email eater - google apps script (with dynamic label support)

Code.gs

// script forked from https://gist.github.com/jamesramsay/9298cf3f4ac584a3dc05
// to start timed execution: select "Install" from the menu above and hit "run"
// to stop timed execution: select "Uninstall" from the menu above and hit "run"
// to initialize a batch run ad-hoc and immediately: select "_processNextBatch" from the menu above and hit "run"

// runbook:
// - namespace labels like ee-
// - name labels like ee-archive-after-8d, ee-delete-after-45d
// - you can give a message more than one label (e.g., ee-archive-after-1d, ee-delete-after-5d)

// Constants for trigger names
const DAILY_TRIGGER_NAME = "dailyProcessTrigger";
const DELAYED_BATCH_TRIGGER_NAME = "delayedBatchTrigger";

// timezone probably doesn't really matter if we're only working in days.
const TIMEZONE = "America/Los Angeles";

// Batch size and timing configuration
const MAX_THREADS_TO_PROCESS_PER_BATCH = 500; // max argument size is 500
const MINUTES_TO_WAIT_BETWEEN_BATCHES = 5; // TODO - why?

const AUTO_ARCHIVED_LABEL = GmailApp.createLabel("ee-auto-archived");

function _getProcessBeforeDate(daysAgo) {
  const today = new Date();
  const age = new Date(today.setDate(today.getDate() - daysAgo));
  return Utilities.formatDate(age, TIMEZONE, "yyyy-MM-dd");
}

function _processNextBatch() {
  console.log('START process next batch');

  // Clear all batch triggers
  _clearAllDelayedBatchTriggers();
  _processEmails();

  console.log('FINISH process batch');
}

function _getLabelsToProcess() {
  const allLabels = GmailApp.getUserLabels();
  return allLabels.filter(label => {
    const labelName = label.getName();
    return labelName.startsWith('ee-') && 
      labelName !== 'ee-auto-archived'; /** TODO - find a better name for this so i don't have to filter it out */;
  });
}

function _processEmails() {
  let threadsProcessedCount = 0;
  const threadsProcessedPerLabel = {};

  _getLabelsToProcess().forEach(function(label) {   
    const labelName = label.getName(); 
    const [_, action, __, threshold] = labelName.split('-');
    const daysAgo = Number(threshold.replace('d', ''));

    const processBeforeDate = _getProcessBeforeDate(daysAgo);

    const threadBudgetLeftForThisBatch = MAX_THREADS_TO_PROCESS_PER_BATCH - threadsProcessedCount;
    if (threadBudgetLeftForThisBatch <= 0) {
      return; // Skip this label if the maximum number of threads to process has been reached
    }

    let searchFilters = [
      'label:' + labelName,
      'before:' + processBeforeDate,
    ];

    console.log('Searching for threads with label: ' + labelName);
    const threads = GmailApp.search(searchFilters.join(' '), 0, threadBudgetLeftForThisBatch);
    const threadsToProcessCount = threads.length;

    console.log('Found ' + threadsToProcessCount + ' threads to process for label: ' + labelName);
    
    for (let i = 0; i < threadsToProcessCount; i++) {
      const thread = threads[i];
      if (action === 'delete') {
        // NB: this moves the thread to the trash. so thread will not get *permanently* deleted 
        //     until 30 days *after* it gets moved to the trash.
        console.log('deleting thread with subject: ' + threads[i].getFirstMessageSubject());
        thread.moveToTrash();
      } else if (action === 'archive') {
        console.log('archiving thread with subject: ' + threads[i].getFirstMessageSubject());
        thread.moveToArchive()
          .removeLabel(label) // remove current label to clean up the label query
          .addLabel(AUTO_ARCHIVED_LABEL); // add this so it's clear this was not a user action 
      }
    }

    threadsProcessedCount += threadsToProcessCount;
    threadsProcessedPerLabel[labelName] = (threadsProcessedPerLabel[labelName] || 0) + threadsToProcessCount;
  });

  // Log the deleted email count per label
  console.log('Processed emails from labels:');
  for (let labelName in threadsProcessedPerLabel) {
    console.log('  ' + labelName + ': ' + threadsProcessedPerLabel[labelName]);
  }

  // Schedule another run if we hit the processing limit.
  // NB: Since we're only loading up to MAX_THREADS_TO_PROCESS_PER_BATCH at a time, we don't 
  //     know if there are more threads to process in the next execution. So, if we reach the limit, 
  //     there are *probably* more threads to process. It's possible there's no more left but it's not 
  //     a big deal to just run it again.
  if (threadsProcessedCount >= MAX_THREADS_TO_PROCESS_PER_BATCH) {
    // TODO - when would threadsProcessedCount be above MAX_THREADS_TO_PROCESS?
    console.log("Reached processing limit, scheduling next batch...");
    ScriptApp.newTrigger(DELAYED_BATCH_TRIGGER_NAME)
             .timeBased()
             .after(MINUTES_TO_WAIT_BETWEEN_BATCHES * 60 * 1000)
             .create();
  } else {
    console.log('Did not reach batch limit, no follow-up needed.');
  }
}

function _clearAllDelayedBatchTriggers() {
  // cancel all delayed jobs
  const existingTriggers = ScriptApp.getProjectTriggers();
  console.log('Checking for triggers other than the daily trigger...');
  let foundDelayedBatchTrigger = false;
  for (let i = 0; i < existingTriggers.length; i++) {
    const trigger = existingTriggers[i];
    if (trigger.getHandlerFunction() === DELAYED_BATCH_TRIGGER_NAME) {
      ScriptApp.deleteTrigger(trigger);
      console.log('Removed delayed batch trigger: ' + trigger.getUniqueId());
      foundDelayedBatchTrigger = true;
    }
  }
  if (!foundDelayedBatchTrigger) {
    console.log('No delayed batch triggers found.')
  }
}


function dailyProcessTrigger() {
  // run this daily to initiate the auto action process
  console.log('START run daily batch for Gmail threads...');
  
  _processNextBatch();

  console.log('FINISH run daily batch.');
}

function delayedBatchTrigger() {
  // run this to start the process again if we didn't finish the first time
  console.log('START process delayed batch');

  _processNextBatch();

  console.log('FINISH process delayed batch');
}

function Install() {
  console.log('Installing triggers...');

  // Clear all existing triggers before setting up new ones
  Uninstall();

  // Set up the new daily trigger
  ScriptApp.newTrigger(DAILY_TRIGGER_NAME)
           .timeBased()
           .everyDays(1)
           .create();

  console.log('Installation complete.');
}

function Uninstall() {
  console.log('Uninstalling all triggers...');

  const triggers = ScriptApp.getProjectTriggers();
  for (let i = 0; i < triggers.length; i++) {
    ScriptApp.deleteTrigger(triggers[i]);
  }

  console.log('All triggers have been removed.');
}