server.js

'use strict';

const http = require('node:http');

const Client = require('./client.js');
const Session = require('./session.js');

const INVALID_TOKEN_CODE = 498;

const routing = {
  '/': async () => '<h1>welcome to homepage</h1><hr>',
  '/start': async (client) => {
    Session.start(client);
    return `Session token is: ${client.token}`;
  },
  '/destroy': async (client) => {
    const result = `Session destroyed: ${client.token}`;
    Session.delete(client);
    return result;
  },
  '/api/method1': async (client) => {
    if (client.session) {
      client.session.set('method1', 'called');
      return { data: 'example result' };
    } else {
      return { data: 'access is denied' };
    }
  },
  '/api/method2': async (client) => ({
    url: client.req.url,
    headers: client.req.headers,
  }),
  '/api/method3': async (client) => {
    if (client.session) {
      return [...client.session.entries()]
        .map(([key, value]) => `<b>${key}</b>: ${value}<br>`)
        .join();
    }
    return 'No session found';
  },
};

const types = {
  object: JSON.stringify,
  string: (s) => s,
  number: (n) => n.toString(),
  undefined: () => 'not found',
};

http.createServer(async (req, res) => {
  try {
    const client = await Client.getInstance(req, res);
  } catch {
    res.statusCode = INVALID_TOKEN_CODE;
    res.end();
    return;
  }
  const { method, url, headers } = req;
  console.log(`${method} ${url} ${headers.cookie}`);
  const handler = routing[url];
  res.on('finish', () => {
    if (client.session) client.session.save();
  });
  if (!handler) {
    res.statusCode = 404;
    res.end('Not found 404');
    return;
  }
  handler(client).then((data) => {
    const type = typeof data;
    const serializer = types[type];
    const result = serializer(data);
    client.sendCookie();
    res.end(result);
  }, (err) => {
    res.statusCode = 500;
    res.end('Internal Server Error 500');
    console.log(err);
  });
}).listen(8000);