/*
 * Copyright (c) 2007, 2008 University of Washington
 *
 * SPDX-License-Identifier: GPL-2.0-only
 */

#ifndef POINT_TO_POINT_NET_DEVICE_H
#define POINT_TO_POINT_NET_DEVICE_H

#include "ns3/address.h"
#include "ns3/callback.h"
#include "ns3/data-rate.h"
#include "ns3/mac48-address.h"
#include "ns3/net-device.h"
#include "ns3/node.h"
#include "ns3/nstime.h"
#include "ns3/packet.h"
#include "ns3/ptr.h"
#include "ns3/queue-fwd.h"
#include "ns3/traced-callback.h"

#include <cstring>

namespace ns3
{

class PointToPointChannel;
class ErrorModel;

/**
 * @defgroup point-to-point Point-To-Point Network Device
 * This section documents the API of the ns-3 point-to-point module. For a
 * functional description, please refer to the ns-3 manual here:
 * http://www.nsnam.org/docs/models/html/point-to-point.html
 *
 * Be sure to read the manual BEFORE going down to the API.
 */

/**
 * @ingroup point-to-point
 * @class PointToPointNetDevice
 * @brief A Device for a Point to Point Network Link.
 *
 * This PointToPointNetDevice class specializes the NetDevice abstract
 * base class.  Together with a PointToPointChannel (and a peer
 * PointToPointNetDevice), the class models, with some level of
 * abstraction, a generic point-to-point or serial link.
 * Key parameters or objects that can be specified for this device
 * include a queue, data rate, and interframe transmission gap (the
 * propagation delay is set in the PointToPointChannel).
 */
class PointToPointNetDevice : public NetDevice
{
  public:
    /**
     * @brief Get the TypeId
     *
     * @return The TypeId for this class
     */
    static TypeId GetTypeId();

    /**
     * Construct a PointToPointNetDevice
     *
     * This is the constructor for the PointToPointNetDevice.  It takes as a
     * parameter a pointer to the Node to which this device is connected,
     * as well as an optional DataRate object.
     */
    PointToPointNetDevice();

    /**
     * Destroy a PointToPointNetDevice
     *
     * This is the destructor for the PointToPointNetDevice.
     */
    ~PointToPointNetDevice() override;

    // Delete copy constructor and assignment operator to avoid misuse
    PointToPointNetDevice& operator=(const PointToPointNetDevice&) = delete;
    PointToPointNetDevice(const PointToPointNetDevice&) = delete;

    /**
     * Set the Data Rate used for transmission of packets.  The data rate is
     * set in the Attach () method from the corresponding field in the channel
     * to which the device is attached.  It can be overridden using this method.
     *
     * @param bps the data rate at which this object operates
     */
    void SetDataRate(DataRate bps);

    /**
     * Set the interframe gap used to separate packets.  The interframe gap
     * defines the minimum space required between packets sent by this device.
     *
     * @param t the interframe gap time
     */
    void SetInterframeGap(Time t);

    /**
     * Attach the device to a channel.
     *
     * @param ch Ptr to the channel to which this object is being attached.
     * @return true if the operation was successful (always true actually)
     */
    bool Attach(Ptr<PointToPointChannel> ch);

    /**
     * Attach a queue to the PointToPointNetDevice.
     *
     * The PointToPointNetDevice "owns" a queue that implements a queueing
     * method such as DropTailQueue or RedQueue
     *
     * @param queue Ptr to the new queue.
     */
    void SetQueue(Ptr<Queue<Packet>> queue);

    /**
     * Get a copy of the attached Queue.
     *
     * @returns Ptr to the queue.
     */
    Ptr<Queue<Packet>> GetQueue() const;

    /**
     * Attach a receive ErrorModel to the PointToPointNetDevice.
     *
     * The PointToPointNetDevice may optionally include an ErrorModel in
     * the packet receive chain.
     *
     * @param em Ptr to the ErrorModel.
     */
    void SetReceiveErrorModel(Ptr<ErrorModel> em);

    /**
     * Receive a packet from a connected PointToPointChannel.
     *
     * The PointToPointNetDevice receives packets from its connected channel
     * and forwards them up the protocol stack.  This is the public method
     * used by the channel to indicate that the last bit of a packet has
     * arrived at the device.
     *
     * @param p Ptr to the received packet.
     */
    void Receive(Ptr<Packet> p);

    // The remaining methods are documented in ns3::NetDevice*

    void SetIfIndex(const uint32_t index) override;
    uint32_t GetIfIndex() const override;

