http_retry_on_auth_fail.dart

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

enum RetryResponseStatus {authFailed, success, unknownError, serverError}

class MRetryResponse{
  final http.Response response;
  final RetryResponseStatus status;

  MRetryResponse(this.response, {this.status : RetryResponseStatus.unknownError,});

  bool get isSuccess => status == RetryResponseStatus.success;

  String get message {
    switch(status){
      case RetryResponseStatus.success:
        return "Success";
        break;
      case RetryResponseStatus.authFailed:
        return "Error: Please log out and login again";
        break;
      case RetryResponseStatus.serverError:
        return "Error: Server problem, please try later";
        break;
      case RetryResponseStatus.unknownError:
      default:
        return "Error: Please check your internet";

    }
  }

}

class RetryRequest{
  static Future<MRetryResponse> retryOnFailure(Function(String authKey) theRequest) async {
    try{
      // call the method
      SharedPreferences prefs = await SharedPreferences.getInstance();
      final token = prefs.getString("key");
      final http.Response currentResponse = await theRequest(token);
      print('retry auth got response');
      print(currentResponse.statusCode);
      print(currentResponse.body);
      if(currentResponse.statusCode == 401){
        /// request failed please refresh token
        print('request failed refreshing token');
        String baseUrl = 'https://api.ebook.com.bd/v1/auth';
        String url = "${baseUrl}/token/refresh/";
        final refreshToken = prefs.getString("Rkey");
        http.Response refreshResponse = await http.post(
          Uri.parse(url),
          body: {
            "refresh": refreshToken,
          },
        );
        print('refreshResponse ${refreshResponse.body}');
        if (refreshResponse.statusCode == 200) {
          print('refreshResponse success');

          /// refresh token
          var data = jsonDecode(refreshResponse.body);
          final newKey = data['access'];
          final refreshKey = data['refresh'];

          print('refresh data access $newKey');
          print('refresh data refresh $refreshKey}');
          if(newKey!= null){
            await prefs.setString("key", newKey);
            await prefs.setString("Rkey", refreshKey);
          }

          /// the currentResponse
          final http.Response currentResponse = await theRequest(newKey);
          if(currentResponse.statusCode == 401){
            print('second time 401');
            /// second time 401
            return MRetryResponse(currentResponse, status: RetryResponseStatus.authFailed,);
          }else if(currentResponse.statusCode>=500 && currentResponse.statusCode<599){
            /// server error with refresh token
            return MRetryResponse(currentResponse, status: RetryResponseStatus.serverError);
          }else{
            /// success in second try
            return MRetryResponse(currentResponse, status: RetryResponseStatus.success);
          }

        }else{
          return MRetryResponse(currentResponse, status: RetryResponseStatus.authFailed);
        }

      }else if(currentResponse.statusCode>=500 && currentResponse.statusCode<599) {
        /// server error
        return MRetryResponse(currentResponse, status: RetryResponseStatus.serverError);
      }else{
        /// success in one try
        return MRetryResponse(currentResponse, status: RetryResponseStatus.success);
      }
    }catch(err, stacktrace){
      print('Custom Http Retry Auth Error');
      print('$err');
      print(stacktrace);
      return MRetryResponse(null, status: RetryResponseStatus.unknownError);
    }

  }
}

USAGE EXAMPLE

Map requestBody = {
      "question": "$questionId",
      "type": errorCause,
 };

Future<http.Response> sendReport(String token) async{
        print('sendReport got Token $token');
        return await http.post(
          Uri.parse(endpoint),
          body: json.encode(requestBody),
          headers: {
            "Authorization": "Bearer " + token,
            "Content-Type": "application/json"
          },
        );
      }
      MRetryResponse mRetryResponse = await RetryRequest.retryOnFailure(sendReport);
      if(mRetryResponse.isSuccess){
        print('success error reporting');
        print(mRetryResponse.response.body);
        apiStatus = {"status": true, "message": "Submitted"};
        return apiStatus;
      }else{
        return apiStatus = {"status": false, "message": mRetryResponse.message};
     }