Automatically select next weekday in homework dialog.

app/lib/homework/homework_dialog/homework_dialog_bloc.dart

@@ -9,9 +9,11 @@
 import 'package:analytics/analytics.dart';
 import 'package:bloc/bloc.dart';
 import 'package:bloc_presentation/bloc_presentation.dart';
+import 'package:clock/clock.dart';
 import 'package:cloud_firestore/cloud_firestore.dart';
 import 'package:common_domain_models/common_domain_models.dart';
 import 'package:date/date.dart';
+import 'package:date/weekday.dart';
 import 'package:equatable/equatable.dart';
 import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:files_basics/files_models.dart';
@@ -372,6 +374,7 @@ class HomeworkDialogBloc extends Bloc<HomeworkDialogEvent, HomeworkDialogState>
   final Analytics analytics;
   final MarkdownAnalytics markdownAnalytics;
   final NextLessonCalculator nextLessonCalculator;
+  final Clock _clock;
   HomeworkDto? _initialHomework;
   late final IList<CloudFile> _initialAttachments;
   late final bool isEditing;
@@ -402,8 +405,10 @@ class HomeworkDialogBloc extends Bloc<HomeworkDialogEvent, HomeworkDialogState>
     required this.nextLessonCalculator,
     required this.analytics,
     required this.markdownAnalytics,
+    Clock? clock,
     HomeworkId? homeworkId,
-  }) : super(homeworkId != null
+  })  : _clock = clock ?? const Clock(),
+        super(homeworkId != null
             ? LoadingHomework(homeworkId, isEditing: true)
             : emptyCreateHomeworkDialogState) {
     isEditing = homeworkId != null;
@@ -574,6 +579,14 @@ class HomeworkDialogBloc extends Bloc<HomeworkDialogEvent, HomeworkDialogState>
             await nextLessonCalculator.tryCalculateNextLesson(course.id);
         if (nextLesson != null) {
           add(DueDateChanged(nextLesson));
+        } else {
+          final today = _clock.now().toDate();
+          final daysUntilNextSchoolday = switch (today.weekDayEnum) {
+            WeekDay.friday => 3, // Monday
+            WeekDay.saturday => 2, // Monday
+            _ => 1 // Tomorrow
+          };
+          add(DueDateChanged(today.addDays(daysUntilNextSchoolday)));
         }
       },
     );

app/test/homework/homework_dialog_bloc_test.dart

@@ -10,6 +10,7 @@ import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:analytics/analytics.dart';
+import 'package:clock/clock.dart';
 import 'package:common_domain_models/common_domain_models.dart';
 import 'package:date/date.dart';
 import 'package:fast_immutable_collections/fast_immutable_collections.dart';
@@ -21,7 +22,6 @@ import 'package:mockito/mockito.dart';
 import 'package:rxdart/rxdart.dart';
 import 'package:sharezone/homework/homework_dialog/homework_dialog_bloc.dart';
 import 'package:sharezone/markdown/markdown_analytics.dart';
-import 'package:sharezone/util/next_lesson_calculator/next_lesson_calculator.dart';
 import 'package:time/time.dart';
 
 import '../analytics/analytics_test.dart';
@@ -44,9 +44,10 @@ void main() {
       analytics = Analytics(analyticsBackend);
     });
 
-    HomeworkDialogBloc createBlocForNewHomeworkDialog() {
+    HomeworkDialogBloc createBlocForNewHomeworkDialog({Clock? clock}) {
       return HomeworkDialogBloc(
         api: homeworkDialogApi,
+        clock: clock,
         nextLessonCalculator: nextLessonCalculator,
         analytics: analytics,
         markdownAnalytics: MarkdownAnalytics(analytics),
@@ -69,6 +70,43 @@ void main() {
       homeworkDialogApi.addCourseForTesting(course);
     }
 
+    test('If no next lesson date is found the next weekday will be taken',
+        () async {
+      Future<void> testNextLessonDate(
+          String currentDate, String expectedLessonDate) async {
+        // The course does not have any lessons in the timetable, so we fallback
+        // to automatically using the next schoolday. We currently assume that
+        // all users have schooldays from Monday to Friday. We also don't take
+        // holidays into account.
+        nextLessonCalculator.dateToReturn = null;
+        final testClock = Clock.fixed(Date.parse(currentDate).toDateTime);
+        addCourse(courseWith(id: 'foo'));
+        final bloc = createBlocForNewHomeworkDialog(clock: testClock);
+
+        bloc.add(CourseChanged(CourseId('foo')));
+        await pumpEventQueue();
+
+        final state = bloc.state as Ready;
+        expect(state.dueDate.$1, Date.parse(expectedLessonDate));
+      }
+
+      //                    | Current date  | Next lesson date |
+      //                          Friday        Monday
+      await testNextLessonDate('2023-10-06', '2023-10-09');
+      //                         Saturday       Monday
+      await testNextLessonDate('2023-10-07', '2023-10-09');
+      //                          Sunday        Monday
+      await testNextLessonDate('2023-10-08', '2023-10-09');
+      //                          Monday        Tuesday
+      await testNextLessonDate('2023-10-09', '2023-10-10');
+      //                          Tuesday      Wednesday
+      await testNextLessonDate('2023-10-10', '2023-10-11');
+      //                         Wednesday      Thursday
+      await testNextLessonDate('2023-10-11', '2023-10-12');
+      //                         Thursday       Friday
+      await testNextLessonDate('2023-10-12', '2023-10-13');
+    });
+
     test(
         'Shows error if title is not filled out when creating a new homework and Save is called',
         () async {
@@ -212,30 +250,6 @@ void main() {
           .firstWhere((element) => element.dueDate.$1 != null);
       expect(state.dueDate.$1, nextLessonDate);
     });
-    test(
-        'leaves due date as not selected if null is returned by $NextLessonCalculator',
-        () async {
-      final bloc = createBlocForNewHomeworkDialog();
-      addCourse(courseWith(
-        id: 'foo_course',
-      ));
-
-      bloc.add(CourseChanged(CourseId('foo_course')));
-
-      nextLessonCalculator.dateToReturn = null;
-      await bloc.stream
-          .whereType<Ready>()
-          .firstWhere((element) => element.course is CourseChosen);
-
-      // Make sure that we wait for the due date to be set (might be delayed,
-      // after the course is set and returned by the view)
-      await pumpEventQueue(times: 100);
-      await Future.delayed(Duration.zero);
-      await pumpEventQueue(times: 100);
-
-      final state = bloc.state as Ready;
-      expect(state.dueDate.$1, null);
-    });
     test('Returns empty dialog when called for creating a new homework', () {
       final bloc = createBlocForNewHomeworkDialog();
       expect(bloc.state, emptyCreateHomeworkDialogState);

lib/date/lib/src/date.dart

@@ -105,6 +105,12 @@ class Date {
   }
 }
 
+extension DateTimeToDate on DateTime {
+  Date toDate() {
+    return Date.fromDateTime(this);
+  }
+}
+
 class DateParser {
   final Date _date;