// usage: node split-css.mjs IN.css OUTDIR — extracts each distinct base64 data:image (png, svg+xml) url() into OUTDIR/img/<sha8>.<ext>
// and rewrites the CSS to url(img/<sha8>.<ext>). Anything else with data: is an error.
import { readFileSync, writeFileSync, mkdirSync } from 'node:fs';
import { createHash } from 'node:crypto';
const [inFile, outDir] = process.argv.slice(2);
const css = readFileSync(inFile, 'latin1');
mkdirSync(outDir + '/img', { recursive: true });
const ext = { png: 'png', 'svg+xml': 'svg' };
const seen = new Map();
const out = css.replace(/url\(\s*(["']?)data:image\/(png|svg\+xml);base64,([A-Za-z0-9+/=]*)\1\s*\)/g, (m, q, kind, data) => {
  const bytes = Buffer.from(data, 'base64');
  const name = createHash('sha256').update(bytes).digest('hex').slice(0, 8) + '.' + ext[kind];
  if (!seen.has(name)) { writeFileSync(`${outDir}/img/${name}`, bytes); seen.set(name, bytes.length); }
  return `url(img/${name})`;
});
if (/data:/.test(out)) throw new Error('data: left in output');
writeFileSync(outDir + '/toastui-editor.css', out, 'latin1');
console.log('data URIs in', (css.match(/data:/g) || []).length, '-> files', seen.size, JSON.stringify([...seen]));
console.log('css bytes in/out', css.length, out.length);