Code-Snippets-Functions/Execute a function on a child site/WooCommerce/display-a-notice-in-checkout-if-a-subscription-item-is-in-cart-for-an-active-subscriber.txt

// Conditional function: Check if a user has active subscriptions
function has_active_subscriptions( $user_id = 0 ) {
    return wcs_user_has_subscription( $user_id > 0?:get_current_user_id(), '', 'active' );
}

// Conditional function: Check if a user has a subscription product in cart
function has_subscription_in_cart( $cart_contents = null ) {
    foreach ( $cart_contents?:WC()->cart->get_cart() as $item ) {
        if ( $item['data']->is_type( array('subscription', 'subscription_variation') ) ) {
            return true;
        }
    }
    return false;
}

// Display a notice in checkout conditionally
add_action( 'template_redirect', 'display_checkout_subscription_notice' );
function display_checkout_subscription_notice() {
    if ( is_checkout() && ! is_wc_endpoint_url() && has_active_subscriptions() && has_subscription_in_cart() ) {
        wc_add_notice( __('By purchasing a new subscription you will cancel your current active one.'), 'notice' );
    }
}