/*
 * Copyright (c) 2017 Universita' degli Studi di Napoli Federico II
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Pasquale Imputato <p.imputato@gmail.com>
 */

#ifndef NETMAP_NET_DEVICE_H
#define NETMAP_NET_DEVICE_H

#include "fd-net-device.h"

#include "ns3/net-device-queue-interface.h"

#include <atomic>
#include <mutex>
#include <net/netmap_user.h>
#include <thread>

namespace ns3
{

/**
 * @ingroup fd-net-device
 *
 * @brief Network device transmission queue with lock
 *
 * This class stores information about a single transmission queue
 * of a network device that is exposed to queue discs. This class extends
 * the NetDeviceQueue base class by introducing a lock for methods which
 * require mutual exclusion on data access in emulation.
 */
class NetDeviceQueueLock : public NetDeviceQueue
{
  public:
    /**
     * @brief Get the type ID.
     * @return the object TypeId
     */
    static TypeId GetTypeId();

    NetDeviceQueueLock();
    virtual ~NetDeviceQueueLock();

    /**
     * Called by the device to start this device transmission queue.
     * This is the analogous to the netif_tx_start_queue function of the Linux kernel.
     */
    virtual void Start();

    /**
     * Called by the device to stop this device transmission queue.
     * This is the analogous to the netif_tx_stop_queue function of the Linux kernel.
     */
    virtual void Stop();

    /**
     * Called by the device to wake the queue disc associated with this
     * device transmission queue. This is done by invoking the wake callback.
     * This is the analogous to the netif_tx_wake_queue function of the Linux kernel.
     */
    virtual void Wake();

    /**
     * @brief Get the status of the device transmission queue.
     * @return true if the device transmission queue is stopped.
     *
     * Called by queue discs to enquire about the status of a given transmission queue.
     * This is the analogous to the netif_xmit_stopped function of the Linux kernel.
     */
    virtual bool IsStopped() const;

    /**
     * @brief Called by the netdevice to report the number of bytes queued to the device queue
     * @param bytes number of bytes queued to the device queue
     */
    virtual void NotifyQueuedBytes(uint32_t bytes);

    /**
     * @brief Called by the netdevice to report the number of bytes it is going to transmit
     * @param bytes number of bytes the device is going to transmit
     */
    virtual void NotifyTransmittedBytes(uint32_t bytes);

  private:
    mutable std::mutex m_mutex; //!< Mutex to serialize the operations performed on the queue
};

/**
 * @ingroup fd-net-device
 *
 * @brief This class performs the actual data reading from the netmap ring.
 */
class NetmapNetDeviceFdReader : public FdReader
{
  public:
    NetmapNetDeviceFdReader();

    /**
     * @brief Set size of the read buffer.
     * @param bufferSize the size of the read buffer
     */
    void SetBufferSize(uint32_t bufferSize);

    /**
     * @brief Set netmap interface representation.
     * @param nifp the netmap interface representation
     */
    void SetNetmapIfp(struct netmap_if* nifp);

  private:
    FdReader::Data DoRead();

    uint32_t m_bufferSize;    //!< size of the read buffer
    struct netmap_if* m_nifp; //!< Netmap interface representation
};

/**
 * @ingroup fd-net-device
 *
 * @brief a NetDevice to read/write network traffic from/into a netmap file descriptor.
 *
 * A NetmapNetDevice object will read and write packets from/to a netmap file descriptor.
 *
 */
class NetmapNetDevice : public FdNetDevice
{
  public:
    /**
     * @brief Get the type ID.
     * @return the object TypeId
     */
    static TypeId GetTypeId();

    NetmapNetDevice();
    virtual ~NetmapNetDevice();

    /**
     * @brief Get the number of bytes currently in the netmap transmission ring.
     * @return the number of bytes in the netmap transmission ring.
     */
    uint32_t GetBytesInNetmapTxRing();

    /**
     * @brief Get the number of slots currently available in the netmap transmission ring.
     * @return the number of slots currently available in the netmap transmission ring.
     */
    int GetSpaceInNetmapTxRing() const;

    /**
     * @brief Set the NetDeviceQueue
     * @param queue the NetDeviceQueue
     */
    void SetNetDeviceQueue(Ptr<NetDeviceQueue> queue);

    /**
     * @brief Set the netmap interface representation
     * @param nifp the pointer to netmap interface representation
     */
    void SetNetmapInterfaceRepresentation(struct netmap_if* nifp);

    /**
     * @brief Set the netmap transmission rings info
     * @param nTxRings the number of transmission rings
     * @param nTxRingsSlots the number of slots for each transmission ring
     */
    void SetTxRingsInfo(uint32_t nTxRings, uint32_t nTxRingsSlots);

    /**
     * @brief Set the netmap receiver rings info
     * @param nRxRings the number of receiver rings
     * @param nRxRingsSlots the number of slots for each receiver ring
     */
    void SetRxRingsInfo(uint32_t nRxRings, uint32_t nRxRingsSlots);

    /**
     * @brief The function Writes a packet into the netmap transmission ring.
     * @param buffer the pointer to packet
     * @param length the packet length
     * @return the number of written bytes
     */
    virtual ssize_t Write(uint8_t* buffer, size_t length);

  private:
    Ptr<FdReader> DoCreateFdReader();
    void DoFinishStartingDevice();
    void DoFinishStoppingDevice();

    /**
     * @brief This function syncs netmap ring and notifies netdevice queue.
     * This function runs in a separate thread.
     */
    virtual void SyncAndNotifyQueue();

    struct netmap_if* m_nifp;                        //!< Netmap interface representation
    uint32_t m_nTxRings;                             //!< Number of transmission rings
    uint32_t m_nTxRingsSlots;                        //!< Number of slots in the transmission rings
    uint32_t m_nRxRings;                             //!< Number of receiver rings
    uint32_t m_nRxRingsSlots;                        //!< Number of slots in the receiver rings
    Ptr<NetDeviceQueue> m_queue;                     //!< NetDevice queue
    uint32_t m_totalQueuedBytes;                     //!< Total queued bytes
    std::thread m_syncAndNotifyQueueThread;          //!< Thread used to perform the flow control
    std::atomic<bool> m_syncAndNotifyQueueThreadRun; //!< Running flag of the flow control thread
    uint8_t m_syncAndNotifyQueuePeriod; //!< The period of time in us after which the device syncs
                                        //!< the netmap ring and notifies queue status
};

} // namespace ns3

#endif /* NETMAP_NET_DEVICE_H */
