/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014,  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 "measurements.hpp"
#include "name-tree.hpp"
#include "pit-entry.hpp"
#include "fib-entry.hpp"

namespace nfd {

Measurements::Measurements(NameTree& nameTree)
  : m_nameTree(nameTree)
  , m_nItems(0)
{
}

Measurements::~Measurements()
{
}

static inline bool
predicate_NameTreeEntry_hasMeasurementsEntry(const name_tree::Entry& entry)
{
  return static_cast<bool>(entry.getMeasurementsEntry());
}

shared_ptr<measurements::Entry>
Measurements::get(shared_ptr<name_tree::Entry> nameTreeEntry)
{
  shared_ptr<measurements::Entry> entry = nameTreeEntry->getMeasurementsEntry();
  if (static_cast<bool>(entry))
    return entry;

  entry = make_shared<measurements::Entry>(nameTreeEntry->getPrefix());
  nameTreeEntry->setMeasurementsEntry(entry);
  ++m_nItems;

  entry->m_expiry = time::steady_clock::now() + getInitialLifetime();
  entry->m_cleanup = scheduler::schedule(getInitialLifetime(),
                                         bind(&Measurements::cleanup, this, entry));

  return entry;
}

shared_ptr<measurements::Entry>
Measurements::get(const Name& name)
{
  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.lookup(name);
  return get(nameTreeEntry);
}

shared_ptr<measurements::Entry>
Measurements::get(const fib::Entry& fibEntry)
{
  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.get(fibEntry);

  BOOST_ASSERT(static_cast<bool>(nameTreeEntry));

  return get(nameTreeEntry);
}

shared_ptr<measurements::Entry>
Measurements::get(const pit::Entry& pitEntry)
{
  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.get(pitEntry);

  BOOST_ASSERT(static_cast<bool>(nameTreeEntry));

  return get(nameTreeEntry);
}

shared_ptr<measurements::Entry>
Measurements::getParent(shared_ptr<measurements::Entry> child)
{
  BOOST_ASSERT(child);

  if (child->getName().size() == 0) {
    return shared_ptr<measurements::Entry>();
  }

  shared_ptr<name_tree::Entry> nameTreeChild = m_nameTree.get(*child);
  shared_ptr<name_tree::Entry> nameTreeEntry = nameTreeChild->getParent();
  if (static_cast<bool>(nameTreeEntry)) {
    return this->get(nameTreeEntry);
  }
  else {
    BOOST_ASSERT(nameTreeChild->getPrefix().size() == 0); // root entry has no parent
    return shared_ptr<measurements::Entry>();
  }
}

shared_ptr<measurements::Entry>
Measurements::findLongestPrefixMatch(const Name& name) const
{
  shared_ptr<name_tree::Entry> nameTreeEntry =
    m_nameTree.findLongestPrefixMatch(name, &predicate_NameTreeEntry_hasMeasurementsEntry);
  if (static_cast<bool>(nameTreeEntry)) {
    return nameTreeEntry->getMeasurementsEntry();
  }
  return shared_ptr<measurements::Entry>();
}

shared_ptr<measurements::Entry>
Measurements::findExactMatch(const Name& name) const
{
  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.lookup(name);
  if (static_cast<bool>(nameTreeEntry))
    return nameTreeEntry->getMeasurementsEntry();
  return shared_ptr<measurements::Entry>();
}

void
Measurements::extendLifetime(shared_ptr<measurements::Entry> entry,
                             const time::nanoseconds& lifetime)
{
  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.get(*entry);
  if (!static_cast<bool>(nameTreeEntry) ||
      nameTreeEntry->getMeasurementsEntry().get() != entry.get()) {
    // entry is already gone; it is a dangling reference
    return;
  }

  time::steady_clock::TimePoint expiry = time::steady_clock::now() + lifetime;
  if (entry->m_expiry >= expiry) {
    // has longer lifetime, not extending
    return;
  }

  scheduler::cancel(entry->m_cleanup);
  entry->m_expiry = expiry;
  entry->m_cleanup = scheduler::schedule(lifetime, bind(&Measurements::cleanup, this, entry));
}

void
Measurements::cleanup(shared_ptr<measurements::Entry> entry)
{
  BOOST_ASSERT(static_cast<bool>(entry));

  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.get(*entry);
  if (static_cast<bool>(nameTreeEntry)) {
    nameTreeEntry->setMeasurementsEntry(shared_ptr<measurements::Entry>());
    m_nameTree.eraseEntryIfEmpty(nameTreeEntry);
    m_nItems--;
  }
}

} // namespace nfd