// 班级 BLoC — 通过 ClassRepository 管理班级数据

import 'package:flutter/foundation.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:nuanji_app/data/models/journal_entry.dart';
import 'package:nuanji_app/data/models/school_class.dart';
import 'package:nuanji_app/data/repositories/class_repository.dart';
import 'package:nuanji_app/data/repositories/journal_repository.dart';

// ===== Events =====

sealed class ClassEvent {
  const ClassEvent();
}

final class ClassLoadMyClasses extends ClassEvent {
  const ClassLoadMyClasses();
}

final class ClassSelected extends ClassEvent {
  final String classId;
  const ClassSelected(this.classId);
}

final class ClassLoadMembers extends ClassEvent {
  final String classId;
  const ClassLoadMembers(this.classId);
}

final class ClassLoadDiaryWall extends ClassEvent {
  final String classId;
  const ClassLoadDiaryWall(this.classId);
}

final class ClassLoadTopics extends ClassEvent {
  final String classId;
  const ClassLoadTopics(this.classId);
}

final class ClassLoadComments extends ClassEvent {
  final String journalId;
  const ClassLoadComments(this.journalId);
}

final class ClassCreate extends ClassEvent {
  final String name;
  final String? schoolName;
  const ClassCreate({required this.name, this.schoolName});
}

final class TopicAssign extends ClassEvent {
  final String classId;
  final String title;
  final String? description;
  final DateTime? dueDate;
  const TopicAssign({
    required this.classId,
    required this.title,
    this.description,
    this.dueDate,
  });
}

final class ClassJoin extends ClassEvent {
  final String classCode;
  final String? nickname;
  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 {
  final String userId;
  final String role;
  final String? nickname;
  final DateTime joinedAt;
  const ClassMember({required this.userId, required this.role, this.nickname, required this.joinedAt});
}

class TopicAssignment {
  final String id;
  final String classId;
  final String teacherId;
  final String title;
  final String? description;
  final DateTime? dueDate;
  final bool isActive;
  const TopicAssignment({required this.id, required this.classId, required this.teacherId, required this.title, this.description, this.dueDate, this.isActive = true});
}

class Comment {
  final String id;
  final String journalId;
  final String authorId;
  final String content;
  final DateTime createdAt;
  const Comment({required this.id, required this.journalId, required this.authorId, required this.content, required this.createdAt});
}

sealed class ClassState {
  const ClassState();
}

final class ClassInitial extends ClassState {
  const ClassInitial();
}

final class ClassLoading extends ClassState {
  const ClassLoading();
}

final class ClassListLoaded extends ClassState {
  final List<SchoolClass> classes;
  final bool isLoading;
  final String? error;
  const ClassListLoaded({this.classes = const [], this.isLoading = false, this.error});
  ClassListLoaded copyWith({List<SchoolClass>? classes, bool? isLoading, String? error, bool clearError = false}) =>
      ClassListLoaded(
        classes: classes ?? this.classes,
        isLoading: isLoading ?? this.isLoading,
        error: clearError ? null : (error ?? this.error),
      );
}

final class ClassDetailLoaded extends ClassState {
  final SchoolClass classInfo;
  final List<ClassMember> members;
  final List<JournalEntry> diaryWall;
  final List<TopicAssignment> topics;
  final List<Comment> comments;
  final bool isLoadingWall;
  final bool isLoadingMembers;
  final String? selectedJournalId;
  final String? error;

  const ClassDetailLoaded({
    required this.classInfo,
    this.members = const [],
    this.diaryWall = const [],
    this.topics = const [],
    this.comments = const [],
    this.isLoadingWall = false,
    this.isLoadingMembers = false,
    this.selectedJournalId,
    this.error,
  });

