/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2020,  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/>.
 */

#include "unix-stream-channel.hpp"
#include "face.hpp"
#include "generic-link-service.hpp"
#include "unix-stream-transport.hpp"
#include "common/global.hpp"

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

namespace nfd {
namespace face {

NFD_LOG_INIT(UnixStreamChannel);

UnixStreamChannel::UnixStreamChannel(const unix_stream::Endpoint& endpoint,
                                     bool wantCongestionMarking)
  : m_endpoint(endpoint)
  , m_acceptor(getGlobalIoService())
  , m_socket(getGlobalIoService())
  , m_size(0)
  , m_wantCongestionMarking(wantCongestionMarking)
{
  setUri(FaceUri(m_endpoint));
  NFD_LOG_CHAN_INFO("Creating channel");
}

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

void
UnixStreamChannel::listen(const FaceCreatedCallback& onFaceCreated,
                          const FaceCreationFailedCallback& onAcceptFailed,
                          int backlog/* = acceptor::max_connections*/)
{
  if (isListening()) {
    NFD_LOG_CHAN_WARN("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;
    boost::asio::local::stream_protocol::socket socket(getGlobalIoService());
    socket.connect(m_endpoint, error);
    NFD_LOG_CHAN_TRACE("connect() on existing socket file returned: " << error.message());
    if (!error) {
      // someone answered, leave the socket alone
      NDN_THROW(Error("Socket file at " + m_endpoint.path() + " belongs to another NFD process"));
    }
    else if (error == boost::asio::error::connection_refused ||
             error == boost::asio::error::timed_out) {
      // no one is listening on the remote side,
      // we can safely remove the stale socket
      NFD_LOG_CHAN_DEBUG("Removing stale socket file");
      fs::remove(socketPath);
    }
  }
  else if (type != fs::file_not_found) {
    NDN_THROW(Error(m_endpoint.path() + " already exists and is not a socket file"));
  }

  m_acceptor.open();
  m_acceptor.bind(m_endpoint);
  m_acceptor.listen(backlog);

  if (::chmod(m_endpoint.path().data(), 0666) < 0) {
    NDN_THROW_ERRNO(Error("Failed to chmod " + m_endpoint.path()));
  }

  accept(onFaceCreated, onAcceptFailed);
  NFD_LOG_CHAN_DEBUG("Started listening");
}

void
UnixStreamChannel::accept(const FaceCreatedCallback& onFaceCreated,
                          const FaceCreationFailedCallback& onAcceptFailed)
{
  m_acceptor.async_accept(m_socket, [=] (const auto& e) { this->handleAccept(e, onFaceCreated, onAcceptFailed); });
}

void
UnixStreamChannel::handleAccept(const boost::system::error_code& error,
                                const FaceCreatedCallback& onFaceCreated,
                                const FaceCreationFailedCallback& onAcceptFailed)
{
  if (error) {
    if (error != boost::asio::error::operation_aborted) {
      NFD_LOG_CHAN_DEBUG("Accept failed: " << error.message());
      if (onAcceptFailed)
        onAcceptFailed(500, "Accept failed: " + error.message());
    }
    return;
  }

  NFD_LOG_CHAN_TRACE("Incoming connection via fd " << m_socket.native_handle());

  GenericLinkService::Options options;
  options.allowCongestionMarking = m_wantCongestionMarking;
  auto linkService = make_unique<GenericLinkService>(options);
  auto transport = make_unique<UnixStreamTransport>(std::move(m_socket));
  auto face = make_shared<Face>(std::move(linkService), std::move(transport));
  face->setChannel(shared_from_this()); // use weak_from_this() in C++17

  ++m_size;
  connectFaceClosedSignal(*face, [this] { --m_size; });

  onFaceCreated(face);

  // prepare accepting the next connection
  accept(onFaceCreated, onAcceptFailed);
}

} // namespace face
} // namespace nfd