    Ptr<Channel> GetChannel() const override;

    void SetAddress(Address address) override;
    Address GetAddress() const override;

    bool SetMtu(const uint16_t mtu) override;
    uint16_t GetMtu() const override;

    bool IsLinkUp() const override;

    void AddLinkChangeCallback(Callback<void> callback) override;

    bool IsBroadcast() const override;
    Address GetBroadcast() const override;

    bool IsMulticast() const override;
    Address GetMulticast(Ipv4Address multicastGroup) const override;

    bool IsPointToPoint() const override;
    bool IsBridge() const override;

    bool Send(Ptr<Packet> packet, const Address& dest, uint16_t protocolNumber) override;
    bool SendFrom(Ptr<Packet> packet,
                  const Address& source,
                  const Address& dest,
                  uint16_t protocolNumber) override;

    Ptr<Node> GetNode() const override;
    void SetNode(Ptr<Node> node) override;

    bool NeedsArp() const override;

    void SetReceiveCallback(NetDevice::ReceiveCallback cb) override;

    Address GetMulticast(Ipv6Address addr) const override;

    void SetPromiscReceiveCallback(PromiscReceiveCallback cb) override;
    bool SupportsSendFrom() const override;

  protected:
    /**
     * @brief Handler for MPI receive event
     *
     * @param p Packet received
     */
    void DoMpiReceive(Ptr<Packet> p);

  private:
    /**
     * @brief Dispose of the object
     */
    void DoDispose() override;

    /**
     * @returns the address of the remote device connected to this device
     * through the point to point channel.
     */
    Address GetRemote() const;

    /**
     * Adds the necessary headers and trailers to a packet of data in order to
     * respect the protocol implemented by the agent.
     * @param p packet
     * @param protocolNumber protocol number
     */
    void AddHeader(Ptr<Packet> p, uint16_t protocolNumber);

    /**
     * Removes, from a packet of data, all headers and trailers that
     * relate to the protocol implemented by the agent
     * @param p Packet whose headers need to be processed
     * @param param An integer parameter that can be set by the function
     * @return Returns true if the packet should be forwarded up the
     * protocol stack.
     */
    bool ProcessHeader(Ptr<Packet> p, uint16_t& param);

    /**
     * Start Sending a Packet Down the Wire.
     *
     * The TransmitStart method is the method that is used internally in the
     * PointToPointNetDevice to begin the process of sending a packet out on
     * the channel.  The corresponding method is called on the channel to let
     * it know that the physical device this class represents has virtually
     * started sending signals.  An event is scheduled for the time at which
     * the bits have been completely transmitted.
     *
     * @see PointToPointChannel::TransmitStart ()
     * @see TransmitComplete()
     * @param p a reference to the packet to send
     * @returns true if success, false on failure
     */
    bool TransmitStart(Ptr<Packet> p);

    /**
     * Stop Sending a Packet Down the Wire and Begin the Interframe Gap.
     *
     * The TransmitComplete method is used internally to finish the process
     * of sending a packet out on the channel.
     */
    void TransmitComplete();

    /**
     * @brief Make the link up and running
     *
     * It calls also the linkChange callback.
     */
    void NotifyLinkUp();

    /**
     * Enumeration of the states of the transmit machine of the net device.
     */
    enum TxMachineState
    {
        READY, /**< The transmitter is ready to begin transmission of a packet */
        BUSY   /**< The transmitter is busy transmitting a packet */
    };

    /**
     * The state of the Net Device transmit state machine.
     */
    TxMachineState m_txMachineState;

    /**
     * The data rate that the Net Device uses to simulate packet transmission
     * timing.
     */
    DataRate m_bps;

    /**
     * The interframe gap that the Net Device uses to throttle packet
     * transmission
     */
    Time m_tInterframeGap;

    /**
     * The PointToPointChannel to which this PointToPointNetDevice has been
     * attached.
     */
    Ptr<PointToPointChannel> m_channel;

    /**
     * The Queue which this PointToPointNetDevice uses as a packet source.
     * Management of this Queue has been delegated to the PointToPointNetDevice
     * and it has the responsibility for deletion.
     * @see class DropTailQueue
     */
    Ptr<Queue<Packet>> m_queue;

    /**
     * Error model for receive packet events
     */
    Ptr<ErrorModel> m_receiveErrorModel;

    /**
     * The trace source fired when packets come into the "top" of the device
     * at the L3/L2 transition, before being queued for transmission.
     */
    TracedCallback<Ptr<const Packet>> m_macTxTrace;

    /**
     * The trace source fired when packets coming into the "top" of the device
     * at the L3/L2 transition are dropped before being queued for transmission.
     */
    TracedCallback<Ptr<const Packet>> m_macTxDropTrace;

    /**
     * The trace source fired for packets successfully received by the device
     * immediately before being forwarded up to higher layers (at the L2/L3
     * transition).  This is a promiscuous trace (which doesn't mean a lot here
     * in the point-to-point device).
     */
    TracedCallback<Ptr<const Packet>> m_macPromiscRxTrace;

