/**
 * workerManager.test.ts — Unit test S37 WorkerManager Safari-safe
 *
 * Copre:
 *  - ensureSpawned: spawn via factory iniettata (DI)
 *  - ensureSpawned: ritorna stesso worker se già spawned
 *  - ensureSpawned: resetta lastUsedAt ad ogni chiamata
 *  - terminate: rimuove handle, chiama worker.terminate()
 *  - terminateAll: termina tutti i worker registrati
 *  - getStatus: "unknown" per worker non spawned
 *  - getStatus: spawned=true dopo ensureSpawned
 *  - onStatusChange: listener chiamato su notify (onerror)
 *  - Idle timer: worker terminato dopo idle timeout (fake timers)
 *  - Idle timer reset: ensureSpawned posticipa l'idle timeout
 *  - isWorkerSupported: false in Node.js test environment
 *  - Risposta "ready": health diventa "alive"
 *  - Risposta "pong": lastPingMs viene settato
 *
 * Pattern DI: _setWorkerFactory(mockFactory) / _resetWorkerFactory()
 * Fake timers: vi.useFakeTimers() per controllare idle timeout senza attesa reale
 *
 * SESSIONE: S37 — WorkerManager Safari-safe
 * S246-Fix: factory ora riceve WorkerType invece di url string
 */

import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import {
  WorkerManager,
  _setWorkerFactory,
  _resetWorkerFactory,
} from "@/lib/runtime/WorkerManager";
import type { WorkerLike, WorkerType } from "@/lib/runtime/WorkerManager";

// ─── Mock Worker factory ──────────────────────────────────────────────────────

interface MockWorker extends WorkerLike {
  _sentMessages:    unknown[];
  _triggerMessage: (data: unknown) => void;
  _triggerError:   () => void;
}

function makeMockWorker(): MockWorker {
  const _sentMessages: unknown[] = [];
  let _onmessage: ((ev: MessageEvent) => void) | null = null;
  let _onerror:   ((ev: ErrorEvent) => void) | null   = null;

  const mock: MockWorker = {
    _sentMessages,

    get onmessage() { return _onmessage; },
    set onmessage(fn) { _onmessage = fn as ((ev: MessageEvent) => void) | null; },

    get onerror() { return _onerror; },
    set onerror(fn) { _onerror = fn as ((ev: ErrorEvent) => void) | null; },

    postMessage(msg: unknown) { _sentMessages.push(msg); },
    terminate:   vi.fn(),

    addEventListener: vi.fn(),
    removeEventListener: vi.fn(),

    _triggerMessage(data: unknown) {
      _onmessage?.({ data } as MessageEvent);
    },
    _triggerError() {
      _onerror?.({} as ErrorEvent);
    },
  };

  return mock;
}

// S246-Fix: factory riceve WorkerType (non url string)
let lastMock: MockWorker;
function mockFactory(_type: WorkerType): MockWorker {
  lastMock = makeMockWorker();
  return lastMock;
}

// ─── Setup / Teardown ─────────────────────────────────────────────────────────

let wm: WorkerManager;

beforeEach(() => {
  vi.useFakeTimers();
  _setWorkerFactory(mockFactory);
  wm = new WorkerManager(500); // idle timeout breve (500ms) per test veloci
});

afterEach(() => {
  wm.terminateAll();
  _resetWorkerFactory();
  vi.useRealTimers();
  vi.restoreAllMocks();
});

// ─── getStatus ────────────────────────────────────────────────────────────────

it("1. getStatus: ritorna status 'unknown' per worker non spawned", () => {
  const s = wm.getStatus("js");
  expect(s.spawned).toBe(false);
  expect(s.health).toBe("unknown");
  expect(s.spawnCount).toBe(0);
  expect(s.lastUsedAt).toBeNull();
});

it("2. getStatus: spawned=true e health='unknown' subito dopo ensureSpawned", () => {
  wm.ensureSpawned("js");
  const s = wm.getStatus("js");
  expect(s.spawned).toBe(true);
  expect(s.health).toBe("unknown"); // nessun "ready" ricevuto ancora
});

