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Ctrl C Signal Bot

Powered by Wechaty TypeScript

Wechaty Ctrl C Signal Bot helps in sending a message when the node process ends using the finis NPM package.

In this tutorial, you will get step-by-step instructions for building the Wechaty Ctrl C Signal Bot from scratch.

Try out the bot​

Edit wechaty-ctrl-c-bot

You can try out the Wechaty Ctrl C Signal Bot using this interactive CodeSandbox.

Just scan the generated QR code with WeChat app, and you are ready to play with the bot!

Requirements​

  1. Node.js v16+
  2. Wechaty v0.40+

Getting started​

You should have Node.js installed on your system. If you do not have Node.js installed (or have a version below 12), then you need to install the latest version of Node.js by following the links below:

Node.js installation docs

Installation guide for Node.js on other platforms can be found here.

You can head over to the Building the bot section to learn how to build the bot on your own.

Otherwise, if you just want to try out the bot on your local system, follow the steps below:

1. Clone the repository​

Use the following commands to clone the GitHub repository and navigate to the directory:

git clone https://github.com/wechaty/wechaty-getting-started.git
cd wechaty-getting-started

2. Install dependencies​

You can install the npm packages required for running the bot, using this command:

npm install

3. Run the bot​

You have to export/set the environment variables:

export WECHATY_LOG=verbose
export WECHATY_PUPPET=wechaty-puppet-wechat

There are various Wechaty puppets available, you can know more about them here.

Run the bot by using the following command:

ts-node examples/professional/ctrl-c-signal-bot.ts

It will generate a QR code, scan it using WeChat or WhatsApp (according to the puppet you have used), and you are ready to play with the bot.

Building the bot​

Let's get started with building the Wechaty Ctrl C Signal Bot using Wechaty.

1. Initialize project​

Create a new folder called ctrl-c-bot and move into that directory:

mkdir ctrl-c-bot
cd ctrl-c-bot

Use the following command to initialize an npm project:

npm init -y

This will generate the package.json file containing these:

{
  "name": "ctrl-c-bot",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
   "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

2. Install dependencies​

The dependencies that you will need for building this bot are:

Install them using the following commands:

npm install wechaty
npm install qrcode-terminal
npm install finis

You will also need to add dependencies for using any Wechaty Puppet which helps to integrate Wechaty with various instant messaging (IM) systems (such as WeChat, WhatsApp, and WeCom):

  1. If you want to use WhatsApp, install wechaty-puppet-whatsapp:

    npm install wechaty-puppet-whatsapp

  2. If you want to use WeChat, you can try the following puppets:

    • Web Protocol: Install wechaty-puppet-wechat:

      npm install wechaty-puppet-wechat

    • iPad Protocol:

    • padlocal: Install wechaty-puppet-padlocal:

      npm install wechaty-puppet-padlocal

      Then get a token like puppet_padlocal_XXX, know more about puppet service padlocal here.

    • paimon: Install wechaty-puppet-service:

      npm install wechaty-puppet-service

      Then get a token like puppet_paimon_XXX, know more about puppet service paimon here.

  3. If you want to use WeCom, install wechaty-puppet-service:

    npm install wechaty-puppet-service

    Then get a token like puppet_wxwork_XXXXX, more about puppet service wxwork here.

You can find more information about the puppets here.

3. Write code for bot​

Start by creating a new file ctrl-c-bot.ts. We will be writing the code here.

