index.js

const http = require("http");
const app = require("express")();
app.get("/", (req,res)=> res.sendFile(__dirname + "/index.html"))
app.listen(9091, ()=>console.log("Listening on http port 9091"))
const websocketServer = require("websocket").server
const httpServer = http.createServer();
httpServer.listen(9090, () => console.log("Listening... on 9090"))

const clients = {};
const games = {};

const wsServer = new websocketServer({
    "httpServer": httpServer
})

wsServer.on("request", request => {
    // Client connects
    const connection = request.accept(null, request.origin);
    connection.on("open", () => console.log("opened!"))
    connection.on("close", () => console.log("closed!"))
    connection.on("message", message => {
        const result = JSON.parse(message.utf8Data)
        // Client creates a game
        if (result.method === "create"){
            const clientId = result.clientId
            const gameId = guid();
            games[gameId] = {
                "id": gameId,
                "bullets": 8,
                "clients": []
            }

            const payLoad = {
                "method": "create",
                "game": games[gameId]
            }

            const con = clients[clientId].connection;
            con.send(JSON.stringify(payLoad));
        }

        // Client wants to join
        if (result.method === "join"){
            const clientId = result.clientId;
            const gameId = result.gameId;
            const game = games[gameId];
    
            if (game.clients.length >= 3){
                return;
            }

            const color = {"0": "Red", "1": "Green", "2": "Blue"}[game.clients.length];
    
            game.clients.push({
                "clientId": clientId,
                "color": color
            })

            if (game.clients.length === 3){
                updateGameState();
            }

            const payLoad = {
                "method": "join",
                "game": game
            }

            // Announce new player to all clients
            game.clients.forEach(c=> {
                clients[c.clientId].connection.send(JSON.stringify(payLoad));
            })
        }

        // A user plays
        if (result.method === "play"){
            const gameId = result.gameId;
            const bulletId = result.bulletId;
            const color = result.color;

            let state = games[gameId].state;
            if (!state){
                state = {}
            }

            state[bulletId] = color;
            games[gameId].state = state;
        }
    })

    // genereate a new client id
    const clientId = guid();
    clients[clientId] = {
        "connection": connection
    }

    const payLoad = {
        "method": "connect",
        "clientId": clientId
    }

    connection.send(JSON.stringify(payLoad))
})


function updateGameState(){
    for (const g of Object.keys(games)){
        const game = games[g]
        const payLoad = {
            "method": "update",
            "game": game 
        }
        game.clients.forEach(c=> {
            clients[c.clientId].connection.send(JSON.stringify(payLoad))
        })
    }
    setTimeout(updateGameState, 500);
}


// Unique GUID generator
function S4() {
    return (((1+Math.random())*0x10000)|0).toString(16).substring(1); 
}

const guid = () => (S4() + S4() + "-" + S4() + "-4" + S4().substr(0,3) + "-" + S4() + "-" + S4() + S4() + S4()).toLowerCase();