/*
 * Copyright (c) 2014 Universita' di Firenze, Italy
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 * Author: Tommaso Pecorella <tommaso.pecorella@unifi.it>
 */

// Network topology
//
//    SRC
//     |<=== source network
//     A-----B
//      \   / \   all networks have cost 1, except
//       \ /  |   for the direct link from C to D, which
//        C  /    has cost 10
//        | /
//        |/
//        D
//        |<=== target network
//       DST
//
//
// A, B, C and D are RIPng routers.
// A and D are configured with static addresses.
// SRC and DST will exchange packets.
//
// After about 3 seconds, the topology is built, and Echo Reply will be received.
// After 40 seconds, the link between B and D will break, causing a route failure.
// After 44 seconds from the failure, the routers will recovery from the failure.
// Split Horizoning should affect the recovery time, but it is not. See the manual
// for an explanation of this effect.
//
// If "showPings" is enabled, the user will see:
// 1) if the ping has been acknowledged
// 2) if a Destination Unreachable has been received by the sender
// 3) nothing, when the Echo Request has been received by the destination but
//    the Echo Reply is unable to reach the sender.
// Examining the .pcap files with Wireshark can confirm this effect.

#include "ns3/core-module.h"
#include "ns3/csma-module.h"
#include "ns3/internet-apps-module.h"
#include "ns3/internet-module.h"
#include "ns3/ipv6-routing-table-entry.h"
#include "ns3/ipv6-static-routing-helper.h"

#include <fstream>

using namespace ns3;

NS_LOG_COMPONENT_DEFINE("RipNgSimpleRouting");

void
TearDownLink(Ptr<Node> nodeA, Ptr<Node> nodeB, uint32_t interfaceA, uint32_t interfaceB)
{
    nodeA->GetObject<Ipv6>()->SetDown(interfaceA);
    nodeB->GetObject<Ipv6>()->SetDown(interfaceB);
}

int
main(int argc, char** argv)
{
    bool verbose = false;
    bool printRoutingTables = false;
    bool showPings = false;
    std::string SplitHorizon("PoisonReverse");

    CommandLine cmd(__FILE__);
    cmd.AddValue("verbose", "turn on log components", verbose);
    cmd.AddValue("printRoutingTables",
                 "Print routing tables at 30, 60 and 90 seconds",
                 printRoutingTables);
    cmd.AddValue("showPings", "Show Ping reception", showPings);
    cmd.AddValue("splitHorizonStrategy",
                 "Split Horizon strategy to use (NoSplitHorizon, SplitHorizon, PoisonReverse)",
                 SplitHorizon);
    cmd.Parse(argc, argv);

    if (verbose)
    {
        LogComponentEnable("RipNgSimpleRouting", LOG_LEVEL_INFO);
        LogComponentEnable("RipNg", LOG_LEVEL_ALL);
        LogComponentEnable("Icmpv6L4Protocol", LOG_LEVEL_INFO);
        LogComponentEnable("Ipv6Interface", LOG_LEVEL_ALL);
        LogComponentEnable("Icmpv6L4Protocol", LOG_LEVEL_ALL);
        LogComponentEnable("NdiscCache", LOG_LEVEL_ALL);
        LogComponentEnable("Ping", LOG_LEVEL_ALL);
    }

    if (SplitHorizon == "NoSplitHorizon")
    {
        Config::SetDefault("ns3::RipNg::SplitHorizon", EnumValue(RipNg::NO_SPLIT_HORIZON));
    }
    else if (SplitHorizon == "SplitHorizon")
    {
        Config::SetDefault("ns3::RipNg::SplitHorizon", EnumValue(RipNg::SPLIT_HORIZON));
    }
    else
    {
        Config::SetDefault("ns3::RipNg::SplitHorizon", EnumValue(RipNg::POISON_REVERSE));
    }

    NS_LOG_INFO("Create nodes.");
    Ptr<Node> src = CreateObject<Node>();
    Names::Add("SrcNode", src);
    Ptr<Node> dst = CreateObject<Node>();
    Names::Add("DstNode", dst);
    Ptr<Node> a = CreateObject<Node>();
    Names::Add("RouterA", a);
    Ptr<Node> b = CreateObject<Node>();
    Names::Add("RouterB", b);
    Ptr<Node> c = CreateObject<Node>();
    Names::Add("RouterC", c);
    Ptr<Node> d = CreateObject<Node>();
    Names::Add("RouterD", d);
    NodeContainer net1(src, a);
    NodeContainer net2(a, b);
    NodeContainer net3(a, c);
    NodeContainer net4(b, c);
    NodeContainer net5(c, d);
    NodeContainer net6(b, d);
    NodeContainer net7(d, dst);
    NodeContainer routers(a, b, c, d);
    NodeContainer nodes(src, dst);

