Display subtotal include discount

Hi, I have been trying to make this happen, I was close to achieving it but it occurred some bugs when there is tax included.

So I’m looking to display a “Subtotal after discount” so our accountant can easily see the real subtotal include discount but without tax.

Here is the screenshot for the one I’m currently having.
https://gyazo.com/5e3d0be662df50e6b9bb5870555124d1

So the ‘Subtotal Discounted’ section displays incorrect number when there is tax including in this order.

Here is my code so far:
/**
* Show discounted subtotal in pdf
*/
add_filter( ‘wpo_wcpdf_woocommerce_totals’, ‘add_discounted_subtotal_to_pdf_invoices’, 10, 2 );
function add_discounted_subtotal_to_pdf_invoices( $totals, $order ) {
// Get ‘subtotal’ raw amount value
$subtotal = strip_tags($totals[‘cart_subtotal’][‘value’]);
$subtotal = (float) preg_replace(‘/[^0-9.]+/’, ”, $subtotal);

// Get ‘discount’ raw amount value
$discount = strip_tags($totals[‘discount’][‘value’]);
$discount = (float) preg_replace(‘/[^0-9.]+/’, ”, $discount);

$new_totals = array();
// Loop through totals lines
foreach( $totals as $key => $values ){
$new_totals[$key] = $totals[$key];
// Inset new calculated ‘Subtotal discounted’ after total discount
if( $key == ‘discount’ && $discount != 0 && !empty($discount) ){
$new_totals[‘subtotal_discounted’] = array(
‘label’ => __(‘Subtotal Discounted’, ‘wpo_wcpdf’),
‘value’ => wc_price($subtotal – $discount)
);
}
}
return $new_totals;
}

Is there anyway to fix it? Any help will be appreciated.