/***************************************************************************
 *   Copyright (C) 2011 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 UTP_PACKETBUFFER_H_
#define UTP_PACKETBUFFER_H_

#include <QSharedPointer>
#include <ktorrent_export.h>
#include <util/constants.h>
#include <util/circularbuffer.h>
#include <util/bufferpool.h>

namespace utp
{
class Header;

/**
 * Special packet buffer for UTP packets
 **/
class KTORRENT_EXPORT PacketBuffer
{
public:
    PacketBuffer();
    ~PacketBuffer();

    PacketBuffer(const PacketBuffer & buf) = default;
    PacketBuffer &operator=(const PacketBuffer & buf) = default;

    /**
     * Is the buffer empty
     * */
    bool isEmpty() const
    {
        return size == 0;
    }

    /**
     * Set the packet's header.
     * @param header Header
     * @param extension_length Length of the extension header
     * @return False if there is not enough head room, true otherwise
     **/
    bool setHeader(const Header & hdr, bt::Uint32 extension_length);

    /// Get a pointer to the extension data
    bt::Uint8* extensionData()
    {
        return extension;
    }

    /**
     * Fill with data from a circular buffer. This will invalidate already filled in headers.
     * @param cbuf The buffer
     * @param to_read Amount to read
     * @return The amount used as payload
     **/
    bt::Uint32 fillData(bt::CircularBuffer & cbuf, bt::Uint32 to_read);

    /**
     * Fill with data from a buffer.
     * @param data The data to copy from
     * @param data_size The data size
     * @return The amount used as payload
     **/
    bt::Uint32 fillData(const bt::Uint8* data, bt::Uint32 data_size);

    /**
     * For testing purpoes fill with dummy data.
     * @param amount Amount to fill
     * */
    void fillDummyData(bt::Uint32 amount);

    /**
     * Clear the PacketBufferDataPool
     **/
    static void clearPool();

    /// Get the data pointer
    const bt::Uint8* data() const
    {
        return header;
    }

    /// Get the buffer size
    bt::Uint32 bufferSize() const
    {
        return size;
    }

    /// Get the size of the payload
    bt::Uint32 payloadSize() const
    {
        return payload ? (buffer->get() + MAX_SIZE) - payload : 0;
    }

    /// Get the amount of headroom (room in front of payload)
    bt::Uint32 headRoom() const
    {
        return payload ? payload - buffer->get() : MAX_SIZE;
    }

    static const bt::Uint32 MAX_SIZE = 1500;

private:
    bt::Buffer::Ptr buffer;
    bt::Uint8* header;
    bt::Uint8* extension;
    bt::Uint8* payload;
    bt::Uint32 size;

    static bt::BufferPool::Ptr pool;
};

}

#endif /* PACKETBUFFER_H_ */
