// RIP as Java FILIUS runs it. tools/java-oracle's RipRun ran rip-chain's
// network in Java FILIUS, each router's pauses drawn from the random the core
// seeds (ripSeed), and wrote every frame each card saw, every change of each
// router's RIP table and the story's calls (rip-java-<story>.java.json). The
// engine plays the same story: the frames must come in the same order, with
// the same content, at about the same distance from each other (javaRun.ts);
// each table must go through the same states at about the same times; the
// calls must return the same.
//
// Java starts the routers some 200 ms after the network (ScenarioNetwork
// starts switches and servers first), one after the other; the engine starts
// all at once. The story's calls come at Java's times less that offset, taken
// from the first RIP message (a router's first beacon comes a second after
// its start). Frames that leave different cards within a few milliseconds
// come in Java in the order its threads happen to run, and its packet log
// misses a sender's own frame when several send at once (then the receiver's
// entry, a cable later, counts): the frames are compared per sending card, in
// order, each at about the same time. A table state Java's poll (every 2 ms)
// could not see — the engine's lasts less than STATE_UNSEEN_MILLISECONDS — is
// left out.
//
// The first seconds depend on the order Java's routers start in: one that
// hears a neighbour before its own first beacon sends the learned route with
// it, where the engine's routers, started together, send their own networks
// first and then at once what they learned. Up to STARTUP_MILLISECONDS
// (Java's time) the tables must reach the same state, and frames are not
// compared; after it, every frame and every change.

import { readFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { describe, expect, it } from 'vitest';
import { RIP_FIRST_BEACON_DELAY_MILLISECONDS, type Id, type IPv4DeliveryResult, type NetworkRuntimeEngine } from '../src/index.js';
import { GAP_TOLERANCE_MILLISECONDS, javaFrames, watchedEngine, type JavaFrame, type SeenFrame } from './javaRun.js';
import type { Scenario } from './scenario.js';

const scenarioDirectory = join(dirname(fileURLToPath(import.meta.url)), 'scenarios');
const PC_A = '00000000-0000-0000-0000-000000000401';
const R3 = '00000000-0000-0000-0000-000000000404';
const STATE_UNSEEN_MILLISECONDS = 5;
const STARTUP_MILLISECONDS = 5_000;

/** The frames by the card that sent them (the source MAC address), each list in order. */
function bySender(frames: readonly SeenFrame[], shift: number): Map<string, SeenFrame[]> {
  const result = new Map<string, SeenFrame[]>();
  for (const frame of frames) {
    const sender = frame.text.slice(0, 17);
    const list = result.get(sender) ?? [];
    list.push({ time: frame.time - shift, text: frame.text });
    result.set(sender, list);
  }
  return result;
}

interface JavaRun {
  frames: Record<string, JavaFrame[]>;
  events: [number, string][];
  tables: [number, Id, string][];
}

/** A ping's result in Java's words: the answer's type and code, or null. */
function pingResult(result: IPv4DeliveryResult, engine: NetworkRuntimeEngine): string {
  if (result.type === 'icmpError') return result.kind === 'destinationNetworkUnreachable' ? 'ICMP 3/0' : `ICMP ${result.kind}`;
  const answered = (engine.state.icmpObservationsByNodeId.get(PC_A) ?? []).some((observation) => observation.message.kind === 'echoReply');
  return answered ? 'ICMP 0/0' : 'null';
}

type Story = (engine: NetworkRuntimeEngine, at: (javaMilliseconds: number) => void, call: (label: string, run: () => string) => void) => void;

const STORIES: Record<string, Story> = {
  converge: (engine, at, call) => {
    at(45_000);
    call('sendProbe 10.0.3.2', () => pingResult(engine.sendIcmpEcho(PC_A, '10.0.3.2'), engine));
  },
  expire: (engine, at, call) => {
    at(10_000);
    // RipRun sets R3's next beacon to never: it sends no more (unless a change sends at once).
    engine.state.pendingEvents = engine.state.pendingEvents.filter((event) => !(event.kind.kind === 'ripBeacon' && event.kind.nodeId === R3));
    at(125_000);
    call('sendProbe 10.0.3.2', () => pingResult(engine.sendIcmpEcho(PC_A, '10.0.3.2'), engine));
  },
};

