feat: support multiple syllabuses per course offering

[rileychh]

What

A course offering can have multiple syllabi — one per teacher who submits one. A syllabus's code is the authoring teacher's code, so each syllabus maps to a teacher.

Changes

• New Syllabuses table holding per-teacher syllabus content (one row per offering + teacher); it replaces the offering's flat syllabus columns, while the shared header fields (course type, enrolled, withdrawn) stay on CourseOfferings.
• Syllabi are fetched lazily per teacher via a watchSyllabus/refreshSyllabus pair keyed by (offeringId, teacherId): a row is created on the first successful fetch and deleted when the teacher hasn't submitted one; the refresh also writes the offering header fields and the instructor email.
• getSyllabus returns null when the teacher hasn't submitted a syllabus (the page shows 尚未登錄, distinct from the session-expiry 尚未登錄入口網站).
• The course offering detail exposes its teachers; the UI fetches each teacher's syllabus on demand (shows the first for now).

Testing

• flutter analyze clean; generated Drift code regenerated.
• Course service integration tests pass against real NTUT; verified a team-taught offering (10 teachers) and the 尚未登錄 (no-syllabus) path.

Temporary syllabus UI (debug)

Temporary debug UI in course_table_detail_sheet.dart listing the offering's teachers, each expandable to lazily fetch and dump its syllabus fields (or 查無大綱 when the teacher hasn't submitted one). Marked // TODO: temporary. Patch:

course_table_detail_sheet.dart.patch

diff --git a/lib/screens/main/course_table/course_table_detail_sheet.dart b/lib/screens/main/course_table/course_table_detail_sheet.dart
index fd0fe91..ded7e5e 100644
--- a/lib/screens/main/course_table/course_table_detail_sheet.dart
+++ b/lib/screens/main/course_table/course_table_detail_sheet.dart
@@ -1,6 +1,10 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:tattoo/database/database.dart';
 import 'package:tattoo/i18n/strings.g.dart';
 import 'package:tattoo/repositories/course_repository.dart';
+import 'package:tattoo/screens/main/course_table/course_table_providers.dart';
+import 'package:tattoo/utils/localized.dart';
 
 Future<void> showCourseTableDetailSheet(
   BuildContext context, {
@@ -19,7 +23,7 @@ Future<void> showCourseTableDetailSheet(
   );
 }
 
-class CourseTableDetailSheet extends StatelessWidget {
+class CourseTableDetailSheet extends ConsumerWidget {
   const CourseTableDetailSheet({
     super.key,
     required this.cell,
@@ -28,12 +32,12 @@ class CourseTableDetailSheet extends StatelessWidget {
   final CourseTableCellData cell;
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
     final theme = Theme.of(context);
 
