/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */

/*

 * Copyright (c) 2005, 2009 INRIA

 * 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: Mathieu Lacage <mathieu.lacage@sophia.inria.fr>

 * Author: Mirko Banchi <mk.banchi@gmail.com>

 */

#ifndef WIFI_MAC_QUEUE_H

#define WIFI_MAC_QUEUE_H

#include <list>

#include <utility>

#include "ns3/packet.h"

#include "ns3/nstime.h"

#include "ns3/object.h"

#include "wifi-mac-header.h"

namespace ns3 {

class QosBlockedDestinations;

/**

 * \ingroup wifi

 *

 * This queue implements the timeout procedure described in IEEE

 * Std. 802.11-2007, section 9.9.1.6, paragraph 6.

 *

 * When a packet is received by the MAC, to be sent to the PHY,

 * it is queued in the internal queue after being tagged by the

 * current time.

 *

 * When a packet is dequeued, the queue checks its timestamp

 * to verify whether or not it should be dropped. If

 * dot11EDCATableMSDULifetime has elapsed, it is dropped.

 * Otherwise, it is returned to the caller.

 */

class WifiMacQueue : public Object

{

public:

  static TypeId GetTypeId (void);

  WifiMacQueue ();

  ~WifiMacQueue ();

  /**

   * Set the maximum queue size.

   *

   * \param maxSize the maximum queue size

   */

  void SetMaxSize (uint32_t maxSize);

  /**

   * Set the maximum delay before the packet is discarded.

   *

   * \param delay the maximum delay

   */

  void SetMaxDelay (Time delay);

  /**

   * Return the maximum queue size.

   *

   * \return the maximum queue size

   */

  uint32_t GetMaxSize (void) const;

  /**

   * Return the maximum delay before the packet is discarded.

   *

   * \return the maximum delay

   */

  Time GetMaxDelay (void) const;

  /**

   * Enqueue the given packet and its corresponding WifiMacHeader at the <i>end</i> of the queue.

   *

   * \param packet the packet to be euqueued at the end

   * \param hdr the header of the given packet

   */

  void Enqueue (Ptr<const Packet> packet, const WifiMacHeader &hdr);

  /**

   * Enqueue the given packet and its corresponding WifiMacHeader at the <i>front</i> of the queue.

   *

   * \param packet the packet to be euqueued at the end

   * \param hdr the header of the given packet

   */

  void PushFront (Ptr<const Packet> packet, const WifiMacHeader &hdr);

  /**

   * Dequeue the packet in the front of the queue.

   *

   * \param hdr the WifiMacHeader of the packet

   * \return the packet

   */

  Ptr<const Packet> Dequeue (WifiMacHeader *hdr);

  /**

   * Peek the packet in the front of the queue. The packet is not removed.

   *

   * \param hdr the WifiMacHeader of the packet

   * \return the packet

   */

  Ptr<const Packet> Peek (WifiMacHeader *hdr);

  /**

   * Searchs and returns, if is present in this queue, first packet having

   * address indicated by <i>type</i> equals to <i>addr</i>, and tid

   * equals to <i>tid</i>. This method removes the packet from this queue.

   * Is typically used by ns3::EdcaTxopN in order to perform correct MSDU

   * aggregation (A-MSDU).

   *

   * \param hdr the header of the dequeued packet

   * \param tid the given TID

   * \param type the given address type

   * \param addr the given destination

   * \return packet

   */

  Ptr<const Packet> DequeueByTidAndAddress (WifiMacHeader *hdr,

                                            uint8_t tid,

                                            WifiMacHeader::AddressType type,

                                            Mac48Address addr);

  /**

   * Searchs and returns, if is present in this queue, first packet having

   * address indicated by <i>type</i> equals to <i>addr</i>, and tid

   * equals to <i>tid</i>. This method doesn't remove the packet from this queue.

   * Is typically used by ns3::EdcaTxopN in order to perform correct MSDU

   * aggregation (A-MSDU).

