/// 学习进度模型
class LearningProgress {
  final String id;
  final String title;
  final String category;
  final int totalWords;
  final int learnedWords;
  final double progress;
  final DateTime? lastStudyDate;

  LearningProgress({
    required this.id,
    required this.title,
    required this.category,
    required this.totalWords,
    required this.learnedWords,
    required this.progress,
    this.lastStudyDate,
  });

  factory LearningProgress.fromJson(Map<String, dynamic> json) {
    return LearningProgress(
      id: json['id'] as String? ?? '',
      title: json['title'] as String? ?? '',
      category: json['category'] as String? ?? '',
      totalWords: json['total_words'] as int? ?? 0,
      learnedWords: json['learned_words'] as int? ?? 0,
      progress: (json['progress'] as num?)?.toDouble() ?? 0.0,
      lastStudyDate: json['last_study_date'] != null
          ? DateTime.tryParse(json['last_study_date'] as String)
          : null,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'title': title,
      'category': category,
      'total_words': totalWords,
      'learned_words': learnedWords,
      'progress': progress,
      'last_study_date': lastStudyDate?.toIso8601String(),
    };
  }

  String get progressPercentage => '${(progress * 100).toInt()}%';
}