Cleaned up code, implemented message queue to notify subscribers of document updates.

lib/core/notifier/document_changed_notifier.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
+import 'dart:developer';
 
+import 'package:flutter/foundation.dart';
 import 'package:paperless_api/paperless_api.dart';
 import 'package:rxdart/subjects.dart';
 
@@ -9,26 +11,40 @@ class DocumentChangedNotifier {
   final Subject<DocumentModel> _updated = PublishSubject();
   final Subject<DocumentModel> _deleted = PublishSubject();
 
+  final Map<dynamic, List<StreamSubscription>> _subscribers = {};
+
   void notifyUpdated(DocumentModel updated) {
+    debugPrint("Notifying updated document ${updated.id}");
     _updated.add(updated);
   }
 
   void notifyDeleted(DocumentModel deleted) {
+    debugPrint("Notifying deleted document ${deleted.id}");
     _deleted.add(deleted);
   }
 
-  List<StreamSubscription> listen({
+  void subscribe(
+    dynamic subscriber, {
     DocumentChangedCallback? onUpdated,
     DocumentChangedCallback? onDeleted,
   }) {
-    return [
-      _updated.listen((value) {
-        onUpdated?.call(value);
-      }),
-      _updated.listen((value) {
-        onDeleted?.call(value);
-      }),
-    ];
+    _subscribers.putIfAbsent(
+      subscriber,
+      () => [
+        _updated.listen((value) {
+          onUpdated?.call(value);
+        }),
+        _deleted.listen((value) {
+          onDeleted?.call(value);
+        }),
+      ],
+    );
+  }
+
+  void unsubscribe(dynamic subscriber) {
+    _subscribers[subscriber]?.forEach((element) {
+      element.cancel();
+    });
   }
 
   void close() {