// Render-regression harness: every screenplay's pinned beats, screenshot
// under a paused Playwright clock, diffed pixel-by-pixel against the
// goldens in deploy/scene-goldens/. The clock is what makes the pixels
// reproducible — pulsing rings, tweens, and fx all advance only when the
// harness says so, so the same beat renders the same bytes every run.
//
//   npx tsx deploy/verify-scenes.mjs            # verify all scenes
//   npx tsx deploy/verify-scenes.mjs --update   # re-bless the goldens
//   npx tsx deploy/verify-scenes.mjs the-rout   # one scene (mixes with --update)
//
// Run from the repo root AFTER `npx vite build` in packages/web (the
// wrapper deploy/verify-scenes.sh does both). Needs the Playwright
// chromium cache (`npx playwright-core install chromium` if missing).
import { execFileSync, spawn } from "node:child_process";
import { existsSync, mkdirSync, mkdtempSync, readFileSync, readdirSync, rmSync, writeFileSync } from "node:fs";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { chromium } from "playwright-core";
import { SCREENPLAYS } from "../packages/web/src/fpv/screenplays.ts";

const args = process.argv.slice(2);
const update = args.includes("--update");
const only = args.filter((a) => !a.startsWith("--"));
const GOLDENS = join(import.meta.dirname, "scene-goldens");
const DIFFS = join(tmpdir(), "wizwar-scene-diffs");
const PORT = 8807;
// A channel may drift this far before a pixel counts as different, and
// this fraction of pixels may differ before a beat fails — headroom for
// raster jitter, far below any real regression.
const CHANNEL_TOL = 6;
const FAIL_FRAC = 0.002;
const EPOCH = new Date("2026-01-01T00:00:00Z").getTime();

function chromiumExe() {
  if (process.env.WIZWAR_CHROME) return process.env.WIZWAR_CHROME;
  const cache = join(process.env.HOME ?? "", "Library", "Caches", "ms-playwright");
  const builds = existsSync(cache)
    ? readdirSync(cache).filter((d) => /^chromium-\d+$/.test(d)).sort()
    : [];
  for (const build of builds.reverse()) {
    const exe = join(cache, build, "chrome-mac-arm64",
      "Google Chrome for Testing.app", "Contents", "MacOS", "Google Chrome for Testing");
    if (existsSync(exe)) return exe;
  }
  throw new Error("no Playwright chromium found — run: npx playwright-core install chromium (or set WIZWAR_CHROME)");
}

/** Decode a PNG to raw RGBA via ffmpeg — the harness's only image dep. */
function rgba(png) {
  return execFileSync("ffmpeg", ["-loglevel", "error", "-i", png,
    "-f", "rawvideo", "-pix_fmt", "rgba", "-"], { maxBuffer: 64 * 1024 * 1024 });
}

function compare(goldenPng, actualPng) {
  const a = rgba(goldenPng), b = rgba(actualPng);
  if (a.length !== b.length) return { frac: 1, why: "size differs" };
  let bad = 0;
  for (let i = 0; i < a.length; i += 4) {
    if (Math.abs(a[i] - b[i]) > CHANNEL_TOL ||
        Math.abs(a[i + 1] - b[i + 1]) > CHANNEL_TOL ||
        Math.abs(a[i + 2] - b[i + 2]) > CHANNEL_TOL) bad++;
  }
  return { frac: bad / (a.length / 4), why: null };
}

// --- A private server on a throwaway data dir. ---------------------------
const dataDir = mkdtempSync(join(tmpdir(), "wizwar-scenes-"));
const server = spawn("npx", ["tsx", "src/index.ts"], {
  cwd: join(import.meta.dirname, "..", "packages", "server"),
  env: { ...process.env, PORT: String(PORT), WIZWAR_DATA_DIR: join(dataDir, "rooms") },
  stdio: "ignore",
});
const up = async () => {
  for (let i = 0; i < 60; i++) {
    try {
      const r = await fetch(`http://127.0.0.1:${PORT}/`);
      if (r.ok) return;
    } catch { /* not yet */ }
    await new Promise((r) => setTimeout(r, 500));
  }
  throw new Error("server never came up");
};

let failures = 0;
try {
  await up();
  mkdirSync(GOLDENS, { recursive: true });
  rmSync(DIFFS, { recursive: true, force: true });
  mkdirSync(DIFFS, { recursive: true });
  const browser = await chromium.launch({
    executablePath: chromiumExe(),
    args: ["--disable-gpu", "--force-color-profile=srgb", "--font-render-hinting=none"],
  });
  const scenes = SCREENPLAYS.filter((sp) => !only.length || only.includes(sp.name));
  if (!scenes.length) throw new Error(`no scenes match: ${only.join(", ")}`);

  for (const sp of scenes) {
    // One page per view: the reel steps forward beat to beat under the
    // paused clock, so a scene's later beats cost only their marginal
    // steps — and every beat's simulated capture time is still exactly
    // (steps so far) × 2.6s, identical every run.
    const takes = [
      { view: "fpv", beats: [...(sp.beats ?? [])].sort((a, b) => a - b) },
      { view: "board", beats: sp.boardBeat === undefined ? [] : [sp.boardBeat] },
    ];
    for (const { view, beats } of takes) {
      if (!beats.length) continue;
      const ctx = await browser.newContext({ viewport: { width: 1280, height: 900 }, deviceScaleFactor: 1 });
      const page = await ctx.newPage();
      await page.clock.install({ time: EPOCH });
      await page.goto(`http://127.0.0.1:${PORT}/?fpv&script=${sp.name}`, { waitUntil: "networkidle" });
      await page.locator("button", { hasText: "❚❚" }).click();
      for (let i = 0; i < 4; i++) await page.locator("button", { hasText: "◀" }).click();
      if (view === "fpv") await page.getByText("your eyes").click();
      // Freeze the world at a fixed instant, then advance it by hand.
      // Steps on the way to a beat get 0.6 simulated seconds; the beat
      // itself gets 2.6 to settle its tween, hold, and fx. The schedule
      // is fixed, so every run renders the same bytes.
      await page.clock.pauseAt(EPOCH + 60_000);
      let at = 0;
      for (const beat of beats) {
        for (; at < beat; at++) {
          await page.locator("button", { hasText: "▶" }).last().click();
          await page.clock.runFor(at === beat - 1 ? 2600 : 600);
        }
        const box = await page.locator(".replay").boundingBox();
        const name = `${sp.name}-s${beat}-${view}.png`;
        const golden = join(GOLDENS, name);
        const shot = update ? golden : join(DIFFS, name);
        await page.screenshot({
          path: shot,
          clip: { x: Math.round(box.x), y: Math.round(box.y), width: Math.round(box.width), height: Math.round(box.height) },
        });
        if (update) {
          console.log(`blessed ${name}`);
        } else if (!existsSync(golden)) {
          console.log(`MISSING golden ${name} — run with --update`);
          failures++;
        } else {
          const { frac, why } = compare(golden, shot);
          if (why || frac > FAIL_FRAC) {
            console.log(`FAIL ${name}: ${why ?? `${(frac * 100).toFixed(2)}% of pixels drifted`} (actual kept at ${shot})`);
            failures++;
          } else {
            console.log(`OK   ${name}`);
          }
        }
      }
      await ctx.close();
    }
  }
  await browser.close();
} finally {
  server.kill();
  rmSync(dataDir, { recursive: true, force: true });
}
if (!update) console.log(`--- ${failures ? `${failures} beat(s) drifted` : "every pinned beat matches its golden"}`);
process.exit(failures ? 1 : 0);