import fs from 'node:fs/promises';

import path from 'node:path';

import { loadConfig, ROOT } from './