/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2018,  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/>.
 */

#include "rib.hpp"
#include "fib-updater.hpp"
#include "core/logger.hpp"

namespace nfd {
namespace rib {

NFD_LOG_INIT(Rib);

bool
operator<(const RibRouteRef& lhs, const RibRouteRef& rhs)
{
  return std::tie(lhs.entry->getName(), lhs.route->faceId, lhs.route->origin) <
         std::tie(rhs.entry->getName(), rhs.route->faceId, rhs.route->origin);
}

static inline bool
sortRoutes(const Route& lhs, const Route& rhs)
{
  return lhs.faceId < rhs.faceId;
}

Rib::Rib()
  : m_nItems(0)
  , m_isUpdateInProgress(false)
{
}

Rib::~Rib() = default;

void
Rib::setFibUpdater(FibUpdater* updater)
{
  m_fibUpdater = updater;
}

Rib::const_iterator
Rib::find(const Name& prefix) const
{
  return m_rib.find(prefix);
}

Route*
Rib::find(const Name& prefix, const Route& route) const
{
  auto ribIt = m_rib.find(prefix);

  // Name prefix exists
  if (ribIt != m_rib.end()) {
    shared_ptr<RibEntry> entry = ribIt->second;
    auto routeIt = entry->findRoute(route);
    if (routeIt != entry->end()) {
      return &*routeIt;
    }
  }

  return nullptr;
}

void
Rib::insert(const Name& prefix, const Route& route)
{
  auto ribIt = m_rib.find(prefix);

  // Name prefix exists
  if (ribIt != m_rib.end()) {
    shared_ptr<RibEntry> entry(ribIt->second);

    RibEntry::iterator entryIt;
    bool didInsert = false;
    std::tie(entryIt, didInsert) = entry->insertRoute(route);

    if (didInsert) {
      // The route was new and we successfully inserted it.
      m_nItems++;

      afterAddRoute(RibRouteRef{entry, entryIt});

      // Register with face lookup table
      m_faceMap[route.faceId].push_back(entry);
    }
    else {
      // Route exists, update fields
      // First cancel old scheduled event, if any, then set the EventId to new one
      if (static_cast<bool>(entryIt->getExpirationEvent())) {
        NFD_LOG_TRACE("Cancelling expiration event for " << entry->getName() << " "
                                                         << (*entryIt));
        scheduler::cancel(entryIt->getExpirationEvent());
      }

      // No checks are required here as the iterator needs to be updated in all cases.
      entryIt->setExpirationEvent(route.getExpirationEvent());

      entryIt->flags = route.flags;
      entryIt->cost = route.cost;
      entryIt->expires = route.expires;
    }
  }
  else {
    // New name prefix
    auto entry = make_shared<RibEntry>();

    m_rib[prefix] = entry;
    m_nItems++;

    entry->setName(prefix);
    auto routeIt = entry->insertRoute(route).first;

    // Find prefix's parent
    shared_ptr<RibEntry> parent = findParent(prefix);

    // Add self to parent's children
    if (parent != nullptr) {
      parent->addChild(entry);
    }

    RibEntryList children = findDescendants(prefix);

    for (const auto& child : children) {
      if (child->getParent() == parent) {
        // Remove child from parent and inherit parent's child
        if (parent != nullptr) {
          parent->removeChild(child);
        }

        entry->addChild(child);
      }
    }

    // Register with face lookup table
    m_faceMap[route.faceId].push_back(entry);

    // do something after inserting an entry
    afterInsertEntry(prefix);
    afterAddRoute(RibRouteRef{entry, routeIt});
  }
}

void
Rib::erase(const Name& prefix, const Route& route)
{
  auto ribIt = m_rib.find(prefix);

  // Name prefix exists
  if (ribIt != m_rib.end()) {
    shared_ptr<RibEntry> entry = ribIt->second;
    auto routeIt = entry->findRoute(route);

    if (routeIt != entry->end()) {
      beforeRemoveRoute(RibRouteRef{entry, routeIt});

      auto faceId = route.faceId;
      entry->eraseRoute(routeIt);
      m_nItems--;

      // If this RibEntry no longer has this faceId, unregister from face lookup table
      if (!entry->hasFaceId(faceId)) {
        m_faceMap[faceId].remove(entry);
      }

