#!/usr/bin/env node

/**
 * perf/hidden-timers.mjs
 *
 * Verifies that non-playback UI intervals are paused when the page is hidden
 * and restored when the page becomes visible again.
 *
 * Assertions:
 *   - While hidden: none of [chips, reanchor, rotateChips, flush, checkBuildTag] is live.
 *   - After becoming visible again: all five gated intervals are live.
 *   - Must-run intervals (e.g. maybeCheck, 120s resume check) remain live while hidden.
 *   - No page errors during lifecycle transitions.
 *   - Exits non-zero on failure.
 */

import { spawn } from 'node:child_process';
import { existsSync, mkdirSync, rmSync, symlinkSync } from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const REPO_ROOT = path.resolve(__dirname, '..');

let pw;
try {
  pw = await import('playwright');
} catch {
  pw = await import(path.join(REPO_ROOT, 'node_modules', 'playwright', 'index.mjs'));
}
const { chromium } = pw;

const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

async function main() {
  const scratchDir = path.join(REPO_ROOT, 'perf', '.tmp', `hidden-timers-${Date.now()}`);
  mkdirSync(scratchDir, { recursive: true });
  const dataDir = path.join(scratchDir, 'data');
  mkdirSync(dataDir, { recursive: true });
  const srvCwd = path.join(scratchDir, 'srv');
  mkdirSync(srvCwd, { recursive: true });
  const publicLink = path.join(srvCwd, 'public');
  symlinkSync(path.join(REPO_ROOT, 'frontend'), publicLink);

  const port = 4900 + Math.floor(Math.random() * 2000);
  const serverProcess = spawn('bun', [path.join(REPO_ROOT, 'server', 'server.js')], {
    cwd: srvCwd,
    env: {
      ...process.env,
      PORT: String(port),
      DATA_DIR: dataDir,
      DB_PATH: path.join(dataDir, 'ytplayer.db'),
      MEDIA_DIR: path.join(dataDir, 'media'),
    },
    stdio: 'ignore',
  });

  const cleanup = () => {
    try {
      if (serverProcess) serverProcess.kill('SIGKILL');
    } catch {}
    try {
      rmSync(scratchDir, { recursive: true, force: true });
    } catch {}
  };

  process.on('SIGINT', () => { cleanup(); process.exit(1); });
  process.on('SIGTERM', () => { cleanup(); process.exit(1); });

  let browser;
  try {
    let ready = false;
    for (let i = 0; i < 50; i++) {
      try {
        const res = await fetch(`http://127.0.0.1:${port}/api/version`);
        if (res.ok) {
          ready = true;
          break;
        }
      } catch {}
      await sleep(100);
    }
    if (!ready) {
      throw new Error(`Bun server failed to start on port ${port}`);
    }

    browser = await chromium.launch({ headless: true });
    const ctx = await browser.newContext({
      viewport: { width: 390, height: 844 },
      hasTouch: true,
      isMobile: true,
      serviceWorkers: 'block',
    });

    await ctx.addInitScript(() => {
      const act = new Map();
      const si = window.setInterval.bind(window);
      const ci = window.clearInterval.bind(window);
      window.setInterval = (fn, ms, ...a) => {
        const id = si(fn, ms, ...a);
        act.set(id, (fn && fn.name) || 'anon' + ms);
        return id;
      };
      window.clearInterval = (id) => {
        act.delete(id);
        return ci(id);
      };
      window.__names = () => [...act.values()].sort();
    });

    const page = await ctx.newPage();
    const pageErrors = [];
    page.on('pageerror', (err) => pageErrors.push(err.message));

    await page.goto(`http://127.0.0.1:${port}/index.html`);
    await page.waitForTimeout(1500);

    const getNames = async () => (await page.evaluate(() => window.__names()));
    const gated = ['chips', 'reanchor', 'rotateChips', 'flush', 'checkBuildTag'];
    const mustRun = ['maybeCheck', 'anon120000'];

    const vt = await page.evaluate(() => typeof window.VisibleTimer);
    if (vt !== 'object') {
      throw new Error(`VisibleTimer not available on window (got ${vt})`);
    }

    // 1. Initial visible state
    const visible1 = await getNames();
    const visibleGated = gated.filter((g) => visible1.includes(g));

    // 2. Transition to hidden
    await page.evaluate(() => {
      Object.defineProperty(document, 'hidden', { configurable: true, get: () => true });
      Object.defineProperty(document, 'visibilityState', { configurable: true, get: () => 'hidden' });
      document.dispatchEvent(new Event('visibilitychange'));
    });
    await page.waitForTimeout(300);
    const hidden = await getNames();
    const hiddenGated = gated.filter((g) => hidden.includes(g));

    // 3. Transition back to visible
    await page.evaluate(() => {
      Object.defineProperty(document, 'hidden', { configurable: true, get: () => false });
      Object.defineProperty(document, 'visibilityState', { configurable: true, get: () => 'visible' });
      document.dispatchEvent(new Event('visibilitychange'));
    });
    await page.waitForTimeout(300);
    const visible2 = await getNames();
    const backVisibleGated = gated.filter((g) => visible2.includes(g));

    console.log('=== Hidden Timers Verification ===');
    console.log(`Initial visible intervals (${visible1.length}):`, visible1.join(', '));
    console.log(`Hidden intervals (${hidden.length}):`, hidden.join(', '));
    console.log(`Restored visible intervals (${visible2.length}):`, visible2.join(', '));
    console.log('Page errors:', pageErrors.length ? pageErrors.join(', ') : 'none');

    // Assertions
    const failures = [];

    // Assert all 5 gated timers were live initially
    for (const name of gated) {
      if (!visible1.includes(name)) {
        failures.push(`Expected '${name}' to be live initially`);
      }
    }

    // Assert none of the 5 gated timers is live while hidden
    if (hiddenGated.length > 0) {
      failures.push(`Expected 0 gated timers while hidden, but found: ${hiddenGated.join(', ')}`);
    }

    // Assert all 5 gated timers are live after becoming visible again
    for (const name of gated) {
      if (!visible2.includes(name)) {
        failures.push(`Expected '${name}' to be live after becoming visible again`);
      }
    }

    // Assert must-run timers stay live while hidden
    for (const name of mustRun) {
      if (!hidden.includes(name)) {
        failures.push(`Expected must-run timer '${name}' to stay live while hidden`);
      }
    }

    // Assert no page errors
    if (pageErrors.length > 0) {
      failures.push(`Encountered page errors: ${pageErrors.join('; ')}`);
    }

    if (failures.length > 0) {
      console.error('\nFAILURES:');
      for (const f of failures) console.error(`  - ${f}`);
      process.exitCode = 1;
    } else {
      console.log('\nResult: ALL ASSERTIONS PASSED');
    }
  } finally {
    if (browser) await browser.close();
    cleanup();
  }
}

main().catch((err) => {
  console.error('Fatal error in hidden-timers check:', err);
  process.exit(1);
});