I am developing an app that allows users to book a chat session with therapists. I have already made the model and it works well but when you only consider one time zone. Currently, I have 20 time slots each representing a specific time. For example, slot 0 => 08:00, slot 1 => 08:45 and so on.. When the user books a session i disable the slot.
Everything works well when both users are in the same time zone, but when they are in different time zones it does not work because the time periods are hardcoded and for example if the timezones is +02:30 from the one where the therapist is, there might not be a time slot that is suited (example 08:30 => 09:15).
I would like some help for how I should structure the data in order to be able to cover the different time zones case. The project is already live and uses firestore, so i need a solution using the same db.