<?php
/**
 * WP REST API Menu routes
 *
 * @package WP_API_Menus
 */

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly
}

if ( ! class_exists( 'WP_REST_Menus' ) ) :


    /**
     * WP REST Menus class.
     *
     * WP API Menus support for WP API v2.
     *
     * @package WP_API_Menus
     * @since 1.2.0
     */
    class WP_REST_Menus {


	    /**
	     * Get WP API namespace.
	     *
	     * @since 1.2.0
	     * @return string
	     */
        public static function get_api_namespace() {
            return 'wp/v2';
        }


	    /**
	     * Get WP API Menus namespace.
	     *
	     * @since 1.2.1
	     * @return string
	     */
	    public static function get_plugin_namespace() {
		    return 'wp-api-menus/v2';
	    }


        /**
         * Register menu routes for WP API v2.
         *
         * @since  1.2.0
         */
        public function register_routes() {

            register_rest_route( self::get_plugin_namespace(), '/menus', array(
                array(
                    'methods'  => WP_REST_Server::READABLE,
                    'callback' => array( $this, 'get_menus' ),
                )
            ) );

            register_rest_route( self::get_plugin_namespace(), '/menus/(?P<id>\d+)', array(
                array(
                    'methods'  => WP_REST_Server::READABLE,
                    'callback' => array( $this, 'get_menu' ),
                    'args'     => array(
                        'context' => array(
                        'default' => 'view',
                        ),
                    ),
                )
            ) );

            register_rest_route( self::get_plugin_namespace(), '/menu-locations', array(
                array(
                    'methods'  => WP_REST_Server::READABLE,
                    'callback' => array( $this, 'get_menu_locations' ),
                )
            ) );

            register_rest_route( self::get_plugin_namespace(), '/menu-locations/(?P<location>[a-zA-Z0-9_-]+)', array(
                array(
                    'methods'  => WP_REST_Server::READABLE,
                    'callback' => array( $this, 'get_menu_location' ),
                )
            ) );
        }


        /**
         * Get menus.
         *
         * @since  1.2.0
         * @return array All registered menus
         */
        public static function get_menus() {

            $rest_url = trailingslashit( get_rest_url() . self::get_plugin_namespace() . '/menus/' );
            $wp_menus = wp_get_nav_menus();

            $i = 0;
            $rest_menus = array();
            foreach ( $wp_menus as $wp_menu ) :

                $menu = (array) $wp_menu;

                $rest_menus[ $i ]                = $menu;
                $rest_menus[ $i ]['ID']          = $menu['term_id'];
                $rest_menus[ $i ]['name']        = $menu['name'];
                $rest_menus[ $i ]['slug']        = $menu['slug'];
                $rest_menus[ $i ]['description'] = $menu['description'];
                $rest_menus[ $i ]['count']       = $menu['count'];

                $rest_menus[ $i ]['meta']['links']['collection'] = $rest_url;
                $rest_menus[ $i ]['meta']['links']['self']       = $rest_url . $menu['term_id'];

                $i ++;
            endforeach;

            return apply_filters( 'rest_menus_format_menus', $rest_menus );
        }


        /**
         * Get a menu.
         *
         * @since  1.2.0
         * @param  $request
         * @return array Menu data
         */
        public function get_menu( $request ) {

            $id             = (int) $request['id'];
            $rest_url       = get_rest_url() . self::get_api_namespace() . '/menus/';
            $wp_menu_object = $id ? wp_get_nav_menu_object( $id ) : array();
            $wp_menu_items  = $id ? wp_get_nav_menu_items( $id ) : array();

            $rest_menu = array();

            if ( $wp_menu_object ) :

                $menu = (array) $wp_menu_object;
                $rest_menu['ID']          = abs( $menu['term_id'] );
                $rest_menu['name']        = $menu['name'];
                $rest_menu['slug']        = $menu['slug'];
                $rest_menu['description'] = $menu['description'];
                $rest_menu['count']       = abs( $menu['count'] );

                $rest_menu_items = array();
                foreach ( $wp_menu_items as $item_object ) {
	                $rest_menu_items[] = $this->format_menu_item( $item_object );
                }

                $rest_menu_items = $this->nested_menu_items($rest_menu_items, 0);

                $rest_menu['items']                       = $rest_menu_items;
                $rest_menu['meta']['links']['collection'] = $rest_url;
                $rest_menu['meta']['links']['self']       = $rest_url . $id;

            endif;

            return apply_filters( 'rest_menus_format_menu', $rest_menu );
        }


        /**
         * Handle nested menu items.
         *
         * Given a flat array of menu items, split them into parent/child items
         * and recurse over them to return children nested in their parent.
         *
         * @since  1.2.0
         * @param  $menu_items
         * @param  $parent
         * @return array
         */
        private function nested_menu_items( &$menu_items, $parent = null ) {

            $parents = array();
            $children = array();

            // Separate menu_items into parents & children.
            array_map( function( $i ) use ( $parent, &$children, &$parents ){
                if ( $i['id'] != $parent && $i['parent'] == $parent ) {
                    $parents[] = $i;
                } else {
                    $children[] = $i;
                }
            }, $menu_items );

            foreach ( $parents as &$parent ) {

                if ( $this->has_children( $children, $parent['id'] ) ) {
                    $parent['children'] = $this->nested_menu_items( $children, $parent['id'] );
                }
            }

            return $parents;
        }


        /**
         * Check if a collection of menu items contains an item that is the parent id of 'id'.
         *
         * @since  1.2.0
         * @param  array $items
         * @param  int $id
         * @return array
         */
        private function has_children( $items, $id ) {
            return array_filter( $items, function( $i ) use ( $id ) {
                return $i['parent'] == $id;
            } );
        }


