Flutter FCM how to remove the token when user uninstall the app - firebase

Question

I'm developing a Flutter app (using Firebase Firestore and FCM) that aims to send notifications to all devices where the user has signed in. When the user signs out from a device, the token will be removed from Firebase. I am looking for a solution to remove the token when user uninstall the app, and in a way, able to store/update the multiple device tokens for a single user without storing the token based on the android id.
What I am using for sending notification:
final FirebaseMessaging firebaseMessaging = FirebaseMessaging();
Future<Map<String, dynamic>> sendAndRetrieveMessage(context) async {
await firebaseMessaging.requestNotificationPermissions(
const IosNotificationSettings(sound: true, badge: true, alert: true, provisional: false),
);
await http.post(
'https://fcm.googleapis.com/fcm/send',
headers: <String, String>{
'Content-Type': 'application/json',
'Authorization': 'key=$server_token',
},
body: jsonEncode(
<String, dynamic>{
'notification': <String, dynamic>{
'body': '${widget.content}',
'title': '${widget.title}',
},
'priority': 'high',
'data': <String, dynamic>{
'click_action': 'FLUTTER_NOTIFICATION_CLICK',
'status': 'done',
'body': '${widget.content}',
'title': '${widget.title}',
},
'registration_ids': user_tokens,
},
),
).then((http.Response response){
final int statusCode = response.statusCode;
print("RESPONSE BODY: " + response.body);
print("STATUS CODE: " + statusCode.toString());
if (statusCode < 200 || statusCode > 400 || response.body == null) {
throw new Exception("Error while fetching data");
}
});
final Completer<Map<String, dynamic>> completer =
Completer<Map<String, dynamic>>();
firebaseMessaging.configure(
onMessage: (Map<String, dynamic> message) async {
completer.complete(message);
},
onLaunch: (Map<String, dynamic> message) async {
completer.complete(message);
},
onResume: (Map<String, dynamic> message) async {
completer.complete(message);
},
);
return completer.future;
}
I have tried these methods for my notification module:
Update signed-in token in Firebase, but updating only one string also means only sending to the latest signed-in device of the user ignoring the other devices
Subscribe user to user_id topic, but topics are limited to 5 per sending notification. My app needs to send to a list of specific users (undetermined by a common topic, but a set of multiple conditions) and I want to avoid using loops as the notification function needs to work simultaneously for all receiving users
Read HTTP response message to detect failed token, the response returns "NotRegistered" but the response does not return the specific failed token
I would like to know if this is doable in Flutter and if there are solutions/simpler methods for this problem. Thank you