import 'package:flutter_secure_storage/flutter_secure_storage.dart';

/// 登录会话持久化：token + 手机号存 secure storage。
/// 启动时读取判断是否已登录；登出/401 时清除回登录页。
/// 另存「已确认更新版本」：用户点过「立即更新」后记录服务器版本号，
/// 与 APK 内 versionName 取较大者参与更新判断（APK 版本号不递增也不会反复提示）。
class SessionStore {
  static const _storage = FlutterSecureStorage();
  static const _tokenKey = 'auth_token';
  static const _phoneKey = 'auth_phone';
  static const _acceptedUpdateKey = 'accepted_update_version';

  static String? _cachedToken;
  static String? _cachedPhone;
  static String? _cachedAcceptedUpdate;

  Future<String?> readToken() async {
    if (_cachedToken != null) return _cachedToken;
    return _cachedToken = await _storage.read(key: _tokenKey);
  }

  Future<String?> readPhone() async {
    if (_cachedPhone != null) return _cachedPhone;
    return _cachedPhone = await _storage.read(key: _phoneKey);
  }

  /// 用户点过「立即更新」的服务器版本号（空串 = 从未接受过更新提示）
  Future<String> readAcceptedUpdateVersion() async {
    if (_cachedAcceptedUpdate != null) return _cachedAcceptedUpdate!;
    return _cachedAcceptedUpdate =
        (await _storage.read(key: _acceptedUpdateKey)) ?? '';
  }

  Future<void> saveAcceptedUpdateVersion(String version) async {
    _cachedAcceptedUpdate = version;
    await _storage.write(key: _acceptedUpdateKey, value: version);
  }

  Future<void> save(String phone, String token) async {
    _cachedPhone = phone;
    _cachedToken = token;
    await _storage.write(key: _phoneKey, value: phone);
    await _storage.write(key: _tokenKey, value: token);
  }

  Future<void> clear() async {
    _cachedPhone = null;
    _cachedToken = null;
    await _storage.delete(key: _phoneKey);
    await _storage.delete(key: _tokenKey);
  }
}