In my Drupal Commerce site, I redirect to a local payment API with a custom module after the user selected the local payment gateway in the review order page. The users enter username and password in the local payment website; if the user is authenticated successfully, the payment gateway server redirects back to my localhost at http://localhost/commerce/sites/all/modules/paymentgateway/CheckoutComplete.php.
In that page, the pay button exists; the user has to click the pay button to finish the payment transaction. After finishing payment, I want the server to redirect to Drupal Commerce's checkout complete page, e.g. http://localhost/commerce/checkout/93/complete.
How do I redirect to this link? Do I have to implement a hook?