import 'dart:async';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import '../models/user.dart';
import 'api_client.dart';

class AuthService {
  final ApiClient _api;
  final FlutterSecureStorage _storage = const FlutterSecureStorage();
  Timer? _refreshTimer;

  AuthService(this._api);

  Future<User> login(String serverUrl, String username, String password,
      {String? fcmToken}) async {
    await _api.setBaseUrl(serverUrl);

    final response = await _api.dio.post('/auth/login', data: {
      'username': username,
      'password': password,
      if (fcmToken != null) 'fcm_token': fcmToken,
    });

    final data = response.data;
    if (data['success'] != true) {
      throw Exception(data['message'] ?? 'Login failed');
    }

    await _storage.write(key: 'access_token', value: data['access_token']);
    await _storage.write(key: 'refresh_token', value: data['refresh_token']);

    _scheduleRefresh(data['expires_in'] as int? ?? 3600);

    return User.fromJson(data['user']);
  }

  Future<bool> tryRestoreSession() async {
    final token = await _storage.read(key: 'access_token');
    if (token == null) return false;

    await _api.restoreBaseUrl();
    if (_api.dio.options.baseUrl.isEmpty) return false;

    try {
      final response = await _api.dio.get('/agent/status');
      return response.statusCode == 200;
    } catch (_) {
      return false;
    }
  }

  Future<void> refreshToken() async {
    final refreshToken = await _storage.read(key: 'refresh_token');
    if (refreshToken == null) throw Exception('No refresh token');

    final response = await _api.dio.post('/auth/refresh', data: {
      'refresh_token': refreshToken,
    });

    final data = response.data;
    if (data['success'] != true) {
      throw Exception('Token refresh failed');
    }

    await _storage.write(key: 'access_token', value: data['access_token']);
    if (data['refresh_token'] != null) {
      await _storage.write(key: 'refresh_token', value: data['refresh_token']);
    }

    _scheduleRefresh(data['expires_in'] as int? ?? 3600);
  }

  void _scheduleRefresh(int expiresInSeconds) {
    _refreshTimer?.cancel();
    // Refresh 2 minutes before expiry
    final refreshIn = Duration(seconds: expiresInSeconds - 120);
    if (refreshIn.isNegative) return;
    _refreshTimer = Timer(refreshIn, () async {
      try {
        await refreshToken();
      } catch (_) {}
    });
  }

  Future<void> logout() async {
    _refreshTimer?.cancel();
    try {
      await _api.dio.post('/auth/logout');
    } catch (_) {}
    await _storage.deleteAll();
  }

  void dispose() {
    _refreshTimer?.cancel();
  }
}