/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2012 University of California, Los Angeles
 *
 * 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: Zhenkai Zhu <zhenkai@cs.ucla.edu>
 *         Chaoyi Bian <bcy@pku.edu.cn>
 *	   Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#ifdef NS3_MODULE
#include <ns3/ccnx-pit.h>
#include <ns3/ccnx.h>
#endif

#include "sync-logic.h"
#include "sync-diff-leaf.h"
#include "sync-full-leaf.h"
#include "sync-log.h"

#include <boost/make_shared.hpp>
#include <boost/foreach.hpp>
#include <boost/lexical_cast.hpp>
#include <vector>

using namespace std;
using namespace boost;

INIT_LOGGER ("SyncLogic");

#ifdef NS3_MODULE
#define GET_RANDOM(var) var.GetValue ()
#else
#define GET_RANDOM(var) var ()
#endif

#define TIME_SECONDS_WITH_JITTER(sec) \
  (TIME_SECONDS (sec) + TIME_MILLISECONDS (GET_RANDOM (m_reexpressionJitter)))

#define TIME_MILLISECONDS_WITH_JITTER(ms) \
  (TIME_MILLISECONDS (ms) + TIME_MILLISECONDS (GET_RANDOM (m_reexpressionJitter)))


namespace Sync
{

SyncLogic::SyncLogic (const std::string &syncPrefix,
                      LogicUpdateCallback onUpdate,
                      LogicRemoveCallback onRemove)
  : m_state (new FullState)
  , m_syncInterestTable (TIME_SECONDS (m_syncInterestReexpress))
  , m_syncPrefix (syncPrefix)
  , m_onUpdate (onUpdate)
  , m_onRemove (onRemove)
  , m_ccnxHandle(new CcnxWrapper())
  , m_recoveryRetransmissionInterval (m_defaultRecoveryRetransmitInterval)
#ifndef NS3_MODULE
  , m_randomGenerator (static_cast<unsigned int> (std::time (0)))
  , m_rangeUniformRandom (m_randomGenerator, uniform_int<> (200,1000))
  , m_reexpressionJitter (m_randomGenerator, uniform_int<> (100,500))
#else
  , m_rangeUniformRandom (200,1000)
  , m_reexpressionJitter (10,500)
#endif
{ 
#ifndef NS3_MODULE
  // In NS3 module these functions are moved to StartApplication method
  
  m_ccnxHandle->setInterestFilter (m_syncPrefix,
                                   bind (&SyncLogic::respondSyncInterest, this, _1));

  m_scheduler.schedule (TIME_SECONDS (0), // no need to add jitter
                        bind (&SyncLogic::sendSyncInterest, this),
                        REEXPRESSING_INTEREST);
#endif
}

SyncLogic::~SyncLogic ()
{
  m_ccnxHandle.reset ();
}

#ifdef NS3_MODULE
void
SyncLogic::StartApplication ()
{
  m_ccnxHandle->SetNode (GetNode ());
  m_ccnxHandle->StartApplication ();

  m_ccnxHandle->setInterestFilter (m_syncPrefix,
                                   bind (&SyncLogic::respondSyncInterest, this, _1));

  m_scheduler.schedule (TIME_SECONDS (0), // need to send first interests at exactly the same time
                        bind (&SyncLogic::sendSyncInterest, this),
                        REEXPRESSING_INTEREST);
}

void
SyncLogic::StopApplication ()
{
  m_ccnxHandle->clearInterestFilter (m_syncPrefix);
  m_ccnxHandle->StopApplication ();
  m_scheduler.cancel (REEXPRESSING_INTEREST);
  m_scheduler.cancel (DELAYED_INTEREST_PROCESSING);
}
#endif

/**
 * Two types of intersts
 *
 * Normal name:    .../<hash>  
 * Recovery name:  .../recovery/<hash>
 */
boost::tuple<DigestConstPtr, std::string>
SyncLogic::convertNameToDigestAndType (const std::string &name)
{
  BOOST_ASSERT (name.find (m_syncPrefix) == 0);

  string hash = name.substr (m_syncPrefix.size (), name.size ()-m_syncPrefix.size ());
  if (hash[0] == '/')
    hash = hash.substr (1, hash.size ()-1);
  string interestType = "normal";

  size_t pos = hash.find ('/');
  if (pos != string::npos)
    {
      interestType = hash.substr (0, pos);
      hash         = hash.substr (pos + 1);
    }

