gistfile1.txt

/**
 * Function to queue up text and email reminders from cron runs.
 */
function compost_customizations_queue_reminders() {

  $now = time();
  $tomorrow_timestamp = $now + 60 * 60 * 24;
  $tomorrow = date('l', $tomorrow_timestamp);
  // Somewhat arbitrary.  Reminders ought to be once a week, but on certain
  // weeks, like holidays, the gap will be larger or smaller.  Three days seems
  // safe that it'll never be less than
  $three_days_ago = $now - 3 * (60 * 60 * 24);
  $hour_of_the_day = date('G', $now);

  $query = new EntityFieldQuery();

  $query->entityCondition('entity_type', 'user')
    ->fieldCondition('field_reminders', 'value', 0, '>')
    ->fieldCondition('field_active', 'value', 1)
    ->fieldCondition('field_collection_day', 'value', $tomorrow)
    ->fieldCondition('field_last_reminded', 'value', $three_days_ago, '<')
    ->fieldCondition('field_reminder_time', 'value', $hour_of_the_day, '<=');

  $result = $query->execute();

  if (!empty($result['user'])) {

    $text_queue = DrupalQueue::get('text_reminders');
    $email_queue = DrupalQueue::get('email_reminders');

    $user_uids = array_keys($result['user']);
    $users = entity_load('user', $user_uids);

    foreach($users as $user) {
      if (!empty($user->field_reminders)) {
        foreach($user->field_reminders[LANGUAGE_NONE] as $reminder) {
          if ($reminder['value'] == 1) {
            $email_queue->createItem($user);
          }
          elseif ($reminder['value'] == 2) {
            $text_queue->createItem($user);
          }
        }
        // Mark them as reminded here.  If the users is not marked here, and
        // rather when the message is sent, they would be queued twice
        $user->field_last_reminded[LANGUAGE_NONE][0]['value'] = $_SERVER['REQUEST_TIME'];
        field_attach_update('user', $user);
      }
    }
  }
}

The basic gist (pun intended) of this function is to send automated weekly email and text reminders to subscribers of a service based on fields they edit on their user profile. They may opt into an email and/or text reminder, and may set the time of day they would like that reminder to be triggered. This function is called by cron.