I am writing a android and windows native app. The native app stores the login details as reated for mulitple other web apps, and logs them into this when browsing to them from the native app.

one of the buttons in my app open a prestashop site for a authenticated user. How can i set the username and password and log that user in to the site programmitcally, giving the illusion and user experience that he has been seemlessly authenticated and accessed to his shop.