Google App script for Gmail to add tags for GitHub notifications

code.gs

function tagInbox() {
  var now = new Date();
  var threads = GmailApp.getInboxThreads();
  for (var i = 0; i < threads.length; i++) {
    var thread = threads[i];
    var messages = thread.getMessages();
    for (var j = messages.length-1; j >= 0; j--) {
      var message = messages[j];
      if (now - message.getDate() > 30*60*1000) { // ignore mails from more than 0.5h ago.
        break;
      }
      if (message.getFrom().indexOf("notifications@github.com") == -1) { // only care about github mails.
        break;
      }
      GmailApp.getUserLabelByName("GitHub").addToThread(thread);
      var body = message.getPlainBody();
      if (body.match(/^Merged #\d+ into [0-9a-zA-Z\.\-_]+\./) != null) {
        GmailApp.getUserLabelByName("GitHub/Merged").addToThread(thread);
      }
      if (body.match(/^Closed #\d+\./) != null) {
        GmailApp.getUserLabelByName("GitHub/Closed").addToThread(thread);
      }
      if (body.match(/ approved this pull request\./) != null) {
        GmailApp.getUserLabelByName("GitHub/Approved").addToThread(thread);
      }
      thread.refresh();
    }
  }
}