load old messages

lib/controllers/events_controller.dart

@@ -0,0 +1,30 @@
+import "package:flutter_riverpod/flutter_riverpod.dart";
+import "package:matrix/matrix.dart";
+import "package:nexus/controllers/from_controller.dart";
+
+class EventsController extends AsyncNotifier<GetRoomEventsResponse> {
+  EventsController(this.room);
+  final Room room;
+
+  @override
+  Future<GetRoomEventsResponse> build({String? from}) async {
+    final response = await room.client.getRoomEvents(
+      room.id,
+      Direction.b,
+      from: from,
+      limit: 32,
+    );
+    ref.watch(FromController.provider(room).notifier).set(response.end);
+    return response;
+  }
+
+  Future<GetRoomEventsResponse> prev() async {
+    final resp = await build(from: ref.read(FromController.provider(room)));
+    return resp;
+  }
+
+  static final provider = AsyncNotifierProvider.autoDispose
+      .family<EventsController, GetRoomEventsResponse, Room>(
+        EventsController.new,
+      );
+}