Custom Endpoints to Fetch Learndash Courses and Users Information for a LD Group

csldapi.php

<?php
/**
 * Plugin Name: Custom LD Rest API
 * Plugin URI: https://elearningevolve.com/
 * Description: Provides custom REST API endpoints utilizing LearnDash
 * Version: 1.0.0
 * Author: eLearning evolve
 * Author URI: https://elearningevolve.com/
 * License: GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 * Text Domain: custom-ld-rest-api
 * Domain Path: /languages
 *
 * @package Custom_LD_Rest_API
 */

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

// Define plugin constants.
define( 'CSLDAPI_VERSION', '1.0.0' );
define( 'CSLDAPI_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
define( 'CSLDAPI_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
define( 'CSLDAPI_PLUGIN_BASENAME', plugin_basename( __FILE__ ) );

if ( ! class_exists( 'Custom_LD_Rest_API' ) ) :

	/**
	 * Main plugin class.
	 */
	class Custom_LD_Rest_API {

		/**
		 * Instance of this class.
		 *
		 * @var Custom_LD_Rest_API
		 */
		protected static $instance = null;

		/**
		 * Initialize the plugin.
		 */
		public function __construct() {
			add_action( 'plugins_loaded', array( $this, 'init' ) );
		}

		/**
		 * Get an instance of this class.
		 *
		 * @return Custom_LD_Rest_API A single instance of this class.
		 */
		public static function get_instance() {
			if ( null === self::$instance ) {
				self::$instance = new self();
			}
			return self::$instance;
		}

		/**
		 * Initialize the plugin.
		 */
		public function init() {
			if ( ! $this->is_learndash_active() ) {
				add_action( 'admin_notices', array( $this, 'learndash_missing_notice' ) );
				return;
			}

			add_action( 'rest_api_init', array( $this, 'register_endpoints' ) );
		}

		/**
		 * Check if LearnDash is active.
		 *
		 * @return bool True if LearnDash is active, false otherwise.
		 */
		private function is_learndash_active() {
			return class_exists( 'SFWD_LMS' );
		}

		/**
		 * Display admin notice if LearnDash is not active.
		 */
		public function learndash_missing_notice() {
			?>
			<div class="notice notice-error">
				<p><?php esc_html_e( 'Custom LD Rest API requires LearnDash to be installed and activated.', 'custom-ld-rest-api' ); ?></p>
			</div>
			<?php
		}

		/**
		 * Register endpoints for API.
		 */
		public function register_endpoints() {
			register_rest_route(
				'csldapi/v1',
				'/groups/(?P<group_id>\d+)/courses',
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'display_courses' ),
					'permission_callback' => array( $this, 'permissions_check' ),
					'args'                => array(
						'group_id' => array(
							'validate_callback' => array( $this, 'validate_group_id' ),
						),
					),
				)
			);

			register_rest_route(
				'csldapi/v1',
				'/groups/(?P<group_id>\d+)/users',
				array(
					'methods'             => WP_REST_Server::READABLE,
					'callback'            => array( $this, 'display_users' ),
					'permission_callback' => array( $this, 'permissions_check' ),
					'args'                => array(
						'group_id' => array(
							'validate_callback' => array( $this, 'validate_group_id' ),
						),
					),
				)
			);
		}

		/**
		 * Check permissions for API.
		 *
		 * @param WP_REST_Request $request The request object.
		 * @return true|WP_Error True if the request has access, WP_Error otherwise.
		 */
		public function permissions_check( $request ) {
			if ( ! $this->validate_group_id( $request['group_id'] ) ) {
				return new WP_Error(
					'rest_invalid_group_id',
					esc_html__( 'Invalid group ID. Please provide a valid positive integer.', 'custom-ld-rest-api' ),
					array( 'status' => 400 )
				);
			}

			$group_id        = (int) $request['group_id'];
			$current_user_id = get_current_user_id();
			$group_leaders   = learndash_get_groups_administrator_ids( $group_id );

			if ( in_array( $current_user_id, $group_leaders, true ) || current_user_can( 'manage_options' ) ) {
				return true;
			}

			return new WP_Error(
				'rest_forbidden',
				esc_html__( 'You do not have permission to access this group.', 'custom-ld-rest-api' ),
				array( 'status' => 403 )
			);
		}

		/**
		 * Gets the list of associated courses.
		 *
		 * @param WP_REST_Request $request The request object.
		 * @return WP_REST_Response|WP_Error The list of courses or WP_Error on failure.
		 */
		public function display_courses( $request ) {
			$group_id   = (int) $request['group_id'];
			$course_ids = learndash_group_enrolled_courses( $group_id );
			$courses    = array();

			foreach ( $course_ids as $course_id ) {
				$courses[] = array(
					'course_id'    => $course_id,
					'course_title' => get_the_title( $course_id ),
				);
			}

			return rest_ensure_response( $courses );
		}

		/**
		 * Get the list of users.
		 *
		 * @param WP_REST_Request $request The request object.
		 * @return WP_REST_Response|WP_Error The list of users or WP_Error on failure.
		 */
		public function display_users( $request ) {
			$group_id  = (int) $request['group_id'];
			$user_ids  = learndash_get_groups_user_ids( $group_id );
			$user_info = array();

			foreach ( $user_ids as $user_id ) {
				$user_data   = get_userdata( $user_id );
				$user_info[] = array(
					'user_id'   => $user_id,
					'user_name' => $user_data->user_login,
				);
			}

			return rest_ensure_response( $user_info );
		}

		/**
		 * Validate group ID.
		 *
		 * @param mixed $param The value to validate.
		 * @return bool|WP_Error True if the parameter is a valid group ID, WP_Error otherwise.
		 */
		public function validate_group_id( $param ) {
			$group_id = (int) $param;

			if ( ! $group_id || ! get_post( $group_id ) ) {
				return new WP_Error(
					'rest_invalid_param',
					esc_html__( 'Invalid group ID.', 'custom-ld-rest-api' ),
					array( 'status' => 404 )
				);
			}

			return true;
		}
	}

endif;

/**
 * Returns the main instance of Custom_LD_Rest_API.
 *
 * @return Custom_LD_Rest_API
 */
function custom_ld_rest_api() {
	return Custom_LD_Rest_API::get_instance();
}

// Initialize the plugin.
custom_ld_rest_api();