server.js

const http = require('http');
const express = require('express');
const MessagingResponse = require('twilio').twiml.MessagingResponse;

const app = express();
var bodyParser = require('body-parser');
const twilio = require('twilio');
app.use(bodyParser.urlencoded({ extended: false }));
//async
app.post('/whatsapp',  async (req, res) => {
  const twiml = new MessagingResponse();//bodyparser
  const GOOGLE_APPLICATION_CREDENTIALS="/Users/longhchung/Desktop/jsexercisedemo/durhack/keys.json"
  async function quickstart(GOOGLE_APPLICATION_CREDENTIALS, req){
    // Imports the Google Cloud client library
    const language = require('@google-cloud/language');

    // Instantiates a client
    const client = new language.LanguageServiceClient();

    // The text to analyze
    const text = req.body.Body;

    const document = {
      content: text,
      type: 'PLAIN_TEXT',
    };

    // Detects the sentiment of the text
    const [result] = await client.analyzeSentiment({document: document});
    const sentiment = result.documentSentiment;
    console.log(sentiment.score)
    




    twiml.message('Text: '+text);
    twiml.message('Sentiment score:'+sentiment.score.toFixed(2));
    if (sentiment.score<-0.5) {
      twiml.message('Probably True') ;
    } else if (sentiment.score < 0.0) {
      twiml.message('Maybe True');
    } else if (sentiment.score < 0.5) {
      twiml.message( 'Maybe False');
    } else {
      twiml.message('Probably False');
    }
    //twiml.message('Sentiment magnitude: '+sentiment.magnitude);

   


    return sentiment
  }

  if (req.body.Body == 'BBC') {
    twiml.message('Hi!');
  } else {
    //twiml.message(sentiment.score.toString());
    let sentiment = await quickstart(GOOGLE_APPLICATION_CREDENTIALS, req)

    console.log(`Sentiment score: ${sentiment.score}`);

        // console.log(`Text: ${text}`);
        // console.log(`Sentiment score: ${sentiment.score}`);
        // console.log(`Sentiment magnitude: ${sentiment.magnitude}`);
  }


  res.writeHead(200, {'Content-Type': 'text/xml'});

  //response.redirect('https://demo.twilio.com/welcome/sms/');
  //https://timberwolf-mastiff-9776.twil.io/demo-reply
  res.end(twiml.toString());
});





http.createServer(app).listen(1337, () => {
  console.log('Express server listening on port 1337');
});
//twilio phone-numbers:update "+447360545958" --sms-url="http://localhost:1337/whatsapp"