_tracker_remove

_tracker_remove($nid, $uid = NULL, $changed = NULL)

function _tracker_remove($nid, $uid = NULL, $changed = NULL) {
  $node = Node::load($nid);

  // The user only keeps their subscription if the node exists.
  if ($node) {
    // And they are the author of the node.
    $keep_subscription = ($node->getOwnerId() == $uid);

    // Or if they have commented on the node.
    if (!$keep_subscription) {
      // Check if the user has commented at least once on the given nid.
      $keep_subscription = \Drupal::entityQuery('comment')
        ->condition('entity_type', 'node')
        ->condition('entity_id', $nid)
        ->condition('uid', $uid)
        ->condition('status', CommentInterface::PUBLISHED)
        ->range(0, 1)
        ->count()
        ->execute();
    }

    // If we haven't found a reason to keep the user's subscription, delete it.
    if (!$keep_subscription) {
      db_delete('tracker_user')
        ->condition('nid', $nid)
        ->condition('uid', $uid)
        ->execute();
    }

    // Now we need to update the (possibly) changed timestamps for other users
    // and the node itself.
    // We only need to do this if the removed item has a timestamp that equals
    // or exceeds the listed changed timestamp for the node.
    $tracker_node = db_query('SELECT nid, changed FROM {tracker_node} WHERE nid = :nid', array(':nid' => $nid))->fetchObject();
    if ($tracker_node && $changed >= $tracker_node->changed) {
      // If we're here, the item being removed is *possibly* the item that
      // established the node's changed timestamp.

      // We just have to recalculate things from scratch.
      $changed = _tracker_calculate_changed($node);

      // And then we push the out the new changed timestamp to our denormalized
      // tables.
      db_update('tracker_node')
        ->fields(array(
          'changed' => $changed,
          'published' => $node->isPublished(),
        ))
        ->condition('nid', $nid)
        ->execute();
      db_update('tracker_node')
        ->fields(array(
          'changed' => $changed,
          'published' => $node->isPublished(),
        ))
        ->condition('nid', $nid)
        ->execute();
    }
  }
  else {
    // If the node doesn't exist, remove everything.
    db_delete('tracker_node')
      ->condition('nid', $nid)
      ->execute();
    db_delete('tracker_user')
      ->condition('nid', $nid)
      ->execute();
  }
}