japp_flutter/lib/features/challenge/view_models/challenge_view_model.dart

import 'package:flutter/material.dart';
import 'package:japp_flutter/core/models/challenge_model.dart';

class ChallengeListViewModel extends ChangeNotifier {
  List<ChallengeModel> _challenges = [];
  bool _isLoading = false;
  String _error = '';

  List<ChallengeModel> get challenges => _challenges;
  bool get isLoading => _isLoading;
  String get error => _error;

  // 模拟数据加载
  Future<void> fetchChallenges() async {
    try {
      _isLoading = true;
      notifyListeners();
      
      // 模拟网络请求延迟
      await Future.delayed(const Duration(seconds: 1));
      
      // 生成模拟数据
      _challenges = [
        ChallengeModel(
          id: '1',
          title: '30天健身挑战',
          description: '每天坚持30分钟有氧运动，塑造健康体魄',
          startDate: DateTime.now().subtract(const Duration(days: 5)),
          endDate: DateTime.now().add(const Duration(days: 25)),
          participants: 2541,
          completed: false,
          difficulty: '中等',
        ),
        ChallengeModel(
          id: '2',
          title: '每日阅读打卡',
          description: '连续21天每天阅读至少30分钟',
          startDate: DateTime.now().subtract(const Duration(days: 10)),
          endDate: DateTime.now().add(const Duration(days: 11)),
          participants: 4217,
          completed: false,
          difficulty: '简单',
        ),
        ChallengeModel(
          id: '3',
          title: '编程马拉松',
          description: '7天内完成一个完整的Flutter应用',
          startDate: DateTime.now().subtract(const Duration(days: 2)),
          endDate: DateTime.now().add(const Duration(days: 5)),
          participants: 876,
          completed: false,
          difficulty: '困难',
        ),
        ChallengeModel(
          id: '4',
          title: '素食30天挑战',
          description: '连续30天坚持素食饮食',
          startDate: DateTime.now().add(const Duration(days: 2)),
          endDate: DateTime.now().add(const Duration(days: 32)),
          participants: 1589,
          completed: false,
          difficulty: '中等',
        ),
      ];
      
      _error = '';
    } catch (e) {
      _error = '加载数据失败: $e';
    } finally {
      _isLoading = false;
      notifyListeners();
    }
  }
}