index.js

const LIBRARIES = {
  Express: require("express"),
  BodyParser: require("body-parser"),
  SocketIO: require("socket.io"),
  Path: require("path"),
  HTTP: require("http"),
  FS: require("fs"),
  LM_TO_NC: require("./LMToNC"),
};

const SETTINGS = JSON.parse(
  LIBRARIES.FS.readFileSync(
    LIBRARIES.Path.join(__dirname, "settings.json"),
    "utf8"
  )
);

// We check that the user has filled in the license key.
if (SETTINGS.licenseKey !== "non-commercial-and-evaluation") {
  console.log("Your license key is invalid.");
  process.exit();
}

// If the application does not have an API key, we generate it.
if (SETTINGS.APIKey == null) {
  SETTINGS.APIKey = random(40);
  LIBRARIES.FS.writeFileSync(
    LIBRARIES.Path.join(__dirname, "settings.json"),
    JSON.stringify(SETTINGS, null, 4),
    "utf8"
  );
}

const EXPRESS = LIBRARIES.Express();
EXPRESS.use(LIBRARIES.BodyParser.urlencoded({ extended: true }));
EXPRESS.use(LIBRARIES.BodyParser.json());
EXPRESS.post("/notification", function requestHandler(req, res) {
  const API_KEY = req.headers["api-key"];
  if (API_KEY != undefined) {
    if (API_KEY == SETTINGS.APIKey) {
      const NOTIFICATION = {
        icon: {
          x: 0,
          y: 0,
          value: null,
        },
        message: {
          x: 0,
          y: 0,
          value: null,
        },
        remaining_time: 5,
        sound: null,
      };
      IO_SERVER.emit("notification", {
        ...NOTIFICATION,
        ...req.body,
      });
      res.end("Notification sended !");
    } else {
      res.end("Wrong API key.");
    }
  } else {
    res.end(
      'An API key is required. You will find it in the "settings.json" file.'
    );
  }
});
EXPRESS.use(LIBRARIES.Express.static(LIBRARIES.Path.join(__dirname, "public")));
const HTTP = LIBRARIES.HTTP.createServer(EXPRESS);

const IO_SERVER = LIBRARIES.SocketIO(HTTP);
IO_SERVER.on("connection", function (socket) {
  IO_SERVER.emit("settings", SETTINGS.client);
  sendIconScripts();

  // The client wants us to download a missing icon.
  socket.on("download_icon", function (_iconName) {
    LIBRARIES.LM_TO_NC.download(_iconName, undefined, () => {
      sendIconScripts();
    });
  });

  // When the user makes a direct request to the server, it is redirected to it.
  socket.on("server", function (_message) {
    //IO_SERVER.emit("server", _message);
  });
});

HTTP.listen(SETTINGS.serverPort, function () {
  console.log(
    "You can access the GUI on http://localhost:" + SETTINGS.serverPort + "."
  );
});

/**
 * This function sends the client the list of available icons.
 */
function sendIconScripts() {
  IO_SERVER.emit(
    "icons",
    LIBRARIES.FS.readdirSync(
      LIBRARIES.Path.join(__dirname, "public", "js", "icons")
    ).filter((file) => file.endsWith(".js"))
  );
}

/**
 * This function returns a random string of characters.
 * @param {*} _length Chain length.
 * @returns Random chain created.
 */
function random(_length) {
  const CHARS =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  let back = "";
  for (let i = 0; i < _length; i++) {
    back += CHARS.charAt(Math.floor(Math.random() * CHARS.length));
  }

  return back;
}