#!/usr/bin/env node
/**
 * Idempotent GLB optimization gate. Runs from deploy.sh BEFORE vite build.
 *
 * Why this exists: the farm emits 1–8 MB PBR GLBs. Shipped raw, 27 of them were
 * 27.3 MB; through `gltf-transform optimize` they are 7.0 MB with the same PBR.
 * That step used to live in my head, which is not a build system. An asset added
 * by hand — or by a farm run that skipped the post-step — would silently ship raw.
 *
 * Skips anything already carrying EXT_meshopt_compression, so it is safe to run
 * every deploy and costs ~0s when there is nothing new.
 */
import { execFileSync } from 'node:child_process';
import { readdirSync, readFileSync, statSync, renameSync, rmSync } from 'node:fs';
import { join } from 'node:path';

const DIR = new URL('../public/assets/models/', import.meta.url).pathname;
const MAX_KB = 900; // per-asset ceiling; a farm regression should fail the build

/** Read the GLB JSON chunk without a glTF library. */
function meta(path) {
  const b = readFileSync(path);
  if (b.length < 20 || b.subarray(0, 4).toString() !== 'glTF') return null;
  const jsonLen = b.readUInt32LE(12);
  try {
    return JSON.parse(b.subarray(20, 20 + jsonLen).toString());
  } catch {
    return null;
  }
}

const files = readdirSync(DIR).filter((f) => f.endsWith('.glb'));
let optimized = 0, skipped = 0, before = 0, after = 0;
const oversize = [];

for (const f of files) {
  const p = join(DIR, f);
  const sizeBefore = statSync(p).size;
  before += sizeBefore;
  const m = meta(p);
  if (m?.extensionsRequired?.includes('EXT_meshopt_compression')) {
    skipped++;
    after += sizeBefore;
  } else {
    const tmp = `${p}.opt`;
    execFileSync('npx', ['--yes', '@gltf-transform/cli@latest', 'optimize', p, tmp,
      '--texture-compress', 'webp', '--texture-size', '1024',
      '--simplify-error', '0.002', '--compress', 'meshopt'],
      { stdio: 'pipe', timeout: 900_000 });
    rmSync(p);
    renameSync(tmp, p);
    optimized++;
    after += statSync(p).size;
    console.log(`  optimized ${f}: ${(sizeBefore / 1024) | 0} KB -> ${(statSync(p).size / 1024) | 0} KB`);
  }
  const kb = (statSync(p).size / 1024) | 0;
  if (kb > MAX_KB) oversize.push(`${f} (${kb} KB)`);
}

console.log(`assets: ${files.length} files, ${optimized} optimized, ${skipped} already lean — ` +
  `${(before / 1048576).toFixed(1)} MB -> ${(after / 1048576).toFixed(1)} MB`);

if (oversize.length) {
  console.error(`\nFAIL: ${oversize.length} asset(s) over ${MAX_KB} KB after optimization:`);
  for (const o of oversize) console.error(`  ${o}`);
  console.error('A mesh this heavy usually means the bake used too dense a pipeline ' +
    '(trellis2 1024_cascade produces ~487k tris; hunyuan3d_mlx is the machine default).');
  process.exit(1);
}