FedoraDiscourseGMailLabeler.gs

//
// HOWTO:
// 1.  Go to script.google.com for the Google account that is receiving the
//     email notifications from Fedora Discourse
// 2.  Create a new project and rename it to "Fedora Discourse GMail Labeler"
// 3.  Copy and paste this whole script in the editor and replace whatever
//     content is there
// 4.  Save the file
// 5.  On the left side next to the editor click on the plus button next to
//     Services and add a "Gmail API" service
// 6.  Now run the script by clicking on the "Run" button
// 7.  You will have to grant the permissions to the project so it can access
//     your inbox
// 8.  Wait until the run completes
// 9.  Change the value of the firstRun variable in this script to false
// 10. Switch to Triggers section on the left side and add a new trigger
//     and make sure that the processFedoraDiscourse function is set in the
//     "Choose which function to run" field. By default the script runs once
//     per hour, but I suggest to run it more often - i.e. once per 15 minutes.
//     To do that set the following parameters:
//       - event source is set to "Time driven"
//       - type of time based trigger is set to "Minutes timer"
//       - minute interval is set to "15 minutes"
// 11. Save the trigger
// 12. One thing that you should keep in mind is that the script doesn't run
//     when new message is delivered, so the messages will stay in your inbox
//     until the trigger triggers. What I would suggest is to create a new GMail
//     filter with the following parameters:
//       - from field set to "from:notifications@fedoraproject.discoursemail.com"
//       - choose "Skip the Inbox (Archive it)"
//       - choose "Fedora Discourse" label in "Apply the label:" field
// 13. Profit!
//

var labelPrefix = "Fedora Discourse"
var categoriesLabelPrefix = labelPrefix + "/categories"
var tagsLabelPrefix = labelPrefix + "/tags"
var genericLabel = labelPrefix + "/generic"

// Change this to false after the first run so the script is not processing
// all the messsages when it's being executed.
var firstRun = true;

function getLabel_(labelName) {
  var label = GmailApp.getUserLabelByName(labelName);
  if (!label) {
    Logger.log("Creating label: " + labelName);
    label = GmailApp.createLabel(labelName);
  }
  return label;
}

function extractHeaderValue_(messageBody, key) {
  var regex = new RegExp("X-Discourse-" + key + ": (.*)$", "m");
  var result = regex.exec(messageBody);
  if (!result)
    return null;

  return result[1];
}

function removeAllOurLabels_(thread) {
  var labels = thread.getLabels();
  labels.forEach(function (label) {
    var name = label.getName();
    if (name.indexOf("/tags/") || name.indexOf("/categories/"))
      thread.removeLabel(label);
  })
}

function processThread_(thread) {
  // Remove all labels that we've previously set to the thread, because tags might have
  // changed or the discussion was moved to a different category. This could definitely
  // be optimized so we can remove the label only when needed.
  removeAllOurLabels_(thread);

  // Get the last message in a given thread as that one should contain the latest
  // and most relevant tags and the actual category.
  var messages = thread.getMessages();
  var index = 0;
  if (messages.length > 1)
      index = messages.length - 1;
  var message = messages[index];

  var body = message.getRawContent();
  var tags = extractHeaderValue_(body, "Tags");
  if (tags) {
    tags.split(" ").forEach(function(tag) {
      var label = getLabel_(tagsLabelPrefix + "/" + tag);
      thread.addLabel(label);
    });
  }
  var category = extractHeaderValue_(body, "Category");
  if (category) {
    var label = getLabel_(categoriesLabelPrefix + "/" + category);
    thread.addLabel(label);
  }

  if (!category && !tags) {
    var label = getLabel_(genericLabel);
    thread.addLabel(label);
  }

  Logger.log("  message with tags: \"" + tags + "\" and category \"" + category + "\"");
}

function processNewThreads_() {
  if (firstRun)
    var threads = GmailApp.search("from:notifications@fedoraproject.discoursemail.com");
  else {
    // GMail can't query anything newer than 1 hour.
    var threads = GmailApp.search("from:notifications@fedoraproject.discoursemail.com newer_than:1h");
  }

  Logger.log("Got threads: " + threads.length);
  threads.forEach(function(thread) {
    Logger.log("Processing thread: " + thread.getFirstMessageSubject());
    processThread_(thread);
  });
}

function setupLabels_() {
  GmailApp.createLabel(labelPrefix);
  GmailApp.createLabel(categoriesLabelPrefix);
  GmailApp.createLabel(tagsLabelPrefix);
  GmailApp.createLabel(genericLabel);
}

function processFedoraDiscourse() {
  setupLabels_();
  processNewThreads_();
}