Refactor message cache handling

lib/api_client.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:convert';
+import 'package:contacts_plus_plus/neos_hub.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_secure_storage/flutter_secure_storage.dart';
@@ -124,9 +125,13 @@ class ApiClient {
 
 class ClientHolder extends InheritedWidget {
   final ApiClient client;
+  late final NeosHub hub;
 
   ClientHolder({super.key, required AuthenticationData authenticationData, required super.child})
-      : client = ApiClient(authenticationData: authenticationData);
+      : client = ApiClient(authenticationData: authenticationData) {
+    hub = NeosHub(apiClient: client);
+  }
+
 
   static ClientHolder? maybeOf(BuildContext context) {
     return context.dependOnInheritedWidgetOfExactType<ClientHolder>();

lib/auxiliary.dart

@@ -53,3 +53,13 @@ class Aux {
     return fullUri;
   }
 }
+
+
+extension Unique<E, Id> on List<E> {
+  List<E> unique([Id Function(E element)? id, bool inplace = true]) {
+    final ids = <Id>{};
+    var list = inplace ? this : List<E>.from(this);
+    list.retainWhere((x) => ids.add(id != null ? id(x) : x as Id));
+    return list;
+  }
+}

lib/main.dart

@@ -1,5 +1,3 @@
-import 'package:contacts_plus_plus/models/message.dart';
-import 'package:contacts_plus_plus/neos_hub.dart';
 import 'package:contacts_plus_plus/widgets/home_screen.dart';
 import 'package:contacts_plus_plus/widgets/login_screen.dart';
 import 'package:flutter/material.dart';
@@ -20,14 +18,10 @@ class ContactsPlusPlus extends StatefulWidget {
 class _ContactsPlusPlusState extends State<ContactsPlusPlus> {
   final Typography _typography = Typography.material2021(platform: TargetPlatform.android);
   AuthenticationData _authData = AuthenticationData.unauthenticated();
-  final Map<String, MessageCache> _messageCache = {};
 
   @override
   Widget build(BuildContext context) {
-    return HubHolder(
+    return ClientHolder(
-      messageCache: _messageCache,
-      authenticationData: _authData,
-      child: ClientHolder(
       authenticationData: _authData,
       child: MaterialApp(
         debugShowCheckedModeBanner: false,
@@ -49,7 +43,6 @@ class _ContactsPlusPlusState extends State<ContactsPlusPlus> {
           },
         ),
       ),
-      ),
     );
   }
 }

lib/models/message.dart

@@ -1,6 +1,9 @@
 import 'dart:async';
 import 'dart:developer';
 
+import 'package:contacts_plus_plus/api_client.dart';
+import 'package:contacts_plus_plus/apis/message_api.dart';
+import 'package:contacts_plus_plus/auxiliary.dart';
 import 'package:contacts_plus_plus/config.dart';
 import 'package:uuid/uuid.dart';
 
@@ -95,10 +98,54 @@ class Message extends Comparable {
 }
 
 class MessageCache {
-  final List<Message> _messages;
+  final List<Message> _messages = [];
+  final ApiClient _apiClient;
+  final String _userId;
+  Future? currentOperation;
 
   List<Message> get messages => _messages;
 
-  MessageCache({required List<Message> messages})
+  MessageCache({required ApiClient apiClient, required String userId}) : _apiClient = apiClient, _userId = userId;
-      : _messages = messages;
+
+  /// Adds a message to the cache, ensuring integrity of the message cache.
+  /// Returns true if the message was inserted into the cache and false if an existing message was overwritten.
+  bool addMessage(Message message) {
+    final existingIdx = _messages.indexWhere((element) => element.id == message.id);
+    if (existingIdx == -1) {
+      _messages.add(message);
+      _ensureIntegrity();
+    } else {
+      _messages[existingIdx] = message;
+      _messages.sort(); // Overwriting can't create duplicates, so we just need to sort.
+    }
+    return existingIdx == -1;
+  }
+
+  /// Sets the state of an existing message by id.
+  /// Returns true if a message with the specified id exists and was modified and false if the message doesn't exist.
+  bool setMessageState(String messageId, MessageState state) {
+    final messageIdx = _messages.indexWhere((element) => element.id == messageId);
+    if (messageIdx == -1) return false;
+    _messages[messageIdx] = _messages[messageIdx].copyWith(state: state);
+    return true;
+  }
+
+  Future<void> loadOlderMessages() async {
+    final oldest = _messages.first;
+    final olderMessages = await MessageApi.getUserMessages(_apiClient, userId: _userId, fromTime: oldest.sendTime);
+    _messages.insertAll(0, olderMessages);
+    _ensureIntegrity();
+  }
+
+  Future<void> loadInitialMessages() async {
+    final messages = await MessageApi.getUserMessages(_apiClient, userId: _userId);
+    _messages.clear();
+    _messages.addAll(messages);
+    _ensureIntegrity();
+  }
+
+  void _ensureIntegrity() {
+    _messages.sort();
+    _messages.unique((element) => element.id);
+  }
 }

