/*
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

//
// Network topology
//
//  n0
//     \ 5 Mb/s, 2ms
//      \          1.5Mb/s, 10ms
//       n2 -------------------------n3
//      /
//     / 5 Mb/s, 2ms
//   n1
//
// - all links are point-to-point links with indicated one-way BW/delay
// - CBR/UDP flows from n0 to n3, and from n3 to n1
// - FTP/TCP flow from n0 to n3, starting at time 1.2 to time 1.35 sec.
// - UDP packet size of 210 bytes, with per-packet interval 0.00375 sec.
//   (i.e., DataRate of 448,000 bps)
// - DropTail queues
// - Tracing of queues and packet receptions to file "simple-global-routing.tr"

#include "ns3/applications-module.h"
#include "ns3/core-module.h"
#include "ns3/flow-monitor-helper.h"
#include "ns3/internet-module.h"
#include "ns3/ipv4-global-routing-helper.h"
#include "ns3/network-module.h"
#include "ns3/point-to-point-module.h"

#include <cassert>
#include <fstream>
#include <iostream>
#include <string>

using namespace ns3;

NS_LOG_COMPONENT_DEFINE("SimpleGlobalRoutingExample");

int
main(int argc, char* argv[])
{
    // Users may find it convenient to turn on explicit debugging
    // for selected modules; the below lines suggest how to do this
#if 0
  LogComponentEnable ("SimpleGlobalRoutingExample", LOG_LEVEL_INFO);
#endif

    // Set up some default values for the simulation.  Use the
    Config::SetDefault("ns3::OnOffApplication::PacketSize", UintegerValue(210));
    Config::SetDefault("ns3::OnOffApplication::DataRate", StringValue("448kb/s"));

    // DefaultValue::Bind ("DropTailQueue::m_maxPackets", 30);

    // Allow the user to override any of the defaults and the above
    // DefaultValue::Bind ()s at run-time, via command-line arguments
    CommandLine cmd(__FILE__);
    bool enableFlowMonitor = false;
    cmd.AddValue("EnableMonitor", "Enable Flow Monitor", enableFlowMonitor);
    cmd.Parse(argc, argv);

    // Here, we will explicitly create four nodes.  In more sophisticated
    // topologies, we could configure a node factory.
    NS_LOG_INFO("Create nodes.");
    NodeContainer c;
    c.Create(4);
    NodeContainer n0n2 = NodeContainer(c.Get(0), c.Get(2));
    NodeContainer n1n2 = NodeContainer(c.Get(1), c.Get(2));
    NodeContainer n3n2 = NodeContainer(c.Get(3), c.Get(2));

    InternetStackHelper internet;
    internet.Install(c);

    // We create the channels first without any IP addressing information
    NS_LOG_INFO("Create channels.");
    PointToPointHelper p2p;
    p2p.SetDeviceAttribute("DataRate", StringValue("5Mbps"));
    p2p.SetChannelAttribute("Delay", StringValue("2ms"));
    NetDeviceContainer d0d2 = p2p.Install(n0n2);

    NetDeviceContainer d1d2 = p2p.Install(n1n2);

    p2p.SetDeviceAttribute("DataRate", StringValue("1500kbps"));
    p2p.SetChannelAttribute("Delay", StringValue("10ms"));
    NetDeviceContainer d3d2 = p2p.Install(n3n2);

    // Later, we add IP addresses.
    NS_LOG_INFO("Assign IP Addresses.");
    Ipv4AddressHelper ipv4;
    ipv4.SetBase("10.1.1.0", "255.255.255.0");
    Ipv4InterfaceContainer i0i2 = ipv4.Assign(d0d2);

    ipv4.SetBase("10.1.2.0", "255.255.255.0");
    Ipv4InterfaceContainer i1i2 = ipv4.Assign(d1d2);

    ipv4.SetBase("10.1.3.0", "255.255.255.0");
    Ipv4InterfaceContainer i3i2 = ipv4.Assign(d3d2);

    // Create router nodes, initialize routing database and set up the routing
    // tables in the nodes.
    Ipv4GlobalRoutingHelper::PopulateRoutingTables();

    // Create the OnOff application to send UDP datagrams of size
    // 210 bytes at a rate of 448 Kb/s
    NS_LOG_INFO("Create Applications.");
    uint16_t port = 9; // Discard port (RFC 863)
    OnOffHelper onoff("ns3::UdpSocketFactory",
                      Address(InetSocketAddress(i3i2.GetAddress(0), port)));
    onoff.SetConstantRate(DataRate("448kb/s"));
    ApplicationContainer apps = onoff.Install(c.Get(0));
    apps.Start(Seconds(1));
    apps.Stop(Seconds(10));

    // Create a packet sink to receive these packets
    PacketSinkHelper sink("ns3::UdpSocketFactory",
                          Address(InetSocketAddress(Ipv4Address::GetAny(), port)));
    apps = sink.Install(c.Get(3));
    apps.Start(Seconds(1));
    apps.Stop(Seconds(10));

    // Create a similar flow from n3 to n1, starting at time 1.1 seconds
    onoff.SetAttribute("Remote", AddressValue(InetSocketAddress(i1i2.GetAddress(0), port)));
    apps = onoff.Install(c.Get(3));
    apps.Start(Seconds(1.1));
    apps.Stop(Seconds(10));

    // Create a packet sink to receive these packets
    apps = sink.Install(c.Get(1));
    apps.Start(Seconds(1.1));
    apps.Stop(Seconds(10));

    AsciiTraceHelper ascii;
    p2p.EnableAsciiAll(ascii.CreateFileStream("simple-global-routing.tr"));
    p2p.EnablePcapAll("simple-global-routing");

    // Flow Monitor
    FlowMonitorHelper flowmonHelper;
    if (enableFlowMonitor)
    {
        flowmonHelper.InstallAll();
    }

    NS_LOG_INFO("Run Simulation.");
    Simulator::Stop(Seconds(11));
    Simulator::Run();
    NS_LOG_INFO("Done.");

    if (enableFlowMonitor)
    {
        flowmonHelper.SerializeToXmlFile("simple-global-routing.flowmon", false, false);
    }

    Simulator::Destroy();
    return 0;
}
