// A core scenario's network (packages/core/test/scenarios/*.scenario.json:
// nodes, links (wireless or not), devices, switches' and hosts' SSIDs,
// dhcpServers, dhcpClients, …) built in Java FILIUS the
// way the core reads it: a port's MAC is its `mac`, else the core's
// stableGeneratedMacAddress. Started as the action mode starts it (every
// system software's starten()); afterwards every frame each network card saw
// (FILIUS' own packet log, the Lauscher) and each host's addresses. Shared by
// DhcpRun and TcpRun.

import filius.gui.GUIContainer;
import filius.hardware.Kabel;
import filius.hardware.NetzwerkInterface;
import filius.hardware.Port;
import filius.hardware.knoten.Gateway;
import filius.hardware.knoten.InternetKnoten;
import filius.hardware.knoten.Knoten;
import filius.hardware.knoten.LokalerKnoten;
import filius.hardware.knoten.Notebook;
import filius.hardware.knoten.Rechner;
import filius.hardware.knoten.Switch;
import filius.hardware.knoten.Vermittlungsrechner;
import filius.rahmenprogramm.nachrichten.Lauscher;
import filius.software.dhcp.DHCPServer;
import filius.software.dns.DNSServer;
import filius.software.netzzugangsschicht.EthernetFrame;
import filius.software.system.Betriebssystem;
import filius.software.system.GatewayFirmware;
import filius.software.system.InternetKnotenBetriebssystem;
import filius.software.system.SwitchFirmware;
import filius.software.system.VermittlungsrechnerBetriebssystem;
import filius.software.transportschicht.Segment;
import filius.software.transportschicht.TcpSegment;
import filius.software.vermittlungsschicht.ArpPaket;
import filius.software.vermittlungsschicht.IcmpPaket;
import filius.software.vermittlungsschicht.IpPaket;

import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.lang.reflect.Field;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

public class ScenarioNetwork {
    final Map<String, Knoten> nodes = new LinkedHashMap<>();
    /** Each card's MAC address, under its node's id (the first card) or `id#index` (the others). */
    final Map<String, String> macByNode = new LinkedHashMap<>();
    final List<String> servers = new ArrayList<>();
    long start;

    @SuppressWarnings("unchecked")
    static ScenarioNetwork read(String path) throws Exception {
        Map<String, Object> scenario = (Map<String, Object>) new JsonReader(
            new String(Files.readAllBytes(Paths.get(path)), StandardCharsets.UTF_8)).value();
        ScenarioNetwork network = new ScenarioNetwork();
        network.build(scenario);
        return network;
    }

    /** The scenario's seed. */
    @SuppressWarnings("unchecked")
    static long seed(String path) throws Exception {
        Map<String, Object> scenario = (Map<String, Object>) new JsonReader(
            new String(Files.readAllBytes(Paths.get(path)), StandardCharsets.UTF_8)).value();
        return ((Number) scenario.get("seed")).longValue();
    }

