/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2024,  Regents of the University of California,
 *                           Arizona Board of Regents,
 *                           Colorado State University,
 *                           University Pierre & Marie Curie, Sorbonne University,
 *                           Washington University in St. Louis,
 *                           Beijing Institute of Technology,
 *                           The University of Memphis.
 *
 * This file is part of NFD (Named Data Networking Forwarding Daemon).
 * See AUTHORS.md for complete list of NFD authors and contributors.
 *
 * NFD is free software: you can redistribute it and/or modify it under the terms
 * of the GNU General Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
 *
 * NFD 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
 * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef NFD_DAEMON_FW_ASF_MEASUREMENTS_HPP
#define NFD_DAEMON_FW_ASF_MEASUREMENTS_HPP

#include "face/face-common.hpp"
#include "fw/strategy-info.hpp"
#include "table/measurements-accessor.hpp"

#include <ndn-cxx/util/rtt-estimator.hpp>

#include <unordered_map>

namespace nfd::fw::asf {

/**
 * \brief Strategy information for each face in a namespace.
 */
class FaceInfo
{
public:
  explicit
  FaceInfo(shared_ptr<const ndn::util::RttEstimator::Options> opts)
    : m_rttEstimator(std::move(opts))
  {
  }

  bool
  isTimeoutScheduled() const
  {
    return !!m_timeoutEvent;
  }

  time::nanoseconds
  scheduleTimeout(const Name& interestName, ndn::scheduler::EventCallback cb);

  void
  cancelTimeout(const Name& prefix);

  void
  recordRtt(time::nanoseconds rtt)
  {
    m_lastRtt = rtt;
    m_rttEstimator.addMeasurement(rtt);
  }

  void
  recordTimeout(const Name& interestName)
  {
    m_lastRtt = RTT_TIMEOUT;
    cancelTimeout(interestName);
  }

  time::nanoseconds
  getLastRtt() const
  {
    return m_lastRtt;
  }

  time::nanoseconds
  getSrtt() const
  {
    return m_rttEstimator.getSmoothedRtt();
  }

  size_t
  getNTimeouts() const
  {
    return m_nTimeouts;
  }

  void
  setNTimeouts(size_t nTimeouts)
  {
    m_nTimeouts = nTimeouts;
  }

public:
  static constexpr time::nanoseconds RTT_NO_MEASUREMENT = -1_ns;
  static constexpr time::nanoseconds RTT_TIMEOUT = -2_ns;

private:
  ndn::util::RttEstimator m_rttEstimator;
  time::nanoseconds m_lastRtt = RTT_NO_MEASUREMENT;
  Name m_lastInterestName;
  size_t m_nTimeouts = 0;

  // Timeout associated with measurement
  ndn::scheduler::ScopedEventId m_measurementExpiration;
  friend class NamespaceInfo;

  // RTO associated with Interest
  ndn::scheduler::ScopedEventId m_timeoutEvent;
};

////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

/**
 * \brief Stores strategy information about each face in this namespace.
 */
class NamespaceInfo final : public StrategyInfo
{
public:
  static constexpr int
  getTypeId()
  {
    return 1030;
  }

  explicit
  NamespaceInfo(shared_ptr<const ndn::util::RttEstimator::Options> opts, time::milliseconds measurementLifetime)
    : m_rttEstimatorOpts(std::move(opts))
    , m_measurementLifetime(measurementLifetime)
  {
  }

  FaceInfo*
  getFaceInfo(FaceId faceId);

  FaceInfo&
  getOrCreateFaceInfo(FaceId faceId);

  void
  extendFaceInfoLifetime(FaceInfo& info, FaceId faceId);

  bool
  isProbingDue() const
  {
    return m_isProbingDue;
  }

  void
  setIsProbingDue(bool isProbingDue)
  {
    m_isProbingDue = isProbingDue;
  }

  bool
  isFirstProbeScheduled() const
  {
    return m_isFirstProbeScheduled;
  }

  void
  setIsFirstProbeScheduled(bool isScheduled)
  {
    m_isFirstProbeScheduled = isScheduled;
  }

private:
  std::unordered_map<FaceId, FaceInfo> m_fiMap;
  shared_ptr<const ndn::util::RttEstimator::Options> m_rttEstimatorOpts;
  time::milliseconds m_measurementLifetime;
  bool m_isProbingDue = false;
  bool m_isFirstProbeScheduled = false;
};

////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

/**
 * \brief Helper class to retrieve and create strategy measurements.
 */
class AsfMeasurements : noncopyable
{
public:
  explicit
  AsfMeasurements(MeasurementsAccessor& measurements);

  FaceInfo*
  getFaceInfo(const fib::Entry& fibEntry, const Name& interestName, FaceId faceId);

  FaceInfo&
  getOrCreateFaceInfo(const fib::Entry& fibEntry, const Name& interestName, FaceId faceId);

  NamespaceInfo*
  getNamespaceInfo(const Name& prefix);

  NamespaceInfo&
  getOrCreateNamespaceInfo(const fib::Entry& fibEntry, const Name& prefix);

  void
  setMeasurementsLifetime(time::milliseconds measurementsLifetime)
  {
    // Measurement lifetime should not expire as soon as it is configured
    BOOST_ASSERT(measurementsLifetime > 0_ms);
    m_measurementsLifetime = measurementsLifetime;
  }

  time::milliseconds
  getMeasurementsLifetime() const
  {
    return m_measurementsLifetime;
  }

private:
  void
  extendLifetime(measurements::Entry& me);

public:
  static constexpr time::milliseconds DEFAULT_MEASUREMENTS_LIFETIME = 5_min;

private:
  time::milliseconds m_measurementsLifetime = DEFAULT_MEASUREMENTS_LIFETIME;
  MeasurementsAccessor& m_measurements;
  shared_ptr<const ndn::util::RttEstimator::Options> m_rttEstimatorOpts;
};

} // namespace nfd::fw::asf

#endif // NFD_DAEMON_FW_ASF_MEASUREMENTS_HPP