dorfteich/deploy/fonts/build-fonts.mjs

#!/usr/bin/env node
// Font catalog build step (ADR 0016): download each catalog family's WOFF2
// weights from google-webfonts-helper (upstream gstatic) and bake them into the
// web app under public/fonts/, plus generate the @font-face stylesheet. Run at
// image build time (the web Dockerfile) — no runtime download, no third-party
// request from a visitor's browser (CSP `font-src 'self'`).
//
//   node deploy/fonts/build-fonts.mjs
//
// Requires the shared package to be built (it owns the catalog). The build
// FAILS if any catalog entry lacks license info — attribution is mandatory.

import { mkdir, writeFile } from 'node:fs/promises';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';

const ROOT = join(dirname(fileURLToPath(import.meta.url)), '..', '..');
// Import from the built shared package directly — this script runs outside any
// workspace package, so `@dorfteich/shared` isn't resolvable by name here.
const { FONT_CATALOG, fontSlug } = await import(
  join(ROOT, 'packages', 'shared', 'dist', 'index.mjs')
);
const OUT_DIR = join(ROOT, 'apps', 'web', 'public', 'fonts');
const GWFH = 'https://gwfh.mranftl.com/api/fonts';
const SUBSETS = 'latin,latin-ext';

/** Reject a catalog that would ship a font without attribution (AC). */
function validateCatalog() {
  const bad = FONT_CATALOG.filter(
    (e) => !e.license || !e.licenseUrl || !e.family || e.weights.length === 0,
  );
  if (bad.length > 0) {
    throw new Error(
      `Font catalog entries missing license/weights: ${bad.map((e) => e.family).join(', ')}`,
    );
  }
}

const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms));

/** GET with a few retries — the image build depends on upstream (gwfh /
 * gstatic), so a transient hiccup must not fail the whole build. */
async function get(url) {
  let lastError;
  for (let attempt = 1; attempt <= 4; attempt += 1) {
    try {
      const res = await fetch(url);
      if (!res.ok) throw new Error(`GET ${url} → ${res.status}`);
      return res;
    } catch (error) {
      lastError = error;
      if (attempt < 4) await sleep(attempt * 1000);
    }
  }
  throw lastError;
}

async function fetchJson(url) {
  return (await get(url)).json();
}

async function fetchBytes(url) {
  return Buffer.from(await (await get(url)).arrayBuffer());
}

async function build() {
  validateCatalog();
  await mkdir(OUT_DIR, { recursive: true });
  const faces = [];
  let total = 0;

  for (const entry of FONT_CATALOG) {
    const slug = fontSlug(entry.family);
    const meta = await fetchJson(`${GWFH}/${entry.id}?subsets=${SUBSETS}`);
    const byWeight = new Map(
      meta.variants.filter((v) => v.fontStyle === 'normal').map((v) => [Number(v.fontWeight), v]),
    );
    await mkdir(join(OUT_DIR, slug), { recursive: true });
    for (const weight of entry.weights) {
      const variant = byWeight.get(weight);
      if (!variant) throw new Error(`${entry.family}: upstream has no weight ${weight}`);
      const bytes = await fetchBytes(variant.woff2);
      const file = `${slug}/${slug}-${weight}.woff2`;
      await writeFile(join(OUT_DIR, file), bytes);
      faces.push(
        `@font-face {\n` +
          `  font-family: '${entry.family}';\n` +
          `  font-style: normal;\n` +
          `  font-weight: ${weight};\n` +
          `  font-display: swap;\n` +
          `  src: url('/fonts/${file}') format('woff2');\n` +
          `}`,
      );
      total += bytes.length;
      console.log(
        `  ${entry.family} ${weight} → ${file} (${(bytes.length / 1024).toFixed(1)} KiB)`,
      );
    }
  }

  const header =
    '/* Generated by deploy/fonts/build-fonts.mjs (ADR 0016) — do not edit.\n' +
    '   Self-hosted catalog fonts; served only from this origin. */\n\n';
  await writeFile(join(OUT_DIR, 'catalog.css'), header + faces.join('\n\n') + '\n');
  console.log(
    `\nWrote ${faces.length} @font-face rules for ${FONT_CATALOG.length} families ` +
      `(${(total / 1024 / 1024).toFixed(2)} MiB) to ${OUT_DIR}`,
  );
}

build().catch((error) => {
  console.error(`font build failed: ${error.message}`);
  process.exit(1);
});