more reliable UP deregistration with proper cross-platform support

lib/controllers/key.dart

@@ -4,6 +4,7 @@ import "package:nexus/controllers/shared_prefs.dart";
 class KeyController(final String key) extends Notifier<String?> {
   static const String spaceKey = "space";
   static const String roomKey = "room";
+  static const String pushKeyKey = "pushKey";
 
   @override
   String? build() =>

lib/controllers/push_key.dart

@@ -0,0 +1,30 @@
+import "dart:convert";
+
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:nexus/controllers/key.dart";
+
+class PushKeyController(final String instance) extends Notifier<String?> {
+  @override
+  String? build() => json.decode(
+    ref.watch(KeyController.provider(KeyController.pushKeyKey)) ?? "{}",
+  )[instance];
+
+  Future<void> set(String? value) async {
+    final provider = KeyController.provider(KeyController.pushKeyKey);
+    final notifier = ref.watch(provider.notifier);
+    final prefs = IMap(json.decode(ref.watch(provider) ?? "{}"));
+
+    state = value;
+    notifier.set(
+      json.encode(
+        prefs.add(instance, value).where((_, value) => value != null),
+      ),
+    );
+  }
+
+  static final provider =
+      NotifierProvider.family<PushKeyController, String?, String>(
+        PushKeyController.new,
+      );
+}

lib/controllers/unified_push.dart

@@ -1,10 +1,12 @@
 import "dart:convert";
 import "dart:io";
 
+import "package:flutter/foundation.dart";
 import "package:flutter_riverpod/flutter_riverpod.dart";
 import "package:intl/intl.dart";
 import "package:nexus/controllers/key.dart";
 import "package:nexus/controllers/notifications.dart";
+import "package:nexus/controllers/push_key.dart";
 import "package:nexus/controllers/rooms.dart";
 import "package:nexus/main.dart";
 import "package:nexus/controllers/client.dart";
@@ -26,7 +28,11 @@ class UnifiedPushController extends AsyncNotifier<bool> {
         storage: UnifiedPushStorageSharedPreferences(),
         background: isInBackground,
       ),
-      onNewEndpoint: (endpoint, instance) => client.registerPusher(
+      onNewEndpoint: (endpoint, instance) async {
+        final pushKey = endpoint.pubKeySet!.pubKey;
+        ref.watch(PushKeyController.provider(instance).notifier).set(pushKey);
+
+        await client.registerPusher(
           .new(
             appDisplayName: "Nexus",
             appId: "nexus.federated.nexus",
@@ -38,9 +44,10 @@ class UnifiedPushController extends AsyncNotifier<bool> {
                 "Nexus on ${toBeginningOfSentenceCase(Platform.operatingSystem)}",
             kind: .webPush,
             lang: "en",
-          pushKey: endpoint.pubKeySet!.pubKey,
-        ),
+            pushKey: pushKey,
           ),
+        );
+      },
       onMessage: (message, instance) async {
         if (message.decrypted == false) {
           throw Exception(
@@ -88,7 +95,12 @@ class UnifiedPushController extends AsyncNotifier<bool> {
         if (isInBackground) exit(0);
       },
       onRegistrationFailed: (error, instance) => throw error,
-      onUnregistered: (instance) => ref.invalidateSelf(),
+      onUnregistered: (instance) async {
+        await ref
+            .watch(PushKeyController.provider(instance).notifier)
+            .set(null);
+        ref.invalidateSelf();
+      },
     );
 
     if (registered) {
@@ -128,17 +140,17 @@ class UnifiedPushController extends AsyncNotifier<bool> {
 
   Future<void> deregister() async {
     final clientState = ref.watch(ClientStateController.provider);
-    final key = await UnifiedPushStorageSharedPreferences().keys.get(
-      clientState!.deviceId!,
-    );
-
-    if (key == null) return;
+    final key = ref.watch(PushKeyController.provider(clientState!.deviceId!));
 
+    if (key != null) {
       await ref
           .watch(ClientController.provider.notifier)
-        .deregisterPusher(
-          .new(appId: "nexus.federated.nexus", pushKey: key.split("=").first),
+          .deregisterPusher(.new(appId: "nexus.federated.nexus", pushKey: key));
+    } else {
+      debugPrint(
+        "No matching pushKey found. Skipping deregistration from homeserver.",
       );
+    }
 
     await UnifiedPush.unregister(clientState.deviceId!);
     ref.invalidateSelf();

lib/controllers/unified_push_allowed.dart

@@ -11,7 +11,7 @@ class UnifiedPushAllowedController extends AsyncNotifier<String?> {
       return "No valid distributors found. Try installing ${Platform.isLinux
           ? "KUnifiedPush"
           : Platform.isAndroid
-          ? "FCM or NTFY"
+          ? "Google Play Services or NTFY"
           : "NTFY"}.";
     }