import 'dart:convert';

import 'package:friendly_map/modules/core/core.dart';

/// 시험용 암호: 진짜 암호는 아니고, "두 사람의 키 + 단위 ID 가 맞아야 풀린다"는 약속만 흉내 낸다.
class FakeCipher implements PayloadCipher {
  FakeCipher(this.myKey);
  final String myKey;

  String _tag(String peer, String context) => '${([myKey, peer]..sort()).join('+')}|$context';

  @override
  Future<String> seal({required String plain, required String peerPublicKey, required String context}) async =>
      '${_tag(peerPublicKey, context)}|${base64Encode(utf8.encode(plain))}';

  @override
  Future<String?> open({required String sealed, required String peerPublicKey, required String context}) async {
    final tag = _tag(peerPublicKey, context);
    if (!sealed.startsWith('$tag|')) return null;
    return utf8.decode(base64Decode(sealed.substring(tag.length + 1)));
  }
}

class FakeIdentity implements IdentityProvider {
  FakeIdentity(this.key);
  final String key;
  @override
  Future<String> myPublicKey() async => key;
}