/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2014-2018, Regents of the University of California
 *
 * This file is part of NAC (Name-Based Access Control for NDN).
 * See AUTHORS.md for complete list of NAC authors and contributors.
 *
 * NAC 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.
 *
 * NAC 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
 * NAC, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Zhiyi Zhang <zhiyi@cs.ucla.edu>
 */

#include "schedule.hpp"
#include "tlv.hpp"

#include <ndn-cxx/encoding/block-helpers.hpp>
#include <ndn-cxx/util/concepts.hpp>

namespace ndn {
namespace nac {

/**
 * @brief Helper functon to calculate black interval results or white interval results
 * @p list The RepetitiveInterval list, which can be white list or the black list
 * @p tp The timestamp
 * @p positiveR The positive result
 * @p negativeR The negative result
 */
static void
calIntervalResult(const std::set<RepetitiveInterval>& list,
                  const TimeStamp& ts,
                  Interval& positiveR,
                  Interval& negativeR)
{
  Interval tempInterval;
  bool isPositive;

  for (const RepetitiveInterval& element : list) {
    std::tie(isPositive, tempInterval) = element.getInterval(ts);
    if (isPositive == true) {
      positiveR || tempInterval;
    }
    else {
      if (!negativeR.isValid())
        negativeR = tempInterval;
      else
        negativeR&& tempInterval;
    }
  }
}

BOOST_CONCEPT_ASSERT((WireEncodable<Schedule>));
BOOST_CONCEPT_ASSERT((WireDecodable<Schedule>));

Schedule::Schedule() = default;

Schedule::Schedule(const Block& block)
{
  wireDecode(block);
}

template<encoding::Tag TAG>
size_t
Schedule::wireEncode(EncodingImpl<TAG>& encoder) const
{
  size_t totalLength = 0;
  size_t blackLength = 0;
  size_t whiteLength = 0;

  // encode the blackIntervalList as an embed TLV structure
  for (auto it = m_blackIntervalList.rbegin(); it != m_blackIntervalList.rend(); it++) {
    blackLength += encoder.prependBlock(it->wireEncode());
  }
  blackLength += encoder.prependVarNumber(blackLength);
  blackLength += encoder.prependVarNumber(tlv::BlackIntervalList);

  // encode the whiteIntervalList as an embed TLV structure
  for (auto it = m_whiteIntervalList.rbegin(); it != m_whiteIntervalList.rend(); it++) {
    whiteLength += encoder.prependBlock(it->wireEncode());
  }
  whiteLength += encoder.prependVarNumber(whiteLength);
  whiteLength += encoder.prependVarNumber(tlv::WhiteIntervalList);

  totalLength = whiteLength + blackLength;
  totalLength += encoder.prependVarNumber(totalLength);
  totalLength += encoder.prependVarNumber(tlv::Schedule);

  return totalLength;
}

const Block&
Schedule::wireEncode() const
{
  if (m_wire.hasWire())
    return m_wire;

  EncodingEstimator estimator;
  size_t estimatedSize = wireEncode(estimator);

  EncodingBuffer buffer(estimatedSize, 0);
  wireEncode(buffer);

  this->m_wire = buffer.block();
  return m_wire;
}

void
Schedule::wireDecode(const Block& wire)
{
  if (wire.type() != tlv::Schedule)
    BOOST_THROW_EXCEPTION(tlv::Error("Unexpected TLV type when decoding RepetitiveInterval"));

  m_wire = wire;
  m_wire.parse();

  if (m_wire.elements_size() != 2)
    BOOST_THROW_EXCEPTION(tlv::Error("RepetitiveInterval tlv does not have two sub-TLVs"));

  Block::element_const_iterator it = m_wire.elements_begin();

  if (it != m_wire.elements_end() && it->type() == tlv::WhiteIntervalList) {
    it->parse();
    Block::element_const_iterator tempIt = it->elements_begin();
    while (tempIt != it->elements_end() && tempIt->type() == tlv::RepetitiveInterval) {
      m_whiteIntervalList.insert(RepetitiveInterval(*tempIt));
      tempIt++;
    }
    it++;
  }
  else
    BOOST_THROW_EXCEPTION(tlv::Error("The first element must be WhiteIntervalList"));

  if (it != m_wire.elements_end() && it->type() == tlv::BlackIntervalList) {
    it->parse();
    Block::element_const_iterator tempIt = it->elements_begin();
    while (tempIt != it->elements_end() && tempIt->type() == tlv::RepetitiveInterval) {
      m_blackIntervalList.insert(RepetitiveInterval(*tempIt));
      tempIt++;
    }
    it++;
  }
  else
    BOOST_THROW_EXCEPTION(tlv::Error("The second element must be BlackIntervalList"));
}

Schedule&
Schedule::addWhiteInterval(const RepetitiveInterval& repetitiveInterval)
{
  m_wire.reset();
  m_whiteIntervalList.insert(repetitiveInterval);
  return *this;
}

Schedule&
Schedule::addBlackInterval(const RepetitiveInterval& repetitiveInterval)
{
  m_wire.reset();
  m_blackIntervalList.insert(repetitiveInterval);
  return *this;
}

std::tuple<bool, Interval>
Schedule::getCoveringInterval(const TimeStamp& ts) const
{
  Interval blackPositiveResult(true);
  Interval whitePositiveResult(true);

  Interval blackNegativeResult;
  Interval whiteNegativeResult;

  // get the blackResult
  calIntervalResult(m_blackIntervalList, ts, blackPositiveResult, blackNegativeResult);

  // if black positive result is not empty, the result must be false
  if (!blackPositiveResult.isEmpty())
    return std::make_tuple(false, blackPositiveResult);

  // get the whiteResult
  calIntervalResult(m_whiteIntervalList, ts, whitePositiveResult, whiteNegativeResult);

  if (whitePositiveResult.isEmpty() && !whiteNegativeResult.isValid()) {
    // there is no white interval covering the timestamp
    // return false and a 24-hour interval
    return std::make_tuple(false,
                           Interval(TimeStamp(ts.date(), boost::posix_time::hours(0)),
                                    TimeStamp(ts.date(), boost::posix_time::hours(24))));
  }

  if (!whitePositiveResult.isEmpty()) {
    // there is white interval covering the timestamp
    // return ture and calculate the intersection
    if (blackNegativeResult.isValid())
      return std::make_tuple(true, whitePositiveResult && blackNegativeResult);
    else
      return std::make_tuple(true, whitePositiveResult);
  }
  else {
    // there is no white interval covering the timestamp
    // return false
    return std::make_tuple(false, whiteNegativeResult);
  }
}

} // namespace nac
} // namespace ndn