import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:shared_preferences/shared_preferences.dart';

/// Stores the auth token in secure storage and falls back to SharedPreferences
/// so debug builds and platforms without a working keyring still persist.
class TokenStorageService {
  TokenStorageService._internal();

  static final TokenStorageService _instance = TokenStorageService._internal();

  factory TokenStorageService() => _instance;

  static const _tokenKey = 'auth_token';
  final FlutterSecureStorage _secureStorage = const FlutterSecureStorage();

  Future<SharedPreferences> get _prefs async =>
      await SharedPreferences.getInstance();

  Future<void> setToken(String token) async {
    try {
      await _secureStorage.write(key: _tokenKey, value: token);
    } catch (_) {
      // ignore secure storage failures in debug/unsupported environments
    }
    final prefs = await _prefs;
    await prefs.setString(_tokenKey, token);
  }

  Future<String?> getToken() async {
    try {
      final secured = await _secureStorage.read(key: _tokenKey);
      if (secured != null && secured.isNotEmpty) {
        return secured;
      }
    } catch (_) {
      // ignore and fall back
    }
    final prefs = await _prefs;
    final token = prefs.getString(_tokenKey);
    return (token == null || token.isEmpty) ? null : token;
  }

  Future<void> clearToken() async {
    try {
      await _secureStorage.delete(key: _tokenKey);
    } catch (_) {
      // ignore
    }
    final prefs = await _prefs;
    await prefs.remove(_tokenKey);
  }

  Future<bool> hasToken() async {
    final token = await getToken();
    return token != null && token.isNotEmpty;
  }
}