     return SafeArea(
       top: false,
-      child: Padding(
+      child: SingleChildScrollView(
         padding: .fromLTRB(16, 8, 16, 16),
         child: Column(
           mainAxisSize: .min,
@@ -81,6 +85,8 @@ class CourseTableDetailSheet extends StatelessWidget {
                 ),
               ),
             ),
+            // TODO: temporary — replace with proper syllabus UI.
+            _SyllabiSection(offeringId: cell.id),
             SizedBox(height: MediaQuery.viewInsetsOf(context).bottom),
             // TODO: scroll up to show more course query features like classmate, course outline, etc.
           ],
@@ -89,3 +95,123 @@ class CourseTableDetailSheet extends StatelessWidget {
     );
   }
 }
+
+/// Temporary debug UI: lists the offering's teachers, each expandable to fetch
+/// and show that teacher's syllabus via [syllabusProvider].
+class _SyllabiSection extends ConsumerWidget {
+  const _SyllabiSection({required this.offeringId});
+
+  final int offeringId;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final detail = ref.watch(courseOfferingProvider(offeringId));
+
+    return switch (detail) {
+      AsyncData(:final value?) when value.teachers.isNotEmpty => Column(
+        crossAxisAlignment: .start,
+        spacing: 8,
+        children: [
+          Text(
+            '課程大綱 (${value.teachers.length})',
+            style: Theme.of(context).textTheme.titleMedium,
+          ),
+          for (final teacher in value.teachers)
+            _SyllabusTile(offeringId: offeringId, teacher: teacher),
+        ],
+      ),
+      _ => const SizedBox.shrink(),
+    };
+  }
+}
+
+class _SyllabusTile extends ConsumerWidget {
+  const _SyllabusTile({required this.offeringId, required this.teacher});
+
+  final int offeringId;
+  final ({String code, String nameZh, String? nameEn}) teacher;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final theme = Theme.of(context);
+    final teacherName = localized(teacher.nameZh, teacher.nameEn);
+
+    return Card(
+      margin: .zero,
+      elevation: 0,
+      shape: RoundedRectangleBorder(
+        borderRadius: .circular(12),
+        side: BorderSide(color: theme.colorScheme.outlineVariant),
+      ),
+      color: theme.colorScheme.surfaceContainer,
+      clipBehavior: .antiAlias,
+      child: ExpansionTile(
+        title: Text(teacherName),
+        subtitle: Text(teacher.code),
+        childrenPadding: .fromLTRB(16, 0, 16, 16),
+        expandedCrossAxisAlignment: .start,
+        children: [
+          _SyllabusContent(offeringId: offeringId, teacherId: teacher.code),
+        ],
+      ),
+    );
+  }
+}
+
+class _SyllabusContent extends ConsumerWidget {
+  const _SyllabusContent({required this.offeringId, required this.teacherId});
+
+  final int offeringId;
+  final String teacherId;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final syllabus = ref.watch(
+      syllabusProvider((offeringId: offeringId, teacherId: teacherId)),
+    );
+
+    return switch (syllabus) {
+      AsyncData(:final value?) => _SyllabusFields(syllabus: value),
+      AsyncData() => const Text('查無大綱'),
+      AsyncError(:final error) => Text('載入失敗: $error'),
+      _ => const Padding(
+        padding: .all(8),
+        child: Center(child: CircularProgressIndicator()),
+      ),
+    };
+  }
+}
+
+class _SyllabusFields extends StatelessWidget {
+  const _SyllabusFields({required this.syllabus});
+
+  final Syllabus syllabus;
+
+  @override
+  Widget build(BuildContext context) {
+    final fields = <(String, String?)>[
+      ('最後更新', syllabus.updatedAt?.toString()),
+      ('課程大綱', syllabus.objective),
+      ('課程進度', syllabus.weeklyPlan),
+      ('評量方式', syllabus.evaluation),
+      ('使用教材', syllabus.textbooks),
+      ('備註', syllabus.remarks),
+    ];
+
+    return Column(
+      crossAxisAlignment: .start,
+      spacing: 8,
+      children: [
+        for (final (label, value) in fields)
+          if (value != null && value.isNotEmpty)
+            Column(
+              crossAxisAlignment: .start,
+              children: [
+                Text(label, style: Theme.of(context).textTheme.labelLarge),
+                Text(value),
+              ],
+            ),
+      ],
+    );
+  }
+}

[github-actions]

PR Preview Builds

Build Number: 1150
Commit: bdcb494
Message: fix: emit refreshed syllabus after blocking fetch, not stale null

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Reviewing files that changed from the base of the PR and between 53c9a20 and bdcb494.

📒 Files selected for processing (11)

• lib/database/actions.dart
• lib/database/database.dart
• lib/database/database.g.dart
• lib/database/schema.dart
• lib/database/views.dart
• lib/repositories/course_repository.dart
• lib/screens/main/course_table/course_table_providers.dart
• lib/services/course/course_service.dart
• lib/services/course/mock_course_service.dart
• lib/services/course/ntut_course_service.dart
• test/services/course_service_test.dart

💤 Files with no reviewable changes (2)

• lib/database/actions.dart
• lib/database/views.dart

🚧 Files skipped from review as they are similar to previous changes (8)

• test/services/course_service_test.dart
• lib/database/database.dart
• lib/screens/main/course_table/course_table_providers.dart
• lib/database/schema.dart
• lib/services/course/course_service.dart
• lib/services/course/mock_course_service.dart
• lib/repositories/course_repository.dart
• lib/services/course/ntut_course_service.dart

---

📝 Walkthrough

Summary by CodeRabbit

• New Features

  • Added separate syllabus loading for each course offering and teacher, so syllabus details can appear independently of the main course list.
  • Course offerings now show up-to-date enrollment and withdrawal counts directly from the database.

