/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014-2015,  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_STREAM_FACE_HPP
#define NFD_DAEMON_FACE_STREAM_FACE_HPP

#include "face.hpp"
#include "local-face.hpp"
#include "core/global-io.hpp"

namespace nfd {

// forward declaration
template<class T, class U, class V> struct StreamFaceSenderImpl;

template<class Protocol, class FaceBase = Face>
class StreamFace : public FaceBase
{
public:
  typedef Protocol protocol;

  StreamFace(const FaceUri& remoteUri, const FaceUri& localUri,
             typename protocol::socket socket, bool isOnDemand);

  // from FaceBase
  void
  sendInterest(const Interest& interest) DECL_OVERRIDE;

  void
  sendData(const Data& data) DECL_OVERRIDE;

  void
  close() DECL_OVERRIDE;

protected:
  void
  processErrorCode(const boost::system::error_code& error);

  void
  sendFromQueue();

  void
  handleSend(const boost::system::error_code& error,
             size_t nBytesSent);

  void
  handleReceive(const boost::system::error_code& error,
                size_t nBytesReceived);

  void
  shutdownSocket();

  void
  deferredClose(const shared_ptr<Face>& face);

protected:
  typename protocol::socket m_socket;

  NFD_LOG_INCLASS_DECLARE();

private:
  uint8_t m_inputBuffer[ndn::MAX_NDN_PACKET_SIZE];
  size_t m_inputBufferSize;
  std::queue<Block> m_sendQueue;

  friend struct StreamFaceSenderImpl<Protocol, FaceBase, Interest>;
  friend struct StreamFaceSenderImpl<Protocol, FaceBase, Data>;
};

// All inherited classes must use
// NFD_LOG_INCLASS_TEMPLATE_SPECIALIZATION_DEFINE(StreamFace, <specialization-parameter>, "Name");


/** \brief Class allowing validation of the StreamFace use
 *
 *  For example, partial specialization based on boost::asio::ip::tcp should check
 *  that local endpoint is loopback
 *
 *  @throws Face::Error if validation failed
 */
template<class Protocol, class U>
struct StreamFaceValidator
{
  static void
  validateSocket(const typename Protocol::socket& socket)
  {
  }
};


template<class T, class FaceBase>
inline
StreamFace<T, FaceBase>::StreamFace(const FaceUri& remoteUri, const FaceUri& localUri,
                                    typename StreamFace::protocol::socket socket, bool isOnDemand)
  : FaceBase(remoteUri, localUri)
  , m_socket(std::move(socket))
  , m_inputBufferSize(0)
{
  NFD_LOG_FACE_INFO("Creating face");

  this->setOnDemand(isOnDemand);
  StreamFaceValidator<T, FaceBase>::validateSocket(m_socket);

  m_socket.async_receive(boost::asio::buffer(m_inputBuffer, ndn::MAX_NDN_PACKET_SIZE),
                         bind(&StreamFace<T, FaceBase>::handleReceive, this,
                              boost::asio::placeholders::error,
                              boost::asio::placeholders::bytes_transferred));
}


template<class Protocol, class FaceBase, class Packet>
struct StreamFaceSenderImpl
{
  static void
  send(StreamFace<Protocol, FaceBase>& face, const Packet& packet)
  {
    bool wasQueueEmpty = face.m_sendQueue.empty();
    face.m_sendQueue.push(packet.wireEncode());

    if (wasQueueEmpty)
      face.sendFromQueue();
  }
};

// partial specialization (only classes can be partially specialized)
template<class Protocol, class Packet>
struct StreamFaceSenderImpl<Protocol, LocalFace, Packet>
{
  static void
  send(StreamFace<Protocol, LocalFace>& face, const Packet& packet)
  {
    bool wasQueueEmpty = face.m_sendQueue.empty();

    if (!face.isEmptyFilteredLocalControlHeader(packet.getLocalControlHeader()))
      {
        face.m_sendQueue.push(face.filterAndEncodeLocalControlHeader(packet));
      }
    face.m_sendQueue.push(packet.wireEncode());

    if (wasQueueEmpty)
      face.sendFromQueue();
  }
};


template<class T, class U>
inline void
StreamFace<T, U>::sendInterest(const Interest& interest)
{
  NFD_LOG_FACE_TRACE(__func__);
  this->emitSignal(onSendInterest, interest);
  StreamFaceSenderImpl<T, U, Interest>::send(*this, interest);
}

template<class T, class U>
inline void
StreamFace<T, U>::sendData(const Data& data)
{
  NFD_LOG_FACE_TRACE(__func__);
  this->emitSignal(onSendData, data);
  StreamFaceSenderImpl<T, U, Data>::send(*this, data);
}

template<class T, class U>
inline void
StreamFace<T, U>::close()
{
  if (!m_socket.is_open())
    return;

