/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2022,  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_FACE_HPP
#define NFD_DAEMON_FACE_FACE_HPP

#include "face-common.hpp"
#include "face-counters.hpp"
#include "link-service.hpp"
#include "transport.hpp"

namespace nfd {
namespace face {

class Channel;

/**
 * \brief Indicates the state of a face.
 */
using FaceState = TransportState;

/** \brief Generalization of a network interface.
 *
 *  A face generalizes a network interface.
 *  It provides best-effort network-layer packet delivery services
 *  on a physical interface, an overlay tunnel, or a link to a local application.
 *
 *  A face combines two parts: LinkService and Transport.
 *  Transport is the lower part, which provides best-effort TLV block deliveries.
 *  LinkService is the upper part, which translates between network-layer packets
 *  and TLV blocks, and may provide additional services such as fragmentation and reassembly.
 */
class Face NFD_FINAL_UNLESS_WITH_TESTS : public std::enable_shared_from_this<Face>, noncopyable
{
public:
  Face(unique_ptr<LinkService> service, unique_ptr<Transport> transport);

  LinkService*
  getLinkService() const noexcept
  {
    return m_service.get();
  }

  Transport*
  getTransport() const noexcept
  {
    return m_transport.get();
  }

  /** \brief Request that the face be closed.
   *
   *  This operation is effective only if face is in the UP or DOWN state; otherwise, it has no effect.
   *  The face will change state to CLOSING, and then perform a cleanup procedure.
   *  When the cleanup is complete, the state will be changed to CLOSED, which may happen
   *  synchronously or asynchronously.
   *
   *  \warning The face must not be deallocated until its state changes to CLOSED.
   */
  void
  close();

public: // upper interface connected to forwarding
  /** \brief Send Interest.
   */
  void
  sendInterest(const Interest& interest);

  /** \brief Send Data.
   */
  void
  sendData(const Data& data);

  /** \brief Send Nack.
   */
  void
  sendNack(const lp::Nack& nack);

  /** \brief Signals on Interest received.
   */
  signal::Signal<LinkService, Interest, EndpointId>& afterReceiveInterest;

  /** \brief Signals on Data received.
   */
  signal::Signal<LinkService, Data, EndpointId>& afterReceiveData;

  /** \brief Signals on Nack received.
   */
  signal::Signal<LinkService, lp::Nack, EndpointId>& afterReceiveNack;

  /** \brief Signals on Interest dropped by reliability system for exceeding allowed number of retx.
   */
  signal::Signal<LinkService, Interest>& onDroppedInterest;

public: // properties
  /**
   * \brief Returns the face ID.
   */
  FaceId
  getId() const noexcept
  {
    return m_id;
  }

  /**
   * \brief Sets the face ID.
   * \note Normally, this should only be invoked by FaceTable.
   */
  void
  setId(FaceId id) noexcept
  {
    m_id = id;
  }

  /**
   * \brief Returns a FaceUri representing the local endpoint.
   */
  FaceUri
  getLocalUri() const;

  /**
   * \brief Returns a FaceUri representing the remote endpoint.
   */
  FaceUri
  getRemoteUri() const;

  /**
   * \brief Returns whether the face is local or non-local for scope control purposes.
   */
  ndn::nfd::FaceScope
  getScope() const;

  /**
   * \brief Returns the current persistency setting of the face.
   */
  ndn::nfd::FacePersistency
  getPersistency() const;

  /**
   * \brief Changes the face persistency setting.
   */
  void
  setPersistency(ndn::nfd::FacePersistency persistency);

  /**
   * \brief Returns the link type of the face (point-to-point, multi-access, ...).
   */
  ndn::nfd::LinkType
  getLinkType() const;

  /**
   * \brief Returns the effective MTU of the face.
   *
   * This function is a wrapper. The effective MTU of a face is determined by the link service.
   */
  ssize_t
  getMtu() const;

  /**
   * \brief Returns the face state.
   */
  FaceState
  getState() const;

  /**
   * \brief Signals after face state changed.
   */
  signal::Signal<Transport, FaceState/*old*/, FaceState/*new*/>& afterStateChange;

  /**
   * \brief Returns the expiration time of the face.
   * \retval time::steady_clock::time_point::max() The face has an indefinite lifetime.
   */
  time::steady_clock::time_point
  getExpirationTime() const;

  const FaceCounters&
  getCounters() const noexcept
  {
    return m_counters;
  }

  FaceCounters&
  getCounters() noexcept
  {
    return m_counters;
  }

  /**
   * \brief Get channel on which face was created (unicast) or the associated channel (multicast).
   */
  weak_ptr<Channel>
  getChannel() const
  {
    return m_channel;
  }

  /**
   * \brief Set channel on which face was created (unicast) or the associated channel (multicast).
   */
  void
  setChannel(weak_ptr<Channel> channel)
  {
    m_channel = std::move(channel);
  }

private:
  FaceId m_id = INVALID_FACEID;
  unique_ptr<LinkService> m_service;
  unique_ptr<Transport> m_transport;
  FaceCounters m_counters;
  weak_ptr<Channel> m_channel;
};

inline void
Face::close()
{
  m_transport->close();
}

inline void
Face::sendInterest(const Interest& interest)
{
  m_service->sendInterest(interest);
}

inline void
Face::sendData(const Data& data)
{
  m_service->sendData(data);
}

inline void
Face::sendNack(const lp::Nack& nack)
{
  m_service->sendNack(nack);
}

inline FaceUri
Face::getLocalUri() const
{
  return m_transport->getLocalUri();
}

inline FaceUri
Face::getRemoteUri() const
{
  return m_transport->getRemoteUri();
}

inline ndn::nfd::FaceScope
Face::getScope() const
{
  return m_transport->getScope();
}

inline ndn::nfd::FacePersistency
Face::getPersistency() const
{
  return m_transport->getPersistency();
}

inline void
Face::setPersistency(ndn::nfd::FacePersistency persistency)
{
  return m_transport->setPersistency(persistency);
}

inline ndn::nfd::LinkType
Face::getLinkType() const
{
  return m_transport->getLinkType();
}

inline ssize_t
Face::getMtu() const
{
  return m_service->getEffectiveMtu();
}

inline FaceState
Face::getState() const
{
  return m_transport->getState();
}

inline time::steady_clock::time_point
Face::getExpirationTime() const
{
  return m_transport->getExpirationTime();
}

std::ostream&
operator<<(std::ostream& os, const FaceLogHelper<Face>& flh);

} // namespace face

using face::Face;

} // namespace nfd

#endif // NFD_DAEMON_FACE_FACE_HPP