  _LOG_TRACE (hash << ", " << interestType);

  DigestPtr digest = make_shared<Digest> ();
  istringstream is (hash);
  is >> *digest;

  return make_tuple (digest, interestType);
}

void
SyncLogic::respondSyncInterest (const string &name)
{
  try
    {
      _LOG_TRACE ("<< I " << name);

      DigestConstPtr digest;
      string type;
      tie (digest, type) = convertNameToDigestAndType (name);

      if (type == "normal") // kind of ineffective...
        {
          processSyncInterest (name, digest);
        }
      else if (type == "recovery") 
        {
          processSyncRecoveryInterest (name, digest);
        }
    }
  catch (Error::DigestCalculationError &e)
    {
      _LOG_TRACE ("Something fishy happened...");
      // log error. ignoring it for now, later we should log it
      return ;
    }
}

void
SyncLogic::respondSyncData (const std::string &name, const std::string &dataBuffer)
{
  try
    {
      _LOG_TRACE ("<< D " << name);
  
      DigestConstPtr digest;
      string type;
      tie (digest, type) = convertNameToDigestAndType (name);

      if (type == "normal")
        {
          processSyncData (name, digest, dataBuffer);
        }
      else
        {
          // timer is always restarted when we schedule recovery
          m_scheduler.cancel (REEXPRESSING_RECOVERY_INTEREST);
          processSyncData (name, digest, dataBuffer);
        }
    }
  catch (Error::DigestCalculationError &e)
    {
      _LOG_TRACE ("Something fishy happened...");
      // log error. ignoring it for now, later we should log it
      return;
    }
}


void
SyncLogic::processSyncInterest (const std::string &name, DigestConstPtr digest, bool timedProcessing/*=false*/)
{
  recursive_mutex::scoped_lock lock (m_stateMutex);

  // Special case when state is not empty and we have received request with zero-root digest
  if (digest->isZero () && !m_state->getDigest()->isZero ())
    {
      sendSyncData (name, digest, m_state);
      return;
    }

  if (*m_state->getDigest() == *digest)
    {
      _LOG_TRACE ("processSyncInterest (): Same state. Adding to PIT");
      m_syncInterestTable.insert (digest, name, false);
      return;
    }
  
  DiffStateContainer::iterator stateInDiffLog = m_log.find (digest);

  if (stateInDiffLog != m_log.end ())
  {
    DiffStateConstPtr stateDiff = (*stateInDiffLog)->diff ();

    sendSyncData (name, digest, stateDiff);
    return;
  }

  if (!timedProcessing)
    {
      bool exists = m_syncInterestTable.insert (digest, name, true);
      if (exists) // somebody else replied, so restart random-game timer
        {
          _LOG_DEBUG ("Unknown digest, but somebody may have already replied, so restart our timer");
          m_scheduler.cancel (DELAYED_INTEREST_PROCESSING);
        }

      uint32_t waitDelay = GET_RANDOM (m_rangeUniformRandom);      
      _LOG_DEBUG ("Digest is not in the log. Schedule processing after small delay: " << waitDelay << "ms");

      m_scheduler.schedule (TIME_MILLISECONDS (waitDelay),
                            bind (&SyncLogic::processSyncInterest, this, name, digest, true),
                            DELAYED_INTEREST_PROCESSING);
    }
  else
    {
      _LOG_TRACE ("                                                      (timed processing)");
      
      m_recoveryRetransmissionInterval = m_defaultRecoveryRetransmitInterval;
      sendSyncRecoveryInterests (digest);
    }
}

void
SyncLogic::processSyncData (const std::string &name, DigestConstPtr digest, const string &dataBuffer)
{
  DiffStatePtr diffLog = make_shared<DiffState> ();
  bool ownInterestSatisfied = false;
  
  try
    {
      recursive_mutex::scoped_lock lock (m_stateMutex);

      m_syncInterestTable.remove (name); // Remove satisfied interest from PIT

      ownInterestSatisfied = (name == m_outstandingInterestName);

