// The echo server and the generic client as Java FILIUS runs them.
// tools/java-oracle's EchoRun played stories of the two programs on tcp-lan's
// network in Java FILIUS and wrote every frame each card saw, Java's tables
// of them, and every line each program wrote into its window
// (echo-java-<story>.java.json). The engine plays the same stories with its
// programs (apps/echo.ts): each card's frames must come in the same order,
// with the same content and rows, at about the same time; each program's
// lines must read as Java's (its German message bundle), in the same order,
// at about the same time.
//
// Java's client looks every 100 ms whether it is connected
// (TCPSocket.verbinden), its server likewise whether a connection came
// (ServerSocket.oeffnen) or it was switched off; the engine at once. Those
// lines come in Java up to POLL_MILLISECONDS later.

import { readFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { describe, expect, it } from 'vitest';
import { withSnapshot, type LogLine, type NetworkRuntimeEngine } from '../src/index.js';
import { expectSameCaptures, GAP_TOLERANCE_MILLISECONDS, watchedEngine, withClientPortText, type JavaFrame, type JavaTables } from './javaRun.js';
import { clientText, CONNECT_FAILURES, isPolled, POLL_MILLISECONDS, serverText } from './programLines.js';
import { snapshotOf, type Scenario } from './scenario.js';

const scenarioDirectory = join(dirname(fileURLToPath(import.meta.url)), 'scenarios');

const SERVER = '00000000-0000-0000-0000-000000000101';
const CLIENT = '00000000-0000-0000-0000-000000000102';
const OTHER_CLIENT = '00000000-0000-0000-0000-000000000103';

type Program = 'server' | 'client' | 'other';

interface JavaRun extends JavaTables {
  frames: Record<string, JavaFrame[]>;
  /** Time, program, and a line of its window or one of the story's calls ("call …", "returned …"). */
  events: [number, Program, string][];
}


type Act = (engine: NetworkRuntimeEngine) => void;
const server = (engine: NetworkRuntimeEngine) => engine.echoServer(SERVER)!;
const client = (engine: NetworkRuntimeEngine) => engine.simpleClient(CLIENT)!;
const other = (engine: NetworkRuntimeEngine) => engine.simpleClient(OTHER_CLIENT)!;

/** Each story's calls at their times, as EchoRun makes them. */
const STORIES: Record<string, [number, Act][]> = {
  exchange: [
    [500, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [2000, (engine) => client(engine).send('Hallo')],
    [4000, (engine) => client(engine).send('Welt')],
    [6000, (engine) => client(engine).disconnect()],
  ],
  closedPort: [[500, (engine) => client(engine).connect('192.168.0.30', 55555)]],
  noRoute: [[500, (engine) => client(engine).connect('10.0.0.1', 55555)]],
  notConnected: [[500, (engine) => client(engine).send('Hallo')]],
  serverOff: [
    [500, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [2000, (engine) => server(engine).setActive(false)],
    [4000, (engine) => client(engine).send('Hallo')],
    [6000, (engine) => server(engine).setActive(true)],
    [7000, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [9000, (engine) => client(engine).send('Welt')],
  ],
  reconnect: [
    [500, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [2000, (engine) => client(engine).disconnect()],
    [4000, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [6000, (engine) => client(engine).send('Hallo')],
  ],
  twoClients: [
    [500, (engine) => client(engine).connect('192.168.0.10', 55555)],
    [1000, (engine) => other(engine).connect('192.168.0.10', 55555)],
    [2000, (engine) => client(engine).send('eins')],
    [3000, (engine) => other(engine).send('zwei')],
    [4000, (engine) => client(engine).disconnect()],
    [5000, (engine) => other(engine).disconnect()],
  ],
  otherPort: [
    [500, (engine) => server(engine).setActive(false)],
    [
      1500,
      (engine) => {
        server(engine).setPort(7);
        server(engine).setActive(true);
      },
    ],
    [2000, (engine) => client(engine).connect('192.168.0.10', 7)],
    [4000, (engine) => client(engine).send('Hallo')],
    [6000, (engine) => other(engine).connect('192.168.0.10', 55555)],
  ],
};

/** The windows' lines, time and text, per program. */
type Lines = Record<Program, [number, string][]>;

function javaLines(java: JavaRun): Lines {
  const lines: Lines = { server: [], client: [], other: [] };
  for (const [time, program, text] of java.events) {
    // Anwendung.starten tells its observers nothing (null), which the window skips.
    if (text === 'null' || text.startsWith('call ') || text.startsWith('returned ')) continue;
    lines[program].push([time, withClientPortText(text)]);
  }
  return lines;
}

function engineLines(engine: NetworkRuntimeEngine): Lines {
  const lines = <E>(log: readonly LogLine<E>[], text: (entry: E) => string): [number, string][] =>
    log.map((line) => [line.timeMilliseconds, withClientPortText(text(line))]);
  return {
    server: lines(server(engine).log.all, serverText),
    client: lines(client(engine).log.all, clientText),
    other: lines(other(engine).log.all, clientText),
  };
}

