text: // Copyright 2021 Google LLC
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #ifndef GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_INTERNAL_GRPC_ACCESS_TOKEN_AUTHENTICATION_H
  #define GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_INTERNAL_GRPC_ACCESS_TOKEN_AUTHENTICATION_H
  
  #include "google/cloud/internal/unified_grpc_credentials.h"
  #include "google/cloud/version.h"
  #include <grpcpp/grpcpp.h>
  
  namespace google {
  namespace cloud {
  inline namespace GOOGLE_CLOUD_CPP_NS {
  namespace internal {
  
  class GrpcAccessTokenAuthentication : public GrpcAuthenticationStrategy {
   public:
    explicit GrpcAccessTokenAuthentication(AccessToken const& access_token)
        : credentials_(grpc::AccessTokenCredentials(access_token.token)) {}
    ~GrpcAccessTokenAuthentication() override = default;
  
    std::shared_ptr<grpc::Channel> CreateChannel(
        std::string const& endpoint,
        grpc::ChannelArguments const& arguments) override;
    bool RequiresConfigureContext() const override;
    Status ConfigureContext(grpc::ClientContext&) override;
    future<StatusOr<std::unique_ptr<grpc::ClientContext>>> AsyncConfigureContext(
        std::unique_ptr<grpc::ClientContext> context) override;
  
   private:
    std::shared_ptr<grpc::CallCredentials> credentials_;
  };
  
  }  // namespace internal
  }  // namespace GOOGLE_CLOUD_CPP_NS
  }  // namespace cloud
  }  // namespace google
  
  #endif  // GOOGLE_CLOUD_CPP_GOOGLE_CLOUD_INTERNAL_GRPC_ACCESS_TOKEN_AUTHENTICATION_H
  