Add additional check to a woocommerce snippet - php

Question

Here's my code below which works but it's not yet fully completed. Currently it just checks if an added product in the cart has tech shipping class then apply a static $5 discount. However, what I want to achieve is to add an additional requirement.
Most of my products on my website are with NO set shipping class and the rest are set with 'tech shipping class'. I want to do the following:
The discount of $5 should only be given if the customer add one or more (it doesn't matter) of products with no shipping class assigned to them. Discount should NOT be given if there are only tech shipping class items in the cart. If there are products with no set class and tech shipping class regardless of the quantity of the items then apply a static $5 discount.
It seems unclear to me how to check if cart has other items and more specifically items with NO set class + tech shipping class then to apply that discount..
Any help is greatly appreciated. Thanks!
add_filter( 'woocommerce_package_rates', 'adjustment_in_rates_of_product_with_shipping_class', 12, 2 );
function adjustment_in_rates_of_product_with_shipping_class( $available_shipping_methods, $package ) {
// Shipping class slug to be eligible for a discount
$shipping_class = array(
'tech',
);
// Discount
$discount = 5;
// Enter the Shipping Method Value
$shipping_services = array(
'flat_rate:2',
);
$shipping_class_exists = false;
foreach(WC()->cart->get_cart_contents() as $key => $values) {
if ( in_array($values['data']->get_shipping_class() , $shipping_class) ) {
$shipping_class_exists = true;
break;
}
}
if ($shipping_class_exists) {
foreach ($available_shipping_methods as $key => $value) {
if ( in_array($value->get_id() , $shipping_services) ) {
$available_shipping_methods[$key]->cost -= $discount;
}
}
}
return $available_shipping_methods;
}

Answer 1

Replace this
if ( in_array($values['data']->get_shipping_class() , $shipping_class) )
For
if ( $values['data']->get_shipping_class() == '' )
I think that with this modification your code will check if there is at least one product in the cart without shipping class and in this case apply the discount.