<?php

function restrict_aga_cd_test_login($user, $username, $password) {

    if ( is_wp_error( $user ) ) {
        return $user;
    }

    if ( ! function_exists( 'wpf_has_tag' ) ) {
        return new WP_Error( 'error', __( 'WP Fusion does not exist.' ) );
    }

    if ( ! wpf_get_contact_id( $user->ID ) ) {
        return new WP_Error( 'authentication_failed', __( 'No Dynamics contact record for the user.' ) );
    }

    if ( ! wpf_has_tag( 'Aga CD Test', $user->ID ) ) {
        return new WP_Error( 'authentication_failed', __( 'Your account is restricted. Please contact support.' ) );
    }

    return $user;
}

add_filter( 'wp_authenticate_user', 'restrict_aga_cd_test_login', 10, 3 );