/** Java's timeout of a TCP attempt (3 round trips at 90 %), and the round trip of a frame between two cards on the switch. */
const JAVA_TIMEOUT_MILLISECONDS = 3 * 2_750;
const CARD_TO_CARD_MILLISECONDS = 111;

/** NumberFormat for Locale.GERMANY. */
const javaNumber = (value: number) => String(value).replace(/\B(?=(\d{3})+(?!\d))/g, '.');

/** Java's rows of a TCP segment without data (Lauscher.datenVorbereiten), with addresses or ports only. */
function tcpRows(number: number, frame: JavaFrame, withAddresses: boolean): (string | null)[][] {
  const end = (address: string, port: number) => (withAddresses ? `${address}:${port}` : String(port));
  return [
    [String(number), frame.source, frame.destination, '', 'Netzzugang', '0x800'],
    [String(number), frame.sourceIp!, frame.destinationIp!, 'IP', 'Vermittlung', 'Protokoll: 6, TTL: 64'],
    [
      String(number),
      end(frame.sourceIp!, frame.sourcePort!),
      end(frame.destinationIp!, frame.destinationPort!),
      'TCP',
      'Transport',
      `SEQ: ${javaNumber(frame.sequence!)}, ACK: ${javaNumber(frame.acknowledgement!)}`,
    ],
  ];
}

/** Java's run with a frame more on a card, in time order, its rows numbered in. */
function withJavaFrame(java: JavaRun, card: string, frame: JavaFrame): JavaRun {
  const frames = java.frames[card]!;
  const index = frames.filter((each) => each.time <= frame.time).length;
  const renumbered = (rows: (string | null)[][], withAddresses: boolean) => [
    ...rows.map((row) => (Number(row[0]) > index ? [String(Number(row[0]) + 1), ...row.slice(1)] : row)),
    ...tcpRows(index + 1, frame, withAddresses),
  ];
  return {
    ...java,
    frames: { ...java.frames, [card]: [...frames.slice(0, index), frame, ...frames.slice(index)] },
    rows: { ...java.rows, [card]: renumbered(java.rows![card]!, true) },
    layeredRows: { ...java.layeredRows, [card]: renumbered(java.layeredRows![card]!, false) },
  };
}

/** When the program last called verbinden: its SYN goes down then, and the attempt's time runs from there. */
const lastConnect = (java: JavaRun, program: Program) => java.events.filter(([, who, text]) => who === program && text.startsWith('call verbinden')).at(-1)![0];

/** Java's connection attempt with one SYN: its failure two attempts later, when the third has timed out. */
function failingAfterThreeAttempts(java: JavaRun, program: Program): JavaRun {
  return {
    ...java,
    events: java.events.map(([time, who, text]) =>
      who === program && text.startsWith('Fehler beim Verbindungsaufbau\n') ? [time + 2 * JAVA_TIMEOUT_MILLISECONDS, who, text] : [time, who, text],
    ),
  };
}

/**
 * Where Java errs, per story: its run corrected, as Java means it.
 *
 * noRoute: the client's socket finds no route for its SYN; the exception
 * ends the socket's thread, and verbinden waits for ever for a state that
 * never comes — the client hangs without a word (and is no longer usable).
 * The engine's connection fails at once (sw_tcpsocket_msg3).
 *
 * closedPort, otherPort: Java's client sends one SYN, not three
 * (tcpJava.test.ts, closedPort); its connection fails two attempts later in
 * the engine.
 *
 * serverOff: switched off, Java's server frees its port (ServerSocket
 * .schliessen) while its connections still close; the client's FIN finds
 * no socket and goes unanswered, the client waits in LAST_ACK in vain. The
 * engine's server answers it with its ACK.
 */
const JAVA_BUGS: Record<string, (java: JavaRun) => JavaRun> = {
  noRoute: (java) => ({
    ...java,
    events: [...java.events, [java.events.find(([, , text]) => text.startsWith('call verbinden'))![0], 'client', `Fehler beim Verbindungsaufbau\n${CONNECT_FAILURES.failed}`]],
  }),
  closedPort: (java) => failingAfterThreeAttempts(java, 'client'),
  otherPort: (java) => failingAfterThreeAttempts(java, 'other'),
  serverOff: (java) => {
    const fin = java.frames[SERVER]!.filter((frame) => frame.tcpFlags === 'F').at(-1)!;
    const ack: JavaFrame = {
      ...fin,
      source: fin.destination,
      destination: fin.source,
      sourceIp: fin.destinationIp!,
      destinationIp: fin.sourceIp!,
      sourcePort: fin.destinationPort!,
      destinationPort: fin.sourcePort!,
      tcpFlags: 'A',
      sequence: java.frames[SERVER]!.find((frame) => frame.tcpFlags === 'F')!.sequence! + 1,
      acknowledgement: fin.sequence! + 1,
    };
    return withJavaFrame(withJavaFrame(java, SERVER, ack), CLIENT, { ...ack, time: fin.time + CARD_TO_CARD_MILLISECONDS });
  },
};

