feat: model undergraduate schools terms and exam queries

mobile/lib/domain/app_snapshot.dart

@@ -3,6 +3,7 @@ import 'course.dart';
 import 'semester.dart';
 import 'exam_schedule.dart';
 import 'school_term.dart';
+import 'school_identity.dart';
 
 class ImportMetadata {
   const ImportMetadata({
@@ -23,9 +24,12 @@ class AppSnapshot {
     this.examSchedule,
     SchoolTerm? schoolTerm,
     this.calendarCleanupPending = false,
+    SupportedSchool? selectedSchool,
     Map<String, String> calendarEventIds = const {},
   }) : settings = settings ?? AppSettings(),
        schoolTerm = schoolTerm ?? _legacyTerm(courses, examSchedule),
+       selectedSchool = selectedSchool ?? schoolTerm?.school ??
+           _legacyTerm(courses, examSchedule)?.school ?? examSchedule?.school,
        courses = List.unmodifiable(courses),
        calendarEventIds = Map.unmodifiable(calendarEventIds);
   final AppSettings settings;
@@ -35,6 +39,7 @@ class AppSnapshot {
   final SchoolTerm? schoolTerm;
   final Map<String, String> calendarEventIds;
   final bool calendarCleanupPending;
+  final SupportedSchool? selectedSchool;
   static SchoolTerm? _legacyTerm(List<Course> courses, ExamSchedule? exams) {
     final ids = courses
         .map(
@@ -42,7 +47,7 @@ class AppSnapshot {
         )
         .whereType<String>()
         .toSet();
-    if (exams != null) ids.add(exams.termId);
+    if (exams?.school == SupportedSchool.uestcGraduate) ids.add(exams!.termId);
     if (ids.length != 1) return null;
     final id = int.tryParse(ids.single);
     return id != null && id >= 1 && id <= 9999 ? SchoolTerm(id) : null;
@@ -58,6 +63,7 @@ class AppSnapshot {
     bool clearExams = false,
     SchoolTerm? schoolTerm,
     bool? calendarCleanupPending,
+    SupportedSchool? selectedSchool,
   }) => AppSnapshot(
     settings: settings ?? this.settings,
     courses: courses ?? this.courses,
@@ -69,11 +75,13 @@ class AppSnapshot {
     calendarEventIds: calendarEventIds ?? this.calendarEventIds,
     calendarCleanupPending:
         calendarCleanupPending ?? this.calendarCleanupPending,
+    selectedSchool:selectedSchool ?? this.selectedSchool,
   );
   Map<String, dynamic> toJson() => {
     'schemaVersion': 1,
     'examSchedule': examSchedule?.toJson(),
     'schoolTerm': schoolTerm?.toJson(),
+    'selectedSchoolId':selectedSchool?.id,
     'courses': courses.map((c) => c.toJson()).toList(),
     'settings': {
       'semester': settings.semester == null
@@ -144,7 +152,8 @@ class AppSnapshot {
               totalWeeks: sem['totalWeeks'] as int,
             );
       final metadata = json['importMetadata'];
-      return AppSnapshot(
+      final snapshot = AppSnapshot(
+        selectedSchool:json['selectedSchoolId']==null ? null : SupportedSchool.fromId(json['selectedSchoolId'] as String),
         schoolTerm: json['schoolTerm'] == null
             ? null
             : SchoolTerm.fromJson(
@@ -181,6 +190,9 @@ class AppSnapshot {
           (k, v) => MapEntry(k as String, v as String),
         ),
       );
+      if(snapshot.schoolTerm?.school != SupportedSchool.uestcUndergraduate &&
+          values.any((c)=>c.endPeriod>11)) throw const FormatException('第12节需要本科课表来源');
+      return snapshot;
     } catch (_) {
       throw const FormatException('保存文件内容无效，未覆盖已有数据');
     }