socket.on(LOGIN, async (data) => {
        if (data && data.username && data.username.length > 0 && !data.username.isEmpty()) {
            const username = data.username.trim().trunc(10);
            if (DEBUG) { console.log(`login ${username}`.debug) }

            players.push(new Player(io, socket, username));
            socket.login = true;
            io.to(socket.id).emit(LOGIN_SUCCESS, { username });
        } else {
            if (DEBUG) { console.log(`invalid username`.debug) }
            io.to(socket.id).emit(LOGIN_ERROR, { text: "invalid username" });
        }
});

var io = require('socket.io')();
var jwtAuth = require('socketio-jwt-auth');
 
// using middleware
io.use(jwtAuth.authenticate({
  secret: 'Your Secret',    // required, used to verify the token's signature
  algorithm: 'HS256'        // optional, default to be HS256
}, function(payload, done) {
  // done is a callback, you can use it as follows
  User.findOne({id: payload.sub}, function(err, user) {
    if (err) {
      // return error
      return done(err);
    }
    if (!user) {
      // return fail with an error message
      return done(null, false, 'user does not exist');
    }
    // return success with a user info
    return done(null, user);
  });
}));