/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013 Universita' di Firenze, Italy
 *
 * 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: Tommaso Pecorella <tommaso.pecorella@unifi.it>
 *         Michele Muccio <michelemuccio@virgilio.it>
 */

#ifndef SIXLOWPAN_NET_DEVICE_H
#define SIXLOWPAN_NET_DEVICE_H

#include <stdint.h>
#include <string>
#include <map>
#include "ns3/traced-callback.h"
#include "ns3/event-id.h"
#include "ns3/nstime.h"
#include "ns3/net-device.h"
#include "ns3/packet.h"
#include "sixlowpan-header.h"
#include "ns3/random-variable-stream.h"

namespace ns3 {

class Node;

/**
 * \defgroup sixlowpan 6LoWPAN
 * \brief Performs 6LoWPAN compression of IPv6 packets as specified by \RFC{4944} and \RFC{6282}
 *
 * This module acts as a shim between IPv6 and a generic NetDevice.
 *
 * The module implements \RFC{4944} and \RFC{6282}, with the following exceptions:
 * <ul>
 * <li> MESH and LOWPAN_BC0 dispatch types are not supported </li>
 * <li> HC2 encoding is not supported </li>
 * <li> IPHC's SAC and DAC are not supported </li>
 *</ul>
 */

/**
 * \ingroup sixlowpan
 *
 * \brief Shim performing 6LoWPAN compression, decompression and fragmentation.
 *
 * This class implements the shim between IPv6 and a generic NetDevice,
 * performing packet compression, decompression and fragmentation in a transparent way.
 * To this end, the class pretend to be a normal NetDevice, masquerading some functions
 * of the underlying NetDevice.
 */
class SixLowPanNetDevice : public NetDevice
{
public:
  /**
   * Enumeration of the dropping reasons in SixLoWPAN.
   */
  enum DropReason
  {
    DROP_FRAGMENT_TIMEOUT = 1, /**< Fragment timeout exceeded */
    DROP_FRAGMENT_BUFFER_FULL, /**< Fragment buffer size exceeded */
    DROP_UNKNOWN_EXTENSION /**< Unsupported compression kind */
  };

  /**
   * \brief Get the type ID.
   * \return The object TypeId.
   */
  static TypeId GetTypeId (void);

  /**
   * Constructor for the SixLowPanNetDevice.
   */
  SixLowPanNetDevice ();

  // inherited from NetDevice base class
  virtual void SetIfIndex (const uint32_t index);
  virtual uint32_t GetIfIndex (void) const;
  virtual Ptr<Channel> GetChannel (void) const;
  virtual void SetAddress (Address address);
  virtual Address GetAddress (void) const;
  virtual bool SetMtu (const uint16_t mtu);

  /**
   * \brief Returns the link-layer MTU for this interface.
   * If the link-layer MTU is smaller than IPv6's minimum MTU (\RFC{4944}),
   * 1280 will be returned.
   *
   * \return The link-level MTU in bytes for this interface.
   */
  virtual uint16_t GetMtu (void) const;
  virtual bool IsLinkUp (void) const;
  virtual void AddLinkChangeCallback (Callback<void> callback);
  virtual bool IsBroadcast (void) const;
  virtual Address GetBroadcast (void) const;
  virtual bool IsMulticast (void) const;
  virtual Address GetMulticast (Ipv4Address multicastGroup) const;
  virtual bool IsPointToPoint (void) const;
  virtual bool IsBridge (void) const;
  virtual bool Send (Ptr<Packet> packet, const Address& dest, uint16_t protocolNumber);
  virtual bool SendFrom (Ptr<Packet> packet, const Address& source, const Address& dest, uint16_t protocolNumber);
  virtual Ptr<Node> GetNode (void) const;
  virtual void SetNode (Ptr<Node> node);
  virtual bool NeedsArp (void) const;
  virtual void SetReceiveCallback (NetDevice::ReceiveCallback cb);
  virtual void SetPromiscReceiveCallback (NetDevice::PromiscReceiveCallback cb);
  virtual bool SupportsSendFrom () const;
  virtual Address GetMulticast (Ipv6Address addr) const;

  /**
   * \brief Returns a smart pointer to the underlying NetDevice.
   *
   * \return A smart pointer to the underlying NetDevice.
   */
  Ptr<NetDevice> GetNetDevice () const;

