uno-online/server.js

const express = require('express')
const socketio = require('socket.io')
const http = require('http')
const cors = require('cors')
const { addUser, removeUser, getUser, getUsersInRoom } = require('./users')

const PORT = process.env.PORT || 5000

const app = express()
const server = http.createServer(app)
const io = socketio(server)

app.use(cors())

io.on('connection', socket => {
    socket.on('join', (payload, callback) => {
        let numberOfUsersInRoom = getUsersInRoom(payload.room).length

        const { error, newUser} = addUser({
            id: socket.id,
            name: numberOfUsersInRoom===0 ? 'Player 1' : 'Player 2',
            room: payload.room
        })

        if(error)
            return callback(error)

        socket.join(newUser.room)

        io.to(newUser.room).emit('roomData', {room: newUser.room, users: getUsersInRoom(newUser.room)})
        socket.emit('currentUserData', {name: newUser.name})
        callback()
    })

    socket.on('initGameState', gameState => {
        const user = getUser(socket.id)
        if(user)
            io.to(user.room).emit('initGameState', gameState)
    })

    socket.on('updateGameState', gameState => {
        const user = getUser(socket.id)
        if(user)
            io.to(user.room).emit('updateGameState', gameState)
    })

    socket.on('disconnect', () => {
        const user = removeUser(socket.id)
        if(user)
            io.to(user.room).emit('roomData', {room: user.room, users: getUsersInRoom(user.room)})
    })
})

server.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`)
})