import { spawn } from 'node:child_process';

const FLAGS = [
  '--headless',
  '--hide-scrollbars',
  /**
   * Measured (idle editor, 20 s): software WebGL 373% of a core at 8 fps, HD 630 via ANGLE/Vulkan 69% at
   * 56 fps; no software fallback on purpose. `--use-angle=gl` and `--use-gl=egl` get no WebGL context at all.
   */
  '--use-angle=vulkan',
  '--ignore-gpu-blocklist',
  '--enable-gpu',
  '--enable-features=Vulkan',
  // None of this serves a headless check, and its stderr was full of GCM sign-in retries.
  '--disable-background-networking',
  '--disable-sync',
  '--disable-extensions',
  '--no-first-run',
  '--mute-audio',
];

/** Starts chromium with the CDP port open; `proc.stderr` carries its last words. */
export function launchBrowser({ port, width, height }) {
  const proc = spawn(
    'chromium',
    // --no-sandbox: this container runs as root, where chromium refuses to start otherwise.
    [
      ...FLAGS,
      '--no-sandbox',
      `--remote-debugging-port=${port}`,
      `--window-size=${width},${height}`,
      'about:blank',
    ],
    { stdio: ['ignore', 'ignore', 'pipe'] },
  );
  return { proc, stop: () => proc.kill('SIGTERM'), where: 'local chromium' };
}