tm_app/lib/data/services/network_manager.dart

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

class NetworkManager {
  final Dio mainDio;

  NetworkManager()
    : mainDio = Dio(
        BaseOptions(
          // baseUrl: 'https://stage.cura-bau.de',
          connectTimeout: const Duration(seconds: 10),
          receiveTimeout: const Duration(seconds: 10),
          contentType: 'application/json',
          headers: {'Accept': 'application/json'},
        ),
      );

  Future<void> init() async {
    await addInterceptors();
  }

  Future<void> addInterceptors() async {
    final requestInterceptor = InterceptorsWrapper(
      onRequest: (options, handler) {
        // TODO: add more
        return handler.next(options);
      },
    );

    mainDio.interceptors.add(requestInterceptor);
  }

  Future<T> makeRequest<T>(
    String endpoint,
    T Function(Map<String, dynamic>) fromJson, {
    String method = 'GET',
    FormData? data,
  }) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();

    Dio dioInstance = mainDio;

    await addInterceptors();

    Future<Response> makeApiCall(String token, String url) async {
      final headers =
          token.isEmpty
              ? <String, String>{}
              : {'Authorization': 'Bearer $token'};
      switch (method.toUpperCase()) {
        case 'POST':
          return await dioInstance.post(
            url + endpoint,
            data: data,
            options: Options(headers: headers),
          );
        case 'PUT':
          return await dioInstance.put(
            url + endpoint,
            data: data,
            options: Options(headers: headers),
          );
        case 'PATCH':
          return await dioInstance.patch(
            url + endpoint,
            data: data,
            options: Options(headers: headers),
          );
        case 'DELETE':
          return await dioInstance.delete(
            url + endpoint,
            data: data,
            options: Options(headers: headers),
          );
        case 'GET':
          return await dioInstance.get(
            url + endpoint,
            data: data,
            options: Options(headers: headers),
          );
        default:
          return await dioInstance.get(
            url + endpoint,
            options: Options(headers: headers),
          );
      }
    }

    try {
      String? bearerToken = prefs.getString('bearer');
      String? url = prefs.getString('url');
      Response res = await makeApiCall(bearerToken ?? '', url ?? '');
      switch (res.statusCode) {
        case 200:
        case 201:
          return fromJson(res.data);
        case 401:
          break;
        case 403:
          throw Exception('Forbidden: ${res.data['message']}');
        case 404:
          throw Exception('Not found: ${res.data['message']}');
        case 423:
          throw Exception('Locked: ${res.data['message']}');
        case 500:
          throw Exception('Internal server error: ${res.data['message']}');
        default:
          throw Exception('Error: ${res.data['message']}');
      }
    } on DioException catch (e) {
      if (e.response?.statusCode == 401) {
        // await api.refreshToken();
        String? bearerToken = prefs.getString('bearer');
        String? url = prefs.getString('url');
        Response res = await makeApiCall(bearerToken ?? '', url ?? '');

        if (res.statusCode == 200 || res.statusCode == 201) {
          return fromJson(res.data);
        }

        throw Exception(e.message ?? 'Error occurred');
      }
    } catch (e) {
      throw Exception(e.toString());
    }

    throw Exception('Unhandled error occurred');
  }
}