/**
 * Allow synchronization of NodeQueues.
 */
function qsync_form_nodequeue_arrange_subqueue_form_alter(&$form, &$form_state) {
  $form['custom-sync'] = array(
    '#type' => 'fieldset',
    '#title' => t('Synchronize queues'),
    '#collapsible' => TRUE,
    '#collapsed' => ($form['#queue']['qid'] == 5) ? FALSE : TRUE, // Custom code here.
  );
  $form['custom-sync']['active_subqueue'] = array(
    '#type' => 'value',
    '#value' => $form['#subqueue']['sqid'],
  );
  $form['custom-sync']['active_queue'] = array(
    '#type' => 'value',
    '#value' => $form['#queue']['qid'],
  );
  // Construct a matching query by allowed node types.
  $in = '';
  foreach ($form['#queue']['types'] as $type) {
    $in .= "'". check_plain($type) ."',";
  }
  $result = db_query("SELECT nq.title, nq.sqid, nq.qid FROM {nodequeue_subqueue} nq INNER JOIN {nodequeue_types} nt ON nt.qid = nq.qid WHERE nq.sqid <> %d AND nq.qid <> %d AND nt.type IN (". trim($in, ',') .")", $form['#subqueue']['sqid'], $form['#queue']['qid']);
  $options = array();
  while($data = db_fetch_object($result)) {
    $options[$data->qid .':'. $data->sqid] = $data->title;
  }
  $form['custom-sync']['target_queue'] = array(
    '#title' => t('Target queue'),
    '#type' => 'select',
    '#default_value' => ($form['#queue']['qid'] == 5) ? '1:1' : '5:5', // This part is custom.
    '#options' => $options,
  );
  $form['custom-sync']['target_action'] = array(
    '#title' => t('Action'),
    '#type' => 'radios',
    '#default_value' => 0,
    '#options' => array(t('Pull changes from target'), t('Push changes to target')),
  );
  $form['custom-sync']['submit'] = array(
    '#value' => t('Synchronize queues'),
    '#type' => 'submit',
    '#submit' => array('nodequeue_arrange_subqueue_form_submit', 'queue_sync_nodequeue_submit'),
  );
}

/**
 * Process a synchronization submission.
 */
function qsync_sync_nodequeue_submit($form, &$form_state) {
  $values = $form_state['values'];
  if ($values['op'] != $values['custom-sync']['submit']) {
    return;
  }
  $sync = $values['custom-sync'];
  list($qid, $sqid) = explode(':', $sync['target_queue']);
  if (empty($sync['target_action'])) {
    db_query("DELETE FROM {nodequeue_nodes} WHERE qid = %d AND sqid = %d", $sync['active_queue'], $sync['active_subqueue']);
    $result = db_query("SELECT * FROM {nodequeue_nodes} WHERE qid = %d AND sqid = %d", $qid, $sqid);
    while ($data = db_fetch_array($result)) {
      $data['qid'] = $sync['active_queue'];
      $data['sqid'] = $sync['active_subqueue'];
      $data['timestamp'] = $_SERVER['REQUEST_TIME'];
      drupal_write_record('nodequeue_nodes', $data);
    }
    drupal_set_message(t('Changes have been updated from the target queue'));
  }
  else {
    db_query("DELETE FROM {nodequeue_nodes} WHERE qid = %d AND sqid = %d", $qid, $sqid);
    $result = db_query("SELECT * FROM {nodequeue_nodes} WHERE qid = %d AND sqid = %d", $sync['active_queue'], $sync['active_subqueue']);
    while ($data = db_fetch_array($result)) {
      $data['qid'] = $qid;
      $data['sqid'] = $sqid;
      $data['timestamp'] = $_SERVER['REQUEST_TIME'];
      drupal_write_record('nodequeue_nodes', $data);
      drupal_set_message(t('Changes have been pushed to the target queue'));
    }
  }
  cache_clear_all();
}