/**
 * Gets all revisions for a Quiz and calculates completed takes for each revision.
 *
 * @param string $vid
 * @return array
 */
function _get_revisions( $vid ) {

  // Fetch node id for the given revision id ($vid).
  $sql = "SELECT nid FROM {node_revisions} WHERE vid = %d";
  $nid = db_result( db_query( $sql, $vid ) );

  // Fetch all revisions of a quiz, and count how many takes
  // for each revision.
  $sql = "SELECT
            nr.vid,
            COUNT(qnr.vid) AS count
          FROM
            node_revisions nr
          INNER JOIN
            quiz_node_results qnr ON qnr.vid = nr.vid
          WHERE
            nr.nid = %d
          GROUP BY
            nr.vid
          ORDER BY
            nr.vid DESC";

  $result = db_query( $sql, $nid );

  // Make for options from last query
  $options = array();
  $revision_count = mysql_num_rows( $result );

  while( $arr = db_fetch_array($result) ) {
    $options[$arr['vid']] = t('Revision %revision (%takes)', array( '%revision' => $revision_count, '%takes' => format_plural($arr['count'], '1 take', '@count takes')));
    $revision_count--;
  }

  // Make form
  $form = array();
  $form['quiz-revision'] = array(
    '#type' => 'fieldset',
    '#title' => t('Select Quiz revision'),
    '#collapsible' => TRUE,
    '#collapsed' => FALSE,
  );

  $form['quiz-revision']['revisions'] = array(
    '#type' => 'select',
    '#title' => t('Choose revision'),
    '#default_value' => $vid,
    '#options' => $options,
    '#description' => t('Change revision and statistics should update to show that revision'),
  );

  // Return form
  return $form;
}