// Regenerates src/panel/fonts/googleFontsCatalog.json, the font browser's offline list of Google
// Fonts families (name, category, weight axis or static weights, popularity rank). Development-time
// only: an app never fetches this list; it downloads font files natively when the owner installs
// one (fonts.googleapis.com / fonts.gstatic.com, see waybetter-host gfonts.rs and fonts.rs).
//
//   node packages/shell/scripts/google-fonts-catalog.mjs [metadata.json]
//
// Without an argument it reads https://fonts.google.com/metadata/fonts. Only families with a Latin
// subset and a name the native side accepts (letters, digits, single spaces) are kept.
import { readFileSync, writeFileSync } from 'node:fs';

const CATEGORY = { 'Sans Serif': 'sans', Serif: 'serif', Display: 'display', Handwriting: 'handwriting', Monospace: 'mono' };
const NAME = /^[A-Za-z0-9]+( [A-Za-z0-9]+)*$/;

const text = process.argv[2]
  ? readFileSync(process.argv[2], 'utf8')
  : await (await fetch('https://fonts.google.com/metadata/fonts')).text();
const metadata = JSON.parse(text.replace(/^\)\]\}'\s*/, ''));
const families = metadata.familyMetadataList
  .filter(font => font.subsets?.includes('latin') && NAME.test(font.family) && font.family.length <= 48 && CATEGORY[font.category])
  .sort((a, b) => a.popularity - b.popularity)
  .map((font, rank) => {
    const axis = font.axes?.find(item => item.tag === 'wght');
    const weights = Object.keys(font.fonts ?? {}).filter(key => /^\d+$/.test(key)).map(Number).sort((a, b) => a - b);
    return [font.family, CATEGORY[font.category], axis ? [axis.min, axis.max] : null, weights, rank + 1];
  });
const out = {
  source: 'https://fonts.google.com/metadata/fonts',
  generated: new Date().toISOString().slice(0, 10),
  fields: ['family', 'category', 'wghtAxis', 'weights', 'rank'],
  families,
};
writeFileSync(new URL('../src/panel/fonts/googleFontsCatalog.json', import.meta.url), `${JSON.stringify(out)}\n`);
console.log(`${families.length} families`);