readful/lib/models/bookmark.dart

/// 书签模型
/// 用于记录和管理阅读位置标记
class Bookmark {
  final String id;
  final String bookId;
  final String? chapterId;
  final String title;
  final String? description;
  final int pageIndex;
  final double position; // 0.0-1.0之间的值，表示在文档中的相对位置
  final String? previewText;
  final DateTime createdTime;
  final int sortOrder;

  // 构造函数...
  const Bookmark(
      {required this.id,
      required this.bookId,
      this.chapterId,
      required this.title,
      this.description,
      required this.pageIndex,
      required this.position,
      this.previewText,
      required this.createdTime,
      required this.sortOrder});

  // copyWith方法...
  Bookmark copyWith(
      {String? id,
      String? bookId,
      String? chapterId,
      String? title,
      String? description,
      int? pageIndex,
      double? position,
      String? previewText,
      DateTime? createdTime,
      int? sortOrder}) {
    return Bookmark(
        id: id ?? this.id, // 如果id不为null就使用新值，否则保持原值
        bookId: bookId ?? this.bookId,
        chapterId: chapterId ?? this.chapterId,
        title: title ?? this.title,
        description: description ?? this.description,
        pageIndex: pageIndex ?? this.pageIndex,
        position: position ?? this.position,
        previewText: previewText ?? this.previewText,
        createdTime: createdTime ?? this.createdTime,
        sortOrder: sortOrder ?? this.sortOrder);
  }

  // toMap/fromMap方法...
  /// toMap方法 - 将对象转换为Map
  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'bookId': bookId,
      'chapterId': chapterId,
      'title': title,
      'description': description,
      'pageIndex': pageIndex,
      'position': position,
      'previewText': previewText,
      'createdTime': createdTime.toIso8601String(),
      'sortOrder': sortOrder
    };
  }

  /// fromMap构造函数 - 从Map创建Book对象
  ///
  /// 这是toMap的逆操作，用于：
  /// 1. 从本地存储中读取数据
  /// 2. 从网络请求中解析数据
  /// 3. 从保存的状态中恢复对象
  factory Bookmark.fromMap(Map<String, dynamic> map) {
    return Bookmark(
        id: map['id'],
        bookId: map['bookId'],
        chapterId: map['chapterId'],
        title: map['title'],
        description: map['description'],
        pageIndex: map['pageIndex'],
        position: map['position'],
        previewText: map['previewText'],
        createdTime: DateTime.parse(map['createdTime']),
        sortOrder: map['sortOrder']);
  }
  // 工厂方法...
  factory Bookmark.create({
    required String bookId,
    required String title,
    required int pageIndex,
    required double position,
    String? chapterId,
    String? description,
    String? previewText,
  }) {
    return Bookmark(
        id: _generateId(), // 生成唯一ID
        bookId: bookId,
        chapterId: chapterId,
        title: title,
        pageIndex: pageIndex,
        position: position,
        description: description,
        previewText: previewText,
        createdTime: DateTime.now(),
        sortOrder: 0);
  }

  // 计算属性和实用方法...
  /// 生成唯一ID的私有方法
  static String _generateId() {
    return '${DateTime.now().millisecondsSinceEpoch}_${(DateTime.now().microsecond).toString()}';
  }

  /// 重写equals和hashCode，用于对象比较
  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    return other is Bookmark && other.id == id;
  }

  @override
  int get hashCode => id.hashCode;


    /// 重写toString方法，便于调试
  @override
  String toString() {
    return 'Bookmark(id: $id, title: $title, bookId: $bookId, sortOrder: $sortOrder)';
  }

  // 更新位置
  Bookmark updatePosition(int newPageIndex, double newPosition) {
    return copyWith(
      pageIndex: newPageIndex,
      position: newPosition,
    );
  }

// 更新标题和描述
  Bookmark updateInfo({String? title, String? description}) {
    return copyWith(
      title: title ?? this.title,
      description: description ?? this.description,
    );
  }

  // 格式化位置显示
  String get positionDisplay => '${(position * 100).toInt()}%';

  // 检查位置是否有效
  bool get isValidPosition => position >= 0.0 && position <= 1.0;
}