/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014-2017,  The University of Memphis,
 *                           Regents of the University of California,
 *                           Arizona Board of Regents.
 *
 * This file is part of NLSR (Named-data Link State Routing).
 * See AUTHORS.md for complete list of NLSR authors and contributors.
 *
 * NLSR 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.
 *
 * NLSR 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
 * NLSR, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 **/

#include <cstdlib>
#include <string>
#include <sstream>
#include <cstdio>
#include <unistd.h>

#include "nlsr.hpp"
#include "adjacent.hpp"
#include "logger.hpp"

#include <ndn-cxx/util/face-uri.hpp>

namespace nlsr {

INIT_LOGGER("nlsr");

const ndn::Name Nlsr::LOCALHOST_PREFIX = ndn::Name("/localhost/nlsr");

using namespace ndn;
using namespace std;

Nlsr::Nlsr(boost::asio::io_service& ioService, ndn::Scheduler& scheduler, ndn::Face& face, ndn::KeyChain& keyChain)
  : m_nlsrFace(face)
  , m_scheduler(scheduler)
  , m_keyChain(keyChain)
  , m_confParam()
  , m_adjacencyList()
  , m_namePrefixList()
  , m_isDaemonProcess(false)
  , m_configFileName("nlsr.conf")
  , m_nlsrLsdb(*this, scheduler)
  , m_adjBuildCount(0)
  , m_isBuildAdjLsaSheduled(false)
  , m_isRouteCalculationScheduled(false)
  , m_isRoutingTableCalculating(false)
  , m_routingTable(scheduler)
  , m_fib(m_nlsrFace, scheduler, m_adjacencyList, m_confParam, m_keyChain)
  , m_namePrefixTable(*this)
  , m_localhostDispatcher(m_nlsrFace, m_keyChain)
  , m_routerNameDispatcher(m_nlsrFace, m_keyChain)
  , m_lsdbDatasetHandler(m_nlsrLsdb,
                         m_localhostDispatcher,
                         m_routerNameDispatcher,
                         m_nlsrFace,
                         m_keyChain)

  , m_helloProtocol(*this, scheduler)
  , m_certificateCache(new ndn::CertificateCacheTtl(ioService))
  , m_validator(m_nlsrFace, DEFAULT_BROADCAST_PREFIX, m_certificateCache, m_certStore)
  , m_controller(m_nlsrFace, m_keyChain, m_validator)
  , m_faceDatasetController(m_nlsrFace, m_keyChain)
  , m_prefixUpdateProcessor(m_nlsrFace,
                            m_namePrefixList,
                            m_nlsrLsdb,
                            DEFAULT_BROADCAST_PREFIX,
                            m_keyChain,
                            m_certificateCache,
                            m_certStore)
  , m_nfdRibCommandProcessor(m_localhostDispatcher,
                             m_namePrefixList,
                             m_nlsrLsdb)
  , m_faceMonitor(m_nlsrFace)
  , m_firstHelloInterval(FIRST_HELLO_INTERVAL_DEFAULT)
{
  m_faceMonitor.onNotification.connect(std::bind(&Nlsr::onFaceEventNotification, this, _1));
  m_faceMonitor.start();
}

void
Nlsr::registrationFailed(const ndn::Name& name)
{
  std::cerr << "ERROR: Failed to register prefix in local hub's daemon" << std::endl;
  BOOST_THROW_EXCEPTION(Error("Error: Prefix registration failed"));
}

void
Nlsr::onRegistrationSuccess(const ndn::Name& name)
{
  _LOG_DEBUG("Successfully registered prefix: " << name);

  if (name.equals(m_confParam.getRouterPrefix())) {
    // the top-level prefixes are added.
    try {
      m_routerNameDispatcher.addTopPrefix(m_confParam.getRouterPrefix(), false, m_signingInfo);
    }
    catch (const std::exception& e) {
      _LOG_ERROR("Error setting top-level prefix in dispatcher: " << e.what() << "\n");
    }
  }
}

void
Nlsr::onLocalhostRegistrationSuccess(const ndn::Name& name)
{
  _LOG_DEBUG("Successfully registered local prefix: " << name);

  m_prefixUpdateProcessor.startListening();
  m_nfdRibCommandProcessor.startListening();
  // All dispatcher-related sub-prefixes *must* be registered before
  // the top-level prefixes are added.
  try {
    m_localhostDispatcher.addTopPrefix(LOCALHOST_PREFIX, false, m_signingInfo);
  }
  catch (const std::exception& e) {
    _LOG_ERROR("Error setting top-level prefix in dispatcher: " << e.what() << "\n");
  }
}

