bot.js

const TelegramBot = require('node-telegram-bot-api');
const storage = require('./storage.js');
const _ = require('lodash');
const config = require('./config.js');
const logger = require('./logger.js');

let currentModes = {}; // userId -> mode

const defaultAnswer = 'Hi there, please use "/" to interact';

const modeAnswers = {
  add: 'We are going to add a car to your watch list! Please enter search string (one or more words)',
  cancel: 'Ok then! Anythyng else?',
  clear: 'Your watch list has been cleared.',
  emptyList: 'Sorry, you have no cars in your watch list.',
};

class Bot {
  constructor() {
    this.bot = new TelegramBot(config.token, { polling: true });
  }

  init() {
    this.bot.on('message', this.processMessage.bind(this));
    logger.info('Bot initialized');
  }

  processMessage(message) {
    const { from, text } = message;
    const command = text.match(/\/(.+)/);

    // command message
    if (command) {
      this.processCommand(from, command.pop());
    // after-command message
    } else if (currentModes[from.id]) {
      this.processAnswer(from, text);
    // new user
    } else {
      this.processNewUser(from);
    }
  }

  processNewUser(user) {
    this.createUser(user);
    this.sendMessage(user.id, defaultAnswer);
  }

  processCommand(user, command) {
    currentModes[user.id] = command;

    switch (command) {
      case 'start':
        this.clearCurrentMode(user);
        this.processNewUser(user);

        break;

      case 'add':
        this.sendMessage(user.id, modeAnswers[command]);

        break;

      case 'cancel':
        this.clearCurrentMode(user);
        this.sendMessage(user.id, modeAnswers[command], { reply_markup: { hide_keyboard: true } });

        break;

      case 'clear':
        this.clearCurrentMode(user);
        storage.removeAllSubscriptions(user.id);
        this.sendMessage(user.id, modeAnswers[command]);

        break;

      case 'list':
        this.clearCurrentMode(user);
        storage
          .getSubscriptions(user.id)
          .then(subscriptions => {
            if (_.isEmpty(subscriptions)) {
              this.sendMessage(user.id, modeAnswers['emptyList']);
            } else {
              let list = '';

              subscriptions.forEach(item => {
                list += item.searchString + '\n';
              });

              this.sendMessage(user.id, 'Here is your watch list:' + '\n\n' + list);
            }
          });

        break;

      case 'delete':
        storage
          .getSubscriptions(user.id)
          .then(subscriptions => {
            if (_.isEmpty(subscriptions)) {
              this.sendMessage(user.id, modeAnswers['emptyList']);
              currentModes[user.id] = '';
            } else {
              const list = [];

              subscriptions.forEach(item => {
                list.push({ text: item.searchString });
              });

              const markup = {
                keyboard: [list],
                resize_keyboard: true,
                one_time_keyboard: true,
              };

              this.sendMessage(user.id, 'Please select what should we delete:', { reply_markup: markup });
            }
          });

        break;

      default:
        break;
    }

    logger.info('CurrentMode of user', user.username, '[', user.id, '] was set to', currentModes[user.id]);
  }

  clearCurrentMode(user) {
    currentModes[user.id] = '';
  }

  processAnswer(user, text) {
    switch (currentModes[user.id]) {
      case 'add':
        storage.addSubscription(user.id, text);
        this.sendMessage(user.id, 'Ok, "' + text + '" was added to your watch list. We`ll keep you updated!');

        break;

      case 'delete':
        storage.removeSubscription(user.id, text);
        this.sendMessage(user.id, 'Ok, "' + text + '" was removed from your watch list.', { reply_markup: { hide_keyboard: true } });

        break;

      default:
        break;
    }
  }

  createUser(user) {
    storage.createUser({
      id: user.id,
      username: user.username,
      firstName: user.first_name,
      lastName: user.last_name,
    });
  }

  sendNotification(userId, car) {
    const price = car.price ? ' - €' + car.price : '';
    const text = 'We found something for you!\n\n' + car.title + price + '\n' + car.link;
    this.sendMessage(userId, text);
  }

  sendMessage(userId, text) {
    this.bot
      .sendMessage(userId, text)
      .catch((error) => {
        logger.error('Send message failed', { userId, text }, error.code, error.response.body);
      });
  }
}

module.exports = new Bot();