#!/usr/bin/env node
/**
 * Post-process for prebake-firstacts: each first-act JSON has imageUrl pointing
 * at https://im.runware.ai/... which adds ~1-2s of remote-CDN download on first
 * click. This script downloads every imageUrl to public/home/firstscene/
 * (webp, compressed) and rewrites the JSON's imageUrl to the local /home/...
 * path, so click-to-play is bottlenecked only by JSON parse + local image
 * decode (sub-100ms).
 *
 * Idempotent: a JSON whose imageUrl already points at /home/firstscene/ is
 * skipped. Pass --force to re-download everything.
 *
 * Run once after prebake-firstacts.mjs completes:
 *   node scripts/localize-firstact-images.mjs
 */

import { fileURLToPath } from "node:url";
import { dirname, resolve, basename, extname } from "node:path";
import {
  existsSync,
  mkdirSync,
  writeFileSync,
  statSync,
  readdirSync,
  readFileSync,
} from "node:fs";
import sharp from "sharp";

const __dirname = dirname(fileURLToPath(import.meta.url));
const WEB_ROOT = resolve(__dirname, "..");
const FIRSTACT_DIR = resolve(WEB_ROOT, "public", "home", "firstact");
const FIRSTSCENE_DIR = resolve(WEB_ROOT, "public", "home", "firstscene");
const PUBLIC_LOCAL_PREFIX = "/home/firstscene/";
const MAX_EDGE = 1600;
const QUALITY = 80;

const FORCE = process.argv.includes("--force");

if (!existsSync(FIRSTACT_DIR)) {
  console.error(`Missing ${FIRSTACT_DIR} — run prebake-firstacts.mjs first.`);
  process.exit(2);
}
if (!existsSync(FIRSTSCENE_DIR)) mkdirSync(FIRSTSCENE_DIR, { recursive: true });

const files = readdirSync(FIRSTACT_DIR).filter((f) => f.toLowerCase().endsWith(".json"));
let downloaded = 0;
let skipped = 0;
let failed = 0;
let bytesIn = 0;
let bytesOut = 0;
const t0 = Date.now();

console.log(`[localize] ${files.length} JSONs → ${FIRSTSCENE_DIR}`);

for (const f of files) {
  const jsonPath = resolve(FIRSTACT_DIR, f);
  const name = basename(f, extname(f)); // m0, f31, etc.
  const localWebp = resolve(FIRSTSCENE_DIR, `${name}.webp`);
  const localPublicPath = `${PUBLIC_LOCAL_PREFIX}${name}.webp`;

  let json;
  try {
    json = JSON.parse(readFileSync(jsonPath, "utf8"));
  } catch (e) {
    failed++;
    console.log(`${name} FAIL parse: ${e.message}`);
    continue;
  }

  // Prefer the live `imageUrl`; fall back to `imageUrlRemote` when this JSON
  // has already been localized in a previous run (the Runware URL we want to
  // re-download lives there, not in `imageUrl`).
  const remote =
    json.imageUrl && json.imageUrl.startsWith("http")
      ? json.imageUrl
      : json.imageUrlRemote;
  const url = remote;
  if (!url) {
    failed++;
    console.log(`${name} FAIL: no Runware URL (imageUrl/imageUrlRemote)`);
    continue;
  }

  if (
    !FORCE &&
    typeof json.imageUrl === "string" &&
    json.imageUrl.startsWith(PUBLIC_LOCAL_PREFIX) &&
    existsSync(localWebp)
  ) {
    skipped++;
    console.log(`${name} skip (already local)`);
    continue;
  }

  if (!url.startsWith("http")) {
    failed++;
    console.log(`${name} FAIL: Runware URL not http(s): ${url.slice(0, 60)}`);
    continue;
  }

  // Runware URLs have a finite TTL — once they 404, the prebaked first-act
  // becomes unplayable. Localizing the JSON pointer is the durable fix; the
  // bytes themselves only need to be re-downloaded when the local webp is
  // actually missing. If the webp is already on disk (44 of 60 today), skip
  // the network and just rewrite the JSON to point at it.
  const localWebpExists = existsSync(localWebp);

  const t = Date.now();
  try {
    let outSize;
    if (localWebpExists && !FORCE) {
      outSize = statSync(localWebp).size;
    } else {
      const res = await fetch(url);
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const buf = Buffer.from(await res.arrayBuffer());
      bytesIn += buf.length;

      // Downscale to 1600px long edge (Runware paints at 1792×1024 by default —
      // the player canvas never needs more than ~1200-1600). Then webp 80.
      const img = sharp(buf);
      const meta = await img.metadata();
      const longEdge = Math.max(meta.width ?? 0, meta.height ?? 0);
      const resized = longEdge > MAX_EDGE
        ? img.resize({
            width: (meta.width ?? 0) >= (meta.height ?? 0) ? MAX_EDGE : undefined,
            height: (meta.height ?? 0) > (meta.width ?? 0) ? MAX_EDGE : undefined,
          })
        : img;
      await resized.webp({ quality: QUALITY, effort: 5 }).toFile(localWebp);

      outSize = statSync(localWebp).size;
      bytesOut += outSize;
    }

    json.imageUrl = localPublicPath;
    // scene.imageUrl is the same image one level deeper — both fields are
    // surfaced by /api/start to the play page, so we localize them in lockstep
    // to keep the JSON self-consistent.
    if (json.scene && typeof json.scene === "object") {
      json.scene.imageUrl = localPublicPath;
    }
    json.imageUrlRemote = url; // keep the Runware URL around for forensics
    writeFileSync(jsonPath, JSON.stringify(json));
    downloaded++;
    if (localWebpExists && !FORCE) {
      console.log(`${name} ok (webp existed, rewrote JSON only) ${(outSize / 1024).toFixed(0)} KB`);
    } else {
      console.log(
        `${name} ok ${(bytesIn ? "" : "")}→ ${(outSize / 1024).toFixed(0)} KB in ${((Date.now() - t) / 1000).toFixed(1)}s`,
      );
    }
  } catch (e) {
    failed++;
    console.log(`${name} FAIL: ${e.message}`);
  }
}

console.log(
  `\n[localize] done in ${Math.round((Date.now() - t0) / 1000)}s — wrote ${downloaded} / skipped ${skipped} / failed ${failed}\n` +
    `[localize] bytes ${(bytesIn / 1024 / 1024).toFixed(1)} MB → ${(bytesOut / 1024 / 1024).toFixed(2)} MB`,
);
process.exit(failed ? 1 : 0);