Dio API Service

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import 'package:dio/dio.dart';
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class ApiService {
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  static const _baseUrl = 'https://api.example.com/v1';
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  late final Dio _dio;
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  ApiService() {
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    _dio = Dio(BaseOptions(
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      baseUrl: _baseUrl,
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      connectTimeout: const Duration(seconds: 10),
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      receiveTimeout: const Duration(seconds: 15),
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      headers: {'Content-Type': 'application/json'},
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    ))
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      ..interceptors.addAll([
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        _AuthInterceptor(),
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        _LoggingInterceptor(),
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        _RetryInterceptor(dio: _dio),
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      ]);
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  }
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  Future<T> get<T>(String path, {Map<String, dynamic>? params, required T Function(dynamic) fromJson}) async {
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    try {
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      final response = await _dio.get(path, queryParameters: params);
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      return fromJson(response.data);
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    } on DioException catch (e) {
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      throw _handleError(e);
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    }
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  }
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  Future<T> post<T>(String path, {required Map<String, dynamic> data, required T Function(dynamic) fromJson}) async {
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    try {
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      final response = await _dio.post(path, data: data);
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      return fromJson(response.data);
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    } on DioException catch (e) {
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      throw _handleError(e);
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    }
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  }
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  Exception _handleError(DioException e) {
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    return switch (e.type) {
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      DioExceptionType.connectionTimeout => const TimeoutException(),
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      DioExceptionType.receiveTimeout => const TimeoutException(),
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      DioExceptionType.badResponse => switch (e.response?.statusCode) {
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          401 => const UnauthorizedException(),
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          403 => const ForbiddenException(),
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          404 => const NotFoundException(),
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          _ => ServerException(e.response?.statusCode ?? 500),
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        },
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      _ => const NetworkException(),
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    };
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  }
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}
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class _AuthInterceptor extends Interceptor {
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  @override
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  void onRequest(RequestOptions options, RequestInterceptorHandler handler) {
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    final token = TokenStorage.read();
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    if (token != null) {
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      options.headers['Authorization'] = 'Bearer $token';
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    }
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    handler.next(options);
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  }
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  @override
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  void onError(DioException err, ErrorInterceptorHandler handler) async {
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    if (err.response?.statusCode == 401) {
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      try {
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        await AuthService.refreshToken();
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        final retryOptions = err.requestOptions;
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        retryOptions.headers['Authorization'] = 'Bearer ${TokenStorage.read()}';
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        final response = await Dio().fetch(retryOptions);
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        handler.resolve(response);
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        return;
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      } catch (_) {
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        AuthService.logout();
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      }
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    }
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    handler.next(err);
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  }
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}