  /**
   * \brief Setup SixLowPan to be a proxy for the specified NetDevice.
   * All the packets incoming and outgoing from the NetDevice will be
   * processed by SixLowPanNetDevice.
   *
   * \param [in] device A smart pointer to the NetDevice to be proxied.
   */
  void SetNetDevice (Ptr<NetDevice> device);

  /**
   * Assign a fixed random variable stream number to the random variables
   * used by this model.  Return the number of streams (possibly zero) that
   * have been assigned.
   *
   * \param [in] stream First stream index to use.
   * \return the number of stream indices assigned by this model.
   */
  int64_t AssignStreams (int64_t stream);

  /**
   * TracedCallback signature for packet send/receive events.
   *
   * \param [in] packet The packet.
   * \param [in] sixNetDevice The SixLowPanNetDevice.
   * \param [in] ifindex The ifindex of the device.
   */
  typedef void (* RxTxTracedCallback)
    (const Ptr<const Packet> packet,
     const Ptr<const SixLowPanNetDevice> sixNetDevice,
     const uint32_t ifindex);

  /**
   * TracedCallback signature for
   *
   * \param [in] reason The reason for the drop.
   * \param [in] packet The packet.
   * \param [in] sixNetDevice The SixLowPanNetDevice.
   * \param [in] ifindex The ifindex of the device.
   */
  typedef void (* DropTracedCallback)
    (const DropReason reason, const Ptr<const Packet> packet,
     const Ptr<const SixLowPanNetDevice> sixNetDevice,
     const uint32_t ifindex);
   
protected:
  virtual void DoDispose (void);

private:
  /**
   * \brief Copy constructor
   *
   * Defined and unimplemented to avoid misuse.
   */
  SixLowPanNetDevice (SixLowPanNetDevice const &);
  /**
   * \brief Copy constructor
   *
   * Defined and unimplemented to avoid misuse.
   * \returns
   */
  SixLowPanNetDevice& operator= (SixLowPanNetDevice const &);
  /**
   * \brief Receives all the packets from a NetDevice for further processing.
   * \param [in] device The NetDevice the packet ws received from.
   * \param [in] packet The received packet.
   * \param [in] protocol The protocol (if known).
   * \param [in] source The source address.
   * \param [in] destination The destination address.
   * \param [in] packetType The packet kind (e.g., HOST, BROADCAST, etc.).
   * \return The IPv6 link-local address.
   */
  void ReceiveFromDevice (Ptr<NetDevice> device, Ptr<const Packet> packet, uint16_t protocol,
                          Address const &source, Address const &destination, PacketType packetType);


  /**
   * \param [in] packet Packet sent from above down to Network Device.
   * \param [in] source Source mac address (only used if doSendFrom is true, i.e., "MAC spoofing").
   * \param [in] dest Mac address of the destination (already resolved).
   * \param [in] protocolNumber Identifies the type of payload contained in
   *        this packet. Used to call the right L3Protocol when the packet
   *        is received.
   * \param [in] doSendFrom Perform a SendFrom instead of a Send.
   *
   *  Called from higher layer to send packet into Network Device
   *  with the specified source and destination Addresses.
   *
   * \return Whether the Send operation succeeded.
   */
  bool DoSend (Ptr<Packet> packet, const Address& source, const Address& dest, uint16_t protocolNumber, bool doSendFrom);

  /**
   * The callback used to notify higher layers that a packet has been received.
   */
  NetDevice::ReceiveCallback m_rxCallback;

  /**
   * The callback used to notify higher layers that a packet has been received in promiscuous mode.
   */
  NetDevice::PromiscReceiveCallback m_promiscRxCallback;

  /**
   * \brief Callback to trace TX (transmission) packets.
   *
   * Data passed:
   * \li Packet received (including 6LoWPAN header)
   * \li Ptr to SixLowPanNetDevice
   * \li interface index
   */
  TracedCallback<Ptr<const Packet>, Ptr<SixLowPanNetDevice>, uint32_t> m_txTrace;

  /**
   * \brief Callback to trace RX (reception) packets.
   *
   * Data passed:
   * \li Packet received (including 6LoWPAN header)
   * \li Ptr to SixLowPanNetDevice
   * \li interface index
   */
  TracedCallback<Ptr<const Packet>, Ptr<SixLowPanNetDevice>, uint32_t> m_rxTrace;

