// 发现页 BLoC — 管理发现页数据加载状态
//
// 职责：调用 /diary/discover API，解析响应，管理加载/成功/失败状态。

import 'package:flutter_bloc/flutter_bloc.dart';

import '../../../data/remote/api_client.dart';
import '../models/discover_models.dart';

part 'discover_event.dart';
part 'discover_state.dart';

class DiscoverBloc extends Bloc<DiscoverEvent, DiscoverState> {
  final ApiClient _api;

  DiscoverBloc({required ApiClient api})
      : _api = api,
        super(const DiscoverInitial()) {
    on<DiscoverLoadData>(_onLoadData);
    on<DiscoverRefresh>(_onRefresh);
  }

  /// 首次加载 — 显示 loading 状态
  Future<void> _onLoadData(
    DiscoverLoadData event,
    Emitter<DiscoverState> emit,
  ) async {
    emit(const DiscoverLoading());
    await _fetchData(emit);
  }

  /// 刷新 — 不显示 loading，静默更新
  Future<void> _onRefresh(
    DiscoverRefresh event,
    Emitter<DiscoverState> emit,
  ) async {
    await _fetchData(emit);
  }

  /// 通用数据获取逻辑
  Future<void> _fetchData(Emitter<DiscoverState> emit) async {
    try {
      final response = await _api.get('/diary/discover');
      final body = response.data as Map<String, dynamic>;

      // 后端信封格式: { success, data: { ... }, message }
      final dataJson = body['data'] as Map<String, dynamic>? ?? {};
      final discoverData = DiscoverData.fromJson(dataJson);

      emit(DiscoverLoaded(discoverData));
    } on OfflineException {
      // 离线时，如果有已加载的数据，保留它
      if (state is DiscoverLoaded) return;
      emit(const DiscoverError('网络不可用，请检查网络连接'));
    } catch (e) {
      if (state is DiscoverLoaded) return;
      emit(DiscoverError('加载失败：${_friendlyError(e)}'));
    }
  }

  /// 将异常转换为用户友好的错误消息
  String _friendlyError(Object error) {
    final msg = error.toString();
    if (msg.contains('SocketException') || msg.contains('Connection refused')) {
      return '无法连接服务器';
    }
    if (msg.contains('401')) {
      return '登录已过期，请重新登录';
    }
    if (msg.contains('403')) {
      return '没有访问权限';
    }
    if (msg.contains('500')) {
      return '服务器错误，请稍后重试';
    }
    return '请稍后重试';
  }
}