timetable performance optimization

lib/state/app/modules/timetable/bloc/timetable_state.dart

@@ -7,6 +7,7 @@ import '../../../../../api/marianumconnect/queries/timetable_get_subjects/timeta
 import '../../../../../api/marianumconnect/queries/timetable_get_timegrid/timetable_get_timegrid_response.dart';
 import '../../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
 import '../../../../../api/mhsl/custom_timetable_event/get/get_custom_timetable_event_response.dart';
+import 'week_cache.dart';
 
 part 'timetable_state.freezed.dart';
 part 'timetable_state.g.dart';
@@ -40,6 +41,23 @@ abstract class TimetableState with _$TimetableState {
   Iterable<McTimetableEntry> getAllKnownLessons() =>
       weekCache.values.expand((response) => response.entries);
 
+  /// This state with [week] cached, or `this` when its content is unchanged
+  /// (so the emit is dropped as equal).
+  TimetableState withFetchedWeek(
+    DateTime weekStart,
+    TimetableGetWeekResponse week,
+  ) {
+    final updated = mergeWeekIntoCache(
+      weekCache,
+      weekStart,
+      week,
+      viewedWeekStart: startDate,
+      now: DateTime.now(),
+    );
+    if (updated == null) return this;
+    return copyWith(weekCache: updated, dataVersion: dataVersion + 1);
+  }
+
   bool get hasReferenceData =>
       rooms != null &&
       subjects != null &&