centurion/backend/src/index.js

const service = require("./service.js");
const state = require("./state.js");

const {io} = require('./app.js');

io.on('connection', socket => {
    const socketId = socket.id;

    console.log('a user connected', socketId);

    const lobby = state.createRandomLobby();
    service.joinLobby(socketId, lobby.name);
    socket.join(lobby.name);
    socket.emit('welcome', {lobby: lobby});

    socket.on('disconnect', (reason) => {
        console.log('Disconnected:', socketId);
        service.leaveLobby(socketId);
    });

    socket.on('join_lobby', (lobbyId, callback) => {
        if (!callback || typeof callback !== 'function') {
            console.error("Join: Callback not a function.");
            return
        }

        if (!lobbyId) {
            return callback('no_lobby_id_given');
        }

        if (!Number.isSafeInteger(+lobbyId)) {
            return callback('lobby_id_not_integer');
        }

        console.log(`${socketId} wants to join '${lobbyId}'.`);

        // Leave current lobby first
        service.leaveLobby(socketId);
        const lobby = service.joinLobby(socketId, lobbyId);

        socket.join(lobby.name);

        callback(null, {
            status: 'ok',
            lobby: lobby
        });
    });

    socket.on('lobby_info', callback => {
        if (!callback || typeof callback !== 'function') {
            console.error("Lobby info: Callback not a function.");
            return
        }

        const lobby = service.getUserLobby(socketId);

        callback(null, {
            status: 'ok',
            lobby: lobby
        });
    });

    socket.on('request_start', (time = null) => {
        console.log('request start', socket.rooms);

        const lobby = service.getUserLobby(socketId);
        if (!lobby.isLeader(socketId)) {
            console.warn("Non leader tried to start.");
            return;
        }

        const ioLobby = io.to(lobby.name + "");
        ioLobby.emit('started');
        lobby.run(ioLobby);

        if (typeof time === 'number' && time) {
            console.log("Starting at", time);
            lobby.seek(ioLobby, time);
        }
    });
});