• Bug Fixes

  • Improved handling when a syllabus has not yet been submitted, preventing missing-content errors.
  • Course data refreshes now use the latest available class information and no longer depend on outdated syllabus linkage.

Walkthrough

The PR moves syllabus content into a separate Syllabuses table, changes course-table parsing to support multiple syllabus IDs, and adds repository and Riverpod paths for nullable, per-teacher syllabus loading.

Changes

Syllabus Extraction and Multi-ID Refactor

Layer / File(s)	Summary
Service contract and parsing lib/services/course/course_service.dart, lib/services/course/ntut_course_service.dart, lib/services/course/mock_course_service.dart, test/services/course_service_test.dart	ScheduleDto uses syllabusIds: List<String>?, getSyllabus returns Future<SyllabusDto?>, and NTUT parsing now collects multiple syllabus IDs and returns null for “尚未登錄”. Mock fixtures and service tests are updated for the nullable syllabus flow.
Database schema and views lib/database/schema.dart, lib/database/database.dart, lib/database/views.dart	CourseOfferings drops syllabus fields, Syllabuses is added with foreign keys and a uniqueness constraint, AppDatabase registers it, and CourseOfferingOverviews now projects enrollment and fetch timestamps.
Course offering upsert cleanup lib/database/actions.dart	upsertCourseOffering removes syllabusId from its signature and from both insert and update companions.
Repository syllabus flow lib/repositories/course_repository.dart	refreshCourseTable stops storing offering-level syllabus IDs, watchCourseOffering becomes DB-only, and new watchSyllabus/refreshSyllabus methods load and persist per-teacher syllabus data.
Riverpod syllabus provider lib/screens/main/course_table/course_table_providers.dart	courseOfferingProvider docs are updated and a new syllabusProvider streams syllabus data by offering and teacher.

Sequence Diagram(s)

sequenceDiagram
  participant UI
  participant CourseRepository
  participant AppDatabase
  participant CourseService
  UI->>CourseRepository: watchSyllabus(offeringId, teacherId)
  CourseRepository->>AppDatabase: stream Syllabuses row
  alt syllabus missing or stale
    CourseRepository->>CourseService: getSyllabus(courseNumber, syllabusId)
    CourseService-->>CourseRepository: SyllabusDto?
    alt remote syllabus is null
      CourseRepository->>AppDatabase: delete Syllabuses row
    else remote syllabus exists
      CourseRepository->>AppDatabase: upsert Syllabuses row
      CourseRepository->>AppDatabase: update CourseOfferings fields
      CourseRepository->>AppDatabase: update TeacherSemesters email
    end
  end
  AppDatabase-->>CourseRepository: Syllabus?
  CourseRepository-->>UI: Stream<Syllabus?>

Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~75 minutes

Possibly related PRs

• NTUT-NPC/tattoo#336: Updates the course-offering teacher shape and persistence used by the new per-teacher syllabus lookup and storage path.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: supporting multiple syllabuses per course offering.
Description check	✅ Passed	The description matches the changeset and accurately describes the new per-teacher syllabus flow and related UI updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Create PR with unit tests
• Commit unit tests in branch add-multiple-syllabuses

---

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

test/services/course_service_test.dart (1)

395-398: ⚡ Quick win

Exercise non-first syllabus IDs in integration tests.

These assertions always use the first ID, so regressions affecting secondary IDs in multi-syllabus offerings can pass undetected. Randomizing (or iterating) the selected ID improves coverage for this PR’s core behavior.

