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'),
);

function apply(html, { title, description, url, robots }) {
  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`);
  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',
    }),
  );
  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',
  }),
);
written.push('404.html');

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