  NFD_LOG_FACE_INFO("Closing face");

  shutdownSocket();
  this->fail("Face closed");
}

template<class T, class U>
inline void
StreamFace<T, U>::processErrorCode(const boost::system::error_code& error)
{
  if (error == boost::asio::error::operation_aborted ||   // when cancel() is called
      error == boost::asio::error::shut_down)             // after shutdown() is called
    return;

  if (!m_socket.is_open())
    {
      this->fail("Connection closed");
      return;
    }

  if (error != boost::asio::error::eof)
    NFD_LOG_FACE_WARN("Send or receive operation failed: " << error.message());

  shutdownSocket();

  if (error == boost::asio::error::eof)
    this->fail("Connection closed");
  else
    this->fail(error.message());
}

template<class T, class U>
inline void
StreamFace<T, U>::sendFromQueue()
{
  boost::asio::async_write(m_socket, boost::asio::buffer(m_sendQueue.front()),
                           bind(&StreamFace<T, U>::handleSend, this,
                                boost::asio::placeholders::error,
                                boost::asio::placeholders::bytes_transferred));
}

template<class T, class U>
inline void
StreamFace<T, U>::handleSend(const boost::system::error_code& error,
                             size_t nBytesSent)
{
  if (error)
    return processErrorCode(error);

  BOOST_ASSERT(!m_sendQueue.empty());

  NFD_LOG_FACE_TRACE("Successfully sent: " << nBytesSent << " bytes");
  this->getMutableCounters().getNOutBytes() += nBytesSent;

  m_sendQueue.pop();
  if (!m_sendQueue.empty())
    sendFromQueue();
}

template<class T, class U>
inline void
StreamFace<T, U>::handleReceive(const boost::system::error_code& error,
                                size_t nBytesReceived)
{
  if (error)
    return processErrorCode(error);

  NFD_LOG_FACE_TRACE("Received: " << nBytesReceived << " bytes");
  this->getMutableCounters().getNInBytes() += nBytesReceived;

  m_inputBufferSize += nBytesReceived;

  size_t offset = 0;

  bool isOk = true;
  Block element;
  while (m_inputBufferSize - offset > 0) {
    std::tie(isOk, element) = Block::fromBuffer(m_inputBuffer + offset, m_inputBufferSize - offset);
    if (!isOk)
      break;

    offset += element.size();

    BOOST_ASSERT(offset <= m_inputBufferSize);

    if (!this->decodeAndDispatchInput(element)) {
      NFD_LOG_FACE_WARN("Received unrecognized TLV block of type " << element.type());
      // ignore unknown packet and proceed
    }
  }

  if (!isOk && m_inputBufferSize == ndn::MAX_NDN_PACKET_SIZE && offset == 0)
    {
      NFD_LOG_FACE_WARN("Failed to parse incoming packet or packet too large to process");
      shutdownSocket();
      this->fail("Failed to parse incoming packet or packet too large to process");
      return;
    }

  if (offset > 0)
    {
      if (offset != m_inputBufferSize)
        {
          std::copy(m_inputBuffer + offset, m_inputBuffer + m_inputBufferSize,
                    m_inputBuffer);
          m_inputBufferSize -= offset;
        }
      else
        {
          m_inputBufferSize = 0;
        }
    }

  m_socket.async_receive(boost::asio::buffer(m_inputBuffer + m_inputBufferSize,
                                             ndn::MAX_NDN_PACKET_SIZE - m_inputBufferSize),
                         bind(&StreamFace<T, U>::handleReceive, this,
                              boost::asio::placeholders::error,
                              boost::asio::placeholders::bytes_transferred));
}

template<class T, class U>
inline void
StreamFace<T, U>::shutdownSocket()
{
  NFD_LOG_FACE_TRACE(__func__);

  // Cancel all outstanding operations and shutdown the socket
  // so that no further sends or receives are possible.
  // Use the non-throwing variants and ignore errors, if any.
  boost::system::error_code error;
  m_socket.cancel(error);
  m_socket.shutdown(protocol::socket::shutdown_both, error);

  // ensure that the Face object is alive at least until all pending
  // handlers are dispatched
  getGlobalIoService().post(bind(&StreamFace<T, U>::deferredClose,
                                 this, this->shared_from_this()));

  // Some bug or feature of Boost.Asio (see http://redmine.named-data.net/issues/1856):
  //
  // When shutdownSocket is called from within a socket event (e.g., from handleReceive),
  // m_socket.shutdown() does not trigger the cancellation of the handleSend callback.
  // Instead, handleSend is invoked as nothing bad happened.
  //
  // In order to prevent the assertion in handleSend from failing, we clear the queue
  // and close the socket in deferredClose, i.e., after all callbacks scheduled up to
  // this point have been executed.  If more send operations are scheduled after this
  // point, they will fail because the socket has been shutdown, and their callbacks
  // will be invoked with error code == asio::error::shut_down.
}

template<class T, class U>
inline void
StreamFace<T, U>::deferredClose(const shared_ptr<Face>& face)
{
  NFD_LOG_FACE_TRACE(__func__);

  // clear send queue
  std::queue<Block> emptyQueue;
  std::swap(emptyQueue, m_sendQueue);

  // use the non-throwing variant and ignore errors, if any
  boost::system::error_code error;
  m_socket.close(error);
}

} // namespace nfd

#endif // NFD_DAEMON_FACE_STREAM_FACE_HPP