  
  public OwnerId getOwnerId() {
    return ownerId;
  }
  
  public Name getName() {
    return name;
  }
  
  public Rooms getRooms() {
    return rooms;
  }
}

BnbWasAdded.java

package com.mywonderfulbnb.bnb.definition

final class BnbWasAdded implements Message {
  private OwnerId ownerId;
  private ReadOnlyBnb bnb;

  public BnbWasAdded(OwnerId ownerId, ReadOnlyBnb bnb) {
    this.ownerId = ownerId;
    this.bnb = bnb;
  }
  
  public OwnerId getOwnerId() {
    return ownerId;
  }
  
  public ReadOnyBnb getBnb() {
    return bnb;
  }
}

Publisher.java

package com.mywonderfulbnb.messaging;

interface Publisher {
  void publish(Message m);
}

ReadOnlyBnb.java

package com.mywonderfulbnb.bnb.definition

interface ReadOnlyBnb {
  BnbId getBnbId();
  OwnerId getOwnerId();
  Name getName();
  Rooms getRooms();
}

RoomWasAdded.java

package com.mywonderfulbnb.bnb.definition

final class RoomWasAdded implements Message {
  private BnbId bnbId;
  private Room room;

  public RoomWasAdded(BnbId bnbId, Room room) {
    this.bnbId = bnbId;
    this.room = room;
  }
  
  public BnbId getBnbId() {
    return bnbId;
  }
  
  public Room getRoom() {
    return room;
  }
}

Service.java

package com.mywonderfulbnb.bnb.definition

final class Service {
  private Bnbs Bnbs;
  private ActivatedOwners activatedOwners;

  public Service(Bnbs bnbs, ActivatedOwners activatedOwners, Publisher publisher) {
    this.bnbs = bnbs;
    this.activatedOwners = activatedOwners;
    tihs.publisher = publisher;
  }

  public addBnb(UUID ownerUuid, UUID bnbUuid, String nameStr) {
    ownerId = new OwnerId(ownerUuid);
    bnbId = new BnbId(bnbUuid);
    name = new Name(nameStr);
    
    assertOwnerIsActivated(ownerId);
    
    bnb = new Bnb(bnbUuid, ownerId, name);
    
    bnbs.save(bnb);
    
    publisher.publish(
      new BnbWasAdded(ownerId, (ReadOnlyBnb) bnb)
    );
  }
  
  public addRoom(UUID bnbUuid, String roomNameStr) {
    bnbId = new BnbId(bnbUuid);
    roomName = new RoomName(roomNameStr);
    
    bnb = loadBnb(bnbId)
    
    room = bnb.addRoomByName(roomName);
    
    bnbs.save(bnb);
    
    publisher.publish(
      new RoomWasAdded(bnbId, room)
    );
  }
  
  private assertOwnerIsActivated(OwnerId ownerId) {
    itExists = activatedOwners.existsOneWithId(ownerId);
    
    if (!itExists) {
      throw new ActivatedOwnerNotFound(ownerId);
    }
  }
  
  private Bnb loadBnb(BnbId bnbid) {
    maybeBnb = bnbs.load(bnbId);
    
    if (!maybeBnb.isPresent()) {
      throw new BnbNotFound(bnbId);
    }
    
    return maybeBnb.get();
  }
}