Add teachers to the timetable (#1629)

## Description

This pull request adds the Sharezone Plus feature to add teachers to the
timetable.

## Demo


https://github.com/SharezoneApp/sharezone-app/assets/24459435/51576d4d-c5ac-42be-bee9-04084cb228a5

Changed the lesson sheet to a dialog:


![image](https://github.com/SharezoneApp/sharezone-app/assets/24459435/a856afb7-9c76-4dd7-8ae0-f4af1466f6e3)

Reason: In the sheet you need to scroll to see the substitutions tiles
and it's not easy to adjust the size of the sheet (depending on the
screen size). A dialog is here the better option.

Users can also add the teacher when adding a lesson:


![image](https://github.com/SharezoneApp/sharezone-app/assets/24459435/cdbff9b2-2d99-4371-906a-414aba708264)

Sharezone Plus page:


![image](https://github.com/SharezoneApp/sharezone-app/assets/24459435/e737e6d5-5bbb-4638-ab2b-cd6d38d882d0)

## Related Tickets

Closes #1608
Opens #1628

app/lib/dashboard/dashboard_page.dart

@@ -45,7 +45,7 @@ import 'package:sharezone/sharezone_v2/sz_v2_announcement_dialog.dart';
 import 'package:sharezone/timetable/src/widgets/events/calender_event_card.dart';
 import 'package:sharezone/timetable/src/widgets/events/event_view.dart';
 import 'package:sharezone/timetable/timetable_add_event/timetable_add_event_dialog.dart';
-import 'package:sharezone/timetable/timetable_page/lesson/timetable_lesson_sheet.dart';
+import 'package:sharezone/timetable/timetable_page/lesson/timetable_lesson_details.dart';
 import 'package:sharezone/timetable/timetable_page/timetable_page.dart';
 import 'package:sharezone/util/cache/key_value_store.dart';
 import 'package:sharezone/util/cache/streaming_key_value_store.dart';

app/lib/sharezone_plus/subscription_service/subscription_service.dart

@@ -118,6 +118,7 @@ enum SharezonePlusFeature {
   homeworkDueDateChips,
   iCalLinks,
   substitutions,
+  addTeachersToTimetable,
 }
 
 void trySetSharezonePlusAnalyticsUserProperties(Analytics analytics,

app/lib/timetable/src/bloc/timetable_bloc.dart

@@ -13,6 +13,7 @@ import 'package:bloc_provider/bloc_provider.dart';
 import 'package:common_domain_models/common_domain_models.dart';
 import 'package:date/date.dart';
 import 'package:date/weektype.dart';
+import 'package:fast_immutable_collections/fast_immutable_collections.dart';
 import 'package:flutter/widgets.dart';
 import 'package:group_domain_models/group_domain_models.dart';
 import 'package:rxdart/rxdart.dart';
@@ -45,6 +46,9 @@ class TimetableBloc extends BlocBase {
   final CourseGateway courseGateway;
   final SchoolClassFilterAnalytics schoolClassFilterAnalytics;
 
+  final _currentTeachersSubject = BehaviorSubject<ISet<String>>.seeded(ISet());
+  ISet<String> get currentTeachers => _currentTeachersSubject.value;
+
   TimetableBloc(
     this.schoolClassGateway,
     this.userGateway,
@@ -103,6 +107,7 @@ class TimetableBloc extends BlocBase {
             List<Lesson>, List<String>, SchoolClassFilter, List<Lesson>>(
         lessonsStream, coursesOfSchoolClass, _selectedSchoolOptionSubject,
         (lessons, coursesOfSchoolClass, schoolClassFilter) {
+      _setCurrentTeachers(lessons);
       if (schoolClassFilter.shouldFilterForClass) {
         lessons = _getLessonsOfASchoolClass(coursesOfSchoolClass, lessons);
       }
@@ -209,6 +214,11 @@ class TimetableBloc extends BlocBase {
     return streamGroup;
   }
 
