/***************************************************************************
 *   Copyright (C) 2010 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 BT_CIRCULARBUFFER_H
#define BT_CIRCULARBUFFER_H

#include <ktorrent_export.h>
#include <util/constants.h>
#include <utility>

namespace bt
{

/**
    Circular buffer class
*/
class KTORRENT_EXPORT CircularBuffer
{
public:
    CircularBuffer(bt::Uint32 cap = 64 * 1024);
    virtual ~CircularBuffer();

    /**
        Read up to max_len bytes from the buffer and store it in data
        @param ptr The place to store the data
        @param max_len Maximum amount to read
        @return The amount read
    */
    virtual bt::Uint32 read(bt::Uint8* ptr, bt::Uint32 max_len);

    /**
        Write up to len bytes from data and store it in the window.
        @param ptr The data to copy
        @param max_len Amount to write
        @return The amount written
    */
    virtual bt::Uint32 write(const bt::Uint8* ptr, bt::Uint32 len);

    /// Is the buffer empty
    bool empty() const
    {
        return buf_size == 0;
    }

    /// Is the buffer full
    bool full() const
    {
        return buf_size == buf_capacity;
    }

    /// How much of the buffer is used
    bt::Uint32 size() const
    {
        return buf_size;
    }

    /// How much capacity is available
    bt::Uint32 capacity() const
    {
        return buf_capacity;
    }

    /// Get the available space
    bt::Uint32 available() const
    {
        return buf_capacity - buf_size;
    }

private:
    typedef std::pair<bt::Uint8*, bt::Uint32> Range;

    /// Get the first range
    Range firstRange();
    Range secondRange();

private:
    bt::Uint8* data;
    bt::Uint32 buf_capacity;
    bt::Uint32 start;
    bt::Uint32 buf_size;
};

}

#endif // BT_CIRCULARBUFFER_H
