node-telegram-bot-api/src/telegramWebHook.js

const debug = require('debug')('node-telegram-bot-api');
const https = require('https');
const http = require('http');
const fs = require('fs');
const bl = require('bl');
const Promise = require('bluebird');


class TelegramBotWebHook {
  /**
   * Sets up a webhook to receive updates
   *
   * @param  {String} token Telegram API token
   * @param  {Boolean|Object} options WebHook options
   * @param  {String} [options.host=0.0.0.0] Host to bind to
   * @param  {Number} [options.port=8443] Port to bind to
   * @param  {String} [options.healthEndpoint=/healthz] An endpoint for health checks that always responds with 200 OK
   * @param  {Function} callback Function for process a new update
   */
  constructor(token, options, callback) {
    // define opts
    if (typeof options === 'boolean') {
      options = {}; // eslint-disable-line no-param-reassign
    }

    this.token = token;
    this.options = options;
    this.options.host = options.host || '0.0.0.0';
    this.options.port = options.port || 8443;
    this.options.https = options.https || {};
    this.options.healthEndpoint = options.healthEndpoint || '/healthz';
    this.callback = callback;
    this._regex = new RegExp(this.token);
    this._healthRegex = new RegExp(this.options.healthEndpoint);
    this._webServer = null;
    this._open = false;
    this._requestListener = this._requestListener.bind(this);
    this._parseBody = this._parseBody.bind(this);

    if (this.options.key && this.options.cert) {
      debug('HTTPS WebHook enabled (by key/cert)');
      this.options.https.key = fs.readFileSync(this.options.key);
      this.options.https.cert = fs.readFileSync(this.options.cert);
      this._webServer = https.createServer(this.options.https, this._requestListener);
    } else if (this.options.pfx) {
      debug('HTTPS WebHook enabled (by pfx)');
      this.options.https.pfx = fs.readFileSync(this.options.pfx);
      this._webServer = https.createServer(this.options.https, this._requestListener);
    } else if (Object.keys(this.options.https).length) {
      debug('HTTPS WebHook enabled by (https)');
      this._webServer = https.createServer(this.options.https, this._requestListener);
    } else {
      debug('HTTP WebHook enabled');
      this._webServer = http.createServer(this._requestListener);
    }
  }

  /**
   * Open WebHook by listening on the port
   * @return {Promise}
   */
  open() {
    if (this.isOpen()) {
      return Promise.resolve();
    }
    return new Promise(resolve => {
      this._webServer.listen(this.options.port, this.options.host, () => {
        debug('WebHook listening on port %s', this.options.port);
        this._open = true;
        return resolve();
      });
    });
  }

  /**
   * Close the webHook
   * @return {Promise}
   */
  close() {
    if (!this.isOpen()) {
      return Promise.resolve();
    }
    return new Promise((resolve, reject) => {
      this._webServer.close(error => {
        if (error) return reject(error);
        this._open = false;
        return resolve();
      });
    });
  }

  /**
   * Return `true` if server is listening. Otherwise, `false`.
   */
  isOpen() {
    // NOTE: Since `http.Server.listening` was added in v5.7.0
    // and we still need to support Node v4,
    // we are going to fallback to 'this._open'.
    // The following LOC would suffice for newer versions of Node.js
    // return this._webServer.listening;
    return this._open;
  }

  // used so that other funcs are not non-optimizable
  _safeParse(json) {
    try {
      return JSON.parse(json);
    } catch (err) {
      debug(err);
      return null;
    }
  }

  /**
   * Handle request body by passing it to 'callback'
   * @private
   */
  _parseBody(err, body) {
    if (err) {
      return debug(err);
    }

    const data = this._safeParse(body);
    if (data) {
      return this.callback(data);
    }

    return null;
  }

  /**
   * Listener for 'request' event on server
   * @private
   * @see https://nodejs.org/docs/latest/api/http.html#http_http_createserver_requestlistener
   * @see https://nodejs.org/docs/latest/api/https.html#https_https_createserver_options_requestlistener
   */
  _requestListener(req, res) {
    debug('WebHook request URL: %s', req.url);
    debug('WebHook request headers: %j', req.headers);

    if (this._regex.test(req.url)) {
      if (req.method !== 'POST') {
        debug('WebHook request isn\'t a POST');
        res.statusCode = 418; // I'm a teabot!
        res.end();
      } else {
        req
          .pipe(bl(this._parseBody))
          .on('finish', () => res.end('OK'));
      }
    } else if (this._healthRegex.test(req.url)) {
      debug('WebHook health check passed');
      res.statusCode = 200;
      res.end('OK');
    } else {
      debug('WebHook request unauthorized');
      res.statusCode = 401;
      res.end();
    }
  }
}

module.exports = TelegramBotWebHook;