const assert = require('node:assert/strict');
const fs = require('node:fs');
const net = require('node:net');
const path = require('node:path');
const { spawn } = require('node:child_process');

const RUNFILES = process.env.JS_BINARY__RUNFILES;
const WORKSPACE = process.env.JS_BINARY__WORKSPACE;
let port;
let baseUrl;
const playwrightPath = path.join(
  RUNFILES,
  WORKSPACE,
  'hg-web/e2e/node_modules/playwright-core',
);
const { chromium } = require(playwrightPath);

function stopProcess(child) {
  if (!child || child.exitCode !== null) return Promise.resolve();
  child.kill('SIGTERM');
  return new Promise(resolve => {
    const timer = setTimeout(() => {
      if (child.exitCode === null) child.kill('SIGKILL');
    }, 3000);
    child.once('exit', () => {
      clearTimeout(timer);
      resolve();
    });
  });
}

async function waitForServer(child, logs) {
  const deadline = Date.now() + 15000;
  while (Date.now() < deadline) {
    if (child.exitCode !== null) {
      throw new Error(`Server exited with ${child.exitCode}\n${logs.join('')}`);
    }
    try {
      const response = await fetch(baseUrl);
      if (response.ok) return;
    } catch {
      // Keep waiting for startup.
    }
    await new Promise(resolve => setTimeout(resolve, 100));
  }
  throw new Error(`Server startup timed out\n${logs.join('')}`);
}

function listFiles(root) {
  const files = [];
  for (const entry of fs.readdirSync(root, { withFileTypes: true })) {
    const absolute = path.join(root, entry.name);
    if (entry.isDirectory()) files.push(...listFiles(absolute));
    else files.push(absolute);
  }
  return files;
}

async function sampleTheme(browser, theme) {
  const context = await browser.newContext({ colorScheme: 'dark' });
  await context.addInitScript(value => {
    localStorage.setItem('theme-preference', value);
  }, theme);
  const page = await context.newPage();
  const errors = [];
  page.on('pageerror', error => errors.push(`pageerror: ${error.message}`));
  page.on('console', message => {
    if (message.type() === 'error') errors.push(`console: ${message.text()}`);
  });
  page.on('requestfailed', request => {
    errors.push(`requestfailed: ${request.url()} ${request.failure()?.errorText || ''}`);
  });
  page.on('response', response => {
    if (response.status() >= 400) {
      errors.push(`response: ${response.status()} ${response.url()}`);
    }
  });

  await page.goto(baseUrl, { waitUntil: 'networkidle' });
  await page.waitForFunction(() => {
    const canvas = document.querySelector('#background');
    if (!canvas) return false;
    const data = canvas.getContext('2d').getImageData(
      0,
      0,
      canvas.width,
      canvas.height,
    ).data;
    for (let index = 3; index < data.length; index += 4) {
      if (data[index] >= 20) return true;
    }
    return false;
  });

  const sample = await page.evaluate(() => {
    const canvas = document.querySelector('#background');
    const data = canvas.getContext('2d').getImageData(
      0,
      0,
      canvas.width,
      canvas.height,
    ).data;
    let count = 0;
    let luminance = 0;
    for (let index = 0; index < data.length; index += 4) {
      if (data[index + 3] < 20) continue;
      count++;
      luminance +=
        data[index] * 0.2126 +
        data[index + 1] * 0.7152 +
        data[index + 2] * 0.0722;
    }
    return {
      count,
      luminance: count ? luminance / count : 0,
      rootClass: document.documentElement.className,
    };
  });

  if (errors.length) throw new Error(`${theme}\n${errors.join('\n')}`);
  await context.close();
  return sample;
}

function findFreePort() {
  return new Promise((resolve, reject) => {
    const socket = net.createServer();
    socket.once('error', reject);
    socket.listen(0, '127.0.0.1', () => {
      const address = socket.address();
      socket.close(error => {
        if (error) reject(error);
        else resolve(String(address.port));
      });
    });
  });
}

(async () => {
  assert.ok(RUNFILES);
  assert.ok(WORKSPACE);
  const runfilesWorkspace = path.join(RUNFILES, WORKSPACE);
  const serverBinary = path.join(
    runfilesWorkspace,
    'mrjunejune/mrjunejune_server',
  );
  const siteRoot = path.join(runfilesWorkspace, 'mrjunejune/src');
  const chromiumPath = path.resolve(process.env.CHROMIUM_PATH);
  const serverLogs = [];
  let server;
  let browser;

  try {
    port = await findFreePort();
    baseUrl = `http://127.0.0.1:${port}`;
    const pngFiles = listFiles(siteRoot).filter(file => file.endsWith('.png'));
    assert.deepEqual(pngFiles, [], `PNG files leaked into runfiles: ${pngFiles}`);

    server = spawn(serverBinary, [], {
      cwd: runfilesWorkspace,
      env: { ...process.env, MRJUNEJUNE_PORT: port },
      stdio: ['ignore', 'pipe', 'pipe'],
    });
    server.stdout.on('data', chunk => serverLogs.push(chunk.toString()));
    server.stderr.on('data', chunk => serverLogs.push(chunk.toString()));
    await waitForServer(server, serverLogs);

    const home = await (await fetch(baseUrl)).text();
    const dogGame = await (
      await fetch(`${baseUrl}/public/dog-game.js`)
    ).text();
    const manifest = await (
      await fetch(`${baseUrl}/public/manifest.json`)
    ).text();
    for (const source of [home, dogGame, manifest]) {
      assert.doesNotMatch(source, /\.png(?:["')]|$)/i);
    }

    for (const asset of [
      'sprite_shiba0.webp',
      'dog-treat.webp',
      'start-large.webp',
      'icon-192.webp',
      'vscode.webp',
    ]) {
      const response = await fetch(`${baseUrl}/public/${asset}`);
      assert.equal(response.status, 200, asset);
      assert.ok((await response.arrayBuffer()).byteLength > 0, asset);
    }

    browser = await chromium.launch({
      executablePath: chromiumPath,
      headless: true,
      args: ['--no-sandbox'],
    });
    const light = await sampleTheme(browser, 'light');
    const dark = await sampleTheme(browser, 'dark');
    assert.ok(light.count > 0);
    assert.ok(dark.count > 0);
    assert.ok(light.luminance < 175, JSON.stringify(light));
    assert.ok(dark.luminance > 200, JSON.stringify(dark));
  } finally {
    if (browser) await browser.close();
    await stopProcess(server);
  }
})().catch(error => {
  console.error(error.stack || error);
  process.exitCode = 1;
});