/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2011 Yufei Cheng
 *
 * 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: Yufei Cheng   <yfcheng@ittc.ku.edu>
 *
 * James P.G. Sterbenz <jpgs@ittc.ku.edu>, director
 * ResiliNets Research Group  http://wiki.ittc.ku.edu/resilinets
 * Information and Telecommunication Technology Center (ITTC)
 * and Department of Electrical Engineering and Computer Science
 * The University of Kansas Lawrence, KS USA.
 *
 * Work supported in part by NSF FIND (Future Internet Design) Program
 * under grant CNS-0626918 (Postmodern Internet Architecture),
 * NSF grant CNS-1050226 (Multilayer Network Resilience Analysis and Experimentation on GENI),
 * US Department of Defense (DoD), and ITTC at The University of Kansas.
 */

#ifndef DSR_RREQ_TABLE_H
#define DSR_RREQ_TABLE_H

#include "ns3/simulator.h"
#include "ns3/timer.h"
#include "ns3/ipv4-address.h"
#include "ns3/callback.h"
#include <list>
#include <vector>
#include <map>

namespace ns3 {
namespace dsr {

enum LinkStates
{
  PROBABLE = 0,            // !< PROBABLE
  QUESTIONABLE = 1,        // !< QUESTIONABLE
};
// / BlackList description
struct BlackList
{
  Ipv4Address m_neighborAddress;
  Time m_expireTime;
  LinkStates m_linkStates;

  BlackList (Ipv4Address ip, Time t)
    : m_neighborAddress (ip),
      m_expireTime (t),
      m_linkStates (PROBABLE)
  {
  }
};
/*
 * The route request table entries
 */
struct RreqTableEntry
{
  uint16_t m_reqNo;
  Time m_expire;
};
/*
 * The route request table id for originators
 * It is responsible for checking duplicate requests from a single source to a specific destination
 */
struct SourceRreqEntry
{
  uint16_t m_identification;
  Ipv4Address m_dst;
  Time m_expire;
};
/**
 * \ingroup dsr
 * \brief maintain list of RreqTable entry
 */
class RreqTable  : public Object
{
public:
  // / c-tor
  /**
   * \brief Get the type identificator.
   * \return type identificator
   */
  static TypeId GetTypeId ();
  /**
   * \brief Constructor.
   */
  RreqTable ();
  /**
   * \brief Destructor.
   */
  virtual ~RreqTable ();

  // /\name Fields
  // \{
  void SetInitHopLimit (uint8_t hl)
  {
    m_initHopLimit = hl;
  }
  uint8_t GetInitHopLimit () const
  {
    return m_initHopLimit;
  }
  void SetRreqTableSize (uint32_t rt)
  {
    m_requestTableSize = rt;
  }
  uint32_t GetRreqTableSize () const
  {
    return m_requestTableSize;
  }
  void SetRreqIdSize (uint32_t id)
  {
    m_requestIdSize = id;
  }
  uint32_t GetRreqIdSize () const
  {
    return m_requestIdSize;
  }
  void SetUniqueRreqIdSize (uint16_t uid)
  {
    m_maxRreqId = uid;
  }
  uint16_t GetUniqueRreqIdSize () const
  {
    return m_maxRreqId;
  }

  // \}
  // / Remove the least used entry
  void RemoveLeastExpire (std::map<Ipv4Address, RreqTableEntry > & rreqDstMap);
  // / Find the entry in the route request queue to see if already exists
  void FindAndUpdate (Ipv4Address dst);
  // / Remove route request entry for dst
  void RemoveRreqEntry (Ipv4Address dst);
  // / Get the request count number for one destination address
  uint16_t GetRreqCnt (Ipv4Address dst);

  //----------------------------------------------------------------------------------------------------------
  /*
   * The following code deals with duplicate request ids
   */
  bool FindSrc (Ipv4Address source, Ipv4Address target, uint16_t id);
  // / Purge the rreq table
  void Purge ();
  // / Set the source rreq expire time to the time of max route expire time
  void SetRreqExpire (Time expire)
  {
    m_rreqEntryExpire = expire;
  }

  //----------------------------------------------------------------------------------------------------------
  /*
   * The following code generates new request id for each destination
   */
  // / Check for duplicate ids and save new entries if the id is not present in the table
  uint16_t CheckUniqueRreqId (Ipv4Address dst);
  // / Get the request id size
  uint16_t GetRreqSize ();

  // ---------------------------------------------------------------------------------------------------------
  /*
   * set the unidirectional entry as QUESTIONABLE state
   */
  void Invalidate ();
  /** Verify if entry is unidirectional or not(e.g. add this neighbor to "blacklist" for blacklistTimeout period)
   * \param neighbor - neighbor address link to which assumed to be unidirectional
   * \return true on success
   */
  BlackList* FindUnidirectional (Ipv4Address neighbor);
  /** Mark entry as unidirectional (e.g. add this neighbor to "blacklist" for blacklistTimeout period)
   * \param neighbor - neighbor address link to which assumed to be unidirectional
   * \param blacklistTimeout - time for which the neighboring node is put into the blacklist
   * \return true on success
   */
  bool MarkLinkAsUnidirectional (Ipv4Address neighbor, Time blacklistTimeout);
  // / Remove all expired black list entries
  void PurgeNeighbor ();

private:
  // / Timer for neighbor's list. Schedule Purge().
  Timer m_ntimer;
  // / The max # of requests to retransmit
  uint32_t MaxRequestRexmt;
  // / The max request period among requests
  Time  MaxRequestPeriod;
  // / The original request period
  Time  RequestPeriod;
  // / The non-propagaton request timeout
  Time  NonpropRequestTimeout;
  // / The source route entry expire time
  Time m_rreqEntryExpire;
  // / The initial hop limit
  uint8_t m_initHopLimit;
  // / The request table size
  uint32_t m_requestTableSize;
  // / The request source id size
  uint32_t m_requestIdSize;
  // / The unique request id for any destination
  uint16_t m_maxRreqId;
  // / The state of the unidirectional link
  LinkStates m_linkStates;
  // / Map of entries
  std::list<SourceRreqEntry> m_sourceRreq;
  // / The id cache to ensure all the ids are unique
  std::map<Ipv4Address, uint16_t> m_rreqIdCache;
  // / The cache to save route request table entries indexed with destination address
  std::map<Ipv4Address, RreqTableEntry > m_rreqDstMap;
  // / The cache to ensure all the route request from unique source
  std::map<Ipv4Address, std::list<SourceRreqEntry> > m_rreqMap;
  // / The Black list
  std::vector<BlackList> m_blackList;
  // / Check if the entry is expired or not
  struct IsExpired
  {
    bool operator() (const struct BlackList & b) const
    {
      return (b.m_expireTime < Simulator::Now ());
    }
  };
};
}  // namespace dsr
}  // namespace ns3

#endif /* DSR_RREQ_TABLE_H */