import 'package:isar/isar.dart';
part 'cache_image.g.dart';

@collection
class CacheImage {
  String? md5;
  Id get isarId => fastHash(md5!);
  List<byte> image = List.empty();
  int? timestamp;
  List<byte> nonce = List.empty();
  String? ext;

  @Index()
  DateTime createTime = DateTime.now();

  /// 针对 Dart 字符串优化的 64 位哈希算法 FNV-1a
  static int fastHash(String string) {
    var hash = 0xcbf29ce484222325;

    var i = 0;
    while (i < string.length) {
      final codeUnit = string.codeUnitAt(i++);
      hash ^= codeUnit >> 8;
      hash *= 0x100000001b3;
      hash ^= codeUnit & 0xFF;
      hash *= 0x100000001b3;
    }

    return hash;
  }
}