auth_provider.dart

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

enum APIAuthorizationType<T extends AuthProvider> {
  // apiKey,
  // userPools,
  iam<IAMAuthProvider>(),
  // oidc,
  // lambda
}

void main() {
  final repo = AuthProviderRepo();
  repo.set(APIAuthorizationType.iam, IAMAuthProvider());
  final iamProvider = repo.get(APIAuthorizationType.iam)!;
  final options = IAMAuthProviderOptions('us-west-2', 'appsync');
  iamProvider.authorizeRequest(http.Request('GET', Uri()), options: options);
}

class AuthProviderRepo {
  final _repo = <String, AuthProvider>{};

  void set<T extends AuthProvider>(
    APIAuthorizationType<T> type,
    AuthProvider provider,
  ) =>
      _repo[type.name] = provider;

  T? get<T extends AuthProvider>(APIAuthorizationType<T> type) =>
      _repo[type.name] as T?;
}

abstract class AuthProvider {
  Future<http.BaseRequest> authorizeRequest(
    http.BaseRequest request, {
    covariant AuthProviderOptions? options,
  });
}

class IAMAuthProvider extends AuthProvider {
  @override
  Future<http.BaseRequest> authorizeRequest(
    http.BaseRequest request, {
    IAMAuthProviderOptions? options,
  }) {
    throw UnimplementedError();
  }
}

class IAMAuthProviderOptions extends AuthProviderOptions {
  const IAMAuthProviderOptions(this.region, this.service);

  final String region;
  final String service;
}

abstract class AuthProviderOptions {
  const AuthProviderOptions();
}