  ClassDetailLoaded copyWith({
    SchoolClass? classInfo,
    List<ClassMember>? members,
    List<JournalEntry>? diaryWall,
    List<TopicAssignment>? topics,
    List<Comment>? comments,
    bool? isLoadingWall,
    bool? isLoadingMembers,
    String? selectedJournalId,
    bool clearSelectedJournal = false,
    String? error,
    bool clearError = false,
  }) =>
      ClassDetailLoaded(
        classInfo: classInfo ?? this.classInfo,
        members: members ?? this.members,
        diaryWall: diaryWall ?? this.diaryWall,
        topics: topics ?? this.topics,
        comments: comments ?? this.comments,
        isLoadingWall: isLoadingWall ?? this.isLoadingWall,
        isLoadingMembers: isLoadingMembers ?? this.isLoadingMembers,
        selectedJournalId: clearSelectedJournal ? null : (selectedJournalId ?? this.selectedJournalId),
        error: clearError ? null : (error ?? this.error),
      );
}

final class ClassError extends ClassState {
  final String message;
  const ClassError(this.message);
}

// ===== BLoC =====

class ClassBloc extends Bloc<ClassEvent, ClassState> {
  final ClassRepository _classRepo;
  final JournalRepository _journalRepo;

  ClassBloc({
    required ClassRepository classRepository,
    required JournalRepository journalRepository,
  })  : _classRepo = classRepository,
        _journalRepo = journalRepository,
        super(const ClassInitial()) {
    on<ClassLoadMyClasses>(_onLoadMyClasses);
    on<ClassSelected>(_onClassSelected);
    on<ClassLoadMembers>(_onLoadMembers);
    on<ClassLoadDiaryWall>(_onLoadDiaryWall);
    on<ClassLoadTopics>(_onLoadTopics);
    on<ClassLoadComments>(_onLoadComments);
    on<ClassCreate>(_onCreateClass);
    on<TopicAssign>(_onTopicAssign);
    on<ClassJoin>(_onJoinClass);
    on<CommentCreate>(_onCommentCreate);
  }

  Future<void> _onLoadMyClasses(
    ClassLoadMyClasses event,
    Emitter<ClassState> emit,
  ) async {
    emit(const ClassListLoaded(isLoading: true));
    try {
      final classes = await _classRepo.getMyClasses();
      emit(ClassListLoaded(classes: classes));
    } catch (e) {
      debugPrint('ClassBloc._onLoadMyClasses 失败: $e');
      emit(const ClassListLoaded());
    }
  }

  Future<void> _onClassSelected(
    ClassSelected event,
    Emitter<ClassState> emit,
  ) async {
    try {
      final classInfo = await _classRepo.getClass(event.classId);
      emit(ClassDetailLoaded(classInfo: classInfo));
      add(ClassLoadDiaryWall(event.classId));
      add(ClassLoadMembers(event.classId));
      add(ClassLoadTopics(event.classId));
    } catch (e) {
      debugPrint('ClassBloc._onClassSelected 失败: $e');
      emit(const ClassError('加载班级失败，请重试'));
    }
  }

  Future<void> _onLoadMembers(
    ClassLoadMembers event,
    Emitter<ClassState> emit,
  ) async {
    if (state is! ClassDetailLoaded) return;
    final current = state as ClassDetailLoaded;
    emit(current.copyWith(isLoadingMembers: true));

    try {
      final dtos = await _classRepo.getMembers(event.classId);
      final members = dtos
          .map((d) => ClassMember(
                userId: d.userId,
                role: d.role,
                nickname: d.nickname,
                joinedAt: d.joinedAt,
              ))
          .toList();
      emit(current.copyWith(members: members, isLoadingMembers: false));
    } catch (e) {
      debugPrint('ClassBloc._onLoadMembers 失败: $e');
      emit(current.copyWith(isLoadingMembers: false));
    }
  }

  Future<void> _onLoadDiaryWall(
    ClassLoadDiaryWall event,
    Emitter<ClassState> emit,
  ) async {
    if (state is! ClassDetailLoaded) return;
    final current = state as ClassDetailLoaded;
    emit(current.copyWith(isLoadingWall: true));

    try {
      // 服务端过滤：按 classId 查询班级公开日记（后端 API 已支持 ?class_id= 参数）
      final journals = await _journalRepo.getJournals(classId: event.classId);
      final classJournals = journals.where((j) => j.sharedToClass).toList();

      emit(current.copyWith(diaryWall: classJournals, isLoadingWall: false));
    } catch (e) {
      debugPrint('ClassBloc._onLoadDiaryWall 失败: $e');
      emit(current.copyWith(isLoadingWall: false));
    }
  }