      // If a RibEntry's route list is empty, remove it from the tree
      if (entry->getRoutes().empty()) {
        eraseEntry(ribIt);
      }
    }
  }
}

void
Rib::onRouteExpiration(const Name& prefix, const Route& route)
{
  NFD_LOG_DEBUG(route << " for " << prefix << " has expired");

  RibUpdate update;
  update.setAction(RibUpdate::UNREGISTER)
        .setName(prefix)
        .setRoute(route);

  beginApplyUpdate(update, nullptr, nullptr);
}

shared_ptr<RibEntry>
Rib::findParent(const Name& prefix) const
{
  for (int i = prefix.size() - 1; i >= 0; i--) {
    auto it = m_rib.find(prefix.getPrefix(i));
    if (it != m_rib.end()) {
      return it->second;
    }
  }

  return nullptr;
}

std::list<shared_ptr<RibEntry>>
Rib::findDescendants(const Name& prefix) const
{
  std::list<shared_ptr<RibEntry>> children;

  RibTable::const_iterator it = m_rib.find(prefix);
  if (it != m_rib.end()) {
    ++it;
    for (; it != m_rib.end(); ++it) {
      if (prefix.isPrefixOf(it->first)) {
        children.push_back((it->second));
      }
      else {
        break;
      }
    }
  }

  return children;
}

std::list<shared_ptr<RibEntry>>
Rib::findDescendantsForNonInsertedName(const Name& prefix) const
{
  std::list<shared_ptr<RibEntry>> children;

  for (const auto& pair : m_rib) {
    if (prefix.isPrefixOf(pair.first)) {
      children.push_back(pair.second);
    }
  }

  return children;
}

Rib::RibTable::iterator
Rib::eraseEntry(RibTable::iterator it)
{
  // Entry does not exist
  if (it == m_rib.end()) {
    return m_rib.end();
  }

  shared_ptr<RibEntry> entry(it->second);

  shared_ptr<RibEntry> parent = entry->getParent();

  // Remove self from parent's children
  if (parent != nullptr) {
    parent->removeChild(entry);
  }

  for (auto childIt = entry->getChildren().begin(); childIt != entry->getChildren().end(); ) {
    shared_ptr<RibEntry> child = *childIt;

    // Advance iterator so it is not invalidated by removal
    ++childIt;

    // Remove children from self
    entry->removeChild(child);

    // Update parent's children
    if (parent != nullptr) {
      parent->addChild(child);
    }
  }

  auto nextIt = m_rib.erase(it);

  // do something after erasing an entry.
  afterEraseEntry(entry->getName());

  return nextIt;
}

Rib::RouteSet
Rib::getAncestorRoutes(const RibEntry& entry) const
{
  RouteSet ancestorRoutes(&sortRoutes);

  shared_ptr<RibEntry> parent = entry.getParent();

  while (parent != nullptr) {
    for (const Route& route : parent->getRoutes()) {
      if (route.isChildInherit()) {
        ancestorRoutes.insert(route);
      }
    }

    if (parent->hasCapture()) {
      break;
    }

    parent = parent->getParent();
  }

  return ancestorRoutes;
}

Rib::RouteSet
Rib::getAncestorRoutes(const Name& name) const
{
  RouteSet ancestorRoutes(&sortRoutes);

  shared_ptr<RibEntry> parent = findParent(name);

  while (parent != nullptr) {
    for (const Route& route : parent->getRoutes()) {
      if (route.isChildInherit()) {
        ancestorRoutes.insert(route);
      }
    }

    if (parent->hasCapture()) {
      break;
    }

    parent = parent->getParent();
  }

  return ancestorRoutes;
}

void
Rib::beginApplyUpdate(const RibUpdate& update,
                      const Rib::UpdateSuccessCallback& onSuccess,
                      const Rib::UpdateFailureCallback& onFailure)
{
  BOOST_ASSERT(m_fibUpdater != nullptr);

  addUpdateToQueue(update, onSuccess, onFailure);

  sendBatchFromQueue();
}

void
Rib::beginRemoveFace(uint64_t faceId)
{
  for (const auto& nameAndRoute : findRoutesWithFaceId(faceId)) {
    RibUpdate update;
    update.setAction(RibUpdate::REMOVE_FACE)
          .setName(nameAndRoute.first)
          .setRoute(nameAndRoute.second);

    addUpdateToQueue(update, nullptr, nullptr);
  }

  sendBatchFromQueue();
}

void
Rib::addUpdateToQueue(const RibUpdate& update,
                      const Rib::UpdateSuccessCallback& onSuccess,
                      const Rib::UpdateFailureCallback& onFailure)
{
  RibUpdateBatch batch(update.getRoute().faceId);
  batch.add(update);

