#!/usr/bin/env node
// Frame-by-frame renderer for a paused-GSAP ad page.
//
// The page must expose window.DURATION (seconds), window.seek(t) and
// window.ready (a promise that resolves once fonts and images are in).
//
//   node render.cjs --stills 0.4,3.2,6.6                 still-<t>.jpg per time
//   node render.cjs --out ad-16x9.mp4 [--web] [--poster 9.6]
//   node render.cjs --format 4x5 --out ad-4x5.mp4        1080×1350 cut
//
// Options: --page index.html  --format 16x9|4x5  --size WxH  --fps 30
//          --crf 18  --web (also writes <out>-web.mp4 at crf 25)
//          --poster <t> (writes <out>-poster.jpg)  --channel chrome|chromium
const { chromium } = require("playwright-core");
const { spawn } = require("child_process");
const path = require("path");
const ffmpeg = require("ffmpeg-static");

const arg = (k, d) => {
  const i = process.argv.indexOf(`--${k}`);
  if (i === -1) return d;
  const v = process.argv[i + 1];
  return v === undefined || v.startsWith("--") ? true : v;
};
const format = arg("format", "16x9");
const [W, H] = String(arg("size", format === "4x5" ? "1080x1350" : "1920x1080")).split("x").map(Number);
const fps = Number(arg("fps", 30));
const page = path.resolve(arg("page", "index.html"));

function run(bin, args) {
  return new Promise((resolve, reject) => {
    const p = spawn(bin, args, { stdio: ["ignore", "inherit", "pipe"] });
    let err = "";
    p.stderr.on("data", (d) => (err += d));
    p.on("close", (code) => (code === 0 ? resolve() : reject(new Error(err.slice(-2000)))));
  });
}

(async () => {
  const browser = await chromium.launch({ channel: arg("channel", "chrome") });
  const p = await browser.newPage({ viewport: { width: W, height: H }, deviceScaleFactor: 1 });
  p.on("pageerror", (e) => console.error("pageerror:", e.message));
  await p.goto(`file://${page}?render&format=${format}`, { waitUntil: "load" });
  await p.evaluate(() => window.ready);
  const duration = await p.evaluate(() => window.DURATION);

  const stills = arg("stills");
  if (stills) {
    for (const t of String(stills).split(",").map(Number)) {
      await p.evaluate((t) => window.seek(t), t);
      await p.screenshot({ path: `still-${t.toFixed(2)}.jpg`, type: "jpeg", quality: 90 });
    }
    console.log(`wrote ${String(stills).split(",").length} stills`);
    return browser.close();
  }

  const out = String(arg("out", `ad-${format}.mp4`));
  const ff = spawn(ffmpeg, ["-y", "-f", "image2pipe", "-framerate", String(fps), "-c:v", "png", "-i", "-",
    "-c:v", "libx264", "-preset", "slow", "-crf", String(arg("crf", 18)), "-pix_fmt", "yuv420p",
    "-profile:v", "high", "-movflags", "+faststart", "-r", String(fps), out], { stdio: ["pipe", "inherit", "pipe"] });
  let ffErr = "";
  ff.stderr.on("data", (d) => (ffErr += d));
  const frames = Math.round(duration * fps);
  const started = Date.now();
  for (let i = 0; i < frames; i++) {
    await p.evaluate((t) => window.seek(t), i / fps);
    const buf = await p.screenshot({ type: "png" });
    if (!ff.stdin.write(buf)) await new Promise((r) => ff.stdin.once("drain", r));
    if (i % 90 === 0) console.log(`frame ${i}/${frames}  ${((Date.now() - started) / 1000).toFixed(0)}s`);
  }
  ff.stdin.end();
  const code = await new Promise((r) => ff.on("close", r));
  await browser.close();
  if (code !== 0) throw new Error(ffErr.slice(-2000));
  console.log(`wrote ${out} (${frames} frames, ${W}×${H})`);

  const base = out.replace(/\.mp4$/, "");
  if (arg("web")) {
    // Smaller encode for web pages: visually close, roughly half the bytes.
    await run(ffmpeg, ["-v", "error", "-y", "-i", out, "-c:v", "libx264", "-preset", "slow", "-crf", "25",
      "-pix_fmt", "yuv420p", "-movflags", "+faststart", "-an", `${base}-web.mp4`]);
    console.log(`wrote ${base}-web.mp4`);
  }
  const poster = arg("poster");
  if (poster) {
    await run(ffmpeg, ["-v", "error", "-y", "-ss", String(poster), "-i", out, "-frames:v", "1", "-q:v", "2", `${base}-poster.jpg`]);
    console.log(`wrote ${base}-poster.jpg`);
  }
})().catch((e) => {
  console.error(e.message || e);
  process.exit(1);
});