+  void _setCurrentTeachers(List<Lesson> lessons) {
+    final teachers = lessons.map((l) => l.teacher).nonNulls;
+    _currentTeachersSubject.add(_currentTeachersSubject.value.addAll(teachers));
+  }
+
   @override
   void dispose() {
     _selectedSchoolOptionSubject.close();

app/lib/timetable/src/models/lesson.dart

@@ -109,7 +109,7 @@ class Lesson {
     int? periodNumber,
     WeekDay? weekday,
     WeekType? weektype,
-    String? teacher,
+    String? Function()? teacher,
     String? place,
     Map<SubstitutionId, Substitution>? substitutions,
   }) {
@@ -125,7 +125,8 @@ class Lesson {
       periodNumber: periodNumber ?? this.periodNumber,
       weekday: weekday ?? this.weekday,
       weektype: weektype ?? this.weektype,
-      teacher: teacher ?? this.teacher,
+      // A function because otherwise one can't set the teacher null
+      teacher: teacher != null ? teacher() : this.teacher,
       place: place ?? this.place,
       substitutions: substitutions ?? this.substitutions,
     );

app/lib/timetable/timetable_add/bloc/timetable_add_bloc.dart

@@ -33,6 +33,7 @@ class TimetableAddBloc extends BlocBase {
   final _weekTypeSubject = BehaviorSubject<WeekType>();
   final _periodSubject = BehaviorSubject<Period?>();
   final _timeTypeSubject = BehaviorSubject.seeded(TimeType.period);
+  final _teacherSubject = BehaviorSubject<String>();
 
   final TimetableGateway gateway;
   final LessonLengthCache cache;
@@ -75,6 +76,7 @@ class TimetableAddBloc extends BlocBase {
   Function(WeekType) get changeWeekType => _weekTypeSubject.sink.add;
   Function(Period) get changePeriod => _periodSubject.sink.add;
   Function(TimeType) get changeTimeType => _timeTypeSubject.sink.add;
+  Function(String) get changeTeacher => _teacherSubject.sink.add;
 
   Future<Time?> _calculateEndTime(Time startTime) async {
     final lessonsLength = await cache.streamLessonLength().first;
@@ -124,6 +126,10 @@ class TimetableAddBloc extends BlocBase {
       final weekType = _weekTypeSubject.valueOrNull ?? WeekType.always;
       final period = _periodSubject.valueOrNull;
       final timeType = _timeTypeSubject.valueOrNull!;
+      String? teacher = _teacherSubject.valueOrNull;
+      if (teacher?.isEmpty == true) {
+        teacher = null;
+      }
       log("isValid: true; ${course.toString()}; $startTime; $endTime; $room $weekDay $period");
 
       final lesson = Lesson(
@@ -134,7 +140,7 @@ class TimetableAddBloc extends BlocBase {
         groupType: GroupType.course,
         startDate: null,
         endDate: null,
-        teacher: null,
+        teacher: teacher,
         place: room,
         weekday: weekDay,
         weektype: weekType,

app/lib/timetable/timetable_add/tabs/room_and_teacher_tab.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2022 Sharezone UG (haftungsbeschränkt)
+// Licensed under the EUPL-1.2-or-later.
+//
+// You may obtain a copy of the Licence at:
+// https://joinup.ec.europa.eu/software/page/eupl
+//
+// SPDX-License-Identifier: EUPL-1.2
+
+part of '../timetable_add_page.dart';
+
+class _RoomAndTeachersTab extends StatelessWidget {
+  const _RoomAndTeachersTab({
+    required this.index,
+  });
+
+  final int index;
+
+  @override
+  Widget build(BuildContext context) {
+    final bloc = BlocProvider.of<TimetableAddBloc>(context);
+    return _TimetableAddSection(
+      index: index,
+      title: 'Gib einen Raum & eine Lehrkraft an (optional)',
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 8),
+        child: Column(
+          children: [
+            RoomField(
+              onChanged: bloc.changeRoom,
+            ),
+            const SizedBox(height: 16),
+            TeacherField(
+              teachers: BlocProvider.of<TimetableBloc>(context).currentTeachers,
+              onTeacherChanged: bloc.changeTeacher,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

app/lib/timetable/timetable_add/timetable_add_page.dart

@@ -26,6 +26,7 @@ import 'package:sharezone/timetable/src/models/lesson.dart';
 import 'package:sharezone/timetable/src/models/time_type.dart';
 import 'package:sharezone/timetable/timetable_add/bloc/timetable_add_bloc.dart';
 import 'package:sharezone/timetable/timetable_add/bloc/timetable_add_bloc_factory.dart';
+import 'package:sharezone/timetable/timetable_edit/lesson/timetable_lesson_edit_page.dart';
 import 'package:sharezone/timetable/timetable_page/timetable_page.dart';
 import 'package:sharezone/widgets/fade_switch_between_index_with_tab_controller.dart';
 import 'package:sharezone/widgets/tabs.dart';
@@ -35,7 +36,7 @@ import 'package:time/time.dart';
 import 'package:user/user.dart';
 
