googleapi.js

'use strict'

const fs = require('fs')
const readline = require('readline')
const { google } = require('googleapis')
const { promisify } = require('es6-promisify');
const config = require('./config.json')

// If modifying these scopes, delete token.json.
const SCOPES = ['https://www.googleapis.com/auth/spreadsheets.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'

/**
 * 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 getNewToken(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 getNewToken(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 while trying to retrieve 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) console.error(err)
        console.log('Token stored to', TOKEN_PATH)
      })
      callback(oAuth2Client)
    })
  })
}

async function pingSheet(auth) {
  const sheets = google.sheets({ version: 'v4', auth })
  const updateSheet = promisify(sheets.spreadsheets.values.update)

  const resource = {
    values: [['Greeting', 'Subject'],['Hello', 'World']]
  }

  const res = await updateSheet({
    spreadsheetId: config.spreadsheetId,        
    resource,
    range: 'Sheet1',
    valueInputOption: 'RAW',
  })
}

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 Sheets API.
  authorize(JSON.parse(content), pingSheet)
})