<?php /*

Plugin Name: Add Children As Menu Items

Work in progress! Mostly a mockup at this point. -Alex

*/

//add_filter( 'wp_nav_menu_objects', 'filter_var_dump', 99 );
function filter_var_dump( $var ) {
    var_dump( $var );
    return $var;
}


class Add_Children_As_Menu_Items {

    public $added = array();

    function __construct() {
        if ( ! is_admin() ) {
            add_filter( 'wp_get_nav_menu_items', array( &$this, 'add_child_pages_to_menu' ), 10, 3 );
        }
    }

    // Add all decendent pages to top level menu items that are pages
    function add_child_pages_to_menu( $items, $menu, $args ) {
        $menu_order = count( $items ) + 1000;
        $filter_added = false;

        foreach ( $items as $item ) {
            // Skip menu items that aren't top level or aren't post_type=page
            if ( 0 != $item->menu_item_parent || 'page' != $item->object )
                continue;

            // Get all decendent pages
            $children = get_pages( array(
                'child_of' => $item->object_id,
                'sort_column' => 'menu_order',
            ) );

            if ( ! $children )
                continue;

            // Menu items are being added, so later fix the "current" values for highlighting
            if ( ! $filter_added )
                add_filter( 'wp_nav_menu_objects',  array( &$this, 'fix_menu_current_item' ) );

            // Add each child page to the menu
            foreach ( $children as $child ) {
                $this->added[$child->ID] = true; // We'll need this later

                $child = wp_setup_nav_menu_item( $child );
                $child->db_id = $child->ID;

                // Set the parent menu item.
                // If the current page is a child of the current menu item,
                // then use that menu item's ID otherwise use the real ID
                // because it's a menu item that this plugin added itself.
                if ( $child->post_parent == $item->object_id )
                    $child->menu_item_parent = $item->ID; // Children
                else
                    $child->menu_item_parent = $child->post_parent; // Grandchildren, etc.

                // The menu_order has to be unique, so make up new ones
                // The items are already sorted anyway due to the get_posts()
                $menu_order++;
                $child->menu_order = $menu_order;

                $items[] = $child;
            }
        }

        //var_dump( $items );

        return $items;
    }

    // Fixes the ancestor/parent settings/classes when viewing a menu item added by this plugin
    function fix_menu_current_item( $items ) {
        global $wp_query;

        $queried_object = $wp_query->get_queried_object();
        $queried_object_id = (int) $wp_query->queried_object_id;

        // Only need to fix items added by this plugin
        if ( empty( $this->added[$queried_object_id] ) )
            return $items;

        _get_post_ancestors( $queried_object );

        foreach ( $items as $item ) {
            if ( ! in_array( $item->object_id, $queried_object->ancestors ) )
                continue;

            $item->current_item_ancestor = true;
            $item->classes[] = 'current-menu-ancestor';
            $item->classes[] = 'current_page_ancestor';

            // If menu item is direct parent of current page
            if ( $item->object_id == $queried_object->post_parent ) {
                $item->current_item_parent = true;
                $item->classes[] = 'current-menu-parent';
                $item->classes[] = 'current_page_parent';
            }
        }

        return $items;
    }
}

$add_children_as_menu_items = new Add_Children_As_Menu_Items();

?>