 part 'tabs/course_tab.dart';
-part 'tabs/room_tab.dart';
+part 'tabs/room_and_teacher_tab.dart';
 part 'tabs/time_tab.dart';
 part 'tabs/weekday_tab.dart';
 part 'tabs/weektype_tab.dart';
@@ -100,7 +101,7 @@ class _TimetableAddPage extends StatelessWidget {
         _WeekDayTab(),
         if (abWeekEnabled) _WeekTypeTab(),
         _TimeTab(index: abWeekEnabled ? 4 : 3),
-        _RoomTab(index: abWeekEnabled ? 5 : 4),
+        _RoomAndTeachersTab(index: abWeekEnabled ? 5 : 4),
       ],
       abWeekEnabled: abWeekEnabled,
     );

app/lib/timetable/timetable_edit/event/timetable_event_edit_page.dart

@@ -17,7 +17,7 @@ import 'package:sharezone/main/application_bloc.dart';
 import 'package:sharezone/markdown/markdown_analytics.dart';
 import 'package:sharezone/timetable/src/edit_date.dart';
 import 'package:sharezone/timetable/src/edit_time.dart';
-import 'package:sharezone/timetable/timetable_page/lesson/timetable_lesson_sheet.dart';
+import 'package:sharezone/timetable/timetable_page/lesson/timetable_lesson_details.dart';
 import 'package:sharezone/timetable/timetable_permissions.dart';
 import 'package:sharezone/util/api/connections_gateway.dart';
 import 'package:sharezone/util/api/timetable_gateway.dart';

app/lib/timetable/timetable_edit/lesson/timetable_lesson_edit_bloc.dart

@@ -30,6 +30,7 @@ class TimetableEditBloc extends BlocBase {
   final _weekDaySubject = BehaviorSubject<WeekDay>();
   final _weekTypeSubject = BehaviorSubject<WeekType>();
   final _periodSubject = BehaviorSubject<Period>();
+  final _teacherSubject = BehaviorSubject<String>();
 
   final Lesson initialLesson;
   final TimetableGateway gateway;
@@ -60,6 +61,9 @@ class TimetableEditBloc extends BlocBase {
         _periodSubject.sink.add(period);
       }
     }
+    if (initialLesson.teacher != null) {
+      _teacherSubject.sink.add(initialLesson.teacher!);
+    }
   }
 
   Stream<Course> get course => _courseSegmentSubject;
@@ -69,13 +73,15 @@ class TimetableEditBloc extends BlocBase {
   Stream<WeekDay> get weekDay => _weekDaySubject;
   Stream<WeekType> get weekType => _weekTypeSubject;
   Stream<Period> get period => _periodSubject;
+  Stream<String> get teacher => _teacherSubject;
 
   Function(Course) get _changeCourse => _courseSegmentSubject.sink.add;
   Function(Time) get changeStartTime => _startTimeSubject.sink.add;
   Function(Time) get changeEndTime => _endTimeSubject.sink.add;
   Function(String) get changeRoom => _roomSubject.sink.add;
   Function(WeekDay) get changeWeekDay => _weekDaySubject.sink.add;
   Function(WeekType) get changeWeekType => _weekTypeSubject.sink.add;
+  Function(String) get changeTeacher => _teacherSubject.sink.add;
 
   void changePeriod(Period period) {
     _periodSubject.sink.add(period);
@@ -104,12 +110,16 @@ class TimetableEditBloc extends BlocBase {
       final weekDay = _weekDaySubject.valueOrNull;
       final weekType = _weekTypeSubject.valueOrNull;
       final period = _periodSubject.valueOrNull;
+      String? teacher = _teacherSubject.valueOrNull;
+      if (teacher?.isEmpty == true) {
+        teacher = null;
+      }
 
       log("isValid: true; ${course.toString()}; $startTime; $endTime; $room $weekDay");
 
       final lesson = initialLesson.copyWith(
         groupID: course?.id,
-        teacher: null,
+        teacher: () => teacher,
         place: room,
         weekday: weekDay,
         weektype: weekType,