♻️ Proposed update

-        final syllabus = await courseService.getSyllabus(
-          courseNumber: course.number!,
-          syllabusId: course.syllabusIds!.first,
-        );
+        final syllabus = await courseService.getSyllabus(
+          courseNumber: course.number!,
+          syllabusId: course.syllabusIds!.pickRandom(),
+        );

Also applies to: 453-456, 503-506

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@test/services/course_service_test.dart` around lines 395 - 398, The test
always uses the first syllabus ID from course.syllabusIds!.first when calling
getSyllabus, which means secondary syllabus IDs are never tested and regressions
affecting them can pass undetected. Instead of always selecting the first ID,
randomize or iterate through different indices of the course.syllabusIds list to
exercise multiple syllabus IDs in the assertions. Apply this change to all three
occurrences of the getSyllabus call in the test file (around lines 395-398,
453-456, and 503-506).

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@lib/repositories/course_repository.dart`:
- Around line 757-767: After the refreshSyllabus(id) call succeeds, the code
currently yields the old syllabus stub instead of the refreshed data. To fix
this, fetch the updated syllabus from the repository after the successful
refreshSyllabus(id) call within the try block, and then yield that refreshed
syllabus. Only yield the original syllabus stub in the catch block to maintain
the current error-handling behavior. This ensures the UI receives the latest
data after a successful refresh rather than the stale pre-refresh version.

---

Nitpick comments:
In `@test/services/course_service_test.dart`:
- Around line 395-398: The test always uses the first syllabus ID from
course.syllabusIds!.first when calling getSyllabus, which means secondary
syllabus IDs are never tested and regressions affecting them can pass
undetected. Instead of always selecting the first ID, randomize or iterate
through different indices of the course.syllabusIds list to exercise multiple
syllabus IDs in the assertions. Apply this change to all three occurrences of
the getSyllabus call in the test file (around lines 395-398, 453-456, and
503-506).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

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📥 Commits

Reviewing files that changed from the base of the PR and between a10c34b and 315392e.

📒 Files selected for processing (11)

• lib/database/actions.dart
• lib/database/database.dart
• lib/database/database.g.dart
• lib/database/schema.dart
• lib/database/views.dart
• lib/repositories/course_repository.dart
• lib/screens/main/course_table/course_table_providers.dart
• lib/services/course/course_service.dart
• lib/services/course/mock_course_service.dart
• lib/services/course/ntut_course_service.dart
• test/services/course_service_test.dart

💤 Files with no reviewable changes (2)

• lib/database/views.dart
• lib/database/actions.dart

[coderabbitai]

🧹 Nitpick comments (1)

lib/database/schema.dart (1)

499-545: 💤 Low value

Consider adding an index on courseOffering for query consistency and performance.

Other tables with a courseOffering foreign key (Schedules, Materials) declare a @TableIndex on that column. Adding one here would maintain consistency and improve lookup performance when fetching syllabi for an offering.

♻️ Suggested change

 /// A teacher-authored syllabus for a course offering (教學大綱與進度).
 ...
 // Without `@DataClassName`, Drift names the row class 'Syllabuse'.
 `@DataClassName`('Syllabus')
+@TableIndex(name: 'syllabus_course_offering', columns: {`#courseOffering`})
 class Syllabuses extends Table with AutoIncrementId, Fetchable {

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@lib/database/schema.dart` around lines 499 - 545, The Syllabuses table is
missing a `@TableIndex` annotation on its courseOffering column, whereas other
tables with courseOffering foreign keys like Schedules and Materials declare
this index. Add a `@TableIndex` annotation on the courseOffering field in the
Syllabuses class to maintain consistency with other tables and improve query
performance when fetching syllabi for a specific course offering.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@lib/database/schema.dart`:
- Around line 499-545: The Syllabuses table is missing a `@TableIndex` annotation
on its courseOffering column, whereas other tables with courseOffering foreign
keys like Schedules and Materials declare this index. Add a `@TableIndex`
annotation on the courseOffering field in the Syllabuses class to maintain
consistency with other tables and improve query performance when fetching
syllabi for a specific course offering.