    private void build(Map<String, Object> scenario) {
        Map<String, Port> ports = new HashMap<>();
        Map<String, NetzwerkInterface> nicsByPort = new HashMap<>();
        for (Object each : list(scenario.get("nodes"))) {
            Map<String, Object> node = map(each);
            String id = (String) node.get("id");
            String kind = (String) node.get("kind");
            List<Object> nodePorts = list(node.get("ports"));
            Knoten knoten;
            switch (kind) {
                case "pc":
                    knoten = new Rechner();
                    break;
                case "notebook":
                    knoten = new Notebook();
                    break;
                case "networkSwitch":
                    knoten = new Switch();
                    break;
                case "router":
                    knoten = new Vermittlungsrechner();
                    ((InternetKnoten) knoten).setzeAnzahlAnschluesse(nodePorts.size());
                    break;
                case "gateway":
                    // Its first card is the WAN port, its second the LAN port.
                    knoten = new Gateway();
                    break;
                default:
                    throw new IllegalArgumentException("node kind " + kind + " is not built by this tool");
            }
            knoten.setName(id);
            if (knoten instanceof InternetKnoten) {
                List<NetzwerkInterface> nics = ((InternetKnoten) knoten).getNetzwerkInterfaces();
                for (int index = 0; index < nodePorts.size(); index++) {
                    Map<String, Object> port = map(nodePorts.get(index));
                    NetzwerkInterface nic = nics.get(index);
                    String mac = port.containsKey("mac") ? (String) port.get("mac") : stableMac((String) port.get("id"));
                    nic.setMac(mac);
                    ports.put((String) port.get("id"), nic.getPort());
                    nicsByPort.put((String) port.get("id"), nic);
                    macByNode.put(index == 0 ? id : id + "#" + index, mac);
                }
            } else {
                LinkedList<Port> switchPorts = ((LokalerKnoten) knoten).getAnschluesse();
                for (int index = 0; index < nodePorts.size(); index++) {
                    ports.put((String) map(nodePorts.get(index)).get("id"), switchPorts.get(index));
                }
            }
            nodes.put(id, knoten);
        }
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("devices", new HashMap<>())).entrySet()) {
            Map<String, Object> device = map(entry.getValue());
            NetzwerkInterface nic = ((InternetKnoten) nodes.get(entry.getKey())).getNetzwerkInterfaces().get(0);
            nic.setIp((String) device.get("ip"));
            nic.setSubnetzMaske((String) device.get("mask"));
            nic.setGateway((String) device.getOrDefault("gateway", ""));
            nic.setDns((String) device.getOrDefault("dns", ""));
        }
        // A router's other cards: `interfaces` names them by port.
        for (Object each : list(scenario.getOrDefault("interfaces", new ArrayList<>()))) {
            Map<String, Object> item = map(each);
            NetzwerkInterface nic = nicsByPort.get(item.get("port"));
            nic.setIp((String) item.get("ip"));
            nic.setSubnetzMaske((String) item.get("mask"));
        }
        for (Object each : list(scenario.get("links"))) {
            Map<String, Object> link = map(each);
            Kabel cable = new Kabel();
            cable.setAnschluesse(new Port[] { ports.get(link.get("sourcePort")), ports.get(link.get("targetPort")) });
            cable.setWireless(Boolean.TRUE.equals(link.get("wireless")));
        }
        // A switch's SSID and learning time; a host's wireless card and the SSID
        // it joins. The SSIDs only the editor reads, to lay a wireless cable.
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("switches", new HashMap<>())).entrySet()) {
            Map<String, Object> config = map(entry.getValue());
            SwitchFirmware firmware = (SwitchFirmware) nodes.get(entry.getKey()).getSystemSoftware();
            firmware.setSSID((String) config.get("ssid"));
            // How long the switch keeps a learned MAC address (Java's default 300 s).
            if (config.containsKey("retention")) firmware.setRetentionTime(((Number) config.get("retention")).longValue());
        }
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("wireless", new HashMap<>())).entrySet()) {
            Betriebssystem os = (Betriebssystem) system(nodes.get(entry.getKey()));
            os.nicWireless(true);
            os.setSsid((String) map(entry.getValue()).get("ssid"));
        }
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("dhcpServers", new HashMap<>())).entrySet()) {
            Map<String, Object> config = map(entry.getValue());
            DHCPServer server = system(nodes.get(entry.getKey())).getDHCPServer();
            server.setUntergrenze((String) config.getOrDefault("lower", "0.0.0.0"));
            server.setObergrenze((String) config.getOrDefault("upper", "0.0.0.0"));
            server.setGatewayip((String) config.getOrDefault("gateway", "0.0.0.0"));
            server.setDnsserverip((String) config.getOrDefault("dns", "0.0.0.0"));
            server.setOwnSettings(Boolean.TRUE.equals(config.get("own")));
            for (Object assignment : list(config.getOrDefault("staticAssignments", new ArrayList<>()))) {
                server.addStaticAssignment((String) list(assignment).get(0), (String) list(assignment).get(1));
            }
            server.setAktiv(Boolean.TRUE.equals(config.get("active")));
            servers.add(entry.getKey());
        }
        // A DNS server: installed, its records written to /dns/hosts (TTL 3600), switched on.
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("dnsServers", new HashMap<>())).entrySet()) {
            Map<String, Object> config = map(entry.getValue());
            InternetKnotenBetriebssystem os = system(nodes.get(entry.getKey()));
            DNSServer dns = new DNSServer();
            dns.setSystemSoftware(os);
            os.getInstallierteAnwendungen().put("filius.software.dns.DNSServer", dns);
            for (Object line : list(config.getOrDefault("records", new ArrayList<>()))) {
                String[] parts = ((String) line).split(" ");
                dns.hinzuRecord(parts[0], parts[1], parts[2]);
            }
            dns.setRecursiveResolutionEnabled(Boolean.TRUE.equals(config.get("recursive")));
            dns.setAktiv(true);
            servers.add(entry.getKey());
        }
        for (Object each : list(scenario.getOrDefault("dhcpClients", new ArrayList<>()))) {
            system(nodes.get((String) each)).setDHCPKonfiguration(true);
        }
        // A home router's port forwarding: rows of protocol, public port, LAN address, LAN port.
        for (Map.Entry<String, Object> entry : map(scenario.getOrDefault("portForwarding", new HashMap<>())).entrySet()) {
            LinkedList<String[]> rows = new LinkedList<>();
            for (Object row : list(entry.getValue())) rows.add(list(row).stream().map(String::valueOf).toArray(String[]::new));
            ((GatewayFirmware) system(nodes.get(entry.getKey()))).setStaticNAT(rows);
        }
        for (Object each : list(scenario.getOrDefault("rip", new ArrayList<>()))) {
            ((VermittlungsrechnerBetriebssystem) system(nodes.get((String) each))).setRipEnabled(true);
        }

