gmail-to-discord.js

// useful at script.google.com

// set these to discord webhooks.
const WEBHOOKS = {
  SLAB: '',
  ASANA: '',
  FIGMA: '',
  GREENHOUSE: ''
}
// these searches work great for me. The first does the search logic in
// this script the other three rely on doing the search logic in gmail.
// I've found doing th search logic in gmail is better. It's faster, and
// helps with debugging/gives a better log of what's happening.
const EMAIL_SEARCHES = {
  SLAB: 'from:notifications@slab.com is:unread',
  ASANA: 'label:notifications-asana is:unread',
  FIGMA: 'label:notifications-figma is:unread',
  GREENHOUSE: 'label:notifications-greenhouse is:unread',
}

// it's okay to leave keys out here, we'll fall back to simplistic parsing
const PARSERS = {
  SLAB: slabParse,
  FIGMA: figmaParse,
  GREENHOUSE: greenhouseParse
}

// discord limits us to 2000 char
const MAX_BODY_LENGTH = 2000

// use tinyurl.com to compress urls which can often be quite long with email
// tracking redirect shinangiens.
const URL_REGEXP = /((([A-Za-z]{3,9}:(?:\/\/)?)(?:[\-;:&=\+\$,\w]+@)?[A-Za-z0-9\.\-]+|(?:www\.|[\-;:&=\+\$,\w]+@)[A-Za-z0-9\.\-]+)((?:\/[\+~%\/\.\w\-_]*)?\??(?:[\-\+=&;%@\.\w_]*)#?(?:[\.\!\/\\\w]*))?)/g
const TINYURL_SUCESS_REGEXP = /<b>(.*)<\/b><div id="success">/
function shortenUrls(body) {
  const rawUrls = body.match(URL_REGEXP)
  if (rawUrls == null) return body
  return rawUrls.reduce(function (out, url) {
    try {
      const resp = UrlFetchApp.fetch('https://tinyurl.com/create.php?url=' + encodeURIComponent(url))
      // we get back a full webpage, look through from the "success" marker and grab the tinyurl
      const urlResults = resp.getContentText().match(TINYURL_SUCESS_REGEXP)
      // ensure we actually found a match in the HTML
      if (urlResults.length > 1) {
        return out.replace(url, urlResults[1])
      }
    }
    catch (e) {
      return out
    }
    return out
  }, body)
}

// 
// parsers
// 
// These functions take in an email subject and body and remove
// extra cruft like headers and footers. Don't worry about shortening
// urls, we'll do that automatically.
function basicParse({subject, body}) {
  return '**' + subject + '**\n' + body.trim()
}

function slabParse({subject, body}) {
  return body
      .replace('[image: Slab Logo]', '')
      .replace(subject, '**' + subject + '**')
}

function figmaParse({subject, body}) {
  const removeRegExp = new RegExp('Figma.*\n(.*)\n------------------------------\n', 'm')
  const removeFooterRegExp = new RegExp('Turn off comment notifications for this file.*\n(.*\n){1,10}', 'm')
  return '**' + subject + '**\n' + body
      .replace(removeRegExp, '')
      .replace(removeFooterRegExp, '')
}

function greenhouseParse({subject, body}) {
  const removeFooterRegExp = new RegExp('Thanks,\n(.*\n){1,10}', 'm')
  const noFooter = body
    .replace('© 2020 Greenhouse / 18 West 18th Street, 9th Floor, New York, NY 10011, USA', '')
    .replace(removeFooterRegExp, '')
  return basicParse({subject, body: noFooter})
}


// Search gmail for the `serach` string, parse the results with a function and
// send them to a webhook. 
function findAndPing({search, parse = basicParse, webhook}) {
  // Search for any notification emails from slab in your inbox
  let emails
  try {
    emails = GmailApp.search(search);
  } catch (e) {
    // if we can't contact gmail, there's nothing to do, just die
    return
  }
  
  // For each email we find
  emails.forEach(thread => {  
    // Get the subject of the email, and create form data for our webhook
    const messages = thread.getMessages();
    const subject = thread.getFirstMessageSubject();
    const lastMessage = messages[messages.length - 1];
    let body = shortenUrls(
      parse({body: lastMessage.getPlainBody(), subject})
      .trim()
    )
    
    if (body.length >= MAX_BODY_LENGTH) {
      body = body.substring(0, MAX_BODY_LENGTH - 1) + '…'
    }
    
    // Send a POST request with the data to our Webhook URL
    const options = {
      method : 'post',
      payload : {content: body}
    }
    try {
      const res = UrlFetchApp.fetch(webhook, options);
      const resCode = res.getResponseCode();
      if (resCode >= 200 && resCode < 400) {
        // Mark as read so this doesn't come up again
        thread.markRead();    
      }
    }
    catch (e) {
      // if we fail to send to the webhook, do nothing. The thread will
      // remain unread, and will re-try next time around
    }
  })
}

// This is the main function! Tell google scripts to run this.
function run() {
  Object.keys(WEBHOOKS).forEach(key => {
    findAndPing({search: EMAIL_SEARCHES[key], parse: PARSERS[key], webhook: WEBHOOKS[key]})
  })
}