// ─── ensureSpawned ────────────────────────────────────────────────────────────

it("3. ensureSpawned: usa factory iniettata — postMessage ping iniziale", () => {
  wm.ensureSpawned("js");
  expect(lastMock._sentMessages).toHaveLength(1);
  expect((lastMock._sentMessages[0] as { type: string }).type).toBe("ping");
});

it("4. ensureSpawned: ritorna lo stesso worker alla seconda chiamata", () => {
  const w1 = wm.ensureSpawned("js");
  const w2 = wm.ensureSpawned("js");
  expect(w1).toBe(w2);
});

it("5. ensureSpawned: aggiorna lastUsedAt ad ogni chiamata", () => {
  wm.ensureSpawned("js");
  const t1 = wm.getStatus("js").lastUsedAt!;

  vi.advanceTimersByTime(100);
  wm.ensureSpawned("js");
  const t2 = wm.getStatus("js").lastUsedAt!;

  expect(t2).toBeGreaterThanOrEqual(t1);
});

it("6. ensureSpawned: spawnCount incrementa solo al primo spawn", () => {
  wm.ensureSpawned("js");
  wm.ensureSpawned("js");
  expect(wm.getStatus("js").spawnCount).toBe(1);
});

// ─── ready / pong ─────────────────────────────────────────────────────────────

it("7. messaggio 'ready': health diventa 'alive', failedPings = 0", () => {
  wm.ensureSpawned("js");
  lastMock._triggerMessage({ type: "ready" });
  const s = wm.getStatus("js");
  expect(s.health).toBe("alive");
  expect(s.failedPings).toBe(0);
});

it("8. messaggio 'pong': lastPingMs viene settato, health rimane alive", () => {
  wm.ensureSpawned("js");
  lastMock._triggerMessage({ type: "ready" });

  const handle = (wm as unknown as { handles: Map<string, { pendingPing: unknown; status: { lastPingMs: number | null } }> }).handles.get("js")!;
  handle.pendingPing = { resolve: vi.fn(), reject: vi.fn(), sentAt: Date.now() - 42 };
  lastMock._triggerMessage({ type: "pong" });

  expect(wm.getStatus("js").lastPingMs).toBeGreaterThanOrEqual(40);
});

// ─── terminate ────────────────────────────────────────────────────────────────

it("9. terminate: rimuove handle e chiama worker.terminate()", () => {
  wm.ensureSpawned("js");
  expect(wm.getStatus("js").spawned).toBe(true);
  wm.terminate("js");
  expect(wm.getStatus("js").spawned).toBe(false);
  expect(lastMock.terminate).toHaveBeenCalled();
});

it("10. terminateAll: termina tutti i worker registrati", () => {
  const m1 = (wm.ensureSpawned("js") as MockWorker);
  const m2 = (wm.ensureSpawned("py") as MockWorker);
  wm.terminateAll();
  expect(m1.terminate).toHaveBeenCalled();
  expect(m2.terminate).toHaveBeenCalled();
  expect(wm.getStatus("js").spawned).toBe(false);
  expect(wm.getStatus("py").spawned).toBe(false);
});

// ─── onStatusChange ───────────────────────────────────────────────────────────

it("11. onStatusChange: listener chiamato quando onerror triggera", () => {
  const changes: string[] = [];
  wm.onStatusChange(s => changes.push(s.health));

  wm.ensureSpawned("js");
  lastMock._triggerError();

  expect(changes).toContain("dead");
});

it("12. onStatusChange: unsub rimuove il listener", () => {
  const changes: string[] = [];
  const unsub = wm.onStatusChange(s => changes.push(s.health));
  unsub();

  wm.ensureSpawned("js");
  lastMock._triggerMessage({ type: "ready" });

  expect(changes).toHaveLength(0);
});

// ─── Idle timeout (S37) ────────────────────────────────────────────────────────

it("13. idle timeout: worker terminato automaticamente dopo idleTimeoutMs", () => {
  wm.ensureSpawned("js");
  lastMock._triggerMessage({ type: "ready" });

  vi.advanceTimersByTime(499);
  expect(wm.getStatus("js").spawned).toBe(true);

  vi.advanceTimersByTime(2);
  expect(wm.getStatus("js").spawned).toBe(false);
  expect(lastMock.terminate).toHaveBeenCalled();
});

it("14. idle timer reset: ensureSpawned posticipa l'idle timeout", () => {
  wm.ensureSpawned("js");
  lastMock._triggerMessage({ type: "ready" });

  vi.advanceTimersByTime(400);
  wm.ensureSpawned("js");
  vi.advanceTimersByTime(400);

  expect(wm.getStatus("js").spawned).toBe(true);

  vi.advanceTimersByTime(200);
  expect(wm.getStatus("js").spawned).toBe(false);
});

// ─── isWorkerSupported ────────────────────────────────────────────────────────

it("15. isWorkerSupported: false in ambiente Node.js (senza browser Worker)", () => {
  expect(WorkerManager.isWorkerSupported()).toBe(false);
});