wc-tier-and-package-prices/includes/class-wc-tpp-admin.php

<?php
/**
 * Admin settings and configuration
 */

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

class WC_TPP_Admin {

    public function __construct() {
        add_action('admin_menu', array($this, 'add_admin_menu'));
        add_action('admin_init', array($this, 'register_settings'));
        add_action('admin_enqueue_scripts', array($this, 'enqueue_admin_scripts'));
    }

    public function add_admin_menu() {
        add_submenu_page(
            'woocommerce',
            __('Tier & Package Prices', 'wc-tier-package-prices'),
            __('Tier & Package Prices', 'wc-tier-package-prices'),
            'manage_woocommerce',
            'wc-tier-package-prices',
            array($this, 'settings_page')
        );
    }

    public function register_settings() {
        register_setting('wc_tpp_settings', 'wc_tpp_enable_tier_pricing');
        register_setting('wc_tpp_settings', 'wc_tpp_enable_package_pricing');
        register_setting('wc_tpp_settings', 'wc_tpp_display_table');
        register_setting('wc_tpp_settings', 'wc_tpp_display_position');
    }

    public function enqueue_admin_scripts($hook) {
        if ('woocommerce_page_wc-tier-package-prices' === $hook || 'post.php' === $hook || 'post-new.php' === $hook) {
            wp_enqueue_style('wc-tpp-admin', WC_TPP_PLUGIN_URL . 'assets/css/admin.css', array(), WC_TPP_VERSION);
            wp_enqueue_script('wc-tpp-admin', WC_TPP_PLUGIN_URL . 'assets/js/admin.js', array('jquery'), WC_TPP_VERSION, true);
        }
    }

    public function settings_page() {
        WC_TPP_Template_Loader::get_instance()->display('admin/settings-page.twig');
    }
}

new WC_TPP_Admin();