bot.js

const { Telegraf } = require('telegraf')
const mongoose = require('mongoose')
const bcrypt = require('bcrypt')
const { Registration, UserChat } = require('./models')

const bot = new Telegraf(process.env.BOT_TOKEN)

bot.start(async (ctx) => {
  const userChat = await UserChat.findOne({ chat_id: ctx.chat.id })
  if (userChat) {
    ctx.reply('Welcome!')
  } else {
    ctx.reply('Welcome!\nPlease register using the command:\n/reg <user_id>#<reg_code>')
  }
})

bot.command('reg', async (ctx) => {
  const userChat = await UserChat.findOne({ chat_id: ctx.chat.id })
  if (userChat) {
    ctx.reply('You are already registered.')
    return
  }
  const splitted = ctx.message.text.split(/\s+/)
  if (splitted.length < 2) {
    ctx.reply('You must enter user id and registration code to register.\nUse commands:\n/reg <user_id>#<reg_code>')
  } else {
    const regInput = splitted[1].split('#')
    if (regInput.length < 2) {
      ctx.reply('You must enter user id and registration code to register.\nUse commands:\n/reg <user_id>#<reg_code>')
    } else {
      const reg = await Registration.findOne({ user_id: regInput[0] })
      if (reg) {
        if (bcrypt.compareSync(regInput[1], reg.reg_code)) {
          const result = await UserChat.findOne({ user_id: reg.user_id })
          if (result) {
            userChat.chat_id = ctx.chat.id
            await userChat.save()
          } else {
            const userChatNew = new UserChat({
              _id: new mongoose.Types.ObjectId(),
              user_id: reg.user_id,
              chat_id: ctx.chat.id
            })
            await userChatNew.save()
          }
          await reg.delete()
          ctx.reply('You have successfully registered.')
        } else {
          ctx.reply('Failed to register!\nWrong user id or registration code.')
        }
      } else {
        ctx.reply('Failed to register!\nWrong user id or registration code.')
      }
    }
  }
})

module.exports = bot