  Future<void> _onLoadTopics(
    ClassLoadTopics event,
    Emitter<ClassState> emit,
  ) async {
    if (state is! ClassDetailLoaded) return;
    final current = state as ClassDetailLoaded;

    try {
      final dtos = await _classRepo.getTopics(event.classId);
      final topics = dtos
          .map((d) => TopicAssignment(
                id: d.id,
                classId: d.classId,
                teacherId: d.teacherId,
                title: d.title,
                description: d.description,
                dueDate: d.dueDate,
                isActive: d.isActive,
              ))
          .toList();
      emit(current.copyWith(topics: topics));
    } catch (e) {
      debugPrint('ClassBloc._onLoadTopics 失败: $e');
      // 保留空列表
    }
  }

  Future<void> _onLoadComments(
    ClassLoadComments event,
    Emitter<ClassState> emit,
  ) async {
    if (state is! ClassDetailLoaded) return;
    final current = state as ClassDetailLoaded;

    try {
      final dtos = await _classRepo.getComments(event.journalId);
      final comments = dtos
          .map((d) => Comment(
                id: d.id,
                journalId: d.journalId,
                authorId: d.authorId,
                content: d.content,
                createdAt: d.createdAt,
              ))
          .toList();
      emit(current.copyWith(comments: comments, selectedJournalId: event.journalId));
    } catch (e) {
      debugPrint('ClassBloc._onLoadComments 失败: $e');
      emit(current.copyWith(selectedJournalId: event.journalId));
    }
  }

  Future<void> _onCreateClass(
    ClassCreate event,
    Emitter<ClassState> emit,
  ) async {
    try {
      final newClass = await _classRepo.createClass(
        name: event.name,
        schoolName: event.schoolName,
      );
      if (state is ClassListLoaded) {
        final current = state as ClassListLoaded;
        emit(current.copyWith(classes: [...current.classes, newClass]));
      }
    } catch (e) {
      debugPrint('ClassBloc._onCreateClass 失败: $e');
      // 创建失败不改变状态，但通知 UI
      if (state is ClassListLoaded) {
        emit((state as ClassListLoaded).copyWith(error: '创建班级失败，请重试'));
      }
    }
  }

  Future<void> _onTopicAssign(
    TopicAssign event,
    Emitter<ClassState> emit,
  ) async {
    try {
      final dto = await _classRepo.assignTopic(
        classId: event.classId,
        title: event.title,
        description: event.description,
        dueDate: event.dueDate,
      );

      // 更新本地 topics 列表（仅在班级详情视图中）
      if (state is ClassDetailLoaded) {
        final current = state as ClassDetailLoaded;
        final newTopic = TopicAssignment(
          id: dto.id,
          classId: dto.classId,
          teacherId: dto.teacherId,
          title: dto.title,
          description: dto.description,
          dueDate: dto.dueDate,
        );
        emit(current.copyWith(topics: [newTopic, ...current.topics]));
      }
    } catch (e) {
      debugPrint('ClassBloc._onTopicAssign 失败: $e');
      // 通知 UI 布置失败
      if (state is ClassDetailLoaded) {
        emit((state as ClassDetailLoaded).copyWith(error: '话题布置失败，请重试'));
      }
    }
  }

  Future<void> _onJoinClass(
    ClassJoin event,
    Emitter<ClassState> emit,
  ) async {
    try {
      await _classRepo.joinClass(event.classCode, nickname: event.nickname);
      // 加入成功后刷新列表
      add(const ClassLoadMyClasses());
    } catch (e) {
      debugPrint('ClassBloc._onJoinClass 失败: $e');
      emit(const ClassError('加入班级失败，请检查班级码'));
    }
  }

  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) {
      debugPrint('ClassBloc._onCommentCreate 失败: $e');
      emit(currentState.copyWith(error: '评语发布失败'));
    }
  }
}