server.js

const express = require('express');
const bodyParser = require('body-parser');
const cors = require('cors');

const Twitter = require('twitter');

process.on('uncaughtException', (error) => {
    console.log('[❗⚠️🛑💢 Something happened with the bot!] ' + error);
    process.exit(1);
});

if (!process.env.NODE_ENV) {
    require('./config');
} else {
    CONSUMER_KEY = process.env.CONSUMER_KEY;
    CONSUMER_SECRET = process.env.CONSUMER_SECRET;
    ACCESS_TOKEN_KEY = process.env.ACCESS_TOKEN_KEY;
    ACCESS_TOKEN_SECRET = process.env.ACCESS_TOKEN_SECRET;
}

const app = express();

app.use(cors()); // for setting Access-Control-Allow-Origin to the * any origin wildcard
app.use(bodyParser.json()); // for using req.body

const twitterClient = new Twitter({
    consumer_key: CONSUMER_KEY,
    consumer_secret: CONSUMER_SECRET,
    access_token_key: ACCESS_TOKEN_KEY,
    access_token_secret: ACCESS_TOKEN_SECRET
});

// For sending server or feedback notifications
app.post('/notification', (req, res) => {
    const originalJSONString = JSON.stringify(req.body, null, ' ');
    const URIEncodedString = encodeURIComponent(originalJSONString);
    const shortenedURIEncodedString = URIEncodedString.substr(0, 280);
    const decodedShortenedURIEncodedString = decodeURIComponent(shortenedURIEncodedString);
    twitterClient.post('statuses/update', { status: decodedShortenedURIEncodedString }, (error, tweet, response) => {
        if (error) {
            // a free heroku account will put up to about 100 console messages into a logging mechanism that you can still access
            console.log('[❌ Failed to post tweet] ' + JSON.stringify({ 'Twitter error': error, notification: req.body }, null, ' '));
            return res.send({ success: false });
        } else {
            console.log('[✉️ Server notification sent] ' + JSON.stringify({ notification: req.body }, null, ' '));
            return res.send({ success: true });
        }
    });
});

// uncaught API error handling route
app.use(function (error, req, res, next) {
    // post the error to Twitter
    const adHocID = Math.random().toString(36).substr(2, 5); // to prevent duplicate tweet errors
    const twitterPost = '[❌ API error] ' + error + '\n\n' + adHocID + '\n\nSee logs for more.';
    const URIEncodedString = encodeURIComponent(twitterPost);
    const shortenedURIEncodedString = URIEncodedString.substr(0, 280);
    const decodedShortenedURIEncodedString = decodeURIComponent(shortenedURIEncodedString);
    twitterClient.post('statuses/update', { status: decodedShortenedURIEncodedString }, (twitterError, tweet, response) => {
        if (twitterError) {
            console.log('[❌❌ Failed to post API error tweet] ' + error + ' ' + JSON.stringify({ 'Twitter error': twitterError, 'API error details': error, 'req.body': req.body }, null, ' '));
        } else {
            console.log('[❌✉️ API error server notification sent] ' + error + ' ' + JSON.stringify({ 'API error details': error, 'req.body': req.body }, null, ' '));
        }
    });

    return res.send({ success: false });
});

const PORT = process.env.PORT || '3000';
app.set('port', PORT);

app.listen(PORT, (error) => {
    if (error) {
        return console.log('[❗ Something unexpected happened when starting up] ', error);
    }

    console.log('[🤖 Twitter Server and Feedback Notification Bot] has been started up 🆙');
});