add fee for auction winner on checkout

add_action( 'woocommerce_cart_calculate_fees', 'custom_auction_charge' );

function custom_auction_charge( $cart_object ) {

    $spfee = 0.00; // initialize special fee
    $spfeeperprod = 0.20; //special fee per product

    foreach ( $cart_object->cart_contents as $key => $value ) {

        $proid = $value['product_id']; //get the product id from cart
        $quantiy = $value['quantity']; //get quantity from cart
        $product = wc_get_product( $proid  ); //

        if('auction' == $product->get_type()) :

            if ($product->get_auction_closed() == 2){
                    $itmprice = $value['data']->get_auction_current_bid(); //get product price
                    $spfee = $spfee + $itmprice * $quantiy * $spfeeperprod;
            }
        endif;

    }
    if($spfee > 0 ) {
        WC()->cart->add_fee( 'Buyers Premium', $spfee, true, 'standard' );
    }
}