GCP Cloud Functions example - Telegram Chatbot echo

echo.js

const botTgApiHost = 'api.telegram.org';
const botTgApiSendMessagePath = '/bot' + process.env.BOT_TOKEN + '/sendMessage'; 

const https = require('https');
const querystring = require('querystring');

// 
// Push message
// 
function pushMessage(chatId, message) {
    // Build the post string from an object
    var post_data = querystring.stringify({
        'chat_id' : chatId,
        'disable_web_page_preview': 1,
        'text': message
    });

    // An object of options to indicate where to post to
    var post_options = {
        host: botTgApiHost,
        port: 443,
        path: botTgApiSendMessagePath,
        method: 'POST',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
            'Content-Length': Buffer.byteLength(post_data)
        }
    };

    // Set up the request
    var post_req = https.request(post_options, function(res) {
        res.setEncoding('utf8');
        res.on('data', function (chunk) {
            console.log('Response: ' + chunk);
        });
    });

    // post the data
    post_req.write(post_data);
    post_req.end();
}

// 
// Endpoint
// 
exports.echo = function echo (req, res) {
    console.log(JSON.stringify(req.body));
    console.log(JSON.stringify(req.headers));

    const message = req.body.message;
    pushMessage(message.chat.id, message.text);
  
    res.status(200).end();
};