        /**
         * Get menu locations.
         *
         * @since 1.2.0
         * @param  $request
         * @return array All registered menus locations
         */
        public static function get_menu_locations( $request ) {

            $locations        = get_nav_menu_locations();
            $registered_menus = get_registered_nav_menus();
	        $rest_url         = get_rest_url() . self::get_api_namespace() . '/menu-locations/';
            $rest_menus       = array();

            if ( $locations && $registered_menus ) :

                foreach ( $registered_menus as $slug => $label ) :

	                // Sanity check
	                if ( ! isset( $locations[ $slug ] ) ) {
		                continue;
	                }

	                $rest_menus[ $slug ]['ID']                          = $locations[ $slug ];
                    $rest_menus[ $slug ]['label']                       = $label;
                    $rest_menus[ $slug ]['meta']['links']['collection'] = $rest_url;
                    $rest_menus[ $slug ]['meta']['links']['self']       = $rest_url . $slug;

                endforeach;

            endif;

            return $rest_menus;
        }


        /**
         * Get menu for location.
         *
         * @since 1.2.0
         * @param  $request
         * @return array The menu for the corresponding location
         */
        public function get_menu_location( $request ) {

            $params     = $request->get_params();
            $location   = $params['location'];
            $locations  = get_nav_menu_locations();

            if ( ! isset( $locations[ $location ] ) ) {
	            return array();
            }

            $wp_menu = wp_get_nav_menu_object( $locations[ $location ] );
            $menu_items = wp_get_nav_menu_items( $wp_menu->term_id );

			/**
			 * wp_get_nav_menu_items() outputs a list that's already sequenced correctly.
			 * So the easiest thing to do is to reverse the list and then build our tree
			 * from the ground up
			 */
			$rev_items = array_reverse ( $menu_items );
			$rev_menu  = array();
			$cache     = array();

			foreach ( $rev_items as $item ) :

				$formatted = array(
					'ID'          => abs( $item->ID ),
					'order'       => (int) $item->menu_order,
					'parent'      => abs( $item->menu_item_parent ),
					'title'       => $item->title,
					'url'         => $item->url,
					'attr'        => $item->attr_title,
					'target'      => $item->target,
					'classes'     => implode( ' ', $item->classes ),
					'xfn'         => $item->xfn,
					'description' => $item->description,
					'object_id'   => abs( $item->object_id ),
					'object'      => $item->object,
					'type'        => $item->type,
					'type_label'  => $item->type_label,
					'children'    => array(),
				);

				if ( array_key_exists( $item->ID , $cache ) ) {
					$formatted['children'] = array_reverse( $cache[ $item->ID ] );
				}

            	$formatted = apply_filters( 'rest_menus_format_menu_item', $formatted );

				if ( $item->menu_item_parent != 0 ) {

					if ( array_key_exists( $item->menu_item_parent , $cache ) ) {
						array_push( $cache[ $item->menu_item_parent ], $formatted );
					} else {
						$cache[ $item->menu_item_parent ] = array( $formatted, );
					}

				} else {

					array_push( $rev_menu, $formatted );
				}

			endforeach;

			return array_reverse ( $rev_menu );
        }


        /**
         * Returns all child nav_menu_items under a specific parent.
         *
         * @since   1.2.0
         * @param int   $parent_id      The parent nav_menu_item ID
         * @param array $nav_menu_items Navigation menu items
         * @param bool  $depth          Gives all children or direct children only
         * @return array	returns filtered array of nav_menu_items
         */
        public function get_nav_menu_item_children( $parent_id, $nav_menu_items, $depth = true ) {

            $nav_menu_item_list = array();

            foreach ( (array) $nav_menu_items as $nav_menu_item ) :

                if ( $nav_menu_item->menu_item_parent == $parent_id ) :

                    $nav_menu_item_list[] = $this->format_menu_item( $nav_menu_item, true, $nav_menu_items );

                    if ( $depth ) {
                        if ( $children = $this->get_nav_menu_item_children( $nav_menu_item->ID, $nav_menu_items ) ) {
                            $nav_menu_item_list = array_merge( $nav_menu_item_list, $children );
                        }
                    }

                endif;

            endforeach;

            return $nav_menu_item_list;
        }


        /**
         * Format a menu item for REST API consumption.
         *
         * @since  1.2.0
         * @param  object|array $menu_item  The menu item
         * @param  bool         $children   Get menu item children (default false)
         * @param  array        $menu       The menu the item belongs to (used when $children is set to true)
         * @return array	a formatted menu item for REST
         */
        public function format_menu_item( $menu_item, $children = false, $menu = array() ) {

            $item = (array) $menu_item;

            $menu_item = array(
                'id'          => abs( $item['ID'] ),
                'order'       => (int) $item['menu_order'],
                'parent'      => abs( $item['menu_item_parent'] ),
                'title'       => $item['title'],
                'url'         => $item['url'],
                'attr'        => $item['attr_title'],
                'target'      => $item['target'],
                'classes'     => implode( ' ', $item['classes'] ),
                'xfn'         => $item['xfn'],
                'description' => $item['description'],
                'object_id'   => abs( $item['object_id'] ),
                'object'      => $item['object'],
                'object_slug' => get_post( $item['object_id'] )->post_name,
                'type'        => $item['type'],
                'type_label'  => $item['type_label'],
            );

            if ( $children === true && ! empty( $menu ) ) {
	            $menu_item['children'] = $this->get_nav_menu_item_children( $item['ID'], $menu );
            }

            return apply_filters( 'rest_menus_format_menu_item', $menu_item );
        }


    }


endif;