Auth Refresh token retry interceptor for flutter with Dio Package

auth_retry_interceptor_gist.dart

import 'dart:async';

import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'package:sabsewa/networks/api_endpoints.dart';
import 'package:sabsewa/app_config/app_colors.dart';
import 'package:sabsewa/networks/secure_storage.dart';
import 'package:flutter/material.dart';
import 'package:sabsewa/views/utils/toast.dart';

class AuthInterceptor extends InterceptorsWrapper {
  final Dio loggedDio; //for logged
  final Dio tokenDio;

  // final Dio tokenDio;
  final SecureStorage secureStorage;

  AuthInterceptor({
    @required this.loggedDio,
    @required this.tokenDio,
    @required this.secureStorage,
  });

  @override
  Future onRequest(RequestOptions options) async {
    options.headers['authorization'] = "Bearer ${await secureStorage.getAccessToken()}";
    return options;
  }

  @override
  Future onError(DioError error) async {
    if (error.response?.statusCode == 401) {
      //This retries the request if the token was updated later on
      final RequestOptions options = error.response.request;
      _lockDio();
      //check if retry count is 1 (retry count gives number of attempt for refresh token renewable
      if (options.headers['Retry-Count'] == 1) {
        _unlockDio();
        // showFlutterToast(AppColors.secondaryColor(1), 'Unauthorized Access! Please login');
        secureStorage.removeData();
        //TODO: logout user here
        return error;
      }
      //request for new refresh token
      return tokenDio.post(APIPathHelper.authAPIs(APIPath.refreshToken), data: {
        secureStorage.refreshToken: await secureStorage.getRefreshToken() ?? ""
      }).then((response) {
        secureStorage.setAccessToken(response.data[secureStorage.accessToken]); //overwriting existing expired token
        secureStorage.setRefreshToken(response.data[secureStorage.refreshToken]); //overwriting existing expired refresh token
      }).whenComplete(() {
        _unlockDio();
      }).then((e) {
        options.headers['Retry-Count'] = 1; //setting retry count to 1 to prevent further concurrent calls
        return loggedDio.request(options.path, options: options);
      }).catchError((e) {
        // showFlutterToast(AppColors.secondaryColor(1), 'Unauthorized Access! Please login');
        secureStorage.removeData();
        //TODO: logout user here
        return e;
      });
    } else {
      return error;
    }
  }

  void _lockDio() {
    loggedDio.lock();
    loggedDio.interceptors.responseLock.lock();
    loggedDio.interceptors.errorLock.lock();
  }

  void _unlockDio() {
    loggedDio.unlock();
    loggedDio.interceptors.responseLock.unlock();
    loggedDio.interceptors.errorLock.unlock();
  }
}