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

/*

 * Copyright 2007 University of Washington

 * 

 * 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

 */

#include <algorithm>

#include <iostream>

#include "ns3/log.h"

#include "ns3/assert.h"

#include "candidate-queue.h"

#include "global-route-manager-impl.h"

/**

 * \brief Stream insertion operator.

 *

 * \param os the reference to the output stream

 * \param t the SPFVertex type

 * \returns the reference to the output stream

 */

std::ostream&

operator<< (std::ostream& os, const SPFVertex::VertexType& t)

{

  switch (t)

    {

    case SPFVertex::VertexRouter:  os << "router"; break;

    case SPFVertex::VertexNetwork: os << "network"; break;

    default:                       os << "unknown"; break;

    };

  return os;

}

std::ostream& 

operator<< (std::ostream& os, const CandidateQueue& q)

{

  typedef CandidateQueue::CandidateList_t List_t;

  typedef List_t::const_iterator CIter_t;

  const CandidateQueue::CandidateList_t& list = q.m_candidates;

  os << "*** CandidateQueue Begin (<id, distance, LSA-type>) ***" << std::endl;

  for (CIter_t iter = list.begin (); iter != list.end (); iter++)

    {

      os << "<" 

      << (*iter)->GetVertexId () << ", "

      << (*iter)->GetDistanceFromRoot () << ", "

      << (*iter)->GetVertexType () << ">" << std::endl;

    }

  os << "*** CandidateQueue End ***";

  return os;

}

CandidateQueue::CandidateQueue()

  : m_candidates ()

{

  NS_LOG_FUNCTION (this);

}

CandidateQueue::~CandidateQueue()

{

  NS_LOG_FUNCTION (this);

  Clear ();

}

void

CandidateQueue::Clear (void)

{

  NS_LOG_FUNCTION (this);

  while (!m_candidates.empty ())

    {

      SPFVertex *p = Pop ();

      delete p;

      p = 0;

    }

}

void

CandidateQueue::Push (SPFVertex *vNew)

{

  NS_LOG_FUNCTION (this << vNew);

  CandidateList_t::iterator i = std::upper_bound (

      m_candidates.begin (), m_candidates.end (), vNew,

      &CandidateQueue::CompareSPFVertex

      );

  m_candidates.insert (i, vNew);

}

SPFVertex *

CandidateQueue::Pop (void)

{

  NS_LOG_FUNCTION (this);

  if (m_candidates.empty ())

    {

      return 0;

    }

  SPFVertex *v = m_candidates.front ();

  m_candidates.pop_front ();

  return v;

}

SPFVertex *

CandidateQueue::Top (void) const

{

  NS_LOG_FUNCTION (this);

  if (m_candidates.empty ())

    {

      return 0;

    }

  return m_candidates.front ();

}

bool

CandidateQueue::Empty (void) const

{

  NS_LOG_FUNCTION (this);

  return m_candidates.empty ();

}

uint32_t

CandidateQueue::Size (void) const

{

  NS_LOG_FUNCTION (this);

  return m_candidates.size ();

}

SPFVertex *

CandidateQueue::Find (const Ipv4Address addr) const

{

  NS_LOG_FUNCTION (this);

  CandidateList_t::const_iterator i = m_candidates.begin ();

  for (; i != m_candidates.end (); i++)

    {

      SPFVertex *v = *i;

      if (v->GetVertexId () == addr)

        {

          return v;

        }

    }

  return 0;

}

void

CandidateQueue::Reorder (void)

{

  NS_LOG_FUNCTION (this);

  m_candidates.sort (&CandidateQueue::CompareSPFVertex);

  NS_LOG_LOGIC ("After reordering the CandidateQueue");

  NS_LOG_LOGIC (*this);

}

/*

 * In this implementation, SPFVertex follows the ordering where

 * a vertex is ranked first if its GetDistanceFromRoot () is smaller;

 * In case of a tie, NetworkLSA is always ranked before RouterLSA.

 *

 * This ordering is necessary for implementing ECMP

 */

bool 

CandidateQueue::CompareSPFVertex (const SPFVertex* v1, const SPFVertex* v2)

{

  NS_LOG_FUNCTION (&v1 << &v2);

  bool result = false;

  if (v1->GetDistanceFromRoot () < v2->GetDistanceFromRoot ())

    {

      result = true;

    }

  else if (v1->GetDistanceFromRoot () == v2->GetDistanceFromRoot ())

    {

      if (v1->GetVertexType () == SPFVertex::VertexNetwork 

          && v2->GetVertexType () == SPFVertex::VertexRouter)

        {

          result = true;

        }

    }

  return result;

}

} // namespace ns3