/* -*-  Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2009 MIRKO BANCHI
 *
 * 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: Mirko Banchi <mk.banchi@gmail.com>
 */
#ifndef BLOCK_ACK_MANAGER_H
#define BLOCK_ACK_MANAGER_H

#include <map>
#include <list>
#include <deque>

#include "ns3/packet.h"

#include "wifi-mac-header.h"
#include "originator-block-ack-agreement.h"
#include "ctrl-headers.h"
#include "qos-utils.h"

using namespace std;

namespace ns3 {

class MgtAddBaResponseHeader;
class MgtAddBaRequestHeader;
class MgtDelBaHeader;
class MacTxMiddle;
class WifiMacQueue;

struct Bar {
    Bar ();
    Bar (Ptr<const Packet> packet,
         Mac48Address recipient,
         uint8_t tid,
         bool immediate);
    Ptr<const Packet> bar;
    Mac48Address recipient;
    uint8_t tid;
    bool immediate;
};

/**
 * \brief Manages all block ack agreements for an originator station.
 */
class BlockAckManager
{
private:
  BlockAckManager (const BlockAckManager&);
  BlockAckManager& operator= (const BlockAckManager&);

public:
  BlockAckManager ();
  ~BlockAckManager ();
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID.
   *
   * Checks if a block ack agreement exists with station addressed by 
   * <i>recipient</i> for tid <i>tid</i>.
   */
  bool ExistsAgreement (Mac48Address recipient, uint8_t tid) const;
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID.
   * \param state The state for block ack agreement

   * Checks if a block ack agreement with a state equals to <i>state</i> exists with
   * station addressed by <i>recipient</i> for tid <i>tid</i>.
   */
  bool ExistsAgreementInState (Mac48Address recipient, uint8_t tid, 
                               enum OriginatorBlockAckAgreement::State state) const;
  /** 
   * \param reqHdr Relative Add block ack request (action frame).
   * \param recipient Address of peer station involved in block ack mechanism.
   *
   * Creates a new block ack agreement in pending state. When a ADDBA response 
   * with a successful status code is received, the relative agreement becomes established. 
   */
  void CreateAgreement (const MgtAddBaRequestHeader *reqHdr, Mac48Address recipient);
  /** 
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Tid Traffic id of transmitted packet.
   *
   * Invoked when a recipient reject a block ack agreement or when a Delba frame
   * is Received/Transmitted.
   */
  void DestroyAgreement (Mac48Address recipient, uint8_t tid);
  /**
   * \param respHdr Relative Add block ack response (action frame).
   * \param recipient Address of peer station involved in block ack mechanism.
   *
   * Invoked upon receipt of a ADDBA response frame from <i>recipient</i>.
   */
  void UpdateAgreement (const MgtAddBaResponseHeader *respHdr, Mac48Address recipient);
  /**
   * \param packet Packet to store.
   * \param hdr 802.11 header for packet.
   * \param tStamp time stamp for packet
   *
   * Stores <i>packet</i> for a possible future retransmission. Retransmission occurs
   * if the packet, in a block ack frame, is indicated by recipient as not received.
   */
  void StorePacket (Ptr<const Packet> packet, const WifiMacHeader &hdr, Time tStamp);
  /**
   * \param hdr 802.11 header of returned packet (if exists).
   *
   * This methods returns a packet (if exists) indicated as not received in
   * corresponding block ack bitmap.
   */
  Ptr<const Packet> GetNextPacket (WifiMacHeader &hdr);
  bool HasBar (struct Bar &bar);
  /**
   * Returns true if there are packets that need of retransmission or at least a
   * BAR is scheduled. Returns false otherwise.
   */
  bool HasPackets (void) const;
  /**
   * \param blockAck The received block ack frame.
   * \param recipient Sender of block ack frame.
   *
   * Invoked upon receipt of a block ack frame. Typically, this function, is called
   * by ns3::EdcaTxopN object. Performs a check on which MPDUs, previously sent
   * with ack policy set to Block Ack, were correctly received by the recipient. 
   * An acknowledged MPDU is removed from the buffer, retransmitted otherwise.  
   */
  void NotifyGotBlockAck (const CtrlBAckResponseHeader *blockAck, Mac48Address recipient);
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID.
   *
   * Returns number of packets buffered for a specified agreement. This methods doesn't return 
   * number of buffered MPDUs but number of buffered MSDUs.
   */
  uint32_t GetNBufferedPackets (Mac48Address recipient, uint8_t tid) const;
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID.
   *
   * Returns number of packets for a specific agreement that need retransmission.
   * This methods doesn't return number of MPDUs that need retransmission but number MSDUs.
   */
  uint32_t GetNRetryNeededPackets (Mac48Address recipient, uint8_t tid) const;
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID of transmitted packet.
   * \param startingSeq starting sequence field
   *
   * Puts corresponding agreement in established state and updates number of packets
   * and starting sequence field. Invoked typically after a block ack refresh.  
   */
  void NotifyAgreementEstablished (Mac48Address recipient, uint8_t tid, uint16_t startingSeq);
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID of transmitted packet.
   *
   * Marks an agreement as unsuccessful. This happens if <i>recipient</i> station reject block ack setup
   * by an ADDBAResponse frame with a failure status code. FOr now we assume that every QoS station accepts
   * a block ack setup.
   */
  void NotifyAgreementUnsuccessful (Mac48Address recipient, uint8_t tid);
  /**
   * \param recipient Address of peer station involved in block ack mechanism.
   * \param tid Traffic ID of transmitted packet.
   *
   * This methods is typically invoked by ns3::EdcaTxopN object every time that a MPDU
   * with ack policy subfield in Qos Control field set to Block Ack is transmitted.
   */
  void NotifyMpduTransmission (Mac48Address recipient, uint8_t tid);
  /**
   * \param nPackets Minimum number of packets for use of block ack.
   *
   * Upon receipt of a block ack frame, if total number of packets (packets in WifiMacQueue
   * and buffered packets) is greater of <i>nPackets</i>, they are transmitted using block ack mechanism.   
   */
  void SetBlockAckThreshold (uint8_t nPackets);
  /**
   * \param queue The WifiMacQueue object.
   */
  void SetQueue (Ptr<WifiMacQueue> queue);
  void SetTxMiddle (MacTxMiddle* txMiddle);
  /**
   * \param bAckType Type of block ack
   *
   * See ctrl-headers.h for more details.
   */
  void SetBlockAckType (enum BlockAckType bAckType);
  /**
   * \param recipient Address of station involved in block ack mechanism.
   * \param tid Traffic ID.
   *
   * This method is invoked by EdcaTxopN object upon receipt of a DELBA frame
   * from recipient. The relative block ack agreement is destroyed.
   */
  void TearDownBlockAck (Mac48Address recipient, uint8_t tid);
  /**
   * \param sequenceNumber Sequence number of the packet which fragment is 
   * part of.
   *
   * Returns true if another fragment with sequence number <i>sequenceNumber</i> is scheduled
   * for retransmission.
   */
  bool HasOtherFragments (uint16_t sequenceNumber) const;
  /**
   * Returns size of the next packet that needs retransmission.
   */
  uint32_t GetNextPacketSize (void) const;
  /**
   * \param maxDelay Max delay for a buffered packet.
   * 
   * This method is always called by ns3::WifiMacQueue object and sets max delay equals
   * to ns3:WifiMacQueue delay value.
   */
  void SetMaxPacketDelay (Time maxDelay);
  /**
   */
  void SetBlockAckInactivityCallback (Callback<void, Mac48Address, uint8_t, bool> callback);
  void SetBlockDestinationCallback (Callback<void, Mac48Address, uint8_t> callback);
  void SetUnblockDestinationCallback (Callback<void, Mac48Address, uint8_t> callback);
  /**
   * Checks if there are in the queue other packets that could be send under block ack.
   * If yes adds these packets in current block ack exchange.
   * However, number of packets exchanged in the current block ack, will not exceed 
   * the value of BufferSize in the corresponding OriginatorBlockAckAgreement object.
   */
  bool SwitchToBlockAckIfNeeded (Mac48Address recipient, uint8_t tid, uint16_t startingSeq);
private:
  /**
   * Checks if all packets, for which a block ack agreement was established or refreshed,
   * have been transmitted. If yes, adds a pair in m_bAckReqs to indicate that 
   * at next channel access a block ack request (for established agreement
   * <i>recipient</i>,<i>tid</i>) is needed.
   */
  Ptr<Packet> ScheduleBlockAckReqIfNeeded (Mac48Address recipient, uint8_t tid);
  /**
   * This method removes packets whose lifetime was exceeded.
   */
  void CleanupBuffers (void);
  void InactivityTimeout (Mac48Address, uint8_t);