lib/neos_hub.dart

@@ -1,7 +1,6 @@
 
 import 'dart:convert';
 import 'dart:developer';
-import 'package:contacts_plus_plus/models/authentication_data.dart';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart' as http;
 
@@ -32,30 +31,34 @@ enum EventTarget {
 class NeosHub {
   static const String eofChar = "";
   static const String _negotiationPacket = "{\"protocol\":\"json\", \"version\":1}$eofChar";
-  final AuthenticationData _authenticationData;
+  final ApiClient _apiClient;
-  final Map<String, MessageCache> _messageCache;
+  final Map<String, MessageCache> _messageCache = {};
   final Map<String, Function> _updateListeners = {};
   WebSocketChannel? _wsChannel;
 
-  NeosHub({required AuthenticationData authenticationData, required Map<String, MessageCache> messageCache})
+  NeosHub({required ApiClient apiClient})
-      : _authenticationData = authenticationData, _messageCache = messageCache {
+      : _apiClient = apiClient {
     start();
   }
 
-  MessageCache? getCache(String index) => _messageCache[index];
+  Future<MessageCache> getCache(String userId) async {
-
+    var cache = _messageCache[userId];
-  void setCache(String index, List<Message> messages) {
+    if (cache == null){
-    _messageCache[index] = MessageCache(messages: messages);
+      cache = MessageCache(apiClient: _apiClient, userId: userId);
+      await cache.loadInitialMessages();
+      _messageCache[userId] = cache;
+    }
+    return cache;
   }
 
   Future<void> start() async {
-    if (!_authenticationData.isAuthenticated) {
+    if (!_apiClient.isAuthenticated) {
       log("Hub not authenticated.");
       return;
     }
     final response = await http.post(
       Uri.parse("${Config.neosHubUrl}/negotiate"),
-      headers: _authenticationData.authorizationHeader,
+      headers: _apiClient.authorizationHeader,
     );
 
     ApiClient.checkResponse(response);
@@ -94,7 +97,7 @@ class NeosHub {
     }
   }
 
-  void _handleMessageEvent(body) {
+  void _handleMessageEvent(body) async {
     final target = EventTarget.parse(body["target"]);
     final args = body["arguments"];
     switch (target) {
@@ -104,49 +107,30 @@ class NeosHub {
       case EventTarget.messageSent:
         final msg = args[0];
         final message = Message.fromMap(msg, withState: MessageState.sent);
-        var cache = getCache(message.recipientId);
+        final cache = await getCache(message.recipientId);
-        if (cache == null) {
+        cache.addMessage(message);
-          setCache(message.recipientId, [message]);
-        } else {
-          // Possible race condition
-          final existingIndex = cache.messages.indexWhere((element) => element.id == message.id);
-          if (existingIndex == -1) {
-            cache.messages.add(message);
-          } else {
-            cache.messages[existingIndex] = message;
-          }
-          cache.messages.sort();
-        }
         notifyListener(message.recipientId);
         break;
       case EventTarget.messageReceived:
         final msg = args[0];
         final message = Message.fromMap(msg);
-        var cache = getCache(message.senderId);
+        final cache = await getCache(message.senderId);
-        if (cache == null) {
+        cache.addMessage(message);
-          setCache(message.senderId, [message]);
-        } else {
-          cache.messages.add(message);
-          cache.messages.sort();
-        }
         notifyListener(message.senderId);
         break;
       case EventTarget.messagesRead:
         final messageIds = args[0]["ids"] as List;
         final recipientId = args[0]["recipientId"];
-        final cache = getCache(recipientId ?? "");
+        final cache = await getCache(recipientId ?? "");
-        if (cache == null) return;
         for (var id in messageIds) {
-          final idx = cache.messages.indexWhere((element) => element.id == id);
+          cache.setMessageState(id, MessageState.read);
-          if (idx == -1) continue;
-          cache.messages[idx] = cache.messages[idx].copyWith(state: MessageState.read);
         }
         notifyListener(recipientId);
         break;
     }
   }
 