void
Nlsr::setInfoInterestFilter()
{
  ndn::Name name(m_confParam.getRouterPrefix());
  _LOG_DEBUG("Setting interest filter for name: " << name);
  getNlsrFace().setInterestFilter(name,
                                  std::bind(&HelloProtocol::processInterest,
                                            &m_helloProtocol, _1, _2),
                                  std::bind(&Nlsr::onRegistrationSuccess, this, _1),
                                  std::bind(&Nlsr::registrationFailed, this, _1),
                                  m_signingInfo,
                                  ndn::nfd::ROUTE_FLAG_CAPTURE);
}

void
Nlsr::setLsaInterestFilter()
{
  ndn::Name name = m_confParam.getLsaPrefix();
  name.append(m_confParam.getSiteName());
  name.append(m_confParam.getRouterName());
  _LOG_DEBUG("Setting interest filter for LsaPrefix: " << name);
  getNlsrFace().setInterestFilter(name,
                                  std::bind(&Lsdb::processInterest,
                                            &m_nlsrLsdb, _1, _2),
                                  std::bind(&Nlsr::onRegistrationSuccess, this, _1),
                                  std::bind(&Nlsr::registrationFailed, this, _1),
                                  m_signingInfo,
                                  ndn::nfd::ROUTE_FLAG_CAPTURE);
}

void
Nlsr::setStrategies()
{
  const std::string strategy("ndn:/localhost/nfd/strategy/multicast");

  ndn::Name broadcastKeyPrefix = DEFAULT_BROADCAST_PREFIX;
  broadcastKeyPrefix.append("KEYS");

  m_fib.setStrategy(m_confParam.getLsaPrefix(), strategy, 0);
  m_fib.setStrategy(broadcastKeyPrefix, strategy, 0);
  m_fib.setStrategy(m_confParam.getChronosyncPrefix(), strategy, 0);
}

void
Nlsr::daemonize()
{
  pid_t process_id = 0;
  pid_t sid = 0;
  process_id = fork();
  if (process_id < 0){
    std::cerr << "Daemonization failed!" << std::endl;
    BOOST_THROW_EXCEPTION(Error("Error: Daemonization process- fork failed!"));
  }
  if (process_id > 0) {
    _LOG_DEBUG("Process daemonized. Process id: " << process_id);
    exit(0);
  }

  umask(0);
  sid = setsid();
  if(sid < 0) {
    BOOST_THROW_EXCEPTION(Error("Error: Daemonization process- setting id failed!"));
  }

  if (chdir("/") < 0) {
    BOOST_THROW_EXCEPTION(Error("Error: Daemonization process-chdir failed!"));
  }
}

void
Nlsr::canonizeContinuation(std::list<Adjacent>::iterator iterator)
{
  canonizeNeighborUris(iterator, [this] (std::list<Adjacent>::iterator iterator) {
      canonizeContinuation(iterator);
  });
}

void
Nlsr::canonizeNeighborUris(std::list<Adjacent>::iterator currentNeighbor,
                           std::function<void(std::list<Adjacent>::iterator)> then)
{
  if (currentNeighbor != m_adjacencyList.getAdjList().end()) {
    ndn::util::FaceUri uri(currentNeighbor->getFaceUri());
    uri.canonize([this, then, currentNeighbor] (ndn::util::FaceUri canonicalUri) {
        _LOG_DEBUG("Canonized URI: " << currentNeighbor->getFaceUri()
                   << " to: " << canonicalUri);
        currentNeighbor->setFaceUri(canonicalUri);
        then(std::next(currentNeighbor));
      },
      [this, then, currentNeighbor] (const std::string& reason) {
        _LOG_ERROR("Could not canonize URI: " << currentNeighbor->getFaceUri()
                   << " because: " << reason);
        then(std::next(currentNeighbor));
      },
      m_nlsrFace.getIoService(),
      TIME_ALLOWED_FOR_CANONIZATION);
  }
  // We have finished canonizing all neighbors, so initialize NLSR.
  else {
    initialize();
  }
}

void
Nlsr::initialize()
{
  _LOG_DEBUG("Initializing Nlsr");
  m_confParam.buildRouterPrefix();
  m_lsdbDatasetHandler.setRouterNameCommandPrefix(m_confParam.getRouterPrefix());
  m_nlsrLsdb.setLsaRefreshTime(ndn::time::seconds(m_confParam.getLsaRefreshTime()));
  m_nlsrLsdb.setThisRouterPrefix(m_confParam.getRouterPrefix().toUri());
  m_fib.setEntryRefreshTime(2 * m_confParam.getLsaRefreshTime());

  m_nlsrLsdb.getSequencingManager().setSeqFileDirectory(m_confParam.getSeqFileDir());
  m_nlsrLsdb.getSequencingManager().initiateSeqNoFromFile(m_confParam.getHyperbolicState());

  m_nlsrLsdb.getSyncLogicHandler().createSyncSocket(m_confParam.getChronosyncPrefix());

