// Auto-complete virtual orders if payment is completed by u/acephaliax
function auto_complete_virtual_orders($order_id) {
    if (!$order_id) {
        return;
    }

    // Get the order object
    $order = wc_get_order($order_id);

    // Check if the order contains virtual products
    $contains_virtual = false;

    foreach ($order->get_items() as $item) {
        $product = $item->get_product();
        if ($product && $product->is_virtual()) {
            $contains_virtual = true;
            break;
        }
    }

    // Check if the payment is completed
    $payment_completed = $order->is_paid();

    // If the order contains virtual products and the payment is completed, auto-complete it
    if ($contains_virtual && $payment_completed) {
        $order->update_status('completed');
    }
}
add_action('woocommerce_order_status_changed', 'auto_complete_virtual_orders', 10, 3);