Moving from billing to pay in 1 step for orders with just a download.

ajax_handlers.php

<?

function download_only_on_process_billing_address_place_order_and_pay($controller, $page, $params)
{

  if (post('ship_to_billing_address'))
  {
    Shop_CheckoutData::copy_billing_to_shipping();
    $controller->action();
  }
  
  Shop_CheckoutData::set_payment_method(Shop_PaymentMethod::find_by_api_code('default')->id);
 
  // Call the default action handler
  $controller->action();

  // Pretend that we are on the Review checkout step
  // to force LemonStand to place the order
  $_POST['checkout_step'] = 'review';
  $controller->action();
}

?>

shopcheckout_billing_info.php

<div class="copyBillingToShipping">
    <input type="checkbox" name="ship_to_billing_address" value="1" checked />
    <label for="Ship to the billing address">Ship to the billing address</label>
 </div>

<? if (!$shipping_required): ?>

<style type="text/css">.copyBillingToShipping { visibility: hidden;}</style>
<button class="button" onclick="return $(this).getForm().sendRequest('download_only_on_process_billing_address_place_order_and_pay', {update:{'checkout_page': 'checkout_partial'}})">Next</button>

<? else: ?>

<button class="button" onclick="return $(this).getForm().sendRequest('on_process_billing_address', {update:{'checkout_page': 'checkout_partial'}})">Next</button>

<? endif ?>