/// Data model representing an item stored in local storage.
/// 
/// This model is used for storing items (e.g., image metadata or records)
/// in the local database. Each item has a unique ID and can contain
/// arbitrary JSON data.
class Item {
  /// Unique identifier for the item.
  final String id;

  /// JSON-serializable data stored with the item.
  final Map<String, dynamic> data;

  /// Timestamp when the item was created (milliseconds since epoch).
  final int createdAt;

  /// Timestamp when the item was last updated (milliseconds since epoch).
  final int updatedAt;

  /// Creates an [Item] instance.
  /// 
  /// [id] - Unique identifier for the item.
  /// [data] - JSON-serializable data to store.
  /// [createdAt] - Creation timestamp (defaults to current time).
  /// [updatedAt] - Update timestamp (defaults to current time).
  Item({
    required this.id,
    required this.data,
    int? createdAt,
    int? updatedAt,
  })  : createdAt = createdAt ?? DateTime.now().millisecondsSinceEpoch,
        updatedAt = updatedAt ?? DateTime.now().millisecondsSinceEpoch;

  /// Creates an [Item] from a database row (Map).
  factory Item.fromMap(Map<String, dynamic> map) {
    return Item(
      id: map['id'] as String,
      data: map['data'] as Map<String, dynamic>,
      createdAt: map['created_at'] as int,
      updatedAt: map['updated_at'] as int,
    );
  }

  /// Converts the [Item] to a Map for database storage.
  Map<String, dynamic> toMap() {
    return {
      'id': id,
      'data': data,
      'created_at': createdAt,
      'updated_at': updatedAt,
    };
  }

  /// Creates a copy of this [Item] with updated fields.
  Item copyWith({
    String? id,
    Map<String, dynamic>? data,
    int? createdAt,
    int? updatedAt,
  }) {
    return Item(
      id: id ?? this.id,
      data: data ?? this.data,
      createdAt: createdAt ?? this.createdAt,
      updatedAt: updatedAt ?? this.updatedAt,
    );
  }

  @override
  String toString() {
    return 'Item(id: $id, data: $data, createdAt: $createdAt, updatedAt: $updatedAt)';
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    return other is Item &&
        other.id == id &&
        other.createdAt == createdAt &&
        other.updatedAt == updatedAt;
  }

  @override
  int get hashCode => id.hashCode ^ createdAt.hashCode ^ updatedAt.hashCode;
}