import '../native/phash_bindings.dart';
import '../native/phash_loader.dart';
import 'hash_library.dart';

class PhashMatch {
  const PhashMatch({
    required this.cardId,
    required this.distance,
    required this.score,
    this.filename,
  });

  final String cardId;
  final int distance;
  final double score;
  final String? filename;

  bool get confident => score >= 75;

  String? get assetPath =>
      filename == null ? null : 'test_assets/$filename';
}

/// Hamming ranking over a local hash library.
class PhashMatcher {
  PhashMatcher({PhashNative? native}) : _native = native ?? PhashNative();

  final PhashNative _native;

  static double scoreFromDistance(int distance, {int bits = kPhashBits}) {
    final raw = 100.0 - (distance / bits) * 100.0;
    return double.parse(raw.toStringAsFixed(2));
  }

  List<PhashMatch> topN(
    String queryHash,
    HashLibrary library, {
    int n = 3,
  }) {
    if (library.items.isEmpty || n <= 0) return const [];

    final scored = <PhashMatch>[];
    for (final item in library.items) {
      final distance = _native.hamming(queryHash, item.hash);
      scored.add(
        PhashMatch(
          cardId: item.cardId,
          distance: distance,
          score: scoreFromDistance(distance),
          filename: item.filename,
        ),
      );
    }
    scored.sort((a, b) => a.distance.compareTo(b.distance));
    if (scored.length <= n) return scored;
    return scored.sublist(0, n);
  }
}