      DiffState diff;
      istringstream ss (dataBuffer);
      ss >> diff;
      BOOST_FOREACH (LeafConstPtr leaf, diff.getLeaves().get<ordered>())
        {
          DiffLeafConstPtr diffLeaf = dynamic_pointer_cast<const DiffLeaf> (leaf);
          BOOST_ASSERT (diffLeaf != 0);

          NameInfoConstPtr info = diffLeaf->getInfo();
          if (diffLeaf->getOperation() == UPDATE)
            {
              SeqNo seq = diffLeaf->getSeq();

              bool inserted = false;
              bool updated = false;
              SeqNo oldSeq;
              tie (inserted, updated, oldSeq) = m_state->update (info, seq);

              if (inserted || updated)
                {
                  diffLog->update (info, seq);
                  m_onUpdate (info->toString (), seq, oldSeq);
                }
            }
          else if (diffLeaf->getOperation() == REMOVE)
            {
              if (m_state->remove (info))
                {
                  diffLog->remove (info);
                  m_onRemove (info->toString ());
                }
            }
          else
            {
              BOOST_ASSERT (false); // just in case
            }
        }

      insertToDiffLog (diffLog);
    }
  catch (Error::SyncXmlDecodingFailure &e)
    {
      _LOG_TRACE ("Something really fishy happened during state decoding " <<
                  diagnostic_information (e));
      diffLog.reset ();
      // don't do anything
    }

  if ((diffLog != 0 && diffLog->getLeaves ().size () > 0) ||
      ownInterestSatisfied)
    {
      // Do it only if everything went fine and state changed

      // this is kind of wrong
      // satisfyPendingSyncInterests (diffLog); // if there are interests in PIT, there is a point to satisfy them using new state
  
      // if state has changed, then it is safe to express a new interest
      m_scheduler.cancel (REEXPRESSING_INTEREST);
      m_scheduler.schedule (TIME_SECONDS_WITH_JITTER (0),
                            bind (&SyncLogic::sendSyncInterest, this),
                            REEXPRESSING_INTEREST);
    }
}

void
SyncLogic::processSyncRecoveryInterest (const std::string &name, DigestConstPtr digest)
{
  recursive_mutex::scoped_lock lock (m_stateMutex);
  
  DiffStateContainer::iterator stateInDiffLog = m_log.find (digest);

  if (stateInDiffLog == m_log.end ())
    {
      _LOG_TRACE ("Could not find " << *digest << " in digest log");
      return;
    }

  sendSyncData (name, digest, m_state);
}

void
SyncLogic::satisfyPendingSyncInterests (DiffStateConstPtr diffLog)
{
  DiffStatePtr fullStateLog = make_shared<DiffState> ();
  {
    recursive_mutex::scoped_lock lock (m_stateMutex);
    BOOST_FOREACH (LeafConstPtr leaf, m_state->getLeaves ()/*.get<timed> ()*/)
      {
        fullStateLog->update (leaf->getInfo (), leaf->getSeq ());
        /// @todo Impose limit on how many state info should be send out
      }
  }
  
  try
    {
      uint32_t counter = 0;
      while (m_syncInterestTable.size () > 0)
        {
          Interest interest = m_syncInterestTable.pop ();

          if (!interest.m_unknown)
            {
              _LOG_TRACE (">> D " << interest.m_name);
              sendSyncData (interest.m_name, interest.m_digest, diffLog);
            }
          else
            {
              _LOG_TRACE (">> D (unknown)" << interest.m_name);
              sendSyncData (interest.m_name, interest.m_digest, fullStateLog);
            }
          counter ++;
        }
      _LOG_DEBUG ("Satisfied " << counter << " pending interests");
    }
  catch (Error::InterestTableIsEmpty &e)
    {
      // ok. not really an error
    }
}

void
SyncLogic::insertToDiffLog (DiffStatePtr diffLog) 
{
  diffLog->setDigest (m_state->getDigest());  
  if (m_log.size () > 0)
    {
      m_log.get<sequenced> ().front ()->setNext (diffLog);
    }
  m_log.erase (m_state->getDigest()); // remove diff state with the same digest.  next pointers are still valid
  /// @todo Optimization
  m_log.get<sequenced> ().push_front (diffLog);
}

void
SyncLogic::addLocalNames (const string &prefix, uint32_t session, uint32_t seq)
{
  DiffStatePtr diff;
  {
    //cout << "Add local names" <<endl;
    recursive_mutex::scoped_lock lock (m_stateMutex);
    NameInfoConstPtr info = StdNameInfo::FindOrCreate(prefix);

