/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2022,  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_RIB_FIB_UPDATER_HPP
#define NFD_DAEMON_RIB_FIB_UPDATER_HPP

#include "core/common.hpp"
#include "fib-update.hpp"
#include "rib.hpp"
#include "rib-update-batch.hpp"

#include <ndn-cxx/mgmt/nfd/controller.hpp>

namespace nfd::rib {

/**
 * \brief Computes FibUpdates based on updates to the RIB and sends them to NFD.
 */
class FibUpdater : noncopyable
{
public:
  class Error : public std::runtime_error
  {
  public:
    using std::runtime_error::runtime_error;
  };

  using FibUpdateList = std::list<FibUpdate>;
  using FibUpdateSuccessCallback = std::function<void(RibUpdateList inheritedRoutes)>;
  using FibUpdateFailureCallback = std::function<void(uint32_t code, const std::string& error)>;

  FibUpdater(Rib& rib, ndn::nfd::Controller& controller);

#ifdef NFD_WITH_TESTS
  virtual
  ~FibUpdater() = default;
#endif

  /** \brief Computes FibUpdates using the provided RibUpdateBatch and then sends the
   *         updates to NFD's FIB.
   *
   *  \note  Caller must guarantee that the previous batch has either succeeded or failed
   *         before calling this method
   */
  void
  computeAndSendFibUpdates(const RibUpdateBatch& batch,
                           const FibUpdateSuccessCallback& onSuccess,
                           const FibUpdateFailureCallback& onFailure);

private:
  /**
   * \brief Determines the type of action that will be performed on the RIB and calls the
   *        corresponding computation method.
   */
  void
  computeUpdates(const RibUpdateBatch& batch);

  /**
   * \brief Sends the passed updates to NFD.
   *
   * onSuccess or onFailure will be called based on the results in
   * onUpdateSuccess or onUpdateFailure.
   *
   * \see FibUpdater::onUpdateSuccess
   * \see FibUpdater::onUpdateFailure
   */
  void
  sendUpdates(const FibUpdateList& updates,
              const FibUpdateSuccessCallback& onSuccess,
              const FibUpdateFailureCallback& onFailure);

  /**
   * \brief Sends the updates in m_updatesForBatchFaceId to NFD if any exist,
   *        otherwise calls FibUpdater::sendUpdatesForNonBatchFaceId.
   */
  void
  sendUpdatesForBatchFaceId(const FibUpdateSuccessCallback& onSuccess,
                            const FibUpdateFailureCallback& onFailure);

  /**
   * \brief Sends the updates in m_updatesForNonBatchFaceId to NFD if any exist,
   *        otherwise calls onSuccess.
   */
  void
  sendUpdatesForNonBatchFaceId(const FibUpdateSuccessCallback& onSuccess,
                               const FibUpdateFailureCallback& onFailure);

NFD_PROTECTED_WITH_TESTS_ELSE_PRIVATE:
  /**
   * \brief Sends a FibAddNextHopCommand to NFD using the parameters supplied by
   *        the passed update.
   * \param nTimeouts the number of times this FibUpdate has failed due to timeout
   */
  NFD_VIRTUAL_WITH_TESTS void
  sendAddNextHopUpdate(const FibUpdate& update,
                       const FibUpdateSuccessCallback& onSuccess,
                       const FibUpdateFailureCallback& onFailure,
                       uint32_t nTimeouts = 0);

  /**
   * \brief Sends a FibRemoveNextHopCommand to NFD using the parameters supplied by
   *        the passed update.
   * \param nTimeouts the number of times this FibUpdate has failed due to timeout
   */
  NFD_VIRTUAL_WITH_TESTS void
  sendRemoveNextHopUpdate(const FibUpdate& update,
                          const FibUpdateSuccessCallback& onSuccess,
                          const FibUpdateFailureCallback& onFailure,
                          uint32_t nTimeouts = 0);

private:
  /**
   * \brief Calculates the FibUpdates generated by a RIB registration.
   */
  void
  computeUpdatesForRegistration(const RibUpdate& update);

  /**
   * \brief Calculates the FibUpdates generated by a RIB unregistration.
   */
  void
  computeUpdatesForUnregistration(const RibUpdate& update);

NFD_PROTECTED_WITH_TESTS_ELSE_PRIVATE:
  /**
   * \brief Callback used by NfdController when a FibAddNextHopCommand or FibRemoveNextHopCommand
   *        is successful.
   *
   * If the update has the same Face ID as the batch being processed, the update is
   * removed from m_updatesForBatchFaceId. If m_updatesForBatchFaceId becomes empty,
   * the updates with a different Face ID than the batch are sent to NFD.
   *
   * If the update has a different Face ID than the batch being processed, the update is
   * removed from m_updatesForBatchNonFaceId. If m_updatesForBatchNonFaceId becomes empty,
   * the FIB update process is considered a success.
   */
  void
  onUpdateSuccess(const FibUpdate& update,
                  const FibUpdateSuccessCallback& onSuccess,
                  const FibUpdateFailureCallback& onFailure);

