// device_identity_test.dart — 稳定 device_id 的生成/持久/读失败语义
import 'package:flutter_test/flutter_test.dart';
import 'package:pangolin_vpn/services/device_identity.dart';

/// 内存版 SecureKV:可模拟读失败,记录写入。
class _FakeKV implements SecureKV {
  _FakeKV({this.failRead = false});
  final Map<String, String> map = {};
  bool failRead;
  int writes = 0;

  @override
  Future<String?> read(String key) async {
    if (failRead) throw Exception('platform read failed');
    return map[key];
  }

  @override
  Future<void> write(String key, String value) async {
    writes++;
    map[key] = value;
  }
}

void main() {
  test('首次:生成并持久化;再读复用同一个', () async {
    final kv = _FakeKV();
    final d1 = DeviceIdentity(store: kv);
    final id1 = await d1.deviceId();
    expect(id1, isNotEmpty);
    expect(kv.writes, 1, reason: '首次应写一次');
    expect(kv.map['pangolin_device_id'], id1);

    // 同实例缓存:不再写。
    expect(await d1.deviceId(), id1);
    expect(kv.writes, 1);

    // 新实例、同存储:读出同一个,不重新生成。
    final d2 = DeviceIdentity(store: kv);
    expect(await d2.deviceId(), id1);
    expect(kv.writes, 1, reason: '已存在不应再写');
  });

  test('读失败 ≠ 不存在:退回临时 id,不写库(不冲掉真实 id)', () async {
    final kv = _FakeKV(failRead: true)..map['pangolin_device_id'] = 'real-id';
    final d = DeviceIdentity(store: kv);
    final id = await d.deviceId();
    expect(id, isNotEmpty);
    expect(id, isNot('real-id'), reason: '读失败拿不到真实值,用临时');
    expect(kv.writes, 0, reason: '读失败绝不写,避免覆盖真实 id');
    // 真实 id 仍在存储里,未被破坏。
    expect(kv.map['pangolin_device_id'], 'real-id');
  });

  test('生成的是 UUID v4 形态', () async {
    final id = await DeviceIdentity(store: _FakeKV()).deviceId();
    expect(RegExp(r'^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$').hasMatch(id), isTrue);
  });
}