/** The table as RipRun writes it: `network/mask gateway interface hops; …`. */
function tableText(engine: NetworkRuntimeEngine, nodeId: Id): string {
  return (engine.state.ripTablesByNodeId.get(nodeId) ?? [])
    .map((route) => `${route.destinationNetwork}/${route.subnetMask} ${route.nextHop} ${route.interfaceIPAddress} ${route.metric}`)
    .join('; ');
}

describe('RIP as Java FILIUS runs it', () => {
  const scenario = JSON.parse(readFileSync(join(scenarioDirectory, 'rip-chain.scenario.json'), 'utf8')) as Scenario;

  for (const [name, story] of Object.entries(STORIES)) {
    it(name, () => {
      const java = JSON.parse(readFileSync(join(scenarioDirectory, `rip-java-${name}.java.json`), 'utf8')) as JavaRun;
      const offset = Math.min(...javaFrames(java.frames).filter((frame) => frame.text.includes(':521 >')).map((frame) => frame.time)) - RIP_FIRST_BEACON_DELAY_MILLISECONDS;
      const { engine, frames } = watchedEngine(scenario);

      // Every change of a table, after each event.
      const tables: [number, Id, string][] = [];
      const routers = [...engine.state.ripTablesByNodeId.keys()];
      const last = new Map<Id, string>();
      const poll = () => {
        for (const router of routers) {
          const text = tableText(engine, router);
          if (last.get(router) === text) continue;
          last.set(router, text);
          tables.push([engine.state.currentTimeMilliseconds, router, text]);
        }
      };
      poll();
      const target = engine as unknown as { processScheduledRuntimeEvent: (kind: unknown) => void };
      const process = target.processScheduledRuntimeEvent.bind(engine);
      target.processScheduledRuntimeEvent = (kind) => {
        process(kind);
        poll();
      };

      const events: [number, string][] = [];
      story(
        engine,
        (javaMilliseconds) => engine.handle({ type: 'advance', toMilliseconds: javaMilliseconds - offset }),
        (label, run) => {
          events.push([engine.state.currentTimeMilliseconds, `${label} called`]);
          const result = run();
          events.push([engine.state.currentTimeMilliseconds, `${label} returned ${result}`]);
        },
      );
      const end = Math.max(...Object.values(java.frames).flat().map((frame) => frame.time), ...java.tables.map(([time]) => time));
      engine.handle({ type: 'advance', toMilliseconds: end - offset + 1_000 });

      const startup = STARTUP_MILLISECONDS - offset;
      const expected = bySender(javaFrames(java.frames).filter((frame) => frame.time >= STARTUP_MILLISECONDS), offset);
      const actual = bySender(frames().filter((frame) => frame.time >= startup), 0);
      expect([...actual.keys()].sort()).toEqual([...expected.keys()].sort());
      for (const [sender, javaList] of expected) {
        const engineList = actual.get(sender)!;
        for (let index = 0; index < Math.max(javaList.length, engineList.length); index += 1) {
          expect(engineList[index]?.text, `${sender} frame #${index + 1}`).toBe(javaList[index]?.text);
          expect(Math.abs(engineList[index]!.time - javaList[index]!.time), `${sender} time of frame #${index + 1}`).toBeLessThanOrEqual(GAP_TOLERANCE_MILLISECONDS);
        }
      }

      // Each router's table: the same state when the startup is over, then the same changes at about the same times.
      for (const router of routers) {
        const settled = <T extends [number, Id, string]>(states: T[], until: number): T[] => {
          const before = states.filter(([time]) => time < until);
          return [...before.slice(-1), ...states.filter(([time]) => time >= until)];
        };
        const javaStates = settled(java.tables.filter(([, node]) => node === router), STARTUP_MILLISECONDS);
        const all = tables.filter(([, node]) => node === router);
        const engineStates = settled(
          all.filter(([time], index) => index === all.length - 1 || all[index + 1]![0] - time >= STATE_UNSEEN_MILLISECONDS),
          startup,
        );
        expect(engineStates.map(([, , text]) => text), router).toEqual(javaStates.map(([, , text]) => text));
        for (const [index, [time]] of engineStates.entries()) {
          if (index === 0) continue;
          expect(Math.abs(time - (javaStates[index]![0] - offset)), `${router} state #${index + 1}`).toBeLessThanOrEqual(GAP_TOLERANCE_MILLISECONDS);
        }
      }

      const javaCalls = java.events.filter(([, event]) => event.startsWith('sendProbe'));
      expect(events.map(([, event]) => event)).toEqual(javaCalls.map(([, event]) => event.replace(/ from .*$/, '')));
      expect(Math.abs(events[1]![0] - events[0]![0] - (javaCalls[1]![0] - javaCalls[0]![0])), 'duration of the ping').toBeLessThanOrEqual(GAP_TOLERANCE_MILLISECONDS);
    });
  }
});