/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2013-2016 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */

#ifndef NDN_SECURITY_TPM_BACK_END_OSX_HPP
#define NDN_SECURITY_TPM_BACK_END_OSX_HPP

#include "back-end.hpp"
#include "helper-osx.hpp"

#ifndef NDN_CXX_HAVE_OSX_SECURITY
#error "This file should not be compiled ..."
#endif

namespace ndn {
namespace security {
namespace tpm {

/**
 * @brief The back-end implementation of TPM based on OS X KeyChain service.
 */
class BackEndOsx : public BackEnd
{
public:
  class Error : public BackEnd::Error
  {
  public:
    explicit
    Error(const std::string& what)
      : BackEnd::Error(what)
    {
    }
  };

public:
  BackEndOsx();

  ~BackEndOsx() override;

public: // management
  /**
   * @brief Set the terminal mode of TPM.
   *
   * In terminal mode, TPM will not ask user permission from GUI.
   */
  void
  setTerminalMode(bool isTerminal);

  /**
   * @brief Check if TPM is in terminal mode
   */
  bool
  isTerminalMode() const;

  /**
   * @return True if TPM is locked, otherwise false
   */
  bool
  isLocked() const;

  /**
   * @brief Unlock TPM
   *
   * @param password       The password to unlock TPM
   * @param passwordLength The password size.
   */
  bool
  unlockTpm(const char* password = nullptr, size_t passwordLength = 0);

public: // crypto transformation
  /**
   * @brief Sign @p buf with @p key using @p digestAlgorithm.
   */
  ConstBufferPtr
  sign(const KeyRefOsx& key, DigestAlgorithm digestAlgorithm, const uint8_t* buf, size_t size) const;

  ConstBufferPtr
  decrypt(const KeyRefOsx& key, const uint8_t* cipherText, size_t cipherSize) const;

  ConstBufferPtr
  derivePublicKey(const KeyRefOsx& key) const;

private: // inherited from tpm::BackEnd

  /**
   * @return True if a key with name @p keyName exists in TPM.
   */
  bool
  doHasKey(const Name& keyName) const final;

  /**
   * @return The handle of a key with name @p keyName, or nullptr if the key does not exist
   */
  unique_ptr<KeyHandle>
  doGetKeyHandle(const Name& keyName) const final;

  /**
   * @brief Create key for @p identityName according to @p params.
   *
   * The created key is named as: /<identityName>/[keyId]/KEY
   * The key name is set in the returned KeyHandle.
   *
   * @return The handle of the created key.
   */
  unique_ptr<KeyHandle>
  doCreateKey(const Name& identityName, const KeyParams& params) final;

  /**
   * @brief Delete a key with name @p keyName.
   *
   * @throws Error if the deletion fails.
   */
  void
  doDeleteKey(const Name& keyName) final;

  /**
   * @return A private key with name @p keyName in encrypted PKCS #8 format using password @p pw
   * @throws Error if the key cannot be exported, e.g., not enough privilege
   */
  ConstBufferPtr
  doExportKey(const Name& keyName, const char* pw, size_t pwLen) final;

  /**
   * @brief Import a private key in encrypted PKCS #8 format
   *
   * @param keyName The name of imported private key
   * @param buf Pointer to the key in encrypted PKCS #8 format
   * @param size The size of the key in encrypted PKCS #8 format
   * @param pw The password to decrypt the private key
   * @param pwLen The length of the password
   * @throws Error if import fails
   */
  void
  doImportKey(const Name& keyName, const uint8_t* buf, size_t size, const char* pw, size_t pwLen) final;

private:
  class Impl;
  unique_ptr<Impl> m_impl;
};

} // namespace tpm
} // namespace security
} // namespace ndn

#endif // NDN_SECURITY_TPM_BACK_END_OSX_HPP