// distribution boxbackup-0.11.1 (svn version: 2821_2827)
// Box Backup, http://www.boxbackup.org/
// 
// Copyright (c) 2003-2010, Ben Summers and contributors.
// All rights reserved.
// 
// Note that this project uses mixed licensing. Any file with this license
// attached, or where the code LICENSE-GPL appears on the first line, falls
// under the "Box Backup GPL" license. See the file COPYING.txt for more
// information about this license.
// 
// ---------------------------------------------------------------------
// 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, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
// 
// [http://www.gnu.org/licenses/old-licenses/gpl-2.0.html#SEC4]
// 
// As a special exception to the GPLv2, the Box Backup Project gives
// permission to link any code falling under this license (the Box Backup
// GPL) with any software that can be downloaded from
// the OpenSSL website [http://www.openssl.org] under either the
// "OpenSSL License" or the "Original SSLeay License", and to distribute
// the linked executables under the terms of the "Box Backup GPL" license.
// 
// As a special exception to the GPLv2, the Box Backup Project gives
// permission to link any code falling under this license (the Box Backup
// GPL) with any version of Microsoft's Volume Shadow Copy Service 7.2 SDK
// or Microsoft Windows Software Development Kit (SDK), including
// vssapi.lib, that can be downloaded from the Microsoft website
// [*.microsoft.com], and to distribute the linked executables under the
// terms of the "Box Backup GPL" license.
// --------------------------------------------------------------------------
//
// File
//		Name:    BackupStoreRefCountDatabase.h
//		Purpose: Main backup store information storage
//		Created: 2003/08/28
//
// --------------------------------------------------------------------------

#ifndef BACKUPSTOREREFCOUNTDATABASE__H
#define BACKUPSTOREREFCOUNTDATABASE__H

#include <memory>
#include <string>
#include <vector>

#include "BackupStoreAccountDatabase.h"
#include "FileStream.h"

class BackupStoreCheck;
class BackupStoreContext;

// set packing to one byte
#ifdef STRUCTURE_PACKING_FOR_WIRE_USE_HEADERS
#include "BeginStructPackForWire.h"
#else
BEGIN_STRUCTURE_PACKING_FOR_WIRE
#endif

typedef struct
{
	uint32_t mMagicValue;	// also the version number
	uint32_t mAccountID;
} refcount_StreamFormat;

// Use default packing
#ifdef STRUCTURE_PACKING_FOR_WIRE_USE_HEADERS
#include "EndStructPackForWire.h"
#else
END_STRUCTURE_PACKING_FOR_WIRE
#endif

// --------------------------------------------------------------------------
//
// Class
//		Name:    BackupStoreRefCountDatabase
//		Purpose: Backup store reference count database storage
//		Created: 2009/06/01
//
// --------------------------------------------------------------------------
class BackupStoreRefCountDatabase
{
	friend class BackupStoreCheck;
	friend class BackupStoreContext;
	friend class HousekeepStoreAccount;

public:
	~BackupStoreRefCountDatabase();
private:
	// Creation through static functions only
	BackupStoreRefCountDatabase(const BackupStoreAccountDatabase::Entry&
		rAccount);
	// No copying allowed
	BackupStoreRefCountDatabase(const BackupStoreRefCountDatabase &);
	
public:
	// Create a new database for a new account. This method will refuse
	// to overwrite any existing file.
	static void CreateNew(const BackupStoreAccountDatabase::Entry& rAccount)
	{
		Create(rAccount, false);
	}
	
	// Load it from the store
	static std::auto_ptr<BackupStoreRefCountDatabase> Load(const
		BackupStoreAccountDatabase::Entry& rAccount, bool ReadOnly);
	
	typedef uint32_t refcount_t;

	// Data access functions
	refcount_t GetRefCount(int64_t ObjectID) const;
	int64_t GetLastObjectIDUsed() const;
	
	// Data modification functions
	void AddReference(int64_t ObjectID);
	// RemoveReference returns false if refcount drops to zero
	bool RemoveReference(int64_t ObjectID);

private:
	// Create a new database for an existing account. Used during
	// account checking if opening the old database throws an exception.
	// This method will overwrite any existing file.
	static void CreateForRegeneration(const
		BackupStoreAccountDatabase::Entry& rAccount)
	{
		Create(rAccount, true);
	}

	static void Create(const BackupStoreAccountDatabase::Entry& rAccount,
		bool AllowOverwrite);

	static std::string GetFilename(const BackupStoreAccountDatabase::Entry&
		rAccount);
	IOStream::pos_type GetSize() const
	{
		return mapDatabaseFile->GetPosition() +
			mapDatabaseFile->BytesLeftToRead();
	}
	IOStream::pos_type GetEntrySize() const
	{
		return sizeof(refcount_t);
	}
	IOStream::pos_type GetOffset(int64_t ObjectID) const
	{
		return ((ObjectID - 1) * GetEntrySize()) +
			sizeof(refcount_StreamFormat);
	}
	void SetRefCount(int64_t ObjectID, refcount_t NewRefCount);
	
	// Location information
	BackupStoreAccountDatabase::Entry mAccount;
	std::string mFilename;
	bool mReadOnly;
	bool mIsModified;
	std::auto_ptr<FileStream> mapDatabaseFile;
};

#endif // BACKUPSTOREREFCOUNTDATABASE__H
