Refactor notifications processing to use max 3 calls on initial load and streamlined older loading

lib/services/notifications_manager.dart

@@ -71,7 +71,9 @@ class NotificationsManager extends ChangeNotifier {
         .canUseFeature(RelaticaFeatures.usingActualFollowRequests);
     var hasMore = true;
     var first = true;
-    while (hasMore) {
+    const maxCalls = 3;
+    var count = 0;
+    while (hasMore && count < maxCalls) {
       final result =
           first ? await pm.initialize(itemsPerQuery) : await pm.nextFromEnd();
 
@@ -85,6 +87,7 @@ class NotificationsManager extends ChangeNotifier {
               !useActualRequests || n.type != NotificationType.follow_request)
           .forEach(notificationsFromRefresh.add);
       hasMore = response.next != null;
+      count++;
     }
 
     // filter out connection requests if going to use the real service for that when doing the query
@@ -111,7 +114,10 @@ class NotificationsManager extends ChangeNotifier {
           : [
               PagedResponse(
                 <String>[],
-                previous: PagingData(minId: highestId),
+                previous: PagingData(
+                  minId: highestId,
+                  limit: itemsPerQuery,
+                ),
               )
             ],
     );
@@ -130,46 +136,15 @@ class NotificationsManager extends ChangeNotifier {
 
   FutureResult<List<UserNotification>, ExecError> loadOlderNotifications(
       {bool withListenerNotification = true}) async {
-    final (lowestId, _) =
-        read.isNotEmpty ? calcLowHigh(read) : calcLowHigh(unread);
-    final pm = _buildPageManager(
-      profile,
-      true,
-      initialPages: read.isEmpty && unread.isEmpty
-          ? []
-          : [
-              PagedResponse(
-                <String>[],
-                next: PagingData(maxId: lowestId),
-              )
-            ],
-    );
-
-    final notifications = <UserNotification>[];
-    if (read.isEmpty) {
-      var hasReadNotification = false;
-      var hasMorePages = false;
-      do {
-        await (notifications.isEmpty
-                ? pm.initialize(itemsPerQuery)
-                : pm.nextFromEnd())
-            .match(onSuccess: (r) {
-          notifications.addAll(r.data);
-          hasMorePages = r.next != null;
-          hasReadNotification = r.data.map((e) => e.dismissed).firstWhere(
-                (t) => t == true,
-                orElse: () => false,
-              );
-        }, onError: (e) {
-          hasMorePages = false;
-          print('Error getting older notifications: $e');
-        });
-      } while (!hasReadNotification && hasMorePages);
-    } else {
-      await pm.nextFromEnd().withResult((r) => notifications.addAll(r.data));
+    if (unread.isNotEmpty) {
+      final result =
+          await _loadOlderUnreadNotifications(withListenerNotification);
+      if (result.getValueOrElse(() => []).isNotEmpty) {
+        return result;
+      }
     }
 
-    return _postFetchOperations(notifications, withListenerNotification);
+    return _loadOlderReadAndUnreadNotifications(withListenerNotification);
   }
 
   FutureResult<bool, ExecError> markSeen(UserNotification notification) async {
@@ -367,6 +342,67 @@ class NotificationsManager extends ChangeNotifier {
       ..addAll(readMap.values)
       ..sort();
   }
+
+  FutureResult<List<UserNotification>, ExecError> _loadOlderUnreadNotifications(
+      bool withListenerNotification) async {
+    final (lowestId, _) = calcLowHigh(unread);
+    final pm = _buildPageManager(
+      profile,
+      false,
+      initialPages: [
+        PagedResponse(
+          <String>[],
+          next: PagingData(
+            maxId: lowestId,
+            limit: itemsPerQuery,
+          ),
+        )
+      ],
+    );
+
+    final result = await pm
+        .nextFromEnd()
+        .andThenAsync(
+          (page) async =>
+              await _postFetchOperations(page.data, withListenerNotification),
+        )
+        .withError(
+            (error) => _logger.info('Error getting more updates: $error'));
+
+    return result.execErrorCast();
+  }
+
+  FutureResult<List<UserNotification>, ExecError>
+      _loadOlderReadAndUnreadNotifications(
+          bool withListenerNotification) async {
+    final (lowestId, _) =
+        read.isNotEmpty ? calcLowHigh(read) : calcLowHigh(unread);
+    final pm = _buildPageManager(
+      profile,
+      true,
+      initialPages: read.isEmpty && unread.isEmpty
+          ? []
+          : [
+              PagedResponse(
+                <String>[],
+                next: PagingData(
+                  maxId: lowestId,
+                  limit: itemsPerQuery,
+                ),
+              )
+            ],
+    );
+    final result = await (read.isEmpty && unread.isEmpty
+            ? pm.initialize(itemsPerQuery)
+            : pm.nextFromEnd())
+        .andThenAsync(
+          (page) async =>
+              await _postFetchOperations(page.data, withListenerNotification),
+        )
+        .withError(
+            (error) => _logger.info('Error getting more updates: $error'));
+    return result.execErrorCast();
+  }
 }
 
 (int lowest, int highest) calcLowHigh(List<UserNotification> notifications) {