/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2024,  Regents of the University of California,
 *                           Arizona Board of Regents,
 *                           Colorado State University,
 *                           University Pierre & Marie Curie, Sorbonne University,
 *                           Washington University in St. Louis,
 *                           Beijing Institute of Technology,
 *                           The University of Memphis.
 *
 * This file is part of NFD (Named Data Networking Forwarding Daemon).
 * See AUTHORS.md for complete list of NFD authors and contributors.
 *
 * NFD is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 *
 * NFD 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef NFD_DAEMON_FACE_TCP_TRANSPORT_HPP
#define NFD_DAEMON_FACE_TCP_TRANSPORT_HPP

#include "stream-transport.hpp"

#include <ndn-cxx/util/scheduler.hpp>

#include <boost/asio/ip/tcp.hpp>

namespace nfd::face {

NFD_LOG_MEMBER_DECL_SPECIALIZED(StreamTransport<boost::asio::ip::tcp>);

/**
 * \brief A Transport that communicates on a connected TCP socket.
 *
 * When persistency is set to permanent, whenever the TCP connection is severed, the transport
 * state is set to DOWN, and the connection is retried periodically with exponential backoff
 * until it is reestablished
 */
class TcpTransport NFD_FINAL_UNLESS_WITH_TESTS : public StreamTransport<boost::asio::ip::tcp>
{
public:
  TcpTransport(boost::asio::ip::tcp::socket&& socket,
               ndn::nfd::FacePersistency persistency,
               ndn::nfd::FaceScope faceScope);

  ssize_t
  getSendQueueLength() final;

protected:
  bool
  canChangePersistencyToImpl(ndn::nfd::FacePersistency newPersistency) const final;

  void
  afterChangePersistency(ndn::nfd::FacePersistency oldPersistency) final;

  void
  doClose() final;

  void
  handleError(const boost::system::error_code& error) final;

NFD_PROTECTED_WITH_TESTS_ELSE_PRIVATE:
  NFD_VIRTUAL_WITH_TESTS void
  reconnect();

  NFD_VIRTUAL_WITH_TESTS void
  handleReconnect(const boost::system::error_code& error);

  NFD_VIRTUAL_WITH_TESTS void
  handleReconnectTimeout();

NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
  /**
   * \brief Delay before the first reconnection attempt after the TCP connection has been severed.
   */
  static constexpr time::milliseconds INITIAL_RECONNECT_DELAY = 1_s;

  /**
   * \brief Maximum amount of time to wait before a reconnection attempt.
   */
  static constexpr time::milliseconds MAX_RECONNECT_DELAY = 5_min;

  /**
   * \brief Multiplier for the exponential backoff of the reconnection timer.
   */
  static constexpr float RECONNECT_DELAY_MULTIPLIER = 2.0f;

private:
  boost::asio::ip::tcp::endpoint m_remoteEndpoint;

  // The following members are valid only when the persistency is set to permanent
  ndn::scheduler::ScopedEventId m_reconnectEvent;
  time::milliseconds m_nextReconnectWait;
};

} // namespace nfd::face

#endif // NFD_DAEMON_FACE_TCP_TRANSPORT_HPP