Automatically Update GMail Filter When Assigning Label

Update_Filters.gs

function Intialize() {
  return;
}

function Install() {
 
  ScriptApp.newTrigger("updateFilter")
           .timeBased().everyMinutes(10).create();

}

function updateFilter (toAddress, labelName) {

  // Get all Filters
  var my_filters = Gmail.Users.Settings.Filters.list('me').filter;
  // Get Labelname
  var my_label = GmailApp.getUserLabelByName('To Sort');
  // Iterate through filters
  for (var i=0; i<my_filters.length; i++) {
    // Get query
    var my_query = my_filters[i].criteria.query;
    // If Query has _Auto_ progress
    if (my_query && my_query.includes("_Auto_")){
      var auto_label = my_query.split("}")[0].split("Auto_")[1].replaceAll("__", " ").replaceAll("_", "");
      console.log("Scanning " + auto_label);
      // Search for label
      var threads = GmailApp.search('label:' + auto_label +' label:to-sort');
      if (threads.length == 0) {
        console.log("Did not update " + auto_label + ". Nothing to sort.");
        continue;
      }
    	// Get Senders
      var filter_senders = my_query.split("from:(")[1].split(")")[0].split(" OR ");
      
      //Iterate Through Threads
      for (var ii = 0; ii < threads.length; ii++) {
        // Get Sender
        try {
          var sender = threads[ii].getMessages()[0].getFrom().split("<")[1].replace(">", "");
        } catch(err) {
          var sender = threads[ii].getMessages()[0].getFrom();
          console.log(err + sender + ". Email was raw email.");
          
        }
        // Add Sender to Array if not exist
        filter_senders.indexOf(sender) === -1 ? filter_senders.push(sender) : console.log(sender + " already exists");
        // Remove "To Sort" label
        threads[ii].removeLabel(my_label);
      }
      // Generate the string of senders for filter
      var filter_string = filter_senders.join(" OR ");

      // If the filter is too long GMail gets upsetty
      while (filter_string.length > 1450) {
        console.log("Filter for " + auto_label + " was a bit long. Splitting into two.")
        var backup_string = filter_string.slice(0, 1400);
        var next_string = filter_string.slice(1400);
        var filter_string_index = next_string.indexOf('OR');
        var backup_string = backup_string + next_string.slice(0, filter_string_index-1);
        var filter_string = next_string.slice(filter_string_index+3);

        var backup_query = my_query.replace("_Auto_", "_Backup_").split("from:(")[0] + "from:(" + backup_string + ")";
        my_filters[i].criteria.query = backup_query;
        Gmail.Users.Settings.Filters.create(my_filters[i], 'me');
      }
      // console.log(filter_string);
      var new_query = my_query.split("from:(")[0] + "from:(" + filter_string + ")";
      // Remove old filter
      try {
        Gmail.Users.Settings.Filters.remove("me", my_filters[i].id);
      } catch(err) {
        console.log("Could not delete filter. " + err.message);
      }
      my_filters[i].criteria.query = new_query;

      
      try {
        Utilities.sleep(500);
        Gmail.Users.Settings.Filters.create(my_filters[i], 'me');
      } catch(err) {
        Utilities.sleep(500);
        my_filters[i].criteria.query = new_query + " OR {E_r_r__o_r " + auto_label + err.message.replace(" ", "") + "}";
        Gmail.Users.Settings.Filters.create(my_filters[i], 'me');
      }
      console.log("Updated " + auto_label);
    }
  }
}