/*
    SPDX-FileCopyrightText: 2011 Joris Guisson <joris.guisson@gmail.com>

    SPDX-License-Identifier: GPL-2.0-or-later
*/

#ifndef UTP_PACKETBUFFER_H_
#define UTP_PACKETBUFFER_H_

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

namespace utp
{
struct 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 hdr 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_ */
