/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2013 University of California, Los Angeles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 *
 */

#include "ndn-tcp-face.hpp"
#include "ndn-ip-face-stack.hpp"

#include "ns3/ndn-l3-protocol.hpp"

#include "ns3/log.h"
#include "ns3/packet.h"
#include "ns3/node.h"
#include "ns3/pointer.h"
#include "ns3/tcp-socket-factory.h"

using namespace std;

NS_LOG_COMPONENT_DEFINE("ndn.TcpFace");

namespace ns3 {
namespace ndn {

class TcpBoundaryHeader : public Header {
public:
  static TypeId
  GetTypeId(void)
  {
    static TypeId tid =
      TypeId("ns3::ndn::TcpFace::BoundaryHeader").SetGroupName("Ndn").SetParent<Header>();
    return tid;
  }

  TcpBoundaryHeader()
    : m_length(0)
  {
  }

  TcpBoundaryHeader(Ptr<Packet> packet)
    : m_length(packet->GetSize())
  {
  }

  TcpBoundaryHeader(uint32_t length)
    : m_length(length)
  {
  }

  uint32_t
  GetLength() const
  {
    return m_length;
  }

  virtual TypeId
  GetInstanceTypeId(void) const
  {
    return TcpBoundaryHeader::GetTypeId();
  }

  virtual void
  Print(std::ostream& os) const
  {
    os << "[" << m_length << "]";
  }

  virtual uint32_t
  GetSerializedSize(void) const
  {
    return 4;
  }

  virtual void
  Serialize(Buffer::Iterator start) const
  {
    start.WriteU32(m_length);
  }

  virtual uint32_t
  Deserialize(Buffer::Iterator start)
  {
    m_length = start.ReadU32();
    return 4;
  }

private:
  uint32_t m_length;
};

NS_OBJECT_ENSURE_REGISTERED(TcpFace);

TypeId
TcpFace::GetTypeId()
{
  static TypeId tid = TypeId("ns3::ndn::TcpFace").SetParent<Face>().SetGroupName("Ndn");
  return tid;
}

/**
 * By default, Ndn face are created in the "down" state.  Before
 * becoming useable, the user must invoke SetUp on the face
 */
TcpFace::TcpFace(Ptr<Node> node, Ptr<Socket> socket, Ipv4Address address)
  : Face(node)
  , m_socket(socket)
  , m_address(address)
  , m_pendingPacketLength(0)
{
  SetMetric(1); // default metric
}

TcpFace::~TcpFace()
{
  NS_LOG_FUNCTION_NOARGS();
}

TcpFace& TcpFace::operator= (const TcpFace &)
{
  return *this;
}

void
TcpFace::RegisterProtocolHandlers(const InterestHandler& interestHandler,
                                  const DataHandler& dataHandler)
{
  NS_LOG_FUNCTION(this);

  Face::RegisterProtocolHandlers(interestHandler, dataHandler);
  m_socket->SetRecvCallback(MakeCallback(&TcpFace::ReceiveFromTcp, this));
}

void
TcpFace::UnRegisterProtocolHandlers()
{
  m_socket->SetRecvCallback(MakeNullCallback<void, Ptr<Socket>>());
  Face::UnRegisterProtocolHandlers();
}

bool
TcpFace::Send(Ptr<Packet> packet)
{
  if (!Face::Send(packet)) {
    return false;
  }

  NS_LOG_FUNCTION(this << packet);

  Ptr<Packet> boundary = Create<Packet>();
  TcpBoundaryHeader hdr(packet);
  boundary->AddHeader(hdr);

  m_socket->Send(boundary);
  m_socket->Send(packet);

  return true;
}

void
TcpFace::ReceiveFromTcp(Ptr<Socket> clientSocket)
{
  NS_LOG_FUNCTION(this << clientSocket);
  TcpBoundaryHeader hdr;

  if (m_pendingPacketLength > 0) {
    if (clientSocket->GetRxAvailable() >= m_pendingPacketLength) {
      Ptr<Packet> realPacket = clientSocket->Recv(m_pendingPacketLength, 0);
      NS_LOG_DEBUG("+++ Expected " << m_pendingPacketLength << " bytes, got "
                                   << realPacket->GetSize() << " bytes");
      if (realPacket == 0)
        return;

      Receive(realPacket);
    }
    else
      return; // still not ready
  }

  m_pendingPacketLength = 0;

  while (clientSocket->GetRxAvailable() >= hdr.GetSerializedSize()) {
    Ptr<Packet> boundary = clientSocket->Recv(hdr.GetSerializedSize(), 0);
    if (boundary == 0)
      return; // no idea why it would happen...

    NS_LOG_DEBUG("Expected 4 bytes, got " << boundary->GetSize() << " bytes");

    boundary->RemoveHeader(hdr);
    NS_LOG_DEBUG("Header specifies length: " << hdr.GetLength());
    m_pendingPacketLength = hdr.GetLength();

    if (clientSocket->GetRxAvailable() >= hdr.GetLength()) {
      Ptr<Packet> realPacket = clientSocket->Recv(hdr.GetLength(), 0);
      if (realPacket == 0) {
        NS_LOG_DEBUG("Got nothing, but requested at least " << hdr.GetLength());
        return;
      }

      NS_LOG_DEBUG("Receiving data " << hdr.GetLength() << " bytes, got " << realPacket->GetSize()
                                     << " bytes");

      Receive(realPacket);
      m_pendingPacketLength = 0;
    }
    else {
      return;
    }
  }
}

void
TcpFace::OnTcpConnectionClosed(Ptr<Socket> socket)
{
  NS_LOG_FUNCTION(this << socket);
  GetNode()->GetObject<IpFaceStack>()->DestroyTcpFace(this);
}

Ipv4Address
TcpFace::GetAddress() const
{
  return m_address;
}

void
TcpFace::SetCreateCallback(Callback<void, Ptr<Face>> callback)
{
  m_onCreateCallback = callback;
}

void
TcpFace::OnConnect(Ptr<Socket> socket)
{
  NS_LOG_FUNCTION(this << socket);

  Ptr<L3Protocol> ndn = GetNode()->GetObject<L3Protocol>();

  ndn->AddFace(this);
  this->SetUp(true);

  socket->SetCloseCallbacks(MakeCallback(&TcpFace::OnTcpConnectionClosed, this),
                            MakeCallback(&TcpFace::OnTcpConnectionClosed, this));

  if (!m_onCreateCallback.IsNull()) {
    m_onCreateCallback(this);
    m_onCreateCallback = IpFaceStack::NULL_CREATE_CALLBACK;
  }
}

std::ostream&
TcpFace::Print(std::ostream& os) const
{
  os << "dev=tcp(" << GetId() << ", " << m_address << ")";
  return os;
}

} // namespace ndn
} // namespace ns3