   *

   * \param hdr the header of the dequeued packet

   * \param tid the given TID

   * \param type the given address type

   * \param addr the given destination

   * \return packet

   */

  Ptr<const Packet> PeekByTidAndAddress (WifiMacHeader *hdr,

                                         uint8_t tid,

                                         WifiMacHeader::AddressType type,

                                         Mac48Address addr);

  /**

   * If exists, removes <i>packet</i> from queue and returns true. Otherwise it

   * takes no effects and return false. Deletion of the packet is

   * performed in linear time (O(n)).

   *

   * \param packet the packet to be removed

   * \return true if the packet was removed, false otherwise

   */

  bool Remove (Ptr<const Packet> packet);

  /**

   * Returns number of QoS packets having tid equals to <i>tid</i> and address

   * specified by <i>type</i> equals to <i>addr</i>.

   *

   * \param tid the given TID

   * \param type the given address type

   * \param addr the given destination

   * \return the number of QoS packets

   */

  uint32_t GetNPacketsByTidAndAddress (uint8_t tid,

                                       WifiMacHeader::AddressType type,

                                       Mac48Address addr);

  /**

   * Returns first available packet for transmission. A packet could be no available

   * if it's a QoS packet with a tid and an address1 fields equal to <i>tid</i> and <i>addr</i>

   * respectively that index a pending agreement in the BlockAckManager object.

   * So that packet must not be transmitted until reception of an ADDBA response frame from station

   * addressed by <i>addr</i>. This method removes the packet from queue.

   *

   * \param hdr the header of the dequeued packet

   * \param tStamp

   * \param blockedPackets

   * \return packet

   */

  Ptr<const Packet> DequeueFirstAvailable (WifiMacHeader *hdr,

                                           Time &tStamp,

                                           const QosBlockedDestinations *blockedPackets);

  /**

   * Returns first available packet for transmission. The packet isn't removed from queue.  

   *

   * \param hdr the header of the dequeued packet

   * \param tStamp

   * \param blockedPackets

   * \return packet

   */

  Ptr<const Packet> PeekFirstAvailable (WifiMacHeader *hdr,

                                        Time &tStamp,

                                        const QosBlockedDestinations *blockedPackets);

  /**

   * Flush the queue.

   */

  void Flush (void);

  /**

   * Return if the queue is empty.

   *

   * \return true if the queue is empty, false otherwise

   */

  bool IsEmpty (void);

  /**

   * Return the current queue size.

   *

   * \return the current queue size

   */

  uint32_t GetSize (void);

protected:

  /**

   * Clean up the queue by removing packets that exceeded the maximum delay.

   */

  virtual void Cleanup (void);

  struct Item;

  /**

   * typedef for packet (struct Item) queue.

   */

  typedef std::list<struct Item> PacketQueue;

  /**

   * typedef for packet (struct Item) queue reverse iterator.

   */

  typedef std::list<struct Item>::reverse_iterator PacketQueueRI;

  /**

   * typedef for packet (struct Item) queue iterator.

   */

  typedef std::list<struct Item>::iterator PacketQueueI;

  /**

   * Return the appropriate address for the given packet (given by PacketQueue iterator).

   *

   * \param type

   * \param it

   * \return the address

   */

  Mac48Address GetAddressForPacket (enum WifiMacHeader::AddressType type, PacketQueueI it);

  /**

   * A struct that holds information about a packet for putting

   * in a packet queue.

   */

  struct Item

  {

    /**

     * Create a struct with the given parameters.

     *

     * \param packet

     * \param hdr

     * \param tstamp

     */

    Item (Ptr<const Packet> packet,

          const WifiMacHeader &hdr,

          Time tstamp);

    Ptr<const Packet> packet; //!< Actual packet

    WifiMacHeader hdr; //!< Wifi MAC header associated with the packet

    Time tstamp; //!< timestamp when the packet arrived at the queue

  };

  PacketQueue m_queue; //!< Packet (struct Item) queue

  uint32_t m_maxSize; //!< Queue capacity

};

} // namespace ns3

#endif /* WIFI_MAC_QUEUE_H */