LexAI/packages/website/inject-seo.mjs

import { mkdirSync, readFileSync, writeFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';

const root = dirname(fileURLToPath(import.meta.url));
const distHtml = join(root, 'dist', 'index.html');
const { origin, routes } = JSON.parse(
  readFileSync(join(root, 'src', 'seo.routes.json'), 'utf8'),
);
const faq = JSON.parse(readFileSync(join(root, 'src', 'faq.json'), 'utf8'));

const CHROME_STORE =
  'https://chromewebstore.google.com/detail/bagpcheidbkfgijnnmolnkgagibbjfnk';
const VSCODE_MARKETPLACE =
  'https://marketplace.visualstudio.com/items?itemName=JuanKibin.lexai-vscode';
const REPO = 'https://git.juankibin.space/kibin/LexAI';

const homeDescription = routes.find((r) => r.path === '/')?.description ?? '';

function softwareGraph() {
  return {
    '@type': 'SoftwareApplication',
    name: 'LexAI',
    applicationCategory: 'BrowserApplication',
    applicationSubCategory: 'Writing assistance',
    operatingSystem: 'Chrome, VS Code, Windows, macOS, Linux',
    url: `${origin}/`,
    downloadUrl: [CHROME_STORE, VSCODE_MARKETPLACE],
    license: `${REPO}/src/branch/main/LICENSE`,
    sameAs: [REPO, CHROME_STORE, VSCODE_MARKETPLACE],
    offers: { '@type': 'Offer', price: '0', priceCurrency: 'USD' },
  };
}

function jsonLd(route) {
  const url = route.path === '/' ? `${origin}/` : `${origin}${route.path}`;
  const graph = [
    {
      '@type': 'WebSite',
      name: 'LexAI',
      url: `${origin}/`,
      description: homeDescription,
    },
    softwareGraph(),
  ];
  if (route.path === '/') {
    graph.push({
      '@type': 'FAQPage',
      mainEntity: faq.map((item) => ({
        '@type': 'Question',
        name: item.q,
        acceptedAnswer: { '@type': 'Answer', text: item.a },
      })),
    });
  } else {
    graph.push({
      '@type': 'BreadcrumbList',
      itemListElement: [
        { '@type': 'ListItem', position: 1, name: 'Home', item: `${origin}/` },
        { '@type': 'ListItem', position: 2, name: route.title, item: url },
      ],
    });
  }
  return JSON.stringify({ '@context': 'https://schema.org', '@graph': graph });
}

function apply(html, { title, description, url, robots, ld }) {
  let out = html;
  out = out.replace(/<title>[\s\S]*?<\/title>/, `<title>${title}</title>`);
  out = out.replace(
    /(<meta\s+name="description"\s+content=")[^"]*(")/,
    `$1${description}$2`,
  );
  out = out.replace(/(<meta\s+name="robots"\s+content=")[^"]*(")/, `$1${robots}$2`);
  out = out.replace(/(<meta\s+property="og:title"\s+content=")[^"]*(")/, `$1${title}$2`);
  out = out.replace(
    /(<meta\s+property="og:description"\s+content=")[^"]*(")/,
    `$1${description}$2`,
  );
  out = out.replace(/(<meta\s+property="og:url"\s+content=")[^"]*(")/, `$1${url}$2`);
  out = out.replace(/(<meta\s+name="twitter:title"\s+content=")[^"]*(")/, `$1${title}$2`);
  out = out.replace(
    /(<meta\s+name="twitter:description"\s+content=")[^"]*(")/,
    `$1${description}$2`,
  );
  out = out.replace(/(<link\s+rel="canonical"\s+href=")[^"]*(")/, `$1${url}$2`);
  out = out.replace(
    /<script type="application\/ld\+json">[\s\S]*?<\/script>/,
    `<script type="application/ld+json">${ld}</script>`,
  );
  return out;
}

const template = readFileSync(distHtml, 'utf8');
if (!template.includes('rel="canonical"') || !template.includes('og:title')) {
  console.error('dist/index.html is missing SEO tags — check index.html');
  process.exit(1);
}

const written = [];
for (const route of routes) {
  const url = route.path === '/' ? `${origin}/` : `${origin}${route.path}`;
  const file = route.path === '/' ? 'index.html' : `${route.path.replace(/^\//, '')}/index.html`;
  const dest = join(root, 'dist', file);
  mkdirSync(dirname(dest), { recursive: true });
  writeFileSync(
    dest,
    apply(template, {
      title: route.title,
      description: route.description,
      url,
      robots: 'index, follow',
      ld: jsonLd(route),
    }),
  );
  written.push(file);
}

writeFileSync(
  join(root, 'dist', '404.html'),
  apply(template, {
    title: 'Page not found — LexAI',
    description: 'That address is not a LexAI page.',
    url: `${origin}/`,
    robots: 'noindex, follow',
    ld: JSON.stringify({
      '@context': 'https://schema.org',
      '@graph': [{ '@type': 'WebSite', name: 'LexAI', url: `${origin}/` }, softwareGraph()],
    }),
  }),
);
written.push('404.html');

const today = new Date().toISOString().slice(0, 10);
const sitemap = `<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
${routes
  .map(
    (r, i) => `  <url>
    <loc>${r.path === '/' ? `${origin}/` : `${origin}${r.path}`}</loc>
    <lastmod>${today}</lastmod>
    <changefreq>${i < 2 ? 'weekly' : 'monthly'}</changefreq>
    <priority>${r.path === '/' ? '1.0' : r.path === '/docs' ? '0.8' : '0.5'}</priority>
  </url>`,
  )
  .join('\n')}
</urlset>
`;
writeFileSync(join(root, 'dist', 'sitemap.xml'), sitemap);
written.push('sitemap.xml');

console.log('SEO HTML written for', written.join(', '));