server.js

const express = require('express')
const app = express()
const http = require('http')
const path = require('path')
const {Server} = require('socket.io')
const ACTIONS = require('./src/Actions')


const server = http.createServer(app)
const io = new Server(server)

app.use(express.static('build'))
app.use((req,res,next) => {
    res.sendFile(path.join(__dirname, 'build', 'index.html'))
})

const userSocketMap = {}

function getAllConnectedClients(roomId){
    return Array.from(io.sockets.adapter.rooms.get(roomId) || []).map((socketId) => {
        return {
            socketId,
            username: userSocketMap[socketId],
        }
    })
}

io.on('connection', (socket) => {
    // console.log('Socket Connected', socket.id);

    socket.on(ACTIONS.JOIN, ({roomId, username})=>{
        userSocketMap[socket.id] = username
        socket.join(roomId)
        const clients = getAllConnectedClients(roomId)
        clients.forEach(({socketId})=>{
            io.to(socketId).emit(ACTIONS.JOINED, {
                clients,
                username,
                socketId: socket.id,
            })
        })
    })

    socket.on(ACTIONS.CODE_CHANGE,({roomId, code})=>{
        socket.in(roomId).emit(ACTIONS.CODE_CHANGE,{code})
    })

    socket.on(ACTIONS.SYNC_CODE,({socketId, code})=>{
        io.to(socketId).emit(ACTIONS.CODE_CHANGE,{code})
    })

    socket.on('disconnecting', () => {
        const rooms = [...socket.rooms] //New syntax of spread operator in JS
        rooms.forEach((roomId) => {
            socket.in(roomId).emit(ACTIONS.DISCONNECTED, {
                socketId: socket.id,
                username: userSocketMap[socket.id],
            })
        })
        delete userSocketMap[socket.id]
        socket.leave()
    })
})


const PORT = process.env.PORT || 5000
server.listen(PORT, () => console.log(`Listening on port ${PORT}`))