/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2012-2014 University of California, Los Angeles
 *
 * This file is part of ChronoSync, synchronization library for distributed realtime
 * applications for NDN.
 *
 * ChronoSync 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.
 *
 * ChronoSync 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
 * ChronoSync, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @author Zhenkai Zhu <http://irl.cs.ucla.edu/~zhenkai/>
 * @author Chaoyi Bian <bcy@pku.edu.cn>
 * @author Alexander Afanasyev <http://lasr.cs.ucla.edu/afanasyev/index.html>
 */

#ifndef SYNC_DIFF_STATE_H
#define SYNC_DIFF_STATE_H

#include "sync-state.h"
#include <iostream>

namespace Sync {

class DiffState;
typedef boost::shared_ptr<DiffState> DiffStatePtr;
typedef boost::shared_ptr<DiffState> DiffStateConstPtr;

/**
 * @ingroup ccnx
 * @brief Differential SYNC state
 */
class DiffState : public State
{
public:
  /**
   * @see Default constructor
   */
  DiffState ();
  virtual ~DiffState ();

  /**
   * @brief Set successor for the diff state
   * @param next successor state
   */
  void
  setNext (DiffStatePtr next)
  {
    m_next = next;
  }

  /**
   * @brief Set digest for the diff state (obtained from a corresponding full state)
   * @param digest A read only smart pointer to a digest object (that should be unmodified anywhere else)
   */
  void
  setDigest (DigestConstPtr digest) { m_digest = digest; }

  /**
   * @brief Get digest for the diff state
   */
  DigestConstPtr
  getDigest () const { return m_digest; }

  /**
   * @brief Accumulate differences from `this' state to the most current state
   * @returns Accumulated differences from `this' state to the most current state
   */
  DiffStatePtr
  diff () const;

  /**
   * @brief Combine differences from `this' and `state'
   * @param state Differential state to combine with
   * @return Combined differences
   *
   * In case of collisions, `this' leaf will be replaced with the leaf of `state'
   */
  DiffState&
  operator += (const DiffState &state);

  // from State
  virtual boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
  update (NameInfoConstPtr info, const SeqNo &seq);

  virtual bool
  remove (NameInfoConstPtr info);

private:
  DiffStatePtr m_next;
  DigestConstPtr m_digest;
};

} // Sync

#endif // SYNC_DIFF_STATE_H