const EventEmitter = require('events');

class User {

constructor(name) {

this.name = name;

this.messages = [];

this.rooms = {};

this.messageListener = (message) => {

this.messages.push(message);

}

}

joinRoom(room) {

this.messageListener = (message) => {

this.messages.push(message);

}

room.on('newMessage', this.messageListener);

this.rooms[room.name] = room;

}

leaveRoom(roomName) {

this.rooms[roomName].removeListener('newMessage', this.messageListener);

delete this.rooms[roomName];

}

getMesssages(roomName) {

return this.messages.filter((message) => {

return message.roomName === roomName;

})

}

printMessages(roomName) {

this.getMesssages(roomName).forEach((message) => {

console.log(`>> [${message.roomName}]:(${message.from}): ${message.message}`);

});

}

sendMessage(roomName, message) {

this.rooms[roomName].emit('newMessage', {

message,

roomName,

from: this.name

});

}

}

class Room extends EventEmitter {

constructor(name) {

super();

this.name = name;

}

}

const bob = new User('Bob');

const kevin = new User('Kevin');

const lobby = new Room('Lobby');

bob.joinRoom(lobby);

kevin.joinRoom(lobby);

bob.sendMessage('Lobby', 'Hi all');

bob.sendMessage('Lobby', 'I am new to this room.');

bob.printMessages('Lobby');

kevin.sendMessage('Lobby', 'Hi bob');

bob.sendMessage('Lobby', 'Hey kevin');

kevin.sendMessage('Lobby', 'Welcome!');

kevin.printMessages('Lobby');

bob.leaveRoom('Lobby');

kevin.sendMessage('Lobby', 'I got a good news for you guys');

bob.printMessages('Lobby');

kevin.printMessages('Lobby');