import 'package:json_annotation/json_annotation.dart';

part 'learning_session_model.g.dart';

/// 学习难度
enum StudyDifficulty {
  @JsonValue('forgot')
  forgot,      // 完全忘记
  @JsonValue('hard')
  hard,        // 困难
  @JsonValue('good')
  good,        // 一般
  @JsonValue('easy')
  easy,        // 容易
  @JsonValue('perfect')
  perfect,     // 完美
}

/// 学习会话
@JsonSerializable()
class LearningSession {
  @JsonKey(fromJson: _idFromJson)
  final String id;
  @JsonKey(name: 'user_id', fromJson: _userIdFromJson)
  final String userId;
  @JsonKey(name: 'book_id')
  final String bookId;
  @JsonKey(name: 'daily_goal')
  final int dailyGoal;
  @JsonKey(name: 'new_words_count')
  final int newWordsCount;
  @JsonKey(name: 'review_count')
  final int reviewCount;
  @JsonKey(name: 'mastered_count')
  final int masteredCount;
  @JsonKey(name: 'started_at')
  final DateTime startedAt;
  @JsonKey(name: 'completed_at')
  final DateTime? completedAt;

  const LearningSession({
    required this.id,
    required this.userId,
    required this.bookId,
    required this.dailyGoal,
    this.newWordsCount = 0,
    this.reviewCount = 0,
    this.masteredCount = 0,
    required this.startedAt,
    this.completedAt,
  });

  factory LearningSession.fromJson(Map<String, dynamic> json) =>
      _$LearningSessionFromJson(json);
  Map<String, dynamic> toJson() => _$LearningSessionToJson(this);
  
  static String _idFromJson(dynamic value) => value.toString();
  static String _userIdFromJson(dynamic value) => value.toString();
}

/// 今日学习任务
@JsonSerializable()
class DailyLearningTasks {
  @JsonKey(name: 'newWords')
  final List<int> newWords;         // 新单词ID列表
  @JsonKey(name: 'reviewWords', fromJson: _reviewWordsFromJson)
  final List<dynamic> reviewWords;  // 复习单词进度列表
  @JsonKey(name: 'masteredCount')
  final int masteredCount;          // 已掌握数量
  @JsonKey(name: 'totalWords')
  final int totalWords;             // 总单词数
  final double progress;            // 整体进度百分比

  const DailyLearningTasks({
    required this.newWords,
    required this.reviewWords,
    required this.masteredCount,
    required this.totalWords,
    required this.progress,
  });

  factory DailyLearningTasks.fromJson(Map<String, dynamic> json) =>
      _$DailyLearningTasksFromJson(json);
  Map<String, dynamic> toJson() => _$DailyLearningTasksToJson(this);

  /// 待学习总数
  int get totalTasks => newWords.length + reviewWords.length;
  
  /// 是否完成
  bool get isCompleted => totalTasks == 0;
  
  static List<dynamic> _reviewWordsFromJson(dynamic value) {
    if (value == null) return [];
    if (value is List) return value;
    return [];
  }
}

/// 学习统计
@JsonSerializable()
class LearningStatistics {
  final int todayNewWords;      // 今日新学单词数
  final int todayReview;        // 今日复习单词数
  final int todayMastered;      // 今日掌握单词数
  final int totalLearned;       // 总学习单词数
  final int totalMastered;      // 总掌握单词数
  final double avgProficiency;  // 平均熟练度
  final int streakDays;         // 连续学习天数

  const LearningStatistics({
    required this.todayNewWords,
    required this.todayReview,
    required this.todayMastered,
    required this.totalLearned,
    required this.totalMastered,
    required this.avgProficiency,
    required this.streakDays,
  });

  factory LearningStatistics.fromJson(Map<String, dynamic> json) =>
      _$LearningStatisticsFromJson(json);
  Map<String, dynamic> toJson() => _$LearningStatisticsToJson(this);
}

/// 学习结果
@JsonSerializable()
class StudyResult {
  final String wordId;
  final StudyDifficulty difficulty;
  final int studyTime;  // 学习时长（毫秒）

  const StudyResult({
    required this.wordId,
    required this.difficulty,
    required this.studyTime,
  });

  factory StudyResult.fromJson(Map<String, dynamic> json) =>
      _$StudyResultFromJson(json);
  Map<String, dynamic> toJson() => _$StudyResultToJson(this);
}