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

/*

 * Copyright (c) 2005,2006 INRIA

 *

 * 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>

 */

#include "wifi-phy-state-helper.h"

#include "ns3/log.h"

#include "ns3/simulator.h"

#include "ns3/trace-source-accessor.h"

NS_LOG_COMPONENT_DEFINE ("WifiPhyStateHelper");

namespace ns3 {

NS_OBJECT_ENSURE_REGISTERED (WifiPhyStateHelper);

TypeId 

WifiPhyStateHelper::GetTypeId (void)

{

  static TypeId tid = TypeId ("ns3::WifiPhyStateHelper")

    .SetParent<Object> ()

    .AddConstructor<WifiPhyStateHelper> ()

    .AddTraceSource ("State",

                     "The state of the PHY layer",

                     MakeTraceSourceAccessor (&WifiPhyStateHelper::m_stateLogger))

    .AddTraceSource ("RxOk",

                     "A packet has been received successfully.",

                     MakeTraceSourceAccessor (&WifiPhyStateHelper::m_rxOkTrace))

    .AddTraceSource ("RxError",

                     "A packet has been received unsuccessfully.",

                     MakeTraceSourceAccessor (&WifiPhyStateHelper::m_rxErrorTrace))

    .AddTraceSource ("Tx", "Packet transmission is starting.",

                     MakeTraceSourceAccessor (&WifiPhyStateHelper::m_txTrace))

    ;

  return tid;

}

WifiPhyStateHelper::WifiPhyStateHelper ()

  : m_syncing (false),

    m_endTx (Seconds (0)),

    m_endSync (Seconds (0)),

    m_endCcaBusy (Seconds (0)),

    m_startTx (Seconds (0)),

    m_startSync (Seconds (0)),

    m_startCcaBusy (Seconds (0)),

    m_previousStateChangeTime (Seconds (0))

{

  NS_LOG_FUNCTION (this);

}

void 

WifiPhyStateHelper::SetReceiveOkCallback (WifiPhy::SyncOkCallback callback)

{

  m_syncOkCallback = callback;

}

void 

WifiPhyStateHelper::SetReceiveErrorCallback (WifiPhy::SyncErrorCallback callback)

{

  m_syncErrorCallback = callback;

}

void 

WifiPhyStateHelper::RegisterListener (WifiPhyListener *listener)

{

  m_listeners.push_back (listener);

}

bool 

WifiPhyStateHelper::IsStateCcaBusy (void)

{

  return GetState () == WifiPhy::CCA_BUSY;

}

bool 

WifiPhyStateHelper::IsStateIdle (void)

{

  return (GetState () == WifiPhy::IDLE)?true:false;

}

bool 

WifiPhyStateHelper::IsStateBusy (void)

{

  return (GetState () != WifiPhy::IDLE)?true:false;

}

bool 

WifiPhyStateHelper::IsStateSync (void)

{

  return (GetState () == WifiPhy::SYNC)?true:false;

}

bool 

WifiPhyStateHelper::IsStateTx (void)

{

  return (GetState () == WifiPhy::TX)?true:false;

}

Time

WifiPhyStateHelper::GetStateDuration (void)

{

  return Simulator::Now () - m_previousStateChangeTime;

}

Time

WifiPhyStateHelper::GetDelayUntilIdle (void)

{

  Time retval;

  switch (GetState ()) {

  case WifiPhy::SYNC:

    retval = m_endSync - Simulator::Now ();

    break;

  case WifiPhy::TX:

    retval = m_endTx - Simulator::Now ();

    break;

  case WifiPhy::CCA_BUSY:

    retval = m_endCcaBusy - Simulator::Now ();

    break;

  case WifiPhy::IDLE:

    retval = Seconds (0);

    break;

  default:

    NS_ASSERT (false);

    // NOTREACHED

    retval = Seconds (0);

    break;

  }

  retval = Max (retval, Seconds (0));

  return retval;

}

Time 

WifiPhyStateHelper::GetLastRxStartTime (void) const

{

  return m_startSync;

}

char const *

WifiPhyStateHelper::StateToString (enum WifiPhy::State state)

{

  switch (state) {

  case WifiPhy::TX:

    return "TX";

    break;

  case WifiPhy::CCA_BUSY:

    return "CCA_BUSY";

    break;

  case WifiPhy::IDLE:

    return "IDLE";

    break;

  case WifiPhy::SYNC:

    return "SYNC";

    break;

  default:

    NS_ASSERT (false);

    // quiet compiler

    return "INVALID";

    break;

  }

}

enum WifiPhy::State 

WifiPhyStateHelper::GetState (void)

{

  if (m_endTx > Simulator::Now ()) 

    {

      return WifiPhy::TX;

    } 

  else if (m_syncing) 

    {

      return WifiPhy::SYNC;

    } 

  else if (m_endCcaBusy > Simulator::Now ()) 

    {

      return WifiPhy::CCA_BUSY;

    } 

  else 

    {

      return WifiPhy::IDLE;

    }

}

void 

WifiPhyStateHelper::NotifyTxStart (Time duration)

{

  for (Listeners::const_iterator i = m_listeners.begin (); i != m_listeners.end (); i++) {

    (*i)->NotifyTxStart (duration);

  }

}

void 

WifiPhyStateHelper::NotifySyncStart (Time duration)

{

  for (Listeners::const_iterator i = m_listeners.begin (); i != m_listeners.end (); i++) {

    (*i)->NotifyRxStart (duration);

  }

}

void 

WifiPhyStateHelper::NotifySyncEndOk (void)