  struct Item;
  typedef std::list<Item> PacketQueue;
  typedef std::list<Item>::iterator PacketQueueI;
  typedef std::list<Item>::const_iterator PacketQueueCI;
  
  typedef std::map<std::pair<Mac48Address, uint8_t>, 
              std::pair<OriginatorBlockAckAgreement, PacketQueue> > Agreements;
  typedef std::map<std::pair<Mac48Address, uint8_t>, 
              std::pair<OriginatorBlockAckAgreement, PacketQueue> >::iterator AgreementsI;
  typedef std::map<std::pair<Mac48Address, uint8_t>, 
              std::pair<OriginatorBlockAckAgreement, PacketQueue> >::const_iterator AgreementsCI;

  struct Item {
    Item ();
    Item (Ptr<const Packet> packet,
          const WifiMacHeader &hdr,
          Time tStamp);
    Ptr<const Packet> packet;
    WifiMacHeader hdr;
    Time timestamp;
  };
  
  /**
   * This data structure contains, for each block ack agreement (recipient, tid), a set of packets
   * for which an ack by block ack is requested.
   * Every packet or fragment indicated as correctly received in block ack frame is 
   * erased from this data structure. Pushed back in retransmission queue otherwise.
   */
  Agreements m_agreements;
  /**
   * This list contains all iterators to stored packets that need to be retransmitted.
   * A packet needs retransmission if it's indicated as not correctly received in a block ack
   * frame.
   */
  std::list<PacketQueueI> m_retryPackets;
  std::list<Bar> m_bars;
  
  uint8_t m_blockAckThreshold;
  enum BlockAckType m_blockAckType;
  Time m_maxDelay;
  MacTxMiddle* m_txMiddle;
  Mac48Address m_address;
  Ptr<WifiMacQueue> m_queue;
  Callback<void, Mac48Address, uint8_t, bool> m_blockAckInactivityTimeout;
  Callback<void, Mac48Address, uint8_t> m_blockPackets;
  Callback<void, Mac48Address, uint8_t> m_unblockPackets;
};

} //namespace ns3

#endif /* BLOCK_ACK_MANAGER_H */