feat(app): 老师点评功能 — CommentCreate事件 + CommentBottomSheet + 日记墙点评按钮

app/lib/features/class_/bloc/class_bloc.dart

@@ -66,6 +66,12 @@ final class ClassJoin extends ClassEvent {
   const ClassJoin({required this.classCode, this.nickname});
 }
 
+final class CommentCreate extends ClassEvent {
+  final String journalId;
+  final String content;
+  const CommentCreate({required this.journalId, required this.content});
+}
+
 // ===== State =====
 
 class ClassMember {
@@ -125,6 +131,7 @@ final class ClassDetailLoaded extends ClassState {
   final bool isLoadingWall;
   final bool isLoadingMembers;
   final String? selectedJournalId;
+  final String? error;
 
   const ClassDetailLoaded({
     required this.classInfo,
@@ -135,6 +142,7 @@ final class ClassDetailLoaded extends ClassState {
     this.isLoadingWall = false,
     this.isLoadingMembers = false,
     this.selectedJournalId,
+    this.error,
   });
 
   ClassDetailLoaded copyWith({
@@ -147,6 +155,8 @@ final class ClassDetailLoaded extends ClassState {
     bool? isLoadingMembers,
     String? selectedJournalId,
     bool clearSelectedJournal = false,
+    String? error,
+    bool clearError = false,
   }) =>
       ClassDetailLoaded(
         classInfo: classInfo ?? this.classInfo,
@@ -157,6 +167,7 @@ final class ClassDetailLoaded extends ClassState {
         isLoadingWall: isLoadingWall ?? this.isLoadingWall,
         isLoadingMembers: isLoadingMembers ?? this.isLoadingMembers,
         selectedJournalId: clearSelectedJournal ? null : (selectedJournalId ?? this.selectedJournalId),
+        error: clearError ? null : (error ?? this.error),
       );
 }
 
@@ -186,6 +197,7 @@ class ClassBloc extends Bloc<ClassEvent, ClassState> {
     on<ClassCreate>(_onCreateClass);
     on<TopicAssign>(_onTopicAssign);
     on<ClassJoin>(_onJoinClass);
+    on<CommentCreate>(_onCommentCreate);
   }
 
   Future<void> _onLoadMyClasses(
@@ -369,4 +381,23 @@ class ClassBloc extends Bloc<ClassEvent, ClassState> {
       emit(ClassError('加入班级失败: $e'));
     }
   }
+
+  Future<void> _onCommentCreate(
+    CommentCreate event,
+    Emitter<ClassState> emit,
+  ) async {
+    final currentState = state;
+    if (currentState is! ClassDetailLoaded) return;
+
+    try {
+      await _classRepo.createComment(
+        journalId: event.journalId,
+        content: event.content,
+      );
+      // 创建成功后重新加载评语列表
+      add(ClassLoadComments(event.journalId));
+    } catch (e) {
+      emit(currentState.copyWith(error: '评语发布失败'));
+    }
+  }
 }