{

  for (Listeners::const_iterator i = m_listeners.begin (); i != m_listeners.end (); i++) {

    (*i)->NotifyRxEndOk ();

  }

}

void 

WifiPhyStateHelper::NotifySyncEndError (void)

{

  for (Listeners::const_iterator i = m_listeners.begin (); i != m_listeners.end (); i++) {

    (*i)->NotifyRxEndError ();

  }

}

void 

WifiPhyStateHelper::NotifyMaybeCcaBusyStart (Time duration)

{

  for (Listeners::const_iterator i = m_listeners.begin (); i != m_listeners.end (); i++) {

    (*i)->NotifyMaybeCcaBusyStart (duration);

  }

}

void

WifiPhyStateHelper::LogPreviousIdleAndCcaBusyStates (void)

{

  Time now = Simulator::Now ();

  Time idleStart = Max (m_endCcaBusy, m_endSync);

  idleStart = Max (idleStart, m_endTx);

  NS_ASSERT (idleStart <= now);

  if (m_endCcaBusy > m_endSync && 

      m_endCcaBusy > m_endTx) {

    Time ccaBusyStart = Max (m_endTx, m_endSync);

    ccaBusyStart = Max (ccaBusyStart, m_startCcaBusy);

    m_stateLogger (ccaBusyStart, idleStart - ccaBusyStart, WifiPhy::CCA_BUSY);

  }

  m_stateLogger (idleStart, now - idleStart, WifiPhy::IDLE);

}

void

WifiPhyStateHelper::SwitchToTx (Time txDuration, Ptr<const Packet> packet, WifiMode txMode, 

			  WifiPreamble preamble, uint8_t txPower)

{

  m_txTrace (packet, txMode, preamble, txPower);

  NotifyTxStart (txDuration);

  Time now = Simulator::Now ();

  switch (GetState ()) {

  case WifiPhy::SYNC:

    /* The packet which is being received as well

     * as its endSync event are cancelled by the caller.

     */

    m_syncing = false;

    m_stateLogger (m_startSync, now - m_startSync, WifiPhy::SYNC);

    m_endSync = now;

    break;

  case WifiPhy::CCA_BUSY: {

    Time ccaStart = Max (m_endSync, m_endTx);

    ccaStart = Max (ccaStart, m_startCcaBusy);

    m_stateLogger (ccaStart, now - ccaStart, WifiPhy::CCA_BUSY);

  } break;

  case WifiPhy::IDLE:

    LogPreviousIdleAndCcaBusyStates ();

    break;

  default:

    NS_ASSERT (false);

    break;

  }

  m_stateLogger (now, txDuration, WifiPhy::TX);

  m_previousStateChangeTime = now;

  m_endTx = now + txDuration;

  m_startTx = now;

}

void

WifiPhyStateHelper::SwitchToSync (Time rxDuration)

{

  NS_ASSERT (IsStateIdle () || IsStateCcaBusy ());

  NS_ASSERT (!m_syncing);

  NotifySyncStart (rxDuration);

  Time now = Simulator::Now ();

  switch (GetState ()) {

  case WifiPhy::IDLE:

    LogPreviousIdleAndCcaBusyStates ();

    break;

  case WifiPhy::CCA_BUSY: {

    Time ccaStart = Max (m_endSync, m_endTx);

    ccaStart = Max (ccaStart, m_startCcaBusy);

    m_stateLogger (ccaStart, now - ccaStart, WifiPhy::CCA_BUSY);

  } break;

  case WifiPhy::SYNC:

  case WifiPhy::TX:

    NS_ASSERT (false);

    break;

  }

  m_previousStateChangeTime = now;

  m_syncing = true;

  m_startSync = now;

  m_endSync = now + rxDuration;

  NS_ASSERT (IsStateSync ());

}

void 

WifiPhyStateHelper::SwitchFromSyncEndOk (Ptr<Packet> packet, double snr, WifiMode mode, enum WifiPreamble preamble)

{

  m_rxOkTrace (packet, snr, mode, preamble);

  NotifySyncEndOk ();

  DoSwitchFromSync ();

  if (!m_syncOkCallback.IsNull ())

    {

      m_syncOkCallback (packet, snr, mode, preamble);

    }

}

void 

WifiPhyStateHelper::SwitchFromSyncEndError (Ptr<const Packet> packet, double snr)

{

  m_rxErrorTrace (packet, snr);

  NotifySyncEndError ();

  DoSwitchFromSync ();

  if (!m_syncErrorCallback.IsNull ())

    {

      m_syncErrorCallback (packet, snr);

    }

}

void

WifiPhyStateHelper::DoSwitchFromSync (void)

{

  NS_ASSERT (IsStateSync ());

  NS_ASSERT (m_syncing);

  Time now = Simulator::Now ();

  m_stateLogger (m_startSync, now - m_startSync, WifiPhy::SYNC);

  m_previousStateChangeTime = now;

  m_syncing = false;

  NS_ASSERT (IsStateIdle () || IsStateCcaBusy ());

}

void

WifiPhyStateHelper::SwitchMaybeToCcaBusy (Time duration)

{

  NotifyMaybeCcaBusyStart (duration);

  Time now = Simulator::Now ();

  switch (GetState ()) {

  case WifiPhy::IDLE:

    LogPreviousIdleAndCcaBusyStates ();

  break;

  case WifiPhy::CCA_BUSY:

    break;

  case WifiPhy::SYNC:

    break;

  case WifiPhy::TX:

    break;

  }

  m_startCcaBusy = now;

  m_endCcaBusy = std::max (m_endCcaBusy, now + duration);

}

} // namespace ns3