    _LOG_DEBUG ("addLocalNames (): old state " << *m_state->getDigest ());

    SeqNo seqN (session, seq);
    m_state->update(info, seqN);

    _LOG_DEBUG ("addLocalNames (): new state " << *m_state->getDigest ());
    
    diff = make_shared<DiffState>();
    diff->update(info, seqN);
    insertToDiffLog (diff);
  }

  // _LOG_DEBUG ("PIT size: " << m_syncInterestTable.size ());
  satisfyPendingSyncInterests (diff);  
}

void
SyncLogic::remove(const string &prefix) 
{
  DiffStatePtr diff;
  {
    recursive_mutex::scoped_lock lock (m_stateMutex);
    NameInfoConstPtr info = StdNameInfo::FindOrCreate(prefix);
    m_state->remove(info);	

    diff = make_shared<DiffState>();
    diff->remove(info);

    insertToDiffLog (diff);
  }

  satisfyPendingSyncInterests (diff);  
}

void
SyncLogic::sendSyncInterest ()
{
  ostringstream os;

  {
    recursive_mutex::scoped_lock lock (m_stateMutex);

    os << m_syncPrefix << "/" << *m_state->getDigest();
    m_outstandingInterestName = os.str ();
    _LOG_TRACE (">> I " << os.str ());
  }

  m_scheduler.cancel (REEXPRESSING_INTEREST);
  m_scheduler.schedule (TIME_SECONDS_WITH_JITTER (m_syncInterestReexpress),
                        bind (&SyncLogic::sendSyncInterest, this),
                        REEXPRESSING_INTEREST);
  
  m_ccnxHandle->sendInterest (os.str (),
                              bind (&SyncLogic::respondSyncData, this, _1, _2));
}

void
SyncLogic::sendSyncRecoveryInterests (DigestConstPtr digest)
{
  ostringstream os;
  os << m_syncPrefix << "/recovery/" << *digest;
  _LOG_TRACE (">> I " << os.str ());

  TimeDuration nextRetransmission = TIME_MILLISECONDS_WITH_JITTER (m_recoveryRetransmissionInterval);
  m_recoveryRetransmissionInterval <<= 1;
    
  m_scheduler.cancel (REEXPRESSING_RECOVERY_INTEREST);
  if (m_recoveryRetransmissionInterval < 100*1000) // <100 seconds
    {
      m_scheduler.schedule (nextRetransmission,
                            bind (&SyncLogic::sendSyncRecoveryInterests, this, digest),
                            REEXPRESSING_RECOVERY_INTEREST);
    }

  m_ccnxHandle->sendInterest (os.str (),
                              bind (&SyncLogic::respondSyncData, this, _1, _2));
}


void
SyncLogic::sendSyncData (const std::string &name, DigestConstPtr digest, StateConstPtr state)
{
  _LOG_TRACE (">> D " << name);
  // sending
  m_ccnxHandle->publishData (name,
                             lexical_cast<string> (*state),
                             m_syncResponseFreshness); // in NS-3 it doesn't have any effect... yet

  // checking if our own interest got satisfied
  bool satisfiedOwnInterest = false;
  {
    recursive_mutex::scoped_lock lock (m_stateMutex);
    satisfiedOwnInterest = (m_outstandingInterestName == name);
  }
  
  if (satisfiedOwnInterest)
    {
      _LOG_TRACE ("Satisfied our own Interest. Re-expressing (hopefully with a new digest)");
      
      m_scheduler.cancel (REEXPRESSING_INTEREST);
      m_scheduler.schedule (TIME_SECONDS_WITH_JITTER (0),
                            bind (&SyncLogic::sendSyncInterest, this),
                            REEXPRESSING_INTEREST);
    }
}


}