---

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📒 Files selected for processing (11)

• lib/database/actions.dart
• lib/database/database.dart
• lib/database/database.g.dart
• lib/database/schema.dart
• lib/database/views.dart
• lib/repositories/course_repository.dart
• lib/screens/main/course_table/course_table_providers.dart
• lib/services/course/course_service.dart
• lib/services/course/mock_course_service.dart
• lib/services/course/ntut_course_service.dart
• test/services/course_service_test.dart

💤 Files with no reviewable changes (2)

• lib/database/views.dart
• lib/database/actions.dart

🚧 Files skipped from review as they are similar to previous changes (7)

• lib/database/database.dart
• lib/services/course/course_service.dart
• lib/screens/main/course_table/course_table_providers.dart
• test/services/course_service_test.dart
• lib/repositories/course_repository.dart
• lib/services/course/mock_course_service.dart
• lib/services/course/ntut_course_service.dart

[Copilot]

Pull request overview

Adds support for multiple syllabi per course offering (one per teacher) by normalizing syllabus content into a new Syllabuses table and fetching syllabus content lazily, while keeping shared “header” fields on CourseOfferings. This fits the app’s existing pattern of caching parsed NTUT data in Drift and exposing reactive watchX() streams to the UI.

Changes:

• Replace single ScheduleDto.syllabusId with syllabusIds and parse all 查詢 links from the course list.
• Add Syllabuses table and repository flows to reconcile per-offering syllabus stubs and lazily watchSyllabus/refreshSyllabus.
• Update course service integration tests and mock data to reflect multiple available syllabi.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/services/course_service_test.dart	Adjusts integration tests to use syllabusIds and pick an available syllabus ID.
lib/services/course/course_service.dart	Updates DTO contract and getSyllabus docs to describe teacher-code-based syllabus IDs.
lib/services/course/ntut_course_service.dart	Parses multiple syllabus IDs from the 查詢 column and plumbs them into DTOs.
lib/services/course/mock_course_service.dart	Updates mock course table data to provide syllabusIds lists.
lib/database/schema.dart	Removes offering-level flat syllabus content columns; adds new Syllabuses table keyed by offering+teacher.
lib/database/database.dart	Registers the new Syllabuses table with the Drift database.
lib/database/views.dart	Removes syllabus content fields from CourseOfferingOverviews view selection.
lib/database/actions.dart	Updates course offering upsert helper to no longer accept/store a single syllabusId.
lib/repositories/course_repository.dart	Adds offering-level syllabi composition, stub reconciliation, and lazy watchSyllabus/refreshSyllabus.
lib/screens/main/course_table/course_table_providers.dart	Adds syllabusProvider and updates offering provider docs to reflect DB-composed detail + lazy syllabus fetch.

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@lib/repositories/course_repository.dart`:
- Around line 696-705: After the `refreshSyllabus` call succeeds (within the try
block), re-fetch the syllabus value from the database before yielding it instead
of yielding the stale `null` value. This ensures that after a successful
refresh, the code queries the updated data from the database and emits that
fresh value, preventing the UI from seeing a stale null state before the
database stream re-emits.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

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Configuration used: Organization UI

Review profile: CHILL

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Run ID: 8d959898-ec95-49bf-9a3a-4ef1f7b70f9f

📥 Commits

Reviewing files that changed from the base of the PR and between 57ee454 and 497ec05.

📒 Files selected for processing (8)

• lib/database/database.g.dart
• lib/database/schema.dart
• lib/repositories/course_repository.dart
• lib/screens/main/course_table/course_table_providers.dart
• lib/services/course/course_service.dart
• lib/services/course/mock_course_service.dart
• lib/services/course/ntut_course_service.dart
• test/services/course_service_test.dart

🚧 Files skipped from review as they are similar to previous changes (1)

• lib/screens/main/course_table/course_table_providers.dart