/*
 * Copyright (c) 2014 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* @file
 * Device model for an ethernet switch
 */

#ifndef __DEV_ETHERSWITCH_HH__
#define __DEV_ETHERSWITCH_HH__

#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/inet.hh"
#include "dev/net/etherint.hh"
#include "dev/net/etherlink.hh"
#include "dev/net/etherpkt.hh"
#include "dev/net/pktfifo.hh"
#include "params/EtherSwitch.hh"
#include "sim/eventq.hh"
#include "sim/serialize.hh"
#include "sim/sim_object.hh"

namespace gem5
{

class EtherSwitch : public SimObject
{
  public:
    using Params = EtherSwitchParams;

    EtherSwitch(const Params &p);
    ~EtherSwitch();

    Port &getPort(const std::string &if_name,
                  PortID idx=InvalidPortID) override;

  protected:
    /**
     * Model for an Ethernet switch port
     */
    class Interface : public EtherInt, public Serializable
    {
      public:
        Interface(const std::string &name, EtherSwitch *_etherSwitch,
                  uint64_t outputBufferSize, Tick delay, Tick delay_var,
                  double rate, unsigned id);
        /**
         * When a packet is received from a device, route it
         * through an (several) output queue(s)
         */
        bool recvPacket(EthPacketPtr packet);
        /**
         * enqueue packet to the outputFifo
         */
        void enqueue(EthPacketPtr packet, unsigned senderId);
        void sendDone() {}
        Tick switchingDelay();

        Interface* lookupDestPort(networking::EthAddr destAddr);
        void learnSenderAddr(networking::EthAddr srcMacAddr, Interface *sender);

        void serialize(CheckpointOut &cp) const;
        void unserialize(CheckpointIn &cp);

      private:
        const double ticksPerByte;
        const Tick switchDelay;
        const Tick delayVar;
        const unsigned interfaceId;

        EtherSwitch *parent;
      protected:
        struct PortFifoEntry : public Serializable
        {
            PortFifoEntry(EthPacketPtr pkt, Tick recv_tick, unsigned id)
                : packet(pkt), recvTick(recv_tick), srcId(id) {}

            EthPacketPtr packet;
            Tick recvTick;
            // id of the port that the packet has been received from
            unsigned srcId;
            ~PortFifoEntry()
            {
                packet = nullptr;
                recvTick = 0;
                srcId = 0;
            }
            void serialize(CheckpointOut &cp) const;
            void unserialize(CheckpointIn &cp);
        };

        class PortFifo : public Serializable
        {
          protected:
            struct EntryOrder
            {
                bool operator() (const PortFifoEntry& lhs,
                                 const PortFifoEntry& rhs) const
                {
                    if (lhs.recvTick == rhs.recvTick)
                        return lhs.srcId < rhs.srcId;
                    else
                        return lhs.recvTick < rhs.recvTick;
                }
            };
            std::set<PortFifoEntry, EntryOrder> fifo;

            const std::string objName;
            const unsigned _maxsize;
            unsigned _size;

          public:
            PortFifo(const std::string &name, int max)
                :objName(name), _maxsize(max), _size(0) {}
            ~PortFifo() {}

            const std::string name() { return objName; }
            // Returns the available capacity of the fifo.
            // It can return a negative value because in "push" function
            // we first push the received packet into the fifo and then
            // check if we exceed the available capacity (if avail() < 0)
            // and remove packets from the end of fifo
            int avail() const { return _maxsize - _size; }

            EthPacketPtr front() { return fifo.begin()->packet; }
            bool empty() const { return _size == 0; }
            unsigned size() const { return _size; }

            /**
             * Push a packet into the fifo
             * and sort the packets with same recv tick by port id
             */
            bool push(EthPacketPtr ptr, unsigned senderId);
            void pop();
            void clear();
            /**
             * Serialization stuff
             */
            void serialize(CheckpointOut &cp) const;
            void unserialize(CheckpointIn &cp);
        };
        /**
         * output fifo at each interface
         */
        PortFifo outputFifo;
        void transmit();
        EventFunctionWrapper txEvent;
    };

    struct SwitchTableEntry
    {
            Interface *interface;
            Tick lastUseTime;
        };

  private:
    // time to live for MAC address mappings
    const double ttl;
    // all interfaces of the switch
    std::vector<Interface*> interfaces;
    // table that maps MAC address to interfaces
    std::map<uint64_t, SwitchTableEntry> forwardingTable;

    void serialize(CheckpointOut &cp) const override;
    void unserialize(CheckpointIn &cp) override;
};

} // namespace gem5

#endif // __DEV_ETHERSWITCH_HH__