  // Logging start
  m_confParam.writeLog();
  m_adjacencyList.writeLog();
  _LOG_DEBUG(m_namePrefixList);
  // Logging end
  initializeKey();
  setStrategies();
  _LOG_DEBUG("Default NLSR identity: " << m_signingInfo.getSignerName());
  setInfoInterestFilter();
  setLsaInterestFilter();

  initializeFaces(std::bind(&Nlsr::processFaceDataset, this, _1),
                  std::bind(&Nlsr::onFaceDatasetFetchTimeout, this, _1, _2, 0));

  // Set event intervals
  setFirstHelloInterval(m_confParam.getFirstHelloInterval());
  m_nlsrLsdb.setAdjLsaBuildInterval(m_confParam.getAdjLsaBuildInterval());
  m_routingTable.setRoutingCalcInterval(m_confParam.getRoutingCalcInterval());

  m_nlsrLsdb.buildAndInstallOwnNameLsa();

  // Install coordinate LSAs if using HR or dry-run HR.
  if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
    m_nlsrLsdb.buildAndInstallOwnCoordinateLsa();
  }

  registerKeyPrefix();
  registerLocalhostPrefix();

  m_helloProtocol.scheduleInterest(m_firstHelloInterval);

  // Need to set direct neighbors' costs to 0 for hyperbolic routing
  if (m_confParam.getHyperbolicState() == HYPERBOLIC_STATE_ON) {

    std::list<Adjacent>& neighbors = m_adjacencyList.getAdjList();

    for (std::list<Adjacent>::iterator it = neighbors.begin(); it != neighbors.end(); ++it) {
      it->setLinkCost(0);
    }
  }
}

void
Nlsr::initializeKey()
{
  ndn::Name defaultIdentity = m_confParam.getRouterPrefix();
  defaultIdentity.append("NLSR");

  try {
    m_keyChain.deleteIdentity(defaultIdentity);
  }
  catch (const std::exception& e) {
  }
  m_signingInfo = ndn::security::SigningInfo(ndn::security::SigningInfo::SIGNER_TYPE_ID, defaultIdentity);

  ndn::Name keyName = m_keyChain.generateRsaKeyPairAsDefault(defaultIdentity, true);

  std::shared_ptr<ndn::IdentityCertificate> certificate =
    std::make_shared<ndn::IdentityCertificate>();
  std::shared_ptr<ndn::PublicKey> pubKey = m_keyChain.getPublicKey(keyName);
  Name certificateName = keyName.getPrefix(-1);
  certificateName.append("KEY").append(keyName.get(-1)).append("ID-CERT").appendVersion();
  certificate->setName(certificateName);
  certificate->setNotBefore(time::system_clock::now() - time::days(1));
  certificate->setNotAfter(time::system_clock::now() + time::days(7300)); // ~20 years
  certificate->setPublicKeyInfo(*pubKey);
  certificate->addSubjectDescription(CertificateSubjectDescription(ndn::oid::ATTRIBUTE_NAME,
                                                                   keyName.toUri()));
  certificate->encode();
  m_keyChain.signByIdentity(*certificate, m_confParam.getRouterPrefix());

  m_keyChain.addCertificateAsIdentityDefault(*certificate);
  loadCertToPublish(certificate);

  m_defaultCertName = certificate->getName();
}

void
Nlsr::registerKeyPrefix()
{
  ndn::Name keyPrefix = DEFAULT_BROADCAST_PREFIX;
  keyPrefix.append("KEYS");
  m_nlsrFace.setInterestFilter(keyPrefix,
                               std::bind(&Nlsr::onKeyInterest,
                                         this, _1, _2),
                               std::bind(&Nlsr::onKeyPrefixRegSuccess, this, _1),
                               std::bind(&Nlsr::registrationFailed, this, _1),
                               m_signingInfo,
                               ndn::nfd::ROUTE_FLAG_CAPTURE);

