index.js

/*
 * Coin game server.
 *
 * This is the entry point for the Node.js application.
 */

const express = require('express');

const app = express();
const http = require('http').Server(app);
const io = require('socket.io')(http);
const game = require('./server/game');

// Images, scripts, stylesheets, and other assets will be in this directory.
app.use(express.static('public'));

// The client application lives on a single HTML page.
app.get('/', (req, res) => {
  res.sendFile(`${__dirname}/public/index.html`);
});

io.on('connection', (socket) => {
  // When first connected, don't accept any messages except `name`. Keep accepting name
  // messages until a name is accepted. When a name is finally accepted, send a `welcome`
  // message and a the current game state, "turn off" the `name` message listener, then
  // start accepting `move` messages.
  const nameListener = (name) => {
    const trimmedName = name.trim();
    game.addPlayer(trimmedName, io, socket, nameListener, (err) => {
      if (err) console.log(err);
      io.to(socket.id).emit('welcome');
      game.state((err, result) => {
        io.emit('state', result);
      });
      socket.removeListener('name', nameListener);
      socket.on('move', (direction) => {
        game.move(direction, name, game, io, (err) => {
          if (err) console.error('Character could not be moved.');
          game.state((err, result) => {
            io.emit('state', result);
          });
        });
      });
    });
  };
  socket.on('name', nameListener);
});

// It begins (https://xkcd.com/1656/)
const port = process.env.PORT || 3000;
http.listen(port, () => {
  console.log(`Server listening on port ${port}`);
});