nj/app/lib/features/templates/bloc/template_bloc.dart

// 模板 BLoC — 通过 API 加载模板列表

import 'package:flutter/material.dart';
import 'package:nuanji_app/data/remote/api_client.dart';

// ===== 模型 =====

/// 日记模板
class Template {
  final String id;
  final String name;
  final String? description;
  final String? previewUrl;
  final Map<String, dynamic>? templateData;
  final String? category;
  final bool isFree;

  /// 用于 UI 显示的 emoji（基于 category 推导）
  String get emoji => switch (category) {
        '日常' => '☀️',
        '旅行' => '🗺️',
        '校园' => '📚',
        '节日' => '🎄',
        '创意' => '✨',
        _ => '📝',
      };

  const Template({
    required this.id,
    required this.name,
    this.description,
    this.previewUrl,
    this.templateData,
    this.category,
    this.isFree = true,
  });
}

// ===== State =====

/// 模板页面状态
class TemplateState {
  final List<Template> templates;
  final String selectedCategory;
  final bool isLoading;
  final String? errorMessage;

  const TemplateState({
    this.templates = const [],
    this.selectedCategory = '全部',
    this.isLoading = false,
    this.errorMessage,
  });

  /// 按分类过滤模板
  List<Template> get filteredTemplates => selectedCategory == '全部'
      ? templates
      : templates.where((t) => t.category == selectedCategory).toList();

  /// 所有分类（去重 + 加"全部"）
  List<String> get categories {
    final cats = templates
        .map((t) => t.category)
        .whereType<String>()
        .toSet()
        .toList();
    return ['全部', ...cats];
  }

  TemplateState copyWith({
    List<Template>? templates,
    String? selectedCategory,
    bool? isLoading,
    String? errorMessage,
  }) =>
      TemplateState(
        templates: templates ?? this.templates,
        selectedCategory: selectedCategory ?? this.selectedCategory,
        isLoading: isLoading ?? this.isLoading,
        errorMessage: errorMessage,
      );
}

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

/// 模板 BLoC — ChangeNotifier 模式
class TemplateBloc extends ChangeNotifier {
  final ApiClient _api;
  TemplateState _state = const TemplateState();
  TemplateState get state => _state;

  TemplateBloc({required ApiClient api}) : _api = api;

  /// 加载模板列表
  void load() {
    _state = _state.copyWith(isLoading: true);
    notifyListeners();
    _fetchTemplates();
  }

  /// 选择分类
  void selectCategory(String category) {
    _state = _state.copyWith(selectedCategory: category);
    notifyListeners();
  }

  Future<void> _fetchTemplates() async {
    try {
      final response = await _api.get('/diary/templates');
      final body = response.data as Map<String, dynamic>;
      final list = body['data'] as List? ?? [];

      final templates = list.map((item) {
        final m = item as Map<String, dynamic>;
        return Template(
          id: m['id'] as String,
          name: m['name'] as String,
          description: m['description'] as String?,
          previewUrl: m['preview_url'] as String?,
          templateData: m['template_data'] as Map<String, dynamic>?,
          category: m['category'] as String?,
          isFree: m['is_free'] as bool? ?? true,
        );
      }).toList();

      _state = _state.copyWith(isLoading: false, templates: templates);
    } catch (e) {
      _state = _state.copyWith(
        isLoading: false,
        errorMessage: '加载模板列表失败',
      );
    }
    notifyListeners();
  }
}