refactor(neon,nextcloud): cleanup PushNotification decryption

Signed-off-by: Nikolas Rimikis <leptopoda@users.noreply.github.com>

packages/neon/neon/lib/src/blocs/push_notifications.dart

@@ -62,7 +62,7 @@ class PushNotificationsBloc extends Bloc implements PushNotificationsBlocEvents,
 
   Future<void> _setupUnifiedPush() async {
     // We just use a single RSA keypair for all accounts
-    final keypair = await PushUtils.loadRSAKeypair();
+    final keypair = PushUtils.loadRSAKeypair();
 
     await UnifiedPush.initialize(
       onNewEndpoint: (final endpoint, final instance) async {

packages/neon/neon/lib/src/models/push_notification.dart

@@ -1,13 +1,26 @@
 import 'package:json_annotation/json_annotation.dart';
 import 'package:meta/meta.dart';
-import 'package:nextcloud/notifications.dart' show DecryptedSubject;
+import 'package:nextcloud/notifications.dart' as notifications;
 
 part 'push_notification.g.dart';
 
+/// The json key for [PushNotification.accountID].
+const String _accountIDKey = 'accountID';
+
+/// The json key for [PushNotification.priority].
+const String _priorityKey = 'priority';
+
+/// The json key for [PushNotification.type].
+const String _typeKey = 'type';
+
+/// The json key for [PushNotification.subject].
+const String _subjectKey = 'subject';
+
+/// Data for a push notification.
 @JsonSerializable()
-@immutable
 @internal
 class PushNotification {
+  /// Creates a new push notification.
   const PushNotification({
     required this.accountID,
     required this.priority,
@@ -15,14 +28,44 @@ class PushNotification {
     required this.subject,
   });
 
+  /// Creates a new PushNotification object from the given [json] data.
+  ///
+  /// Use [PushNotification.fromEncrypted] when you the [subject] is still encrypted.
   factory PushNotification.fromJson(final Map<String, dynamic> json) => _$PushNotificationFromJson(json);
+
+  /// Creates a new PushNotification object from the given [json] data containing an encrypted [subject].
+  ///
+  /// Use [PushNotification.fromJson] when the [subject] is not encrypted.
+  factory PushNotification.fromEncrypted(
+    final Map<String, dynamic> json,
+    final notifications.RSAPrivateKey privateKey,
+  ) {
+    final subject = notifications.decryptPushNotificationSubject(privateKey, json[_subjectKey] as String);
+
+    return PushNotification(
+      accountID: json[_accountIDKey] as String,
+      priority: json[_priorityKey] as String,
+      type: json[_typeKey] as String,
+      subject: subject,
+    );
+  }
+
+  /// Parses this object into a json like map.
   Map<String, dynamic> toJson() => _$PushNotificationToJson(this);
 
+  /// The account associated to this notification.
+  @JsonKey(name: _accountIDKey)
   final String accountID;
 
+  /// The priority of the notification.
+  @JsonKey(name: _priorityKey)
   final String priority;
 
+  /// The type of the notification.
+  @JsonKey(name: _typeKey)
   final String type;
 
-  final DecryptedSubject subject;
+  /// The subject of this notification.
+  @JsonKey(name: _subjectKey)
+  final notifications.DecryptedSubject subject;
 }

packages/neon/neon/lib/src/utils/push_utils.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:ui';
 
@@ -23,17 +24,17 @@ import 'package:nextcloud/notifications.dart' as notifications;
 class PushUtils {
   const PushUtils._();
 
-  static Future<notifications.RSAKeypair> loadRSAKeypair() async {
+  static notifications.RSAKeypair loadRSAKeypair() {
     const storage = AppStorage(StorageKeys.notifications);
     const keyDevicePrivateKey = 'device-private-key';
 
-    late notifications.RSAKeypair keypair;
+    final notifications.RSAKeypair keypair;
-    if (!storage.containsKey(keyDevicePrivateKey) || (storage.getString(keyDevicePrivateKey)?.isEmpty ?? true)) {
+    if (!storage.containsKey(keyDevicePrivateKey) || (storage.getString(keyDevicePrivateKey)!.isEmpty)) {
       debugPrint('Generating RSA keys for push notifications');
       // The key size has to be 2048, other sizes are not accepted by Nextcloud (at the moment at least)
       // ignore: avoid_redundant_argument_values
       keypair = notifications.RSAKeypair.fromRandom(keySize: 2048);
-      await storage.setString(keyDevicePrivateKey, keypair.privateKey.toPEM());
+      unawaited(storage.setString(keyDevicePrivateKey, keypair.privateKey.toPEM()));
     } else {
       keypair = notifications.RSAKeypair(notifications.RSAPrivateKey.fromPEM(storage.getString(keyDevicePrivateKey)!));
     }
@@ -74,16 +75,10 @@ class PushUtils {
     );
     await NeonStorage.init();
 
-    final keypair = await loadRSAKeypair();
+    final keypair = loadRSAKeypair();
-
     for (final message in Uri(query: utf8.decode(messages)).queryParameters.values) {
       final data = json.decode(message) as Map<String, dynamic>;
-      final pushNotification = PushNotification(
+      final pushNotification = PushNotification.fromEncrypted(data, keypair.privateKey);
-        accountID: instance,
-        priority: data['priority']! as String,
-        type: data['type']! as String,
-        subject: notifications.decryptPushNotificationSubject(keypair.privateKey, data['subject']! as String),
-      );
 
       if (pushNotification.subject.delete ?? false) {
         await localNotificationsPlugin.cancel(_getNotificationID(instance, pushNotification));