-  void sendMessage(Message message) {
+  void sendMessage(Message message) async {
     if (_wsChannel == null) throw "Neos Hub is not connected";
     final msgBody = message.toMap();
     final data = {
@@ -156,35 +140,9 @@ class NeosHub {
         msgBody
       ],
     };
-    _wsChannel!.sink.add(jsonEncode(data)+eofChar);
+    final cache = await getCache(message.recipientId);
-    var cache = _messageCache[message.recipientId];
-    if (cache == null) {
-      setCache(message.recipientId, [message]);
-      cache = getCache(message.recipientId);
-    } else {
     cache.messages.add(message);
-    }
+    _wsChannel!.sink.add(jsonEncode(data)+eofChar);
     notifyListener(message.recipientId);
   }
 }
-
-class HubHolder extends InheritedWidget {
-  HubHolder({super.key, required AuthenticationData authenticationData, required Map<String, MessageCache> messageCache, required super.child})
-      : hub = NeosHub(authenticationData: authenticationData, messageCache: messageCache);
-
-  final NeosHub hub;
-
-  static HubHolder? maybeOf(BuildContext context) {
-    return context.dependOnInheritedWidgetOfExactType<HubHolder>();
-  }
-
-  static HubHolder of(BuildContext context) {
-    final HubHolder? result = maybeOf(context);
-    assert(result != null, 'No HubHolder found in context');
-    return result!;
-  }
-
-  @override
-  bool updateShouldNotify(covariant HubHolder oldWidget) => hub._authenticationData != oldWidget.hub._authenticationData
-      || hub._messageCache != oldWidget.hub._messageCache;
-}

lib/widgets/messages.dart

@@ -1,14 +1,11 @@
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:contacts_plus_plus/api_client.dart';
-import 'package:contacts_plus_plus/apis/message_api.dart';
 import 'package:contacts_plus_plus/auxiliary.dart';
 import 'package:contacts_plus_plus/models/friend.dart';
 import 'package:contacts_plus_plus/models/message.dart';
 import 'package:contacts_plus_plus/models/session.dart';
-import 'package:contacts_plus_plus/neos_hub.dart';
 import 'package:contacts_plus_plus/widgets/generic_avatar.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
 import 'package:intl/intl.dart';
 
 class Messages extends StatefulWidget {
@@ -21,54 +18,34 @@ class Messages extends StatefulWidget {
 }
 
 class _MessagesState extends State<Messages> {
-  Future<Iterable<Message>>? _messagesFuture;
+  Future<MessageCache>? _messageCacheFuture;
   final TextEditingController _messageTextController = TextEditingController();
   final ScrollController _sessionListScrollController = ScrollController();
   ClientHolder? _clientHolder;
-  HubHolder? _cacheHolder;
 
   bool _isSendable = false;
   bool _showSessionListChevron = false;
   double get _shevronOpacity => _showSessionListChevron ? 1.0 : 0.0;
 
