// TortoiseSVN - a Windows shell extension for easy version control

// Copyright (C) 2007-2008 - TortoiseSVN

// This program 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 2
// of the License, or (at your option) any later version.

// This program 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 this program; if not, write to the Free Software Foundation,
// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
#pragma once

///////////////////////////////////////////////////////////////
// include
///////////////////////////////////////////////////////////////

#include "LogCacheGlobals.h"

///////////////////////////////////////////////////////////////
// forward declarations
///////////////////////////////////////////////////////////////

class IHierarchicalInStream;
class IHierarchicalOutStream;

///////////////////////////////////////////////////////////////
// begin namespace LogCache
///////////////////////////////////////////////////////////////

namespace LogCache
{

/**
 * a simple class to map from revision number to revision index.
 *
 * To handle high revision counts efficiently, only the range of revisions is
 * stored which actually maps to revision indices (i.e. revisions at the
 * upper and lower ends may be omitted).
 */
class CRevisionIndex
{
private:

    /// the mapping and its bias

    revision_t firstRevision;
    std::vector<index_t> indices;

    /// sub-stream IDs

    enum
    {
        INDEX_STREAM_ID = 1
    };

public:

    /// construction / destruction

    CRevisionIndex(void);
    ~CRevisionIndex(void);

    /// range of (possibly available) revisions:
    /// GetFirstRevision() .. GetLastRevision()-1

    revision_t GetFirstRevision() const
    {
        return firstRevision;
    }
    revision_t GetLastRevision() const
    {
        return firstRevision + (revision_t)indices.size();
    }

    /// range of actually available revisions:
    /// GetFirstCachedRevision() .. GetLastCachedRevision()-1

    revision_t GetFirstCachedRevision() const;
    revision_t GetLastCachedRevision() const;

    /// first revision that is not cached
    /// (returns start for empty caches)

    revision_t GetFirstMissingRevision (revision_t start) const;

    /// read

    index_t operator[](revision_t revision) const
    {
        revision -= firstRevision;
        return revision < indices.size()
            ? indices[revision]
            : NO_INDEX;
    }

    /// insert info (must be NO_INDEX before)

    void SetRevisionIndex (revision_t revision, index_t index);

    /// return false if concurrent read accesses
    /// would potentially access invalid data.

    bool CanSetRevisionIndexThreadSafely (revision_t revision) const;

    /// reset content

    void Clear();

    /// stream I/O

    friend IHierarchicalInStream& operator>> ( IHierarchicalInStream& stream
                                             , CRevisionIndex& container);
    friend IHierarchicalOutStream& operator<< ( IHierarchicalOutStream& stream
                                              , const CRevisionIndex& container);

    /// for statistics

    friend class CLogCacheStatistics;
};

/// stream I/O

IHierarchicalInStream& operator>> ( IHierarchicalInStream& stream
                                  , CRevisionIndex& container);
IHierarchicalOutStream& operator<< ( IHierarchicalOutStream& stream
                                   , const CRevisionIndex& container);

///////////////////////////////////////////////////////////////
// end namespace LogCache
///////////////////////////////////////////////////////////////

}