/***************************************************************************
 *   Copyright (C) 2005 by Joris Guisson                                   *
 *   joris.guisson@gmail.com                                               *
 *                                                                         *
 *   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.             *
 ***************************************************************************/
#ifndef BTDNDFILE_H
#define BTDNDFILE_H

#include <QSharedPointer>
#include <QString>
#include <util/constants.h>

namespace bt
{
class TorrentFile;

/**
 * @author Joris Guisson <joris.guisson@gmail.com>
 *
 * Special file where we keep the first and last chunk of a file which is marked as do not download.
 * THe first and last chunk of a file will most certainly be partial chunks.
 */
class DNDFile
{
public:
    DNDFile(const QString &path, const TorrentFile *tf, Uint32 chunk_size);
    virtual ~DNDFile();

    /// Change the path of the file
    void changePath(const QString &npath);

    /**
     * CHeck integrity of the file, create it if it doesn't exist.
     */
    void checkIntegrity();

    /**
     * Read the (partial)first chunk into a buffer.
     * @param buf The buffer
     * @param off Offset off chunk
     * @param size How many bytes to read of the first chunk
     */
    Uint32 readFirstChunk(Uint8 *buf, Uint32 off, Uint32 size);

    /**
     * Read the (partial)last chunk into a buffer.
     * @param buf The buffer
     * @param off Offset off chunk
     * @param size How many bytes to read of the last chunk
     */
    Uint32 readLastChunk(Uint8 *buf, Uint32 off, Uint32 size);

    /**
     * Write the partial first chunk.
     * @param buf The buffer
     * @param off Offset into partial chunk
     * @param size Size to write
     */
    void writeFirstChunk(const Uint8 *buf, Uint32 off, Uint32 size);

    /**
     * Write the partial last chunk.
     * @param buf The buffer
     * @param off Offset into partial chunk
     * @param size Size to write
     */
    void writeLastChunk(const Uint8 *buf, Uint32 off, Uint32 size);

    typedef QSharedPointer<DNDFile> Ptr;

private:
    void create();

private:
    QString path;
    Uint32 first_size;
    Uint32 last_size;
};

}

#endif
