/* -*- 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;
  };

public:
  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);

  NFD_VIRTUAL_WITH_TESTS
  ~FibUpdater() = default;

  /** \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 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,
                              const 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,
                                 const 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