js 中介者模式

// 抽象中介者
class Mediator {
  constructor() {
    this.colleagues = [];
  }

  addColleague(colleague) {
    this.colleagues.push(colleague);
  }

  send(message, from, to) {
    // 默认情况下，消息会广播给所有同事
    if (!to) {
      this.colleagues.forEach(colleague => {
        if (colleague !== from) {
          colleague.receive(message);
        }
      });
    } else {
      to.receive(message);
    }
  }
}

// 具体中介者
class ChatRoom extends Mediator {
  send(message, from, to) {
    console.log(`${from.name} to ${to ? to.name : 'all'}: ${message}`);
    super.send(message, from, to);
  }
}

// 同事类
class User {
  constructor(name, mediator) {
    this.name = name;
    this.mediator = mediator;
  }

  send(message, to) {
    this.mediator.send(message, this, to);
  }

  receive(message) {
    console.log(`${this.name} received: ${message}`);
  }
}

// 使用示例
const chatRoom = new ChatRoom();

const user1 = new User('Alice', chatRoom);
const user2 = new User('Bob', chatRoom);
const user3 = new User('Charlie', chatRoom);

chatRoom.addColleague(user1);
chatRoom.addColleague(user2);
chatRoom.addColleague(user3);

user1.send('Hello everyone!');
user2.send('Hi Alice, how are you?');
user1.send('I am fine, thanks!', user2);