// Runs rip-chain's network in Java FILIUS (ScenarioNetwork) and records what
// RIP really does: every frame each card saw, every change of each router's
// RIP table, and the calls of the story.
//
//   RipRun <scenario.json> <story> <milliseconds> <out.json>
//
// PC 10.0.1.2 - R1 (10.0.1.1, 10.0.12.1) - R2 (10.0.12.2, 10.0.23.2) -
// R3 (10.0.23.3, 10.0.3.1) - PC 10.0.3.2, each router with RIP. Java draws a
// router's pauses from a new Random; this tool gives each the seed the core
// gives it (ripSeed: the scenario's seed, 0x52495000 and the FNV-1a hash of
// the router's id). The stories:
//   converge  the tables fill; at 45 s 10.0.1.2 pings 10.0.3.2
//   expire    at 10 s R3 falls silent (its next beacon never comes); its
//             network expires at R2, which tells R1; at 125 s the ping again

import filius.hardware.knoten.Knoten;
import filius.software.rip.RIPBeacon;
import filius.software.rip.RIPRoute;
import filius.software.rip.RIPTable;
import filius.software.system.VermittlungsrechnerBetriebssystem;
import filius.software.vermittlungsschicht.IcmpPaket;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;

public class RipRun {
    static final String PC_A = "00000000-0000-0000-0000-000000000401";
    static final String R3 = "00000000-0000-0000-0000-000000000404";

    static ScenarioNetwork network;
    static final List<Object[]> events = new ArrayList<>();
    static final List<Object[]> tables = new ArrayList<>();
    static final Map<String, String> lastTables = new LinkedHashMap<>();

    static synchronized void event(String what) {
        events.add(new Object[] { System.currentTimeMillis() - network.start, what });
    }

    /** The table as one line: `network/mask gateway interface hops; …`, in its order. */
    static String tableText(RIPTable table) {
        StringBuilder text = new StringBuilder();
        synchronized (table) {
            for (RIPRoute route : table.routes) {
                if (text.length() > 0) text.append("; ");
                text.append(route.getNetAddress()).append('/').append(route.getNetMask()).append(' ').append(route.getGateway())
                    .append(' ').append(route.getInterfaceIpAddress()).append(' ').append(route.hops);
            }
        }
        return text.toString();
    }

    static synchronized void pollTables() {
        for (Map.Entry<String, Knoten> entry : network.nodes.entrySet()) {
            if (!(entry.getValue().getSystemSoftware() instanceof VermittlungsrechnerBetriebssystem)) continue;
            RIPTable table = ((VermittlungsrechnerBetriebssystem) entry.getValue().getSystemSoftware()).getRIPTable();
            if (table == null) continue;
            String text = tableText(table);
            if (!text.equals(lastTables.get(entry.getKey()))) {
                lastTables.put(entry.getKey(), text);
                tables.add(new Object[] { System.currentTimeMillis() - network.start, entry.getKey(), text });
            }
        }
    }

    /** The core's ripSeed. */
    static long ripSeed(long seed, String nodeId) {
        int hash = 0x811c9dc5;
        for (int index = 0; index < nodeId.length(); index++) {
            hash = (hash ^ nodeId.charAt(index)) * 0x01000193;
        }
        return seed ^ 0x52495000L ^ (hash & 0xffffffffL);
    }

    static String icmp(IcmpPaket packet) {
        return packet == null ? "null" : "ICMP " + packet.getIcmpType() + "/" + packet.getIcmpCode() + " from " + packet.getSender();
    }

    static void ping(String target) {
        event("sendProbe " + target + " called");
        IcmpPaket answer = network.system(PC_A).holeICMP().sendProbe(target, 64, 1, 1);
        event("sendProbe " + target + " returned " + icmp(answer));
    }

    static void sleepUntil(long milliseconds) throws InterruptedException {
        long rest = network.start + milliseconds - System.currentTimeMillis();
        if (rest > 0) Thread.sleep(rest);
    }

    public static void main(String[] args) throws Exception {
        network = ScenarioNetwork.read(args[0]);
        String story = args[1];
        long end = Long.parseLong(args[2]);
        long seed = ScenarioNetwork.seed(args[0]);
        network.start();
        Field beaconField = VermittlungsrechnerBetriebssystem.class.getDeclaredField("ripbeacon");
        beaconField.setAccessible(true);
        Field randomField = RIPBeacon.class.getDeclaredField("rand");
        randomField.setAccessible(true);
        for (Map.Entry<String, Knoten> entry : network.nodes.entrySet()) {
            if (!(entry.getValue().getSystemSoftware() instanceof VermittlungsrechnerBetriebssystem)) continue;
            VermittlungsrechnerBetriebssystem os = (VermittlungsrechnerBetriebssystem) entry.getValue().getSystemSoftware();
            if (!os.isRipEnabled()) continue;
            randomField.set(beaconField.get(os), new Random(ripSeed(seed, entry.getKey())));
        }
        event("seeded");
        Thread poller = new Thread(() -> {
            while (true) {
                pollTables();
                try {
                    Thread.sleep(2);
                } catch (InterruptedException e) {
                    return;
                }
            }
        });
        poller.setDaemon(true);
        poller.start();

        switch (story) {
            case "converge":
                sleepUntil(45_000);
                ping("10.0.3.2");
                break;
            case "expire":
                sleepUntil(10_000);
                ((VermittlungsrechnerBetriebssystem) network.system(R3)).getRIPTable().setNextBeacon(Long.MAX_VALUE);
                event("R3 silent");
                sleepUntil(125_000);
                ping("10.0.3.2");
                break;
            default:
                throw new IllegalArgumentException("unknown story " + story);
        }
        sleepUntil(end);
        pollTables();

        ScenarioNetwork.Json out = new ScenarioNetwork.Json();
        out.open('{');
        network.writeFrames(out);
        synchronized (RipRun.class) {
            out.key("events").open('[');
            for (Object[] each : events) out.open('[').number((Long) each[0]).string((String) each[1]).close(']');
            out.close(']');
            out.key("tables").open('[');
            for (Object[] each : tables) out.open('[').number((Long) each[0]).string((String) each[1]).string((String) each[2]).close(']');
            out.close(']');
        }
        out.close('}');
        network.stop();
        ScenarioNetwork.write(args[3], out);
        System.exit(0);
    }
}