/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014-2015,  Regents of the University of California.
 *
 * This file is part of ndn-tools (Named Data Networking Essential Tools).
 * See AUTHORS.md for complete list of ndn-tools authors and contributors.
 *
 * ndn-tools 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.
 *
 * ndn-tools 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
 * ndn-tools, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Yingdi Yu <yingdi@cs.ucla.edu>
 */

#include "key-cache.hpp"

namespace ndn {
namespace pib {

KeyCacheEntry::KeyCacheEntry(const Name& name, shared_ptr<PublicKey> key)
  : name(name)
  , key(key)
{
  BOOST_ASSERT(static_cast<bool>(key));
}

KeyCache::KeyCache(size_t capacity)
  : m_capacity(capacity)
{
}

void
KeyCache::insert(const Name& name, shared_ptr<PublicKey> key)
{
  // check if key exist
  KeyContainer::index<byName>::type::iterator it = m_keys.get<byName>().find(name);
  if (it != m_keys.get<byName>().end()) {
    adjustLru(it);
    return;
  }

  // evict key when capacity is reached
  if (size() >= m_capacity)
    evictKey();

  // insert entry
  m_keys.insert(KeyCacheEntry(name, key));
}

shared_ptr<PublicKey>
KeyCache::find(const Name& name) const
{
  // check if key exist
  KeyContainer::index<byName>::type::iterator it = m_keys.get<byName>().find(name);
  if (it == m_keys.get<byName>().end())
    return shared_ptr<PublicKey>();
  else {
    // adjust lru
    shared_ptr<PublicKey> key = it->key;
    adjustLru(it);
    return key;
  }
}

void
KeyCache::erase(const Name& name)
{
  // check if key exist
  KeyContainer::index<byName>::type::iterator it = m_keys.get<byName>().find(name);
  if (it != m_keys.get<byName>().end()) {
    m_keys.erase(it);
  }
}

size_t
KeyCache::size() const
{
  return m_keys.size();
}

void
KeyCache::evictKey()
{
  if (!m_keys.get<byUsedTime>().empty()) {
    KeyContainer::index<byUsedTime>::type::iterator it = m_keys.get<byUsedTime>().begin();
    m_keys.erase(m_keys.project<0>(it));
  }
}

void
KeyCache::adjustLru(KeyContainer::iterator it) const
{
  KeyCacheEntry entry = std::move(*it);
  m_keys.erase(it);
  m_keys.insert(entry);
}

} // namespace pib
} // namespace ndn