just

index.php

<?php

if (!defined('ABSPATH'))
    exit;

class AWDP_Api
{

    /**
     * @var    object
     * @access  private
     * @since    1.0.0
     */
    private static $_instance = null;

    /**
     * The version number.
     * @var     string
     * @access  public
     * @since   1.0.0
     */
    public $_version;
    private $_active = false;

    public function __construct()
    {
        add_action('rest_api_init', function () {
            register_rest_route('awdp/v1', '/rules/', array(
                'methods' => 'GET',
                'callback' => array($this, 'get_rules'),
                'permission_callback' => array($this, 'get_permission')
            ));
        });
    }

    /**
     *
     * Ensures only one instance of AWDP is loaded or can be loaded.
     *
     * @since 1.0.0
     * @static
     * @see WordPress_Plugin_Template()
     * @return Main AWDP instance
     */
    public static function instance($file = '', $version = '1.0.0')
    {
        if (is_null(self::$_instance)) {
            self::$_instance = new self($file, $version);
        }
        return self::$_instance;
    }

    function action_delete($data)
    {
        $data = $data->get_params();
        if ($data['id']) {
            $pt = get_post_type($data['id']);

            if ($pt == AWDP_POST_TYPE && wp_delete_post($data['id'], true)) {
                return admin_url('admin.php?page=awdp_admin_ui');
            } else if ($pt == AWDP_PRODUCT_LIST && wp_delete_post($data['id'], true)) {
                return admin_url('admin.php?page=awdp_admin_product_lists');
            }
        }
    }

    /**
     * Permission Callback
     **/
    public function get_permission()
    {
        if (current_user_can('administrator') || current_user_can('manage_woocommerce')) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Cloning is forbidden.
     *
     * @since 1.0.0
     */
    public function __clone()
    {
        _doing_it_wrong(__FUNCTION__, __('Cheatin&#8217; huh?'), $this->_version);
    }

    /**
     * Unserializing instances of this class is forbidden.
     *
     * @since 1.0.0
     */
    public function __wakeup()
    {
        _doing_it_wrong(__FUNCTION__, __('Cheatin&#8217; huh?'), $this->_version);
    }

}