nodejsでExpressをつかってLineボットを作成する

index.js

const express = require('express')
const request = require('request')
const bodyParser = require('body-parser');
const crypto = require("crypto");
const app = express()
const port = process.env.PORT || 3000;

app.use(bodyParser.urlencoded({
  extended: true
}));
app.use(bodyParser.json());
app.get('/', (req, res) => {
  res.send('Hello world')
})
app.post('/hook', function (req, res) {

  if (!validateSignature(req.headers['x-line-signature'], req.body)) {
    return;
  }

  const events = req.body.events;
  const userId = events[0].source.userId;
  const type = events[0].source.type;
  const message = events[0].message;

  if(type == 'user'){
    request.get( getProfileOption(userId), function (error, response, body) {
      if (!error && response.statusCode == 200) {
        const options = {
          url: 'https://api.line.me/v2/bot/message/reply',
          headers: {
            'Content-Type': 'application/json',
            'Authorization': 'Bearer {' + process.env.LINE_CHANNEL_ACCESS_TOKEN + '}',
          },
          json: true,
          body: {
            'replyToken': req.body['events'][0]['replyToken'],
            'messages': [{
              "type": "text",
              "text": message.text + ' って言ったの？\n' + body['displayName'] + 'さん'
            }]
          }
        };
        request.post(options, function (error, response, body) {
          if (!error && response.statusCode == 200) {
            console.log('success');
          }
        });
      }
    })
  }
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

function getProfileOption(userId) {
  return {
    url: 'https://api.line.me/v2/bot/profile/' + userId,
    json: true,
    headers: {
      'Authorization': 'Bearer {' + process.env.LINE_CHANNEL_ACCESS_TOKEN + '}'
    }
  };
}
function validateSignature(signature, body) {
  const hmac = crypto.createHmac('sha256', process.env.LINE_CHANNEL_SECRET);
  const data = new Buffer(JSON.stringify(body), 'utf8');
  const result = hmac.update(data).digest('base64');
  return signature == result;
}