I'm building an app that would include functionality to allow users to keep track of their visits to a shop. I have a stamp card and the idea is that when the user visits a shop physically and buys something, they can collect a stamp by clicking a button on my app - and my firebase database would update the visitNumber for that shop to increase by 1.
However, to avoid misuse, I want to have some sort of verification mechanism for the shop-owner to confirm that the user has indeed visited. For example, would it be possible for the user to click the stamp, and then the shop-owner would receive an email/text with a link to confirm instantly? Or have the shop give out some unique code that the user can input into the app? If the shop-owner then clicks the link/the code is correct, only then the stamp goes from pending to collected?
Any idea how to implement such functionality that would work real-time? I'm less interested in the UX but more querying if this type of instant third-party verification would be possible to implement.
Thank you!