    NS_LOG_INFO("Create channels.");
    CsmaHelper csma;
    csma.SetChannelAttribute("DataRate", DataRateValue(5000000));
    csma.SetChannelAttribute("Delay", TimeValue(MilliSeconds(2)));
    NetDeviceContainer ndc1 = csma.Install(net1);
    NetDeviceContainer ndc2 = csma.Install(net2);
    NetDeviceContainer ndc3 = csma.Install(net3);
    NetDeviceContainer ndc4 = csma.Install(net4);
    NetDeviceContainer ndc5 = csma.Install(net5);
    NetDeviceContainer ndc6 = csma.Install(net6);
    NetDeviceContainer ndc7 = csma.Install(net7);

    NS_LOG_INFO("Create IPv6 and routing");
    RipNgHelper ripNgRouting;

    // Rule of thumb:
    // Interfaces are added sequentially, starting from 0
    // However, interface 0 is always the loopback...
    ripNgRouting.ExcludeInterface(a, 1);
    ripNgRouting.ExcludeInterface(d, 3);

    ripNgRouting.SetInterfaceMetric(c, 3, 10);
    ripNgRouting.SetInterfaceMetric(d, 1, 10);

    Ipv6ListRoutingHelper listRH;
    listRH.Add(ripNgRouting, 0);
    Ipv6StaticRoutingHelper staticRh;
    listRH.Add(staticRh, 5);

    InternetStackHelper internetv6;
    internetv6.SetIpv4StackInstall(false);
    internetv6.SetRoutingHelper(listRH);
    internetv6.Install(routers);

    InternetStackHelper internetv6Nodes;
    internetv6Nodes.SetIpv4StackInstall(false);
    internetv6Nodes.Install(nodes);

    // Assign addresses.
    // The source and destination networks have global addresses
    // The "core" network just needs link-local addresses for routing.
    // We assign global addresses to the routers as well to receive
    // ICMPv6 errors.
    NS_LOG_INFO("Assign IPv6 Addresses.");
    Ipv6AddressHelper ipv6;

    ipv6.SetBase(Ipv6Address("2001:1::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic1 = ipv6.Assign(ndc1);
    iic1.SetForwarding(1, true);
    iic1.SetDefaultRouteInAllNodes(1);

    ipv6.SetBase(Ipv6Address("2001:0:1::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic2 = ipv6.Assign(ndc2);
    iic2.SetForwarding(0, true);
    iic2.SetForwarding(1, true);

    ipv6.SetBase(Ipv6Address("2001:0:2::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic3 = ipv6.Assign(ndc3);
    iic3.SetForwarding(0, true);
    iic3.SetForwarding(1, true);

    ipv6.SetBase(Ipv6Address("2001:0:3::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic4 = ipv6.Assign(ndc4);
    iic4.SetForwarding(0, true);
    iic4.SetForwarding(1, true);

    ipv6.SetBase(Ipv6Address("2001:0:4::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic5 = ipv6.Assign(ndc5);
    iic5.SetForwarding(0, true);
    iic5.SetForwarding(1, true);

    ipv6.SetBase(Ipv6Address("2001:0:5::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic6 = ipv6.Assign(ndc6);
    iic6.SetForwarding(0, true);
    iic6.SetForwarding(1, true);

    ipv6.SetBase(Ipv6Address("2001:2::"), Ipv6Prefix(64));
    Ipv6InterfaceContainer iic7 = ipv6.Assign(ndc7);
    iic7.SetForwarding(0, true);
    iic7.SetDefaultRouteInAllNodes(0);

    if (printRoutingTables)
    {
        Ptr<OutputStreamWrapper> routingStream = Create<OutputStreamWrapper>(&std::cout);

        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(30), a, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(30), b, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(30), c, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(30), d, routingStream);

        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(60), a, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(60), b, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(60), c, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(60), d, routingStream);

        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(90), a, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(90), b, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(90), c, routingStream);
        Ipv6RoutingHelper::PrintRoutingTableAt(Seconds(90), d, routingStream);
    }

    NS_LOG_INFO("Create Applications.");
    uint32_t packetSize = 1024;
    Time interPacketInterval = Seconds(1);
    PingHelper ping(iic7.GetAddress(1, 1));

    ping.SetAttribute("Interval", TimeValue(interPacketInterval));
    ping.SetAttribute("Size", UintegerValue(packetSize));
    if (showPings)
    {
        ping.SetAttribute("VerboseMode", EnumValue(Ping::VerboseMode::VERBOSE));
    }
    ApplicationContainer apps = ping.Install(src);
    apps.Start(Seconds(1));
    apps.Stop(Seconds(110));

    AsciiTraceHelper ascii;
    csma.EnableAsciiAll(ascii.CreateFileStream("ripng-simple-routing.tr"));
    csma.EnablePcapAll("ripng-simple-routing", true);

    Simulator::Schedule(Seconds(40), &TearDownLink, b, d, 3, 2);

    /* Now, do the actual simulation. */
    NS_LOG_INFO("Run Simulation.");
    Simulator::Stop(Seconds(120));
    Simulator::Run();
    Simulator::Destroy();
    NS_LOG_INFO("Done.");

    return 0;
}