Let's import the required packages in the TypeScript file:

import { generate } from 'qrcode-terminal'
import { finis } from 'finis'
import { Wechaty, log, qrcodeValueToImageUrl } from 'wechaty'

Now we will write some functions which will be required for handling different events of the bot.

onLogin

This function will print message when a user logs into the bot and also send a message about it to the user.

function onLogin(user: Contact) {
  log.info('Bot', `${user.name()} login`)
  bot.say('Wechaty login').catch(console.error)
}

onScan

This function will be required for generating a QR code for the puppet specified and display it on console.

function onScan(qrcode: string, status: ScanStatus, data: Boolean) {
  generate(qrcode, { small: true })
  if (data) {
    console.log(data)
  }
  console.log(qrcodeValueToImageUrl(qrcode))
  console.log('^^^ Online QR Code Image URL ^^^ ')
  console.log(`[${status}] ${qrcode} Scan QR Code above url to log in: `)
}

onMessage

This will retrieve the message sent by someone to your account and print it on the console.

async function onMessage(msg: Message) {
  console.log(msg.toString())
  console.log('Please press Ctrl+C to kill me!')
  console.log(`Then I'll send my last word to myself, check it out on your Wechat!`)
}

onError

This will print the error message on console and if the bot is logged in then say it as a message to the user.

async function onError(e: Error) {
  log.error('Bot', 'error: %s', e)
  if (bot.logonoff()) {
    await bot.say('Wechaty error: ' + e.message).catch(console.error)
  }
}

Initialize the bot by providing a name.

const bot = new Wechaty({
  name: 'ctrl-c-bot',
})

Assigning proper functions to call when an event is triggered.

bot
  .on('login', onLogin)
  .on('scan', onScan)
  .on('message', onMessage)
  .on('error', onError)

Declare two variables, killChrome of type NodeJS.SignalsListener and quitting of type Boolean:

let killChrome: NodeJS.SignalsListener
let quitting = false

For starting the bot, you can use the following:

bot.start()
  .then(() => {
    const listenerList = process.listeners('SIGINT')
    for (const listener of listenerList) {
      if (listener.name === 'killChrome') {
        process.removeListener('SIGINT', listener)
        killChrome = listener
      }
    }
  })
  .catch(async e => {
    log.error('Bot', 'start() fail: %s', e)
    await bot.stop()
    process.exit(-1)
  })

Define the finis callback function to handle the SIGINT signals:

finis(async (code, signal) => {
  log.info('Bot', 'finis(%s, %s)', code, signal)

  if (!bot.logonoff()) {
    log.info('Bot', 'finis() bot had been already stopped')
    doExit(code)
  }

  if (quitting) {
    log.warn('Bot', 'finis() already quitting... return and wait...')
    return
  }

  quitting = true
  let done = false

  const exitMsg = `Wechaty will exit ${code} because of ${signal} `

  log.info('Bot', 'finis() broadcast quitting message for bot')
  await bot.say(exitMsg)
    .catch(e => log.error('Bot', 'finis() catch rejection: %s', e))
    .then(() => done = true)

  setImmediate(checkForExit)

  function checkForExit() {
    log.info('Bot', 'finis() checkForExit() checking done: %s', done)
    if (done) {
      log.info('Bot', 'finis() checkForExit() done!')
      setTimeout(() => doExit(code), 1000)  // delay 1 second
      return
    }
    setTimeout(checkForExit, 100)
  }
})

The doExit function is used to exit the Node.js process:

function doExit(code: number): void {
  log.info('Bot', 'doExit(%d)', code)
  if (killChrome) {
    killChrome('SIGINT')
  }
  process.exit(code)
}

Running the bot​

In order to run the bot, first you have to export/set an environment variable with the type of puppet to use:

export WECHATY_LOG=verbose
export WECHATY_PUPPET=wechaty-puppet-wechat

# For using WhatsApp:
# export WECHATY_PUPPET=wechaty-puppet-whatsapp

# For using WeCom:
# export WECHATY_PUPPET=wechaty-puppet-service
# export WECHATY_PUPPET_SERVICE_TOKEN="puppet_wxwork_XXXXX"

If you are using WeCom, you can get token from puppet service wxwork.

Run the bot using the following command:

ts-node ctrl-c-bot.ts

This will start the bot and generate a QR code.

Scan it using your WeChat/WhatsApp as per the puppet you have selected, and you are ready to play with the bot!

References​