/**
 * Generate wiki's page tree
 *
 * @param page_wiki $page. A wiki page object
 * @param navigation_node $node. Starting navigation_node
 * @param array $keys. An array to store keys
 * @return an array with all tree nodes
 */
function wiki_build_tree($page, $node, &$keys)
{
    $content = array();
    static $icon;
    $icon = new pix_icon('f/odt', '');
    $pages = wiki_get_linked_pages($page->id);
    foreach ($pages as $p) {
        $key = $page->id . ':' . $p->id;
        if (in_array($key, $keys)) {
            break;
        }
        array_push($keys, $key);
        $l = wiki_parser_link($p);
        $link = new moodle_url('/mod/wiki/view.php', array('pageid' => $p->id));
        // navigation_node::get_content will format the title for us
        $nodeaux = $node->add($p->title, $link, null, null, null, $icon);
        if ($l['new']) {
            $nodeaux->add_class('wiki_newentry');
        }
        wiki_build_tree($p, $nodeaux, $keys);
    }
    $content[] = $node;
    return $content;
}

    /**
     * Prints the index page tab content
     *
     *
     */
    private function print_index_content() {
        global $OUTPUT;
        $page = $this->page;

        if ($page->timerendered + WIKI_REFRESH_CACHE_TIME < time()) {
            $fresh = wiki_refresh_cachedcontent($page);
            $page = $fresh['page'];
        }

        // navigation_node get_content calls format string for us
        $node = new navigation_node($page->title);

        $keys = array();
        $tree = array();
        $tree = wiki_build_tree($page, $node, $keys);

        $table = new html_table();
        $table->head = array(get_string('pageindex', 'wiki') . $OUTPUT->help_icon('pageindex', 'wiki'));
        $table->attributes['class'] = 'wiki_editor generalbox';
        $table->data[] = array($this->render_navigation_node($tree));

        echo html_writer::table($table);
    }