// Copyright 2019 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 TINK_INTEGRATION_GCPKMS_GCP_KMS_CLIENT_H_
#define TINK_INTEGRATION_GCPKMS_GCP_KMS_CLIENT_H_

#include <memory>
#include <string>
#include <utility>

#include "google/cloud/kms/v1/service.grpc.pb.h"
#include "grpcpp/channel.h"
#include "absl/strings/string_view.h"
#include "tink/aead.h"
#include "tink/kms_client.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"

namespace crypto {
namespace tink {
namespace integration {
namespace gcpkms {

// GcpKmsClient is an implementation of KmsClient for Google Cloud KMS
// (https://cloud.google.com/kms/).
class GcpKmsClient : public crypto::tink::KmsClient {
 public:
  // Move only.
  GcpKmsClient(GcpKmsClient&& other) = default;
  GcpKmsClient& operator=(GcpKmsClient&& other) = default;
  GcpKmsClient(const GcpKmsClient&) = delete;
  GcpKmsClient& operator=(const GcpKmsClient&) = delete;

  // Creates a new GcpKmsClient that is bound to the key specified in `key_uri`,
  // and that uses the specified credentials when communicating with the KMS.
  //
  // Either argument can be empty.
  // If `key_uri` is empty, then the client is not bound to any particular key.
  // If `credential_path` is empty, then default credentials will be used.
  static crypto::tink::util::StatusOr<std::unique_ptr<GcpKmsClient>> New(
      absl::string_view key_uri, absl::string_view credentials_path);

  // Creates a new client and registers it in KMSClients.
  static crypto::tink::util::Status RegisterNewClient(
      absl::string_view key_uri, absl::string_view credentials_path);

  // Returns true iff this client does support KMS key specified by `key_uri`.
  bool DoesSupport(absl::string_view key_uri) const override;

  // Returns an Aead-primitive backed by KMS key specified by `key_uri`,
  // provided that this KmsClient does support `key_uri`.
  crypto::tink::util::StatusOr<std::unique_ptr<Aead>> GetAead(
      absl::string_view key_uri) const override;

 private:
  explicit GcpKmsClient(
      std::string key_name,
      std::shared_ptr<google::cloud::kms::v1::KeyManagementService::Stub>
          kms_stub)
      : key_name_(key_name), kms_stub_(std::move(kms_stub)) {}

  std::string key_name_;
  std::shared_ptr<google::cloud::kms::v1::KeyManagementService::Stub> kms_stub_;
};

}  // namespace gcpkms
}  // namespace integration
}  // namespace tink
}  // namespace crypto

#endif  // TINK_INTEGRATION_GCPKMS_GCP_KMS_CLIENT_H_