WooCommerce: How to add checkout payment Fee for a specific payment gateway

/**
 * @snippet       How to add checkout payment Fee for a specific payment gateway - WooCommerce
 */
  
// Step 1: Define Fee
  
add_action( 'woocommerce_cart_calculate_fees', 'mycode_add_checkout_fee' );
  
function mycode_add_checkout_fee() {
    $chosen_gateway = WC()->session->get( 'chosen_payment_method' );
    if ( $chosen_gateway == 'your-payment-gatway' ) {
       WC()->cart->add_fee( 'Payment Gateway Fee', 3 );
    }
}
  
// Part 2: Reload checkout page after select the payment gateway
  
add_action( 'woocommerce_review_order_before_payment', 'mycode_refresh_checkoutpage' );
  
function mycode_refresh_checkoutpage(){
    ?>
    <script type="text/javascript">
        (function($){
            $( 'form.checkout' ).on( 'change', 'input[name^="payment_method"]', function() {
                $('body').trigger('update_checkout');
            });
        })(jQuery);
    </script>
    <?php
}