/**
 * Migrate comment and forum to nodecomment and nodeforum
 **/
function nodecomment_upgrade() {
  $ret = array();
  // set up a temp table for our nid/vid sequence to get new node_comment nids
  $ret[] = update_sql("
    CREATE TABLE {temp_ncids} (
      nvid int(10) NOT NULL AUTO_INCREMENT,
      cid int(10) NOT NULL default '0',
      PRIMARY KEY (nvid)
    )
  ");

  // set the intial values that are equal to the drupal sequences table values
  $ret[] = update_sql("
    INSERT INTO {temp_ncids} (nvid, cid)
    VALUES (
      (SELECT id
        FROM {sequences}
        WHERE name = 'node_revisions_vid'),
      0)
  ");

  // increment the temp table by inserting the comments we have
  $ret[] = update_sql("
    INSERT INTO {temp_ncids} (cid)
    SELECT cid FROM {comments}
  ");

  // create the node table records
  // note that we are setting them all to comment type for now
  // forum_replies are fixed in a later query
  $ret[] = update_sql("
    INSERT INTO {node} (nid, vid, type, title, uid, status, created, changed, comment, promote, moderate, sticky)
    SELECT t.nvid, t.nvid, 'comment', c.subject, c.uid, 1, c.timestamp, c.timestamp, 0, 0, 0, 0
    FROM {comments} c, {temp_ncids} t
    WHERE c.cid = t.cid
  ");

  // create the node_revisions table records
  $ret[] = update_sql("
    INSERT INTO node_revisions (nid, vid, uid, title, body, teaser, log, timestamp, format)
    SELECT t.nvid, t.nvid, c.uid, c.subject, c.comment, c.comment, '', c.timestamp, c.format
    FROM {comments} c, {temp_ncids} t
    WHERE c.cid = t.cid
  ");

  // move the comments data into the node_comments table
  $ret[] = update_sql("
    INSERT INTO {node_comments} (cid, pid, nid, hostname, thread, name, mail, homepage)
    SELECT t.nvid, c.pid, c.nid, c.hostname, c.thread, c.name, c.mail, c.homepage
    FROM {comments} c, temp_ncids t
    WHERE c.cid = t.cid
  ");

  // migrate the term_node data to the new nodes
  $ret[] = update_sql("
    INSERT INTO {term_node} (nid, tid)
    SELECT t.nvid, tn.tid
    FROM {temp_ncids} t, {term_node} tn
    WHERE t.nvid = tn.nid
  ");

  // change the forum comments to the forum_reply content type
  $ret[] = update_sql("
    UPDATE node n
    SET n.type = 'forum_reply'
    WHERE n.nid IN (
      SELECT nc.cid
      FROM forum f, node_comments nc
      WHERE f.nid = nc.nid
    )
  ");

  // reset the sequences table
  $ret[] = update_sql("
    UPDATE {sequences}
    SET id = (
      SELECT MAX(nid)
      FROM {node}
    )
    WHERE name = 'node_nid'
    OR name = 'node_revisions_vid'
    OR name = 'comments_cid'
  ");

  // copy over nodeforum data
  $ret[] = update_sql("
    INSERT INTO {nodeforum} (nid, vid, tid)
    SELECT nid, vid, tid
    FROM {forum}
  ");

  // clean up old tables
  $ret[] = update_sql("DROP TABLE {temp_ncids}");
  $ret[] = update_sql("DROP TABLE {comments}");
  $ret[] = update_sql("DROP TABLE {forum}");

  variable_set('default_comment_type', 'comment');
  variable_set('comment_type_forum', 'forum_reply');
  variable_set('comment_view_forum', 'forum_replies');
  variable_set('comment_forum_reply', 0);
  variable_set('comment_comment', 0);
  variable_set('nodeforum_nav_vocabulary', 3);

  return $ret;
}