/* -*- 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_STATE_H
#define SYNC_STATE_H

#include "sync-state-leaf-container.h"
#include <boost/exception/all.hpp>
#include "boost/tuple/tuple.hpp"
#include "sync-state.pb.h"

/**
 * \defgroup sync SYNC protocol
 *
 * Implementation of SYNC protocol
 */
namespace Sync {

/**
 * \ingroup sync
 * @brief this prefix will be used for the dummy node which increases its sequence number whenever
 * a remove operation happens; this is to prevent the reversion of root digest when we prune
 * a branch, i.e. help the root digest to be forward only
 * No corresponding data msg would be published and no attempt would be made to retrieve the
 * data msg
 */
const std::string forwarderPrefix = "/d0n0t18ak/t0ps8cr8t";

class State;
typedef boost::shared_ptr<State> StatePtr;
typedef boost::shared_ptr<State> StateConstPtr;

/**
 * \ingroup sync
 * @brief Container for state leaves and definition of the abstract interface to work with State objects
 */
class State
{
public:
  virtual ~State () { };

  /**
   * @brief Add or update leaf to the state tree
   *
   * @param info name of the leaf
   * @param seq  sequence number of the leaf
   */
  virtual boost::tuple<bool/*inserted*/, bool/*updated*/, SeqNo/*oldSeqNo*/>
  update (NameInfoConstPtr info, const SeqNo &seq) = 0;

  /**
   * @brief Remove leaf from the state tree
   * @param info name of the leaf
   */
  virtual bool
  remove (NameInfoConstPtr info) = 0;

  /**
   * @brief Get state leaves
   */
  const LeafContainer &
  getLeaves () const
  { return m_leaves; }

protected:
  LeafContainer m_leaves;
};


/**
 * @brief Formats a protobuf SyncStateMsg msg
 * @param oss output SyncStateMsg msg
 * @param state state
 * @returns output SyncStateMsg msg
 */
SyncStateMsg &
operator << (SyncStateMsg &ossm, const State &state);


/**
 * @brief Parse a protobuf SyncStateMsg msg
 * @param iss input SyncStateMsg msg
 * @param state state
 * @returns SyncStateMsg msg
 */
SyncStateMsg &
operator >> (SyncStateMsg &issm, State &state);

namespace Error {
/**
 * @brief Will be thrown when data cannot be properly decoded to SyncStateMsg
 */
struct SyncStateMsgDecodingFailure : virtual boost::exception, virtual std::exception { };
}

} // Sync

#endif // SYNC_STATE_H