import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:shared_preferences/shared_preferences.dart';
import '../config/api_config.dart';

class AuthService {
  static const String _tokenKey = 'auth_token';
  static const String _expiresKey = 'token_expires';
  static const String _usernameKey = 'username';

  String? _token;
  DateTime? _expiresAt;
  String? _username;

  String? get token => _token;
  String? get username => _username;
  bool get isAuthenticated => _token != null && !isExpired;
  bool get isExpired =>
      _expiresAt != null && DateTime.now().isAfter(_expiresAt!);

  Future<void> loadStoredAuth() async {
    final prefs = await SharedPreferences.getInstance();
    _token = prefs.getString(_tokenKey);
    _username = prefs.getString(_usernameKey);
    final expiresStr = prefs.getString(_expiresKey);
    if (expiresStr != null) {
      _expiresAt = DateTime.tryParse(expiresStr);
    }
  }

  String? lastError;

  Future<bool> login(String username, String password) async {
    lastError = null;
    try {
      final response = await http.post(
        Uri.parse('${ApiConfig.baseUrl}/auth/login'),
        headers: {'Content-Type': 'application/json'},
        body: jsonEncode({'username': username, 'password': password}),
      ).timeout(ApiConfig.connectionTimeout);

      if (response.statusCode == 200) {
        final data = jsonDecode(response.body);
        _token = data['token'];
        _expiresAt = DateTime.parse(data['expires_at']);
        _username = username;

        // Save to storage
        final prefs = await SharedPreferences.getInstance();
        await prefs.setString(_tokenKey, _token!);
        await prefs.setString(_expiresKey, _expiresAt!.toIso8601String());
        await prefs.setString(_usernameKey, _username!);

        return true;
      }
      lastError = 'Invalid credentials (${response.statusCode})';
      return false;
    } catch (e) {
      lastError = 'Connection error: $e';
      return false;
    }
  }

  Future<void> logout() async {
    _token = null;
    _expiresAt = null;
    _username = null;

    final prefs = await SharedPreferences.getInstance();
    await prefs.remove(_tokenKey);
    await prefs.remove(_expiresKey);
    await prefs.remove(_usernameKey);
  }
}