Forward email marked with custom label to Telegram #google-script #gas

gmail_label_to_telegram.gs

/**
Forward email marked with custom label to Telegram.

Sergei Eremenko (https://github.com/SmartFinn) © 2020
**/

// Custom trigger to run script every 1 min
function startCustomTrigger() {
  ScriptApp.newTrigger('checkInbox').timeBased().everyMinutes(1).create()
}

// Global Variables
const userProperties = PropertiesService.getUserProperties();
const scriptProperties = PropertiesService.getScriptProperties();
const telegramToken = scriptProperties.getProperty('telegramToken')
const telegramChatId = scriptProperties.getProperty('telegramChatId')


String.prototype.escapeSpecialChars = function() {
  return this.replace(/&/g, '\&')
             .replace(/</g, '\&lt;')
             .replace(/>/g, '\&gt;');
};


Number.prototype.humanReadableFileSize = function() {
  let size = this;
  const units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB'];

  for (let i = 0; i < units.length; i++) {
    if (size >= 1024) { size /= 1024; } else {
      return `${size.toFixed(i > 2 ? 2 : i)} ${units[i]}`;
    }
  }

  return this + ' B'; // in case the size is too big
};


String.prototype.truncateText = function(max = 2000, ending = ' …\n') {
  return this.length > max ? this.substr(0, max - ending.length) + ending : this
}

// const escapeSpecialChars = text => text.replace(/&/g, '\&amp;')
//                                        .replace(/</g, '\&lt;')
//                                        .replace(/>/g, '\&gt;')

// const humanReadableFileSize = (size, divider = 1024, units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB']) => {
//   for (let i = 0; i < units.length; i++) {
//     if (size >= divider) { size /= divider; } else {
//       return `${size.toFixed(i > 2 ? 2 : i)} ${units[i]}`;
//     }
//   }
//
//   return `${size} ${units[0]}`; // in case the size is too big
// };

// const truncateText = (text, max = 2000, ending = ' …\n') => text.length > max ? text.substr(0, max - ending.length) + ending : text;


function telegramApiRequest(method, data) {
  const options = {
    'method' : 'post',
    'contentType': 'application/json',
    'payload' : JSON.stringify(data)
  };

  const response = UrlFetchApp.fetch(`https://api.telegram.org/bot${telegramToken}/${method}`, options);

  if (response.getResponseCode() == 200) {
    return JSON.parse(response.getContentText());
  }

  return false;
}


function telegramSendMessage(chat_id, text, opts = {}) {
  return telegramApiRequest('sendMessage', {chat_id, text, ...opts});
}


function checkInbox() {
  Logger.log("Script running ...");

  // Grab gmail inbox
  const labelNew = GmailApp.getUserLabelByName('Telegram/New');
  const labelDone = GmailApp.getUserLabelByName('Telegram');
  const seenMessages = userProperties.getProperty('SEEN_MESSAGES') != null
                       ? userProperties.getProperty('SEEN_MESSAGES').split(',')
                       : [];  // get ids of messages that already sent

  for (let thread of labelNew.getThreads()) {
    const threadLink = thread.getPermalink();

    for (let msg of thread.getMessages()) {
      const msgId = msg.getId();

      if (seenMessages.includes(msgId)) {
        Logger.log(`Skip message with ${msgId} id.`);
        continue;
      } else {
        seenMessages.push(msgId);
      }

      const formattedDate = Utilities.formatDate(msg.getDate(), Session.getScriptTimeZone(), "dd MMM yyyy' at 'HH:mm:ss");
      const msgAttachments = msg.getAttachments().map(att => `📎 ${att.getName()} (${att.getSize().humanReadableFileSize()})`)

      // Message template
      const msgHtml =
`📧 <b>${msg.getSubject().escapeSpecialChars()}</b>

<i>From: ${msg.getFrom().escapeSpecialChars()}</i>
<i>Date: ${formattedDate}</i>

${msg.getPlainBody().escapeSpecialChars().truncateText()}
${msgAttachments.join('\n')}

<a href="${threadLink}">Show original</a>`
      // End of the message template

      Logger.log(msgHtml);
      telegramSendMessage(telegramChatId, msgHtml, {'parse_mode': 'HTML', 'disable_web_page_preview': true});
    }

    userProperties.setProperty('SEEN_MESSAGES', seenMessages.join(',')); // save ids of sent messages
    labelNew.removeFromThread(thread);  // Remove the label from the thread
    labelDone.addToThread(thread);  // Set label to thread
    GmailApp.markThreadRead(thread);
  }

  Logger.log("Script finished.");
}