}

void
Nlsr::registerLocalhostPrefix()
{
  m_nlsrFace.registerPrefix(LOCALHOST_PREFIX,
                            std::bind(&Nlsr::onLocalhostRegistrationSuccess, this, _1),
                            std::bind(&Nlsr::registrationFailed, this, _1));
}

void
Nlsr::onKeyInterest(const ndn::Name& name, const ndn::Interest& interest)
{
  const ndn::Name& interestName = interest.getName();
  ndn::Name certName = interestName.getSubName(name.size());

  if (certName[-2].toUri() == "ID-CERT")
    {
      certName = certName.getPrefix(-1);
    }
  else if (certName[-1].toUri() != "ID-CERT")
    {
      _LOG_DEBUG("certName for interest " << interest << " is malformed,"
                 << " contains incorrect namespace syntax");
      return;
    }

  std::shared_ptr<const ndn::IdentityCertificate> cert = getCertificate(certName);

  if (!static_cast<bool>(cert))
    {
      _LOG_DEBUG("cert is not found for " << interest);
      return; // cert is not found
    }

  std::shared_ptr<ndn::Data> data = std::make_shared<ndn::Data>();
  data->setName(interestName);
  data->setContent(cert->wireEncode());
  m_keyChain.signWithSha256(*data);

  m_nlsrFace.put(*data);
}

void
Nlsr::onKeyPrefixRegSuccess(const ndn::Name& name)
{
}

void
Nlsr::onFaceEventNotification(const ndn::nfd::FaceEventNotification& faceEventNotification)
{
  _LOG_TRACE("Nlsr::onFaceEventNotification called");

  switch (faceEventNotification.getKind()) {
    case ndn::nfd::FACE_EVENT_DESTROYED: {
      uint64_t faceId = faceEventNotification.getFaceId();

      auto adjacent = m_adjacencyList.findAdjacent(faceId);

      if (adjacent != m_adjacencyList.end()) {
        _LOG_DEBUG("Face to " << adjacent->getName() << " with face id: " << faceId << " destroyed");

        adjacent->setFaceId(0);

        // Only trigger an Adjacency LSA build if this node is changing
        // from ACTIVE to INACTIVE since this rebuild will effectively
        // cancel the previous Adjacency LSA refresh event and schedule
        // a new one further in the future.
        //
        // Continuously scheduling the refresh in the future will block
        // the router from refreshing its Adjacency LSA. Since other
        // routers' Name prefixes' expiration times are updated when
        // this router refreshes its Adjacency LSA, the other routers'
        // prefixes will expire and be removed from the RIB.
        //
        // This check is required to fix Bug #2733 for now. This check
        // would be unnecessary to fix Bug #2733 when Issue #2732 is
        // completed, but the check also helps with optimization so it
        // can remain even when Issue #2732 is implemented.
        if (adjacent->getStatus() == Adjacent::STATUS_ACTIVE) {
          adjacent->setStatus(Adjacent::STATUS_INACTIVE);

          // A new adjacency LSA cannot be built until the neighbor is marked INACTIVE and
          // has met the HELLO retry threshold
          adjacent->setInterestTimedOutNo(m_confParam.getInterestRetryNumber());

          if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
            getRoutingTable().scheduleRoutingTableCalculation(*this);
          }
          else {
            m_nlsrLsdb.scheduleAdjLsaBuild();
          }
        }
      }
      break;
    }
    case ndn::nfd::FACE_EVENT_CREATED: {
      // Find the neighbor in our adjacency list
      _LOG_DEBUG("Face created event received.");
      auto adjacent = m_adjacencyList.findAdjacent(
        ndn::util::FaceUri(faceEventNotification.getRemoteUri()));
      // If we have a neighbor by that FaceUri and it has no FaceId, we
      // have a match.
      if (adjacent != m_adjacencyList.end()) {
        _LOG_DEBUG("Face creation event matches neighbor: " << adjacent->getName()
                   << ". New Face ID: " << faceEventNotification.getFaceId()
                   << ". Registering prefixes.");
        adjacent->setFaceId(faceEventNotification.getFaceId());

        registerAdjacencyPrefixes(*adjacent, ndn::time::milliseconds::max());
      }
      break;
    }
    default:
      break;
  }
}

void
Nlsr::initializeFaces(const FetchDatasetCallback& onFetchSuccess,
                      const FetchDatasetTimeoutCallback& onFetchFailure)
{
  _LOG_TRACE("Initializing Faces...");

  m_faceDatasetController.fetch<ndn::nfd::FaceDataset>(onFetchSuccess, onFetchFailure);