  /**
   * \brief Callback to trace drop packets.
   *
   * Data passed:
   * \li DropReason
   * \li Packet dropped (including 6LoWPAN header)
   * \li Ptr to SixLowPanNetDevice
   * \li interface index
   */
  TracedCallback<DropReason, Ptr<const Packet>, Ptr<SixLowPanNetDevice>, uint32_t> m_dropTrace;

  /**
   * \brief Make a link-local address from a MAC address.
   * \param [in] addr The MAC address.
   * \return The IPv6 link-local address.
   */
  Ipv6Address MakeLinkLocalAddressFromMac (Address const &addr);

  /**
   * \brief Make a global address from a MAC address.
   * \param [in] addr the MAC address.
   * \param [in] prefix The address prefix.
   * \return The IPv6 address.
   */
  Ipv6Address MakeGlobalAddressFromMac (Address const &addr, Ipv6Address prefix);

  /**
   * \brief Compress the headers according to HC1 compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] src The MAC source address.
   * \param [in] dst The MAC destination address.
   * \return The size of the removed headers.
   */
  uint32_t CompressLowPanHc1 (Ptr<Packet> packet, Address const &src, Address const &dst);

  /**
   * \brief Decompress the headers according to HC1 compression.
   * \param [in] packet the packet to be compressed.
   * \param [in] src the MAC source address.
   * \param [in] dst the MAC destination address.
   */
  void DecompressLowPanHc1 (Ptr<Packet> packet, Address const &src, Address const &dst);

  /**
   * \brief Compress the headers according to IPHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] src The MAC source address.
   * \param [in] dst The MAC destination address.
   * \return The size of the removed headers.
   */
  uint32_t CompressLowPanIphc (Ptr<Packet> packet, Address const &src, Address const &dst);

  /**
   * \brief Checks if the next header can be compressed using NHC.
   * \param [in] headerType The header kind to be compressed.
   * \return True if the header can be compressed.
   */
  bool CanCompressLowPanNhc (uint8_t headerType);

  /**
   * \brief Decompress the headers according to IPHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] src The MAC source address.
   * \param [in] dst The MAC destination address.
   */
  void DecompressLowPanIphc (Ptr<Packet> packet, Address const &src, Address const &dst);

  /**
   * \brief Compress the headers according to NHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] headerType The header type.
   * \param [in] src The MAC source address.
   * \param [in] dst The MAC destination address.
   * \return The size of the removed headers.
   */
  uint32_t CompressLowPanNhc (Ptr<Packet> packet, uint8_t headerType, Address const &src, Address const &dst);

  /**
   * \brief Decompress the headers according to NHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] src The MAC source address.
   * \param [in] dst The MAC destination address.
   * \param [in] srcAddress The IPv6 source address.
   * \param [in] dstAddress The IPv6 destination address.
   * \return The decompressed header type.
   */
  uint8_t DecompressLowPanNhc (Ptr<Packet> packet, Address const &src, Address const &dst, Ipv6Address srcAddress, Ipv6Address dstAddress);

  /**
   * \brief Compress the headers according to NHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] omitChecksum Omit UDP checksum (if true).
   * \return The size of the removed headers.
   */
  uint32_t CompressLowPanUdpNhc (Ptr<Packet> packet, bool omitChecksum);

  /**
   * \brief Decompress the headers according to NHC compression.
   * \param [in] packet The packet to be compressed.
   * \param [in] saddr The IPv6 source address.
   * \param [in] daddr The IPv6 destination address.
   */
  void DecompressLowPanUdpNhc (Ptr<Packet> packet, Ipv6Address saddr, Ipv6Address daddr);

  /**
   * Fragment identifier type: src/dst address src/dst port.
   */
  typedef std::pair< std::pair<Address, Address>, std::pair<uint16_t, uint16_t> > FragmentKey;

  /**
   * \class Fragments
   * \brief A Set of Fragment.
   */
  class Fragments : public SimpleRefCount<Fragments>
  {
public:
    /**
     * \brief Constructor.
     */
    Fragments ();

    /**
     * \brief Destructor.
     */
    ~Fragments ();

    /**
     * \brief Add a fragment to the pool.
     * \param [in] fragment the fragment.
     * \param [in] fragmentOffset the offset of the fragment.
     */
    void AddFragment (Ptr<Packet> fragment, uint16_t fragmentOffset);

    /**
     * \brief Add the first packet fragment. The first fragment is needed to
     * allow the post-defragmentation decompression.
     * \param [in] fragment The fragment.
     */
    void AddFirstFragment (Ptr<Packet> fragment);

