/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014  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
 *
 * 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/>.
 **/

#include "unix-stream-channel.hpp"
#include "core/global-io.hpp"

#include <boost/filesystem.hpp>
#include <sys/stat.h> // for chmod()

namespace nfd {

NFD_LOG_INIT("UnixStreamChannel");

using namespace boost::asio::local;

UnixStreamChannel::UnixStreamChannel(const unix_stream::Endpoint& endpoint)
  : m_endpoint(endpoint)
  , m_isListening(false)
{
  setUri(FaceUri(endpoint));
}

UnixStreamChannel::~UnixStreamChannel()
{
  if (m_isListening)
    {
      // use the non-throwing variants during destruction
      // and ignore any errors
      boost::system::error_code error;
      m_acceptor->close(error);
      NFD_LOG_TRACE("[" << m_endpoint << "] Removing socket file");
      boost::filesystem::remove(m_endpoint.path(), error);
    }
}

void
UnixStreamChannel::listen(const FaceCreatedCallback& onFaceCreated,
                          const ConnectFailedCallback& onAcceptFailed,
                          int backlog/* = acceptor::max_connections*/)
{
  if (m_isListening) {
    NFD_LOG_WARN("[" << m_endpoint << "] Already listening");
    return;
  }

  namespace fs = boost::filesystem;

  fs::path socketPath(m_endpoint.path());
  fs::file_type type = fs::symlink_status(socketPath).type();

  if (type == fs::socket_file)
    {
      boost::system::error_code error;
      stream_protocol::socket socket(getGlobalIoService());
      socket.connect(m_endpoint, error);
      NFD_LOG_TRACE("[" << m_endpoint << "] connect() on existing socket file returned: "
                    + error.message());
      if (!error)
        {
          // someone answered, leave the socket alone
          throw Error("Socket file at " + m_endpoint.path()
                      + " belongs to another NFD process");
        }
      else if (error == boost::system::errc::connection_refused ||
               error == boost::system::errc::timed_out)
        {
          // no one is listening on the remote side,
          // we can safely remove the socket file
          NFD_LOG_INFO("[" << m_endpoint << "] Removing stale socket file");
          fs::remove(socketPath);
        }
    }
  else if (type != fs::file_not_found)
    {
      throw Error(m_endpoint.path() + " already exists and is not a socket file");
    }

  m_acceptor = make_shared<stream_protocol::acceptor>(boost::ref(getGlobalIoService()));
  m_acceptor->open();
  m_acceptor->bind(m_endpoint);
  m_acceptor->listen(backlog);
  m_isListening = true;

  if (::chmod(m_endpoint.path().c_str(), 0666) < 0)
    {
      throw Error("Failed to chmod() socket file at " + m_endpoint.path());
    }

  shared_ptr<stream_protocol::socket> clientSocket =
    make_shared<stream_protocol::socket>(boost::ref(getGlobalIoService()));

  m_acceptor->async_accept(*clientSocket,
                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
                                boost::asio::placeholders::error, clientSocket,
                                onFaceCreated, onAcceptFailed));
}

void
UnixStreamChannel::handleSuccessfulAccept(const boost::system::error_code& error,
                                          const shared_ptr<stream_protocol::socket>& socket,
                                          const FaceCreatedCallback& onFaceCreated,
                                          const ConnectFailedCallback& onAcceptFailed)
{
  if (error) {
    if (error == boost::system::errc::operation_canceled) // when socket is closed by someone
      return;

    NFD_LOG_DEBUG("[" << m_endpoint << "] Connection failed: " << error.message());
    onAcceptFailed("Connection failed: " + error.message());
    return;
  }

  NFD_LOG_DEBUG("[" << m_endpoint << "] << Incoming connection");

  shared_ptr<stream_protocol::socket> clientSocket =
    make_shared<stream_protocol::socket>(boost::ref(getGlobalIoService()));

  // prepare accepting the next connection
  m_acceptor->async_accept(*clientSocket,
                           bind(&UnixStreamChannel::handleSuccessfulAccept, this,
                                boost::asio::placeholders::error, clientSocket,
                                onFaceCreated, onAcceptFailed));

  shared_ptr<UnixStreamFace> face = make_shared<UnixStreamFace>(boost::cref(socket));
  onFaceCreated(face);
}

} // namespace nfd