  UpdateQueueItem item{batch, onSuccess, onFailure};
  m_updateBatches.push_back(std::move(item));
}

void
Rib::sendBatchFromQueue()
{
  if (m_updateBatches.empty() || m_isUpdateInProgress) {
    return;
  }

  m_isUpdateInProgress = true;

  UpdateQueueItem item = std::move(m_updateBatches.front());
  m_updateBatches.pop_front();

  RibUpdateBatch& batch = item.batch;

  // Until task #1698, each RibUpdateBatch contains exactly one RIB update
  BOOST_ASSERT(batch.size() == 1);

  const Rib::UpdateSuccessCallback& managerSuccessCallback = item.managerSuccessCallback;
  const Rib::UpdateFailureCallback& managerFailureCallback = item.managerFailureCallback;

  m_fibUpdater->computeAndSendFibUpdates(batch,
                                         bind(&Rib::onFibUpdateSuccess, this,
                                              batch, _1, managerSuccessCallback),
                                         bind(&Rib::onFibUpdateFailure, this,
                                              managerFailureCallback, _1, _2));

  if (m_onSendBatchFromQueue != nullptr) {
    m_onSendBatchFromQueue(batch);
  }
}

void
Rib::onFibUpdateSuccess(const RibUpdateBatch& batch,
                        const RibUpdateList& inheritedRoutes,
                        const Rib::UpdateSuccessCallback& onSuccess)
{
  for (const RibUpdate& update : batch) {
    switch (update.getAction()) {
    case RibUpdate::REGISTER:
      insert(update.getName(), update.getRoute());
      break;
    case RibUpdate::UNREGISTER:
    case RibUpdate::REMOVE_FACE:
      erase(update.getName(), update.getRoute());
      break;
    }
  }

  // Add and remove precalculated inherited routes to RibEntries
  modifyInheritedRoutes(inheritedRoutes);

  m_isUpdateInProgress = false;

  if (onSuccess != nullptr) {
    onSuccess();
  }

  // Try to advance the batch queue
  sendBatchFromQueue();
}

void
Rib::onFibUpdateFailure(const Rib::UpdateFailureCallback& onFailure,
                        uint32_t code, const std::string& error)
{
  m_isUpdateInProgress = false;

  if (onFailure != nullptr) {
    onFailure(code, error);
  }

  // Try to advance the batch queue
  sendBatchFromQueue();
}

void
Rib::modifyInheritedRoutes(const RibUpdateList& inheritedRoutes)
{
  for (const RibUpdate& update : inheritedRoutes) {
    auto ribIt = m_rib.find(update.getName());
    BOOST_ASSERT(ribIt != m_rib.end());
    shared_ptr<RibEntry> entry(ribIt->second);

    switch (update.getAction()) {
    case RibUpdate::REGISTER:
      entry->addInheritedRoute(update.getRoute());
      break;
    case RibUpdate::UNREGISTER:
      entry->removeInheritedRoute(update.getRoute());
      break;
    case RibUpdate::REMOVE_FACE:
      break;
    }
  }
}

std::list<Rib::NameAndRoute>
Rib::findRoutesWithFaceId(uint64_t faceId)
{
  std::list<NameAndRoute> routes;

  auto lookupIt = m_faceMap.find(faceId);
  if (lookupIt == m_faceMap.end()) {
    // No RIB entries have this face
    return routes;
  }

  // For each RIB entry that has faceId
  for (const auto& entry : lookupIt->second) {
    // Find the routes in the entry
    for (const Route& route : *entry) {
      if (route.faceId == faceId) {
        routes.emplace_back(entry->getName(), route);
      }
    }
  }

  return routes;
}

std::ostream&
operator<<(std::ostream& os, const Rib& rib)
{
  for (const auto& item : rib) {
    os << *item.second << "\n";
  }

  return os;
}

} // namespace rib
} // namespace nfd