    /**
     * \brief If all fragments have been added.
     * \returns True if the packet is entire.
     */
    bool IsEntire () const;

    /**
     * \brief Get the entire packet.
     * \return The entire packet.
     */
    Ptr<Packet> GetPacket () const;

    /**
     * \brief Set the packet-to-be-defragmented size.
     * \param [in] packetSize The packet size (bytes).
     */
    void SetPacketSize (uint32_t packetSize);

    /**
     * \brief Get a list of the current stored fragments.
     */
    std::list< Ptr<Packet> > GetFraments () const;

private:
    /**
     * \brief The size of the reconstructed packet (bytes).
     */
    uint32_t m_packetSize;

    /**
     * \brief The current fragments.
     */
    std::list<std::pair<Ptr<Packet>, uint16_t> > m_fragments;

    /**
     * \brief The very first fragment.
     */
    Ptr<Packet> m_firstFragment;

  };

  /**
   * \brief Performs a packet fragmentation.
   * \param [in] packet the packet to be fragmented (with headers already compressed with 6LoWPAN).
   * \param [in] origPacketSize the size of the IP packet before the 6LoWPAN header compression, including the IP/L4 headers.
   * \param [in] origHdrSize the size of the IP header before the 6LoWPAN header compression.
   * \param [out] listFragments A reference to the list of the resulting packets, all with the proper headers in place.
   */
  void DoFragmentation (Ptr<Packet> packet, uint32_t origPacketSize, uint32_t origHdrSize,
                        std::list<Ptr<Packet> >& listFragments);

  /**
   * \brief Process a packet fragment.
   * \param [in] packet The packet.
   * \param [in] src The source MAC address.
   * \param [in] dst The destination MAC address.
   * \param [in] isFirst True if it is the first fragment, false otherwise.
   * \return True is the fragment completed the packet.
   */
  bool ProcessFragment (Ptr<Packet>& packet, Address const &src, Address const &dst, bool isFirst);

  /**
   * \brief Process the timeout for packet fragments.
   * \param [in] key A key representing the packet fragments.
   * \param [in] iif Input Interface.
   */
  void HandleFragmentsTimeout ( FragmentKey key, uint32_t iif);

  /**
   * \brief Drops the oldest fragment set.
   */
  void DropOldestFragmentSet ();

  /**
   * Container for fragment key -> fragments.
   */
  typedef std::map< FragmentKey, Ptr<Fragments> > MapFragments_t;
  /**
   * Container Iterator for fragment key -> fragments.
   */
  typedef std::map< FragmentKey, Ptr<Fragments> >::iterator MapFragmentsI_t;
  /**
   * Container for fragment key -> expiration event.
   */
  typedef std::map< FragmentKey, EventId > MapFragmentsTimers_t;
  /**
   * Container Iterator for fragment key -> expiration event.
   */
  typedef std::map< FragmentKey, EventId >::iterator MapFragmentsTimersI_t;

  MapFragments_t       m_fragments; //!< Fragments hold to be rebuilt.
  MapFragmentsTimers_t m_fragmentsTimers; //!< Timers related to fragment rebuilding.
  Time                 m_fragmentExpirationTimeout; //!< Time limit for fragment rebuilding.

  /**
   * \brief How many packets can be rebuilt at the same time.
   * Some real implementation do limit this. Zero means no limit.
   */
  uint16_t             m_fragmentReassemblyListSize;

  bool m_useIphc; //!< Use IPHC or HC1.

  Ptr<Node> m_node; //!< Smart pointer to the Node.
  Ptr<NetDevice> m_netDevice; //!< Smart pointer to the underlying NetDevice.
  uint32_t m_ifIndex; //!< Interface index.

  /**
   * \brief Force the EtherType number.
   * Also implying that the underlying NetDevice is using 48-bit Addresses, e.g., Ethernet, Wi-Fi, etc.
   */
  bool m_forceEtherType;

  uint16_t m_etherType; //!< EtherType number (used only if m_forceEtherType is true).
  bool m_omitUdpChecksum; //!< Omit UDP checksum in NC1 encoding.

  uint32_t m_compressionThreshold; //!< Minimum L2 payload size.

  Ptr<UniformRandomVariable> m_rng; //!< Rng for the fragments tag.
};

} // namespace ns3

#endif /* SIXLOWPAN_NET_DEVICE_H */