Stock availability

Hello,
I have following code that adds a simple notice about stock availability and shipping into product on shop/archive page, but in case when product stock quantity is 0 (is out of stock) notice is not showing up. Can someone help? Thanks a lot.

add_action( 'woocommerce_after_shop_loop_item','show_stock_shop', 90 );

function show_stock_shop() {
    global $product;

    $regular = $product->regular_price;
    $sale = $product->sale_price;
//  $stock = the_field('stock-available');

    if ( $product->stock ) { // if manage stock is enabled 
        if ( $product->get_stock_quantity() > 0 && $regular >= 500 || $sale >= 500  ) { // in stock, free shipping
            echo '<div class="remaining text-center pt-2 pb-2">Skladom. <span class="doprava-zadarmo">Doprava zadarmo</span></div>';
        } elseif ( $product->get_stock_quantity() == 0 && $regular >= 500 || $sale >= 500 ) { // out of stock, free shipping
            echo '<div class="remaining text-center pt-2 pb-2"><s>(nie je skladom)</s>. <span class="doprava-zadarmo">Doprava zadarmo</span></div>';
        } elseif ( $product->get_stock_quantity() > 0 && $regular < 500 || $sale < 500 ) { // in stock, not free shipping
            echo '<div class="remaining text-center pt-2 pb-2">Skladom. <span class="doprava-zadarmo">Doprava zadarmo od 500 eur</span></div>';
        } elseif ( $product->get_stock_quantity() == 0 && $regular < 500 || $sale < 500 ) { // out of stock, not free shipping
            echo '<div class="remaining text-center pt-2 pb-2"><s>(nie je skladom)</s>. <span class="doprava-zadarmo">Doprava zadarmo od 500 eur</span></div>';
        } else {
            echo '<div class="remaining text-center pt-2 pb-2">Do ' . /*$stock .*/ ' dní</div>'; 
        }
    }
}