    /**
     * The trace source fired for packets successfully received by the device
     * immediately before being forwarded up to higher layers (at the L2/L3
     * transition).  This is a non-promiscuous trace (which doesn't mean a lot
     * here in the point-to-point device).
     */
    TracedCallback<Ptr<const Packet>> m_macRxTrace;

    /**
     * The trace source fired for packets successfully received by the device
     * but are dropped before being forwarded up to higher layers (at the L2/L3
     * transition).
     */
    TracedCallback<Ptr<const Packet>> m_macRxDropTrace;

    /**
     * The trace source fired when a packet begins the transmission process on
     * the medium.
     */
    TracedCallback<Ptr<const Packet>> m_phyTxBeginTrace;

    /**
     * The trace source fired when a packet ends the transmission process on
     * the medium.
     */
    TracedCallback<Ptr<const Packet>> m_phyTxEndTrace;

    /**
     * The trace source fired when the phy layer drops a packet before it tries
     * to transmit it.
     */
    TracedCallback<Ptr<const Packet>> m_phyTxDropTrace;

    /**
     * The trace source fired when a packet begins the reception process from
     * the medium -- when the simulated first bit(s) arrive.
     */
    TracedCallback<Ptr<const Packet>> m_phyRxBeginTrace;

    /**
     * The trace source fired when a packet ends the reception process from
     * the medium.
     */
    TracedCallback<Ptr<const Packet>> m_phyRxEndTrace;

    /**
     * The trace source fired when the phy layer drops a packet it has received.
     * This happens if the receiver is not enabled or the error model is active
     * and indicates that the packet is corrupt.
     */
    TracedCallback<Ptr<const Packet>> m_phyRxDropTrace;

    /**
     * A trace source that emulates a non-promiscuous protocol sniffer connected
     * to the device.  Unlike your average everyday sniffer, this trace source
     * will not fire on PACKET_OTHERHOST events.
     *
     * On the transmit size, this trace hook will fire after a packet is dequeued
     * from the device queue for transmission.  In Linux, for example, this would
     * correspond to the point just before a device \c hard_start_xmit where
     * \c dev_queue_xmit_nit is called to dispatch the packet to the PF_PACKET
     * ETH_P_ALL handlers.
     *
     * On the receive side, this trace hook will fire when a packet is received,
     * just before the receive callback is executed.  In Linux, for example,
     * this would correspond to the point at which the packet is dispatched to
     * packet sniffers in \c netif_receive_skb.
     */
    TracedCallback<Ptr<const Packet>> m_snifferTrace;

    /**
     * A trace source that emulates a promiscuous mode protocol sniffer connected
     * to the device.  This trace source fire on packets destined for any host
     * just like your average everyday packet sniffer.
     *
     * On the transmit size, this trace hook will fire after a packet is dequeued
     * from the device queue for transmission.  In Linux, for example, this would
     * correspond to the point just before a device \c hard_start_xmit where
     * \c dev_queue_xmit_nit is called to dispatch the packet to the PF_PACKET
     * ETH_P_ALL handlers.
     *
     * On the receive side, this trace hook will fire when a packet is received,
     * just before the receive callback is executed.  In Linux, for example,
     * this would correspond to the point at which the packet is dispatched to
     * packet sniffers in \c netif_receive_skb.
     */
    TracedCallback<Ptr<const Packet>> m_promiscSnifferTrace;

    Ptr<Node> m_node;                                    //!< Node owning this NetDevice
    Mac48Address m_address;                              //!< Mac48Address of this NetDevice
    NetDevice::ReceiveCallback m_rxCallback;             //!< Receive callback
    NetDevice::PromiscReceiveCallback m_promiscCallback; //!< Receive callback
                                                         //   (promisc data)
    uint32_t m_ifIndex;                                  //!< Index of the interface
    bool m_linkUp;                                       //!< Identify if the link is up or not
    TracedCallback<> m_linkChangeCallbacks;              //!< Callback for the link change event

    static const uint16_t DEFAULT_MTU = 1500; //!< Default MTU

    /**
     * @brief The Maximum Transmission Unit
     *
     * This corresponds to the maximum
     * number of bytes that can be transmitted as seen from higher layers.
     * This corresponds to the 1500 byte MTU size often seen on IP over
     * Ethernet.
     */
    uint32_t m_mtu;

    Ptr<Packet> m_currentPkt; //!< Current packet processed

    /**
     * @brief PPP to Ethernet protocol number mapping
     * @param protocol A PPP protocol number
     * @return The corresponding Ethernet protocol number
     */
    static uint16_t PppToEther(uint16_t protocol);

    /**
     * @brief Ethernet to PPP protocol number mapping
     * @param protocol An Ethernet protocol number
     * @return The corresponding PPP protocol number
     */
    static uint16_t EtherToPpp(uint16_t protocol);
};

} // namespace ns3

#endif /* POINT_TO_POINT_NET_DEVICE_H */
