function wiki_add_entry(&$wiki, &$course, $userid=0, $groupid=0) {
/// Adds a new wiki entry of the specified type, unless already entered.
/// No checking is done here. It is assumed that the caller has the correct
/// privileges to add this entry.

    global $USER;

    /// If this wiki already has a wiki_type entry, return false.
    if (wiki_get_entry($wiki, $course, $userid, $groupid) !== false) {
        return false;
    }

    $wiki_entry = new Object();

    switch ($wiki->wtype) {

    case 'student':
        $wiki_entry->wikiid = $wiki->id;
        $wiki_entry->userid = $userid ? $userid : $USER->id;
        $wiki_entry->pagename = wiki_page_name($wiki);
        $wiki_entry->timemodified = time();
        break;

    case 'group':
        /// Get the groupmode. It's been added to the wiki object.
        $groupmode = groups_get_activity_groupmode($wiki);

        ///give the first groupid by default and try
        $mygroups = mygroupid($course->id);

        /// If there is a groupmode, get the group id.
        if ($groupmode) {
            $groupid = $groupid ? $groupid : $mygroups[0]/*mygroupid($course->id)*/;
        }
        /// If mode is 'nogroups', then groupid is zero.
        else {
            $groupid = 0;
        }
        $wiki_entry->wikiid = $wiki->id;
        $wiki_entry->groupid = $groupid;
        $wiki_entry->pagename = wiki_page_name($wiki);
        $wiki_entry->timemodified = time();

        break;

    case 'teacher':
        /// Get the groupmode. It's been added to the wiki object.
        $groupmode = groups_get_activity_groupmode($wiki);

        /// If there is a groupmode, get the user's group id.
        if ($groupmode and $groupid == 0) {
            $mygroupid = mygroupid($course->id);
            $groupid = $mygroupid[0]/*mygroupid($course->id)*/;
        }

        $wiki_entry->wikiid = $wiki->id;
        $wiki_entry->course = $wiki->course;
        $wiki_entry->groupid = $groupid;
        $wiki_entry->pagename = wiki_page_name($wiki);
        $wiki_entry->timemodified = time();
        break;
    }
    $wiki_entry->pagename = addslashes($wiki_entry->pagename);

    return insert_record("wiki_entries", $wiki_entry, true);
}