  /**
   * \brief Callback used by NfdController when a FibAddNextHopCommand or FibRemoveNextHopCommand
   *        is successful.
   *
   * If the update has not reached the max number of timeouts allowed, the update
   * is retried.
   *
   * If the update failed due to a non-existent face and the update has the same Face ID
   * as the update batch, the FIB update process fails.
   *
   * If the update failed due to a non-existent face and the update has a different
   * face than the update batch, the update is not retried and the error is
   * ignored.
   *
   * Otherwise, a non-recoverable error has occurred and an exception is thrown.
   */
  void
  onUpdateError(const FibUpdate& update,
                const FibUpdateSuccessCallback& onSuccess,
                const FibUpdateFailureCallback& onFailure,
                const ndn::nfd::ControlResponse& response, uint32_t nTimeouts);

private:
  /**
   * \brief Adds the update to an update list based on its Face ID.
   *
   * If the update has the same Face ID as the update batch, the update is added
   * to m_updatesForBatchFaceId.
   *
   * Otherwise, the update is added to m_updatesForBatchNonFaceId.
   */
  void
  addFibUpdate(const FibUpdate& update);

  /**
   * \brief Creates records of the passed routes added to the entry and creates FIB updates.
   */
  void
  addInheritedRoutes(const RibEntry& entry, const Rib::RouteSet& routesToAdd);

  /**
   * \brief Creates records of the passed routes added to the name and creates FIB updates.
   *        Routes in \p routesToAdd with the same Face ID as ignore will be not be considered.
   */
  void
  addInheritedRoutes(const Name& name, const Rib::RouteSet& routesToAdd, const Route& ignore);

  /**
   * \brief Creates records of the passed routes removed from the entry and creates FIB updates.
   */
  void
  removeInheritedRoutes(const RibEntry& entry, const Rib::RouteSet& routesToRemove);

  /**
   * \brief Calculates updates for a name that will create a new RIB entry.
   */
  void
  createFibUpdatesForNewRibEntry(const Name& name, const Route& route,
                                 const Rib::RibEntryList& children);

  /**
   * \brief Calculates updates for a new route added to a RIB entry.
   */
  void
  createFibUpdatesForNewRoute(const RibEntry& entry, const Route& route,
                              bool captureWasTurnedOn);

  /**
   * \brief Calculates updates for changes to an existing route for a RIB entry.
   */
  void
  createFibUpdatesForUpdatedRoute(const RibEntry& entry, const Route& route,
                                  const Route& existingRoute);

  /**
   * \brief Calculates updates for a an existing route removed from a RIB entry.
   */
  void
  createFibUpdatesForErasedRoute(const RibEntry& entry, const Route& route,
                                 bool captureWasTurnedOff);

  /**
   * \brief Calculates updates for an entry that will be removed from the RIB.
   */
  void
  createFibUpdatesForErasedRibEntry(const RibEntry& entry);

  /**
   * \brief Adds and removes passed routes to children's inherited routes.
   */
  void
  modifyChildrensInheritedRoutes(const Rib::RibEntryList& children,
                                 const Rib::RouteSet& routesToAdd,
                                 const Rib::RouteSet& routesToRemove);

  /**
   * \brief Traverses the entry's children adding and removing the passed routes.
   */
  void
  traverseSubTree(const RibEntry& entry, Rib::RouteSet routesToAdd, Rib::RouteSet routesToRemove);

  /**
   * \brief Creates a record of a calculated inherited route that should be added to the entry.
   */
  void
  addInheritedRoute(const Name& name, const Route& route);

  /**
   * \brief Creates a record of an existing inherited route that should be removed from the entry.
   */
  void
  removeInheritedRoute(const Name& name, const Route& route);

private:
  const Rib& m_rib;
  ndn::nfd::Controller& m_controller;
  uint64_t m_batchFaceId;

NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
  FibUpdateList m_updatesForBatchFaceId;
  FibUpdateList m_updatesForNonBatchFaceId;

  /**
   * \brief List of inherited routes generated during FIB update calculation;
   *        passed to the RIB when updates are completed successfully.
   */
  RibUpdateList m_inheritedRoutes;
};

} // namespace nfd::rib

#endif // NFD_DAEMON_RIB_FIB_UPDATER_HPP