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

import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:japp_flutter/core/models/challenge_model.dart';
import 'package:japp_flutter/core/proviers/repository_providers.dart';
import 'package:japp_flutter/core/repositories/challenge_repository.dart';

final challengeEditProvider = AsyncNotifierProvider.autoDispose<ChallengeEditViewModel, ChallengeModel?>(
  ChallengeEditViewModel.new,
);

class ChallengeEditViewModel extends AutoDisposeAsyncNotifier<ChallengeModel?> {
  ChallengeRepository get _repository => ref.read(challengeRepositoryProvider);

  @override
  Future<ChallengeModel?> build() async {
    // 初始化为 null，由外部传入初始数据
    return null;
  }

  /// 初始化编辑数据（从详情页传入）
  void initialize(ChallengeModel challenge) {
    state = AsyncData(challenge);
  }

  /// 更新挑战标题
  void updateTitle(String title) {
    state.whenData((challenge) {
      state = AsyncData(challenge!.copyWith(title: title));
    });
  }

  /// 更新挑战描述
  void updateDescription(String description) {
    state.whenData((challenge) {
      state = AsyncData(challenge!.copyWith(description: description));
    });
  }

  /// 更新难度
  void updateDifficulty(String difficulty) {
    state.whenData((challenge) {
      state = AsyncData(challenge!.copyWith(difficulty: difficulty));
    });
  }

  /// 保存挑战
  Future<void> saveChallenge() async {
    final challenge = state.value;
    if (challenge == null) return;

    state = const AsyncLoading();
    state = await AsyncValue.guard(() => _repository.updateChallenge(challenge));
  }
}