text: const router = require('express').Router()
  module.exports = router
  const fs = require('fs')
  const readline = require('readline')
  const {google} = require('googleapis')
  
  // If modifying these scopes, delete token.json.
  const SCOPES = ['https://www.googleapis.com/auth/calendar.readonly']
  // The file token.json stores the user's access and refresh tokens, and is
  // created automatically when the authorization flow completes for the first
  // time.
  const TOKEN_PATH = 'token.json'
  
  // Load client secrets from a local file.
  
  router.use('/', (req, res, next) => {
    fs.readFile('credentials.json', (err, content) => {
      if (err) return console.log('Error loading client secret file:', err)
      // Authorize a client with credentials, then call the Google Calendar API.
      authorize(JSON.parse(content), listEvents)
    })
  
    /**
     * Create an OAuth2 client with the given credentials, and then execute the
     * given callback function.
     * @param {Object} credentials The authorization client credentials.
     * @param {function} callback The callback to call with the authorized client.
     */
    function authorize(credentials, callback) {
      const {client_secret, client_id, redirect_uris} = credentials.installed
      const oAuth2Client = new google.auth.OAuth2(
        client_id,
        client_secret,
        redirect_uris[0]
      )
  
      // Check if we have previously stored a token.
      fs.readFile(TOKEN_PATH, (err, token) => {
        if (err) return getAccessToken(oAuth2Client, callback)
        oAuth2Client.setCredentials(JSON.parse(token))
        callback(oAuth2Client)
      })
    }
  
    /**
     * Get and store new token after prompting for user authorization, and then
     * execute the given callback with the authorized OAuth2 client.
     * @param {google.auth.OAuth2} oAuth2Client The OAuth2 client to get token for.
     * @param {getEventsCallback} callback The callback for the authorized client.
     */
    function getAccessToken(oAuth2Client, callback) {
      const authUrl = oAuth2Client.generateAuthUrl({
        access_type: 'offline',
        scope: SCOPES
      })
      console.log('Authorize this app by visiting this url:', authUrl)
      const rl = readline.createInterface({
        input: process.stdin,
        output: process.stdout
      })
      rl.question('Enter the code from that page here: ', code => {
        rl.close()
        oAuth2Client.getToken(code, (err, token) => {
          if (err) return console.error('Error retrieving access token', err)
          oAuth2Client.setCredentials(token)
          // Store the token to disk for later program executions
          fs.writeFile(TOKEN_PATH, JSON.stringify(token), err => {
            if (err) return console.error(err)
            console.log('Token stored to', TOKEN_PATH)
          })
          callback(oAuth2Client)
        })
      })
    }
    let events = []
  
    /**
     * Lists the next 10 events on the user's primary calendar.
     * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
     */
    function listEvents(auth) {
      const calendar = google.calendar({version: 'v3', auth})
      calendar.events.list(
        {
          calendarId: 'primary',
          timeMin: new Date().toISOString(),
          maxResults: 30,
          singleEvents: true,
          orderBy: 'startTime'
        },
        (err, res) => {
          if (err) return console.log('The API returned an error: ' + err)
          events = res.data.items
          //   res.json(events)
  
          if (events.length) {
            console.log('Upcoming 10 events:')
            events.map((event, i) => {
              const start = event.start.dateTime || event.start.date
              console.log(`${start} - ${event.summary}`)
            })
          } else {
            console.log('No upcoming events found.')
          }
        }
      )
    }
  })
  