    }

    /** Starts the simulation; times in the log count from here. */
    void start() throws InterruptedException {
        // Switches and DHCP servers first: FILIUS' client waits for every active
        // server to have started (waitUntilDhcpServerStarted, through the GUI's
        // node list, which this tool has not got).
        // FILIUS' window exists before a simulation starts; created lazily and
        // unsynchronized, the first clients to ask for it would race.
        GUIContainer.getGUIContainer();
        start = System.currentTimeMillis();
        for (Map.Entry<String, Knoten> entry : nodes.entrySet()) {
            if (entry.getValue() instanceof Switch || servers.contains(entry.getKey())) entry.getValue().getSystemSoftware().starten();
        }
        Thread.sleep(200);
        for (Map.Entry<String, Knoten> entry : nodes.entrySet()) {
            if (!(entry.getValue() instanceof Switch || servers.contains(entry.getKey()))) entry.getValue().getSystemSoftware().starten();
        }
    }

    InternetKnotenBetriebssystem system(String nodeId) {
        return (InternetKnotenBetriebssystem) nodes.get(nodeId).getSystemSoftware();
    }

    /** Every frame each host's card saw, by node. */
    void writeFrames(Json out) throws Exception {
        Field field = Lauscher.class.getDeclaredField("datenEinheiten");
        field.setAccessible(true);
        @SuppressWarnings("unchecked")
        Map<String, LinkedList<Object[]>> log = (Map<String, LinkedList<Object[]>>) field.get(Lauscher.getLauscher());
        out.key("frames").open('{');
        for (Map.Entry<String, String> entry : macByNode.entrySet()) {
            out.key(entry.getKey()).open('[');
            LinkedList<Object[]> frames = log.get(entry.getValue());
            if (frames != null) {
                synchronized (frames) {
                    for (Object[] stamped : frames) frame(out, ((Long) stamped[0]) - start, (EthernetFrame) stamped[1]);
                }
            }
            out.close(']');
        }
        out.close('}');
        writeRows(out, "rows", true);
        writeRows(out, "layeredRows", false);
    }

