WordPress Custom REST API Endpoint With JWT Authentication

/**
 * Custom WordPress REST API endpoint with JWT authentication.
 *
 * @param WP_REST_Request $request The request object.
 * @return WP_REST_Response|WP_Error The response or error object.
 * @throws Exception If authentication fails or an error occurs.
 */
function ifci_custom_rest_endpoint( WP_REST_Request $request ) {
    // Check if the request is authenticated
    if ( ! is_user_logged_in() ) {
        return new WP_Error( 'rest_not_authenticated', 'You are not authenticated.', array( 'status' => 401 ) );
    }

    // Validate the request data
    $data = $request->get_json_params();
    if ( empty( $data ) || ! is_array( $data ) ) {
        return new WP_Error( 'rest_invalid_request', 'Invalid request data.', array( 'status' => 400 ) );
    }

    // Verify the JWT token
    $token = $request->get_header( 'Authorization' );
    if ( empty( $token ) ) {
        return new WP_Error( 'rest_missing_token', 'Missing JWT token.', array( 'status' => 401 ) );
    }

    // Authenticate the token
    try {
        $auth = new JWTAuth();
        $user_id = $auth->authenticate( $token );
        if ( ! $user_id ) {
            throw new Exception( 'Invalid token.' );
        }
    } catch ( Exception $e ) {
        return new WP_Error( 'rest_invalid_token', 'Invalid JWT token.', array( 'status' => 401 ) );
    }

    // Process the request
    try {
        // Example processing: retrieve user data
        $user = get_user_by( 'id', $user_id );
        if ( ! $user ) {
            throw new Exception( 'User not found.' );
        }

        $response = array(
            'user_id' => $user->ID,
            'username' => $user->user_login,
        );

        return rest_ensure_response( $response );
    } catch ( Exception $e ) {
        return new WP_Error( 'rest_error', $e->getMessage(), array( 'status' => 500 ) );
    }
}

// Register the custom REST API endpoint
add_action( 'rest_api_init', function () {
    register_rest_route( 'ifci/v1', '/custom', array(
        'methods' => 'GET',
        'callback' => 'ifci_custom_rest_endpoint',
        'permission_callback' => function () {
            return is_user_logged_in();
        },
    ) );
} );