}

void
Nlsr::processFaceDataset(const std::vector<ndn::nfd::FaceStatus>& faces)
{
  // Iterate over each neighbor listed in nlsr.conf
  bool anyFaceChanged = false;
  for (auto&& adjacency : m_adjacencyList.getAdjList()) {

    const std::string faceUriString = adjacency.getFaceUri().toString();
    // Check the list of FaceStatus objects we got for a match
    for (const ndn::nfd::FaceStatus& faceStatus : faces) {

      // Set the adjacency FaceID if we find a URI match and it was
      // previously unset. Change the boolean to true.
      if (adjacency.getFaceId() == 0 && faceUriString == faceStatus.getRemoteUri()) {
        adjacency.setFaceId(faceStatus.getFaceId());
        anyFaceChanged = true;
        // Register the prefixes for each neighbor
        this->registerAdjacencyPrefixes(adjacency, ndn::time::milliseconds::max());
      }
    }
    // If this adjacency has no information in this dataset, then one
    // of two things is happening: 1. NFD is starting slowly and this
    // Face wasn't ready yet, or 2. NFD is configured
    // incorrectly and this Face isn't available.
    if (adjacency.getFaceId() == 0) {
      _LOG_WARN("The adjacency " << adjacency.getName() <<
                " has no Face information in this dataset.");
    }
  }

  if (anyFaceChanged) {
    // Only do these things if something has changed.  Schedule an
    // adjacency LSA build to update with all of the new neighbors if
    // HR is off.
    if (m_confParam.getHyperbolicState() != HYPERBOLIC_STATE_OFF) {
      getRoutingTable().scheduleRoutingTableCalculation(*this);
    }
    else {
      m_nlsrLsdb.scheduleAdjLsaBuild();
    }

    // Begin the Hello Protocol loop immediately, so we don't wait.
    m_helloProtocol.sendScheduledInterest(0);
  }

  scheduleDatasetFetch();
}

void
Nlsr::registerAdjacencyPrefixes(const Adjacent& adj,
                                const ndn::time::milliseconds& timeout)
{
    std::string faceUri = adj.getFaceUri().toString();
    double linkCost = adj.getLinkCost();

    m_fib.registerPrefix(adj.getName(), faceUri, linkCost,
                         timeout, ndn::nfd::ROUTE_FLAG_CAPTURE, 0);

    m_fib.registerPrefix(m_confParam.getChronosyncPrefix(),
                                 faceUri, linkCost, timeout,
                                 ndn::nfd::ROUTE_FLAG_CAPTURE, 0);

    m_fib.registerPrefix(m_confParam.getLsaPrefix(),
                                 faceUri, linkCost, timeout,
                                 ndn::nfd::ROUTE_FLAG_CAPTURE, 0);

    ndn::Name broadcastKeyPrefix = DEFAULT_BROADCAST_PREFIX;
    broadcastKeyPrefix.append("KEYS");
    m_fib.registerPrefix(broadcastKeyPrefix,
                                 faceUri, linkCost, timeout,
                                 ndn::nfd::ROUTE_FLAG_CAPTURE, 0);
}

void
Nlsr::onFaceDatasetFetchTimeout(uint32_t code,
                                const std::string& msg,
                                uint32_t nRetriesSoFar)
{
  // If we have exceeded the maximum attempt count, do not try again.
  if (nRetriesSoFar++ < m_confParam.getFaceDatasetFetchTries()) {
    _LOG_DEBUG("Failed to fetch dataset: " << msg << ". Attempting retry #" << nRetriesSoFar);
    m_faceDatasetController.fetch<ndn::nfd::FaceDataset>(std::bind(&Nlsr::processFaceDataset,
                                                        this, _1),
                                              std::bind(&Nlsr::onFaceDatasetFetchTimeout,
                                                        this, _1, _2, nRetriesSoFar));
  }
  else {
    _LOG_ERROR("Failed to fetch dataset: " << msg << ". Exceeded limit of " <<
               m_confParam.getFaceDatasetFetchTries() << ", so not trying again this time.");
    // If we fail to fetch it, just do nothing until the next
    // interval.  Since this is a backup mechanism, we aren't as
    // concerned with retrying.
    scheduleDatasetFetch();
  }
}

void
Nlsr::scheduleDatasetFetch()
{
  m_scheduler.scheduleEvent(m_confParam.getFaceDatasetFetchInterval(),
    [this] {
      this->initializeFaces(
        [this] (const std::vector<ndn::nfd::FaceStatus>& faces) {
         this->processFaceDataset(faces);
        },
        [this] (uint32_t code, const std::string& msg) {
         this->onFaceDatasetFetchTimeout(code, msg, 0);
        });
  });
}

void
Nlsr::startEventLoop()
{
  m_nlsrFace.processEvents();
}

} // namespace nlsr