-  void _loadMessages() {
-    final cache = _cacheHolder?.hub.getCache(widget.friend.id);
-    if (cache != null) {
-      _messagesFuture = Future(() => cache.messages);
-    } else {
-      _messagesFuture = MessageApi.getUserMessages(
-          _clientHolder!.client, userId: widget.friend.id)
-        ..then((value) {
-          final list = value.toList();
-          list.sort();
-          _cacheHolder?.hub.setCache(widget.friend.id, list);
-          _cacheHolder?.hub.registerListener(
-              widget.friend.id, () => setState(() {}));
-          return list;
-        });
-    }
-  }
-
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
     final clientHolder = ClientHolder.of(context);
-    bool dirty = false;
     if (_clientHolder != clientHolder) {
       _clientHolder = clientHolder;
-      dirty = true;
     }
-    final cacheHolder = HubHolder.of(context);
+    _loadMessages();
-    if (_cacheHolder != cacheHolder) {
-      _cacheHolder = cacheHolder;
-      dirty = true;
   }
-    if (dirty) _loadMessages();
+
+  void _loadMessages() {
+    _messageCacheFuture = _clientHolder?.hub.getCache(widget.friend.id);
+    _clientHolder?.hub.registerListener(
+        widget.friend.id, () => setState(() {}));
   }
 
   @override
   void dispose() {
-    _cacheHolder?.hub.unregisterListener(widget.friend.id);
+    _clientHolder?.hub.unregisterListener(widget.friend.id);
     _messageTextController.dispose();
     _sessionListScrollController.dispose();
     super.dispose();
@@ -107,52 +84,19 @@ class _MessagesState extends State<Messages> {
         title: Text(widget.friend.username),
         scrolledUnderElevation: 0.0,
         backgroundColor: appBarColor,
-        /*bottom: sessions.isEmpty ? null : PreferredSize(
-          preferredSize: Size.fromHeight(_headerHeight),
-          child: Column(
-            children: sessions.getRange(0, _headerExpanded ? sessions.length : 1).map((e) => Row(
-              mainAxisSize: MainAxisSize.max,
-              mainAxisAlignment: MainAxisAlignment.start,
-              children: [
-                Padding(
-                  padding: const EdgeInsets.all(8.0),
-                  child: GenericAvatar(imageUri: Aux.neosDbToHttp(e.thumbnail),),
-                ),
-                Expanded(
-                  child: Column(
-                    mainAxisAlignment: MainAxisAlignment.spaceEvenly,
-                    crossAxisAlignment: CrossAxisAlignment.start,
-                    children: [
-                      Text(e.name),
-                      Text("${e.sessionUsers.length} users active"),
-                    ],
-                  ),
-                ),
-                const Spacer(),
-                if (sessions.length > 1) TextButton(onPressed: (){
-                  setState(() {
-                    _headerExpanded = !_headerExpanded;
-                  });
-                }, child: Text("+${sessions.length-1}"),)
-              ],
-            )).toList(),
-          ),
-        ),*/
       ),
       body: Stack(
         children: [
           FutureBuilder(
-            future: _messagesFuture,
+            future: _messageCacheFuture,
             builder: (context, snapshot) {
               if (snapshot.hasData) {
-                final data = _cacheHolder?.hub
+                final cache = snapshot.data as MessageCache;
-                    .getCache(widget.friend.id)
-                    ?.messages ?? [];
                 return ListView.builder(
                   reverse: true,
-                  itemCount: data.length,
+                  itemCount: cache.messages.length,
                   itemBuilder: (context, index) {
-                    final entry = data.elementAt(index);
+                    final entry = cache.messages[index];
                     return entry.senderId == apiClient.userId
                         ? MyMessageBubble(message: entry)
                         : OtherMessageBubble(message: entry);
@@ -298,7 +242,7 @@ class _MessagesState extends State<Messages> {
                 padding: const EdgeInsets.only(left: 8, right: 4.0),
                 child: IconButton(
                   splashRadius: 24,
-                  onPressed: _isSendable ? () async {
+                  onPressed: _isSendable && _clientHolder != null ? () async {
                     setState(() {
                       _isSendable = false;
                     });
@@ -311,10 +255,7 @@ class _MessagesState extends State<Messages> {
                       sendTime: DateTime.now().toUtc(),
                     );
                     try {
-                      if (_cacheHolder == null) {
+                      _clientHolder!.hub.sendMessage(message);
-                        throw "Hub not connected.";
-                      }
-                      _cacheHolder!.hub.sendMessage(message);
                       _messageTextController.clear();
                       setState(() {});
                     } catch (e) {