I would like to send a notification to my users if their data (stored in Firestore) fit certain criterias that I want to verify daily. I'm hesitating between two ways:
The first is with a Firebase Function that wouldcheck the data of all my users and send the notification via FCM
The second doing it on the client's side with an AlertManager that would check its own data.
I would tend to choose the latter, I think that a Firebase Functions might hit some limitations after a certain number of users, plus it will be easier to manage different time zones cause it will consider the client's clock. But I'm not sure to consider everything, any hint would be apprecited.
If your decision( fit certain criteria) is based on the local data, then it would be a great idea that you use Notification Builder for showing notifications from the device itself.
But if you have to make a decision( fit certain criteria) on data which is on the server, then FCm would be great.
Check out the link below
https://developer.android.com/reference/android/app/Notification.Builder