    /**
     * The packet capture's table of each card as FILIUS shows it
     * (Lauscher.getDaten): with addresses and ports (`rows`, the data exchange
     * window) or ports only (`layeredRows`, the layered view). Each row: number,
     * source, destination, protocol, layer, comment — its time (the wall clock)
     * left out.
     */
    void writeRows(Json out, String key, boolean withAddresses) {
        out.key(key).open('{');
        for (Map.Entry<String, String> entry : macByNode.entrySet()) {
            out.key(entry.getKey()).open('[');
            for (Object[] row : Lauscher.getLauscher().getDaten(entry.getValue(), withAddresses, 1)) {
                out.open('[');
                for (int column = 0; column < row.length; column++) {
                    if (column == 1) continue;
                    out.string(row[column] == null ? null : String.valueOf(row[column]));
                }
                out.close(']');
            }
            out.close(']');
        }
        out.close('}');
    }

    /** Each host's address, mask, gateway and DNS server. */
    void writeDevices(Json out) {
        out.key("devices").open('{');
        for (Map.Entry<String, Knoten> entry : nodes.entrySet()) {
            if (!(entry.getValue() instanceof InternetKnoten)) continue;
            NetzwerkInterface nic = ((InternetKnoten) entry.getValue()).getNetzwerkInterfaces().get(0);
            out.key(entry.getKey()).open('[').string(nic.getIp()).string(nic.getSubnetzMaske()).string(nic.getGateway())
                .string(nic.getDns()).close(']');
        }
        out.close('}');
    }

    void stop() {
        for (Knoten knoten : nodes.values()) {
            try {
                knoten.getSystemSoftware().beenden();
            } catch (Exception e) {}
        }
    }

    static void write(String path, Json out) throws Exception {
        try (Writer writer = new OutputStreamWriter(new FileOutputStream(path), StandardCharsets.UTF_8)) {
            writer.write(out.toString());
            writer.write('\n');
        }
    }

    private static void frame(Json out, long time, EthernetFrame frame) {
        out.open('{').key("time").number(time).key("source").string(frame.getQuellMacAdresse()).key("destination")
            .string(frame.getZielMacAdresse());
        Object data = frame.getDaten();
        if (data instanceof ArpPaket) {
            ArpPaket arp = (ArpPaket) data;
            out.key("arp").number(arp.getOperation()).key("senderIp").string(arp.getSenderIP()).key("targetIp")
                .string(arp.getTargetIP());
        } else if (data instanceof IcmpPaket) {
            IcmpPaket icmp = (IcmpPaket) data;
            out.key("icmp").number(icmp.getIcmpType()).key("icmpCode").number(icmp.getIcmpCode()).key("sourceIp")
                .string(icmp.getSender()).key("destinationIp").string(icmp.getEmpfaenger()).key("sequence")
                .number(icmp.getSeqNr());
        } else if (data instanceof IpPaket) {
            IpPaket ip = (IpPaket) data;
            Segment segment = ip.getSegment();
            out.key("sourceIp").string(ip.getSender()).key("destinationIp").string(ip.getEmpfaenger()).key("protocol")
                .number(ip.getProtocol()).key("sourcePort").number(segment.getQuellPort()).key("destinationPort")
                .number(segment.getZielPort()).key("payload").string(segment.getDaten());
            if (segment instanceof TcpSegment) {
                TcpSegment tcp = (TcpSegment) segment;
                String flags = (tcp.isSyn() ? "S" : "") + (tcp.isAck() ? "A" : "") + (tcp.isFin() ? "F" : "")
                    + (tcp.isPush() ? "P" : "") + (tcp.isRst() ? "R" : "");
                out.key("tcpFlags").string(flags).key("sequence").number(tcp.getSeqNummer()).key("acknowledgement")
                    .number(tcp.getAckNummer());
            }
        }
        out.close('}');
    }

    private static InternetKnotenBetriebssystem system(Knoten knoten) {
        return (InternetKnotenBetriebssystem) knoten.getSystemSoftware();
    }

    /** The core's stableGeneratedMacAddress (packages/core/src/model/node.ts). */
    static String stableMac(String portId) {
        String compact = portId.toUpperCase().replace("-", "");
        String suffix = compact.substring(compact.length() - 10);
        StringBuilder mac = new StringBuilder("02");
        for (int offset = 0; offset < suffix.length(); offset += 2) mac.append(':').append(suffix, offset, offset + 2);
        return mac.toString();
    }

    @SuppressWarnings("unchecked")
    private static Map<String, Object> map(Object value) {
        return (Map<String, Object>) value;
    }

    @SuppressWarnings("unchecked")
    private static List<Object> list(Object value) {
        return (List<Object>) value;
    }

    /** Just enough JSON for a scenario: objects, arrays, strings, numbers, booleans, null. */
    static final class JsonReader {
        private final String text;
        private int position;

        JsonReader(String text) {
            this.text = text;
        }

        Object value() {
            skip();
            char c = text.charAt(position);
            if (c == '{') {
                Map<String, Object> result = new TreeMap<>();
                position++;
                skip();
                if (text.charAt(position) == '}') {
                    position++;
                    return result;
                }
                for (;;) {
                    skip();
                    String key = (String) value();
                    skip();
                    expect(':');
                    result.put(key, value());
                    skip();
                    if (text.charAt(position++) == '}') return result;
                }
            }
            if (c == '[') {
                List<Object> result = new ArrayList<>();
                position++;
                skip();
                if (text.charAt(position) == ']') {
                    position++;
                    return result;
                }
                for (;;) {
                    result.add(value());
                    skip();
                    if (text.charAt(position++) == ']') return result;
                }
            }
            if (c == '"') {
                StringBuilder result = new StringBuilder();
                position++;
                for (char each = text.charAt(position++); each != '"'; each = text.charAt(position++)) {
                    if (each == '\\') {
                        char escaped = text.charAt(position++);
                        switch (escaped) {
                            case 'n':
                                result.append('\n');
                                break;
                            case 't':
                                result.append('\t');
                                break;
                            case 'u':
                                result.append((char) Integer.parseInt(text.substring(position, position + 4), 16));
                                position += 4;
                                break;
                            default:
                                result.append(escaped);
                        }
                    } else {
                        result.append(each);
                    }
                }
                return result.toString();
            }
            if (text.startsWith("true", position)) {
                position += 4;
                return Boolean.TRUE;
            }
            if (text.startsWith("false", position)) {
                position += 5;
                return Boolean.FALSE;
            }
            if (text.startsWith("null", position)) {
                position += 4;
                return null;
            }
            int begin = position;
            while (position < text.length() && "+-.eE0123456789".indexOf(text.charAt(position)) >= 0) position++;
            return Double.parseDouble(text.substring(begin, position));
        }

        private void skip() {
            while (position < text.length() && Character.isWhitespace(text.charAt(position))) position++;
        }

        private void expect(char c) {
            if (text.charAt(position++) != c) throw new IllegalArgumentException("expected " + c + " at " + (position - 1));
        }
    }

    /** A JSON writer with commas and indentation. */
    static final class Json {
        private final StringBuilder text = new StringBuilder();
        private final LinkedList<Boolean> first = new LinkedList<>();
        private boolean afterKey;

        private void separate() {
            if (afterKey) {
                afterKey = false;
                return;
            }
            if (first.isEmpty()) return;
            if (!first.peek()) text.append(',');
            first.pop();
            first.push(false);
            text.append('\n');
            for (int i = 0; i < first.size(); i++) text.append("  ");
        }

        Json open(char bracket) {
            separate();
            text.append(bracket);
            first.push(true);
            return this;
        }

        Json close(char bracket) {
            boolean empty = first.pop();
            if (!empty) {
                text.append('\n');
                for (int i = 0; i < first.size(); i++) text.append("  ");
            }
            text.append(bracket);
            return this;
        }

        Json key(String key) {
            separate();
            quote(key);
            text.append(": ");
            afterKey = true;
            return this;
        }

        Json string(String value) {
            separate();
            if (value == null) text.append("null");
            else quote(value);
            return this;
        }

        Json number(long value) {
            separate();
            text.append(value);
            return this;
        }

        private void quote(String value) {
            text.append('"');
            for (char c : value.toCharArray()) {
                if (c == '"' || c == '\\') text.append('\\').append(c);
                else if (c == '\n') text.append("\\n");
                else if (c < 0x20) text.append(String.format("\\u%04x", (int) c));
                else text.append(c);
            }
            text.append('"');
        }

        @Override
        public String toString() {
            return text.toString();
        }
    }
}