// Drives the SSR bundle (built by `vite build --ssr`) to bake one static HTML
// file per route into dist/. Reads the client build's dist/index.html as the
// template, then for each route injects: route <title>/description/og tags, a
// schema.org JSON-LD block, the server-rendered markup into #root, and the
// dehydrated react-query cache as window.__RQ_STATE__ for hydration.
//
// nginx serves these via `try_files $uri $uri/ /index.html`: /cv → cv/index.html,
// /blog/<slug> → blog/<slug>/index.html, etc., with unbaked routes (e.g.
// /activity/:timespan) SPA-falling-back to the home page and rendering client-side.

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

const here = dirname(fileURLToPath(import.meta.url));
const distDir = join(here, 'dist');
const SITE_URL = 'https://rob.tn';

const { collectRoutes, renderRoute } = await import(
  pathToFileURL(join(here, 'dist-server', 'entry-server.js')).href
);

const escapeText = (s) =>
  s.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
const escapeAttr = (s) => escapeText(s).replace(/"/g, '&quot;');

// JS line/paragraph separators are valid in JSON strings but illegal in a
// <script>; written here as escape sequences so the source file stays ASCII.
const JS_LINE_SEPARATORS = new RegExp('[\u2028\u2029]', 'g');

/** Safe for embedding JSON inside an inline <script>: neutralise `<` (so a
 *  `</script>` in the data can't close the tag) and the line separators. */
const serialize = (value) =>
  JSON.stringify(value)
    .replace(/</g, '\\u003c')
    .replace(JS_LINE_SEPARATORS, (c) => '\\u' + c.charCodeAt(0).toString(16));

function replaceOrAppendHead(html, regex, tag) {
  return regex.test(html)
    ? html.replace(regex, tag)
    : html.replace('</head>', `    ${tag}\n  </head>`);
}

function applyHead(html, head, url) {
  let out = html.replace(
    /<title>[\s\S]*?<\/title>/,
    `<title>${escapeText(head.title)}</title>`,
  );

  const desc = escapeAttr(head.description);
  out = replaceOrAppendHead(
    out,
    /<meta\s+name="description"[^>]*>/i,
    `<meta name="description" content="${desc}" />`,
  );
  out = replaceOrAppendHead(
    out,
    /<meta\s+property="og:title"[^>]*>/i,
    `<meta property="og:title" content="${escapeAttr(head.title)}" />`,
  );
  out = replaceOrAppendHead(
    out,
    /<meta\s+property="og:description"[^>]*>/i,
    `<meta property="og:description" content="${desc}" />`,
  );
  out = replaceOrAppendHead(
    out,
    /<meta\s+property="og:url"[^>]*>/i,
    `<meta property="og:url" content="${escapeAttr(url)}" />`,
  );

  const ld = `<script type="application/ld+json">${serialize(head.jsonLd)}</script>`;
  return out.replace('</head>', `    ${ld}\n  </head>`);
}

function outPathFor(route) {
  if (route === '/') return join(distDir, 'index.html');
  return join(distDir, route.replace(/^\//, ''), 'index.html');
}

const template = await readFile(join(distDir, 'index.html'), 'utf8');
let routes = await collectRoutes();

// Optional filter args: `node run-prerender.mjs /activity /cv` bakes only the
// routes whose path starts with one of the given prefixes (useful for quick
// iteration). With no args, every route is baked.
const filters = process.argv.slice(2);
if (filters.length > 0) {
  routes = routes.filter((r) => filters.some((f) => r === f || r.startsWith(f)));
}

let ok = 0;
let failed = 0;

for (const route of routes) {
  const url = route === '/' ? `${SITE_URL}/` : `${SITE_URL}${route}`;
  try {
    const { html, state, head } = await renderRoute(route);
    let page = applyHead(template, head, url);
    page = page.replace(
      '<div id="root"></div>',
      `<div id="root">${html}</div>\n    <script>window.__RQ_STATE__=${serialize(state)}</script>`,
    );
    const outPath = outPathFor(route);
    await mkdir(dirname(outPath), { recursive: true });
    await writeFile(outPath, page);
    ok += 1;
    console.log(`prerendered ${route}`);
  } catch (err) {
    // Don't fail the whole build for one route — write the bare template so the
    // route still resolves and hydrates client-side, and surface the error.
    failed += 1;
    console.error(`prerender FAILED for ${route}: ${err?.stack || err}`);
    const outPath = outPathFor(route);
    await mkdir(dirname(outPath), { recursive: true });
    await writeFile(outPath, template);
  }
}

console.log(`prerender complete: ${ok} ok, ${failed} failed, ${routes.length} routes`);
// A handful of failed routes still ship a working client-rendered fallback, so
// don't block the deploy for those. Only fail the build if nothing prerendered
// at all (e.g. the API was unreachable), which signals a genuinely broken build.
if (ok === 0) {
  console.error('prerender produced no pages — failing the build');
  process.exitCode = 1;
}