//
// Copyright 2020 gRPC authors.
//
// 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 GRPCPP_SECURITY_TLS_CERTIFICATE_PROVIDER_H
#define GRPCPP_SECURITY_TLS_CERTIFICATE_PROVIDER_H

#include <grpc/grpc_security_constants.h>
#include <grpc/status.h>
#include <grpc/support/log.h>
#include <grpcpp/impl/codegen/grpc_library.h>
#include <grpcpp/support/config.h>

#include <memory>
#include <vector>

// TODO(yihuazhang): remove the forward declaration here and include
// <grpc/grpc_security.h> directly once the insecure builds are cleaned up.
typedef struct grpc_tls_certificate_provider grpc_tls_certificate_provider;

namespace grpc {
namespace experimental {

// Interface for a class that handles the process to fetch credential data.
// Implementations should be a wrapper class of an internal provider
// implementation.
class CertificateProviderInterface {
 public:
  virtual ~CertificateProviderInterface() = default;
  virtual grpc_tls_certificate_provider* c_provider() = 0;
};

// A struct that stores the credential data presented to the peer in handshake
// to show local identity. The private_key and certificate_chain should always
// match.
struct IdentityKeyCertPair {
  std::string private_key;
  std::string certificate_chain;
};

// A basic CertificateProviderInterface implementation that will load credential
// data from static string during initialization. This provider will always
// return the same cert data for all cert names, and reloading is not supported.
class StaticDataCertificateProvider : public CertificateProviderInterface {
 public:
  StaticDataCertificateProvider(
      const std::string& root_certificate,
      const std::vector<IdentityKeyCertPair>& identity_key_cert_pairs);

  StaticDataCertificateProvider(const std::string& root_certificate)
      : StaticDataCertificateProvider(root_certificate, {}) {}

  StaticDataCertificateProvider(
      const std::vector<IdentityKeyCertPair>& identity_key_cert_pairs)
      : StaticDataCertificateProvider("", identity_key_cert_pairs) {}

  ~StaticDataCertificateProvider();

  grpc_tls_certificate_provider* c_provider() override { return c_provider_; }

 private:
  grpc_tls_certificate_provider* c_provider_ = nullptr;
};

}  // namespace experimental
}  // namespace grpc

#endif  // GRPCPP_SECURITY_TLS_CERTIFICATE_PROVIDER_H