/**
 * Where each card's capture is compared only up to a time (Java's).
 * closedPort, otherPort: the engine's second and third SYN come when the
 * switch has forgotten the server (tcp-lan: 5 s) and floods them to every
 * card; compared up to the second.
 */
const CAPTURE_UNTIL: Record<string, (java: JavaRun) => number> = {
  closedPort: (java) => lastConnect(java, 'client') + JAVA_TIMEOUT_MILLISECONDS - GAP_TOLERANCE_MILLISECONDS,
  otherPort: (java) => lastConnect(java, 'other') + JAVA_TIMEOUT_MILLISECONDS - GAP_TOLERANCE_MILLISECONDS,
};

describe('the echo server and the generic client as Java FILIUS runs them', () => {
  it('cuts only where the engine goes on beyond Java', () => {
    for (const [name, until] of Object.entries(CAPTURE_UNTIL)) {
      const java = JSON.parse(readFileSync(join(scenarioDirectory, `echo-java-${name}.java.json`), 'utf8')) as JavaRun;
      const cut = until(java);
      expect(Object.values(java.frames).flat().every((frame) => frame.time < cut), name).toBe(true);
    }
  });

  it('corrects Java only where it errs', () => {
    for (const [name, correct] of Object.entries(JAVA_BUGS)) {
      const java = JSON.parse(readFileSync(join(scenarioDirectory, `echo-java-${name}.java.json`), 'utf8')) as JavaRun;
      expect(JSON.stringify(correct(java)), name).not.toBe(JSON.stringify(java));
    }
  });

  const scenario = JSON.parse(readFileSync(join(scenarioDirectory, 'tcp-lan.scenario.json'), 'utf8')) as Scenario;
  const snapshot = withSnapshot(snapshotOf(scenario), {
    echoServersByNodeId: new Map([[SERVER, { port: 55555, isActive: true }]]),
    simpleClientsByNodeId: new Map([
      [CLIENT, { targetAddress: '', targetPort: 55555 }],
      [OTHER_CLIENT, { targetAddress: '', targetPort: 55555 }],
    ]),
  });

  for (const [name, acts] of Object.entries(STORIES)) {
    it(name, () => {
      const measured = JSON.parse(readFileSync(join(scenarioDirectory, `echo-java-${name}.java.json`), 'utf8')) as JavaRun;
      const java = JAVA_BUGS[name]?.(measured) ?? measured;
      const { engine } = watchedEngine(scenario, snapshot);
      for (const [time, act] of acts) {
        engine.handle({ type: 'advance', toMilliseconds: time });
        act(engine);
      }
      engine.handle({ type: 'advance', toMilliseconds: Math.max(...java.events.map(([time]) => time)) + 5_000 });

      expectSameCaptures(engine, scenario, java.frames, { text: withClientPortText, until: CAPTURE_UNTIL[name]?.(measured), tables: java });

      const expected = javaLines(java);
      const actual = engineLines(engine);
      for (const program of ['server', 'client', 'other'] as const) {
        expect(actual[program].map(([, text]) => text), `${program}'s lines`).toEqual(expected[program].map(([, text]) => text));
        for (const [index, [javaTime, text]] of expected[program].entries()) {
          const late = javaTime - actual[program][index]![0];
          const [least, most] = isPolled(text) ? [-GAP_TOLERANCE_MILLISECONDS, POLL_MILLISECONDS + GAP_TOLERANCE_MILLISECONDS] : [-GAP_TOLERANCE_MILLISECONDS, GAP_TOLERANCE_MILLISECONDS];
          expect(late, `${program}'s line ${JSON.stringify(text)}: Java ${late} ms later`).toBeGreaterThanOrEqual(least);
          expect(late, `${program}'s line ${JSON.stringify(text)}: Java ${late} ms later`).toBeLessThanOrEqual(most);
        }
      }
    });
  }
});