class BP_Walker_Nav_Menu_Checklist extends Walker_Nav_Menu {

	/**
	 * Constructor.
	 *
	 * @see Walker_Nav_Menu::__construct() for a description of parameters.
	 *
	 * @param array|bool $fields See {@link Walker_Nav_Menu::__construct()}.
	 */
	public function __construct( $fields = false ) {
		if ( $fields ) {
			$this->db_fields = $fields;
		}
	}

	/**
	 * Create the markup to start a tree level.
	 *
	 * @see Walker_Nav_Menu::start_lvl() for description of parameters.
	 *
	 * @param string $output See {@Walker_Nav_Menu::start_lvl()}.
	 * @param int    $depth  See {@Walker_Nav_Menu::start_lvl()}.
	 * @param array  $args   See {@Walker_Nav_Menu::start_lvl()}.
	 */
	public function start_lvl( &$output, $depth = 0, $args = array() ) {
		$indent = str_repeat( "\t", $depth );
		$output .= "\n$indent<ul class='children'>\n";
	}

	/**
	 * Create the markup to end a tree level.
	 *
	 * @see Walker_Nav_Menu::end_lvl() for description of parameters.
	 *
	 * @param string $output See {@Walker_Nav_Menu::end_lvl()}.
	 * @param int    $depth  See {@Walker_Nav_Menu::end_lvl()}.
	 * @param array  $args   See {@Walker_Nav_Menu::end_lvl()}.
	 */
	public function end_lvl( &$output, $depth = 0, $args = array() ) {
		$indent = str_repeat( "\t", $depth );
		$output .= "\n$indent</ul>";
	}

	/**
	 * Create the markup to start an element.
	 *
	 * @see Walker::start_el() for description of parameters.
	 *
	 * @param string       $output Passed by reference. Used to append additional
	 *                             content.
	 * @param object       $item   Menu item data object.
	 * @param int          $depth  Depth of menu item. Used for padding.
	 * @param object|array $args   See {@Walker::start_el()}.
	 * @param int          $id     See {@Walker::start_el()}.
	 */
	function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
		global $_nav_menu_placeholder;

		$_nav_menu_placeholder = ( 0 > $_nav_menu_placeholder ) ? intval($_nav_menu_placeholder) - 1 : -1;
		$possible_object_id = isset( $item->post_type ) && 'nav_menu_item' == $item->post_type ? $item->object_id : $_nav_menu_placeholder;
		$possible_db_id = ( ! empty( $item->ID ) ) && ( 0 < $possible_object_id ) ? (int) $item->ID : 0;

		$indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

		$output .= $indent . '<li>';
		$output .= '<label class="menu-item-title">';
		$output .= '<input type="checkbox" class="menu-item-checkbox';

		if ( property_exists( $item, 'label' ) ) {
			$title = $item->label;
		}

		$output .= '" name="menu-item[' . $possible_object_id . '][menu-item-object-id]" value="'. esc_attr( $item->object_id ) .'" /> ';
		$output .= isset( $title ) ? esc_html( $title ) : esc_html( $item->title );
		$output .= '</label>';

		if ( empty( $item->url ) ) {
			$item->url = $item->guid;
		}

		if ( ! in_array( array( 'bp-menu', 'bp-'. $item->post_excerpt .'-nav' ), $item->classes ) ) {
			$item->classes[] = 'bp-menu';
			$item->classes[] = 'bp-'. $item->post_excerpt .'-nav';
		}

		// Menu item hidden fields.
		$output .= '<input type="hidden" class="menu-item-db-id" name="menu-item[' . $possible_object_id . '][menu-item-db-id]" value="' . $possible_db_id . '" />';
		$output .= '<input type="hidden" class="menu-item-object" name="menu-item[' . $possible_object_id . '][menu-item-object]" value="'. esc_attr( $item->object ) .'" />';
		$output .= '<input type="hidden" class="menu-item-parent-id" name="menu-item[' . $possible_object_id . '][menu-item-parent-id]" value="'. esc_attr( $item->menu_item_parent ) .'" />';
		$output .= '<input type="hidden" class="menu-item-type" name="menu-item[' . $possible_object_id . '][menu-item-type]" value="custom" />';
		$output .= '<input type="hidden" class="menu-item-title" name="menu-item[' . $possible_object_id . '][menu-item-title]" value="'. esc_attr( $item->title ) .'" />';
		$output .= '<input type="hidden" class="menu-item-url" name="menu-item[' . $possible_object_id . '][menu-item-url]" value="'. esc_attr( $item->url ) .'" />';
		$output .= '<input type="hidden" class="menu-item-target" name="menu-item[' . $possible_object_id . '][menu-item-target]" value="'. esc_attr( $item->target ) .'" />';
		$output .= '<input type="hidden" class="menu-item-attr_title" name="menu-item[' . $possible_object_id . '][menu-item-attr_title]" value="'. esc_attr( $item->attr_title ) .'" />';
		$output .= '<input type="hidden" class="menu-item-classes" name="menu-item[' . $possible_object_id . '][menu-item-classes]" value="'. esc_attr( implode( ' ', $item->classes ) ) .'" />';
		$output .= '<input type="hidden" class="menu-item-xfn" name="menu-item[' . $possible_object_id . '][menu-item-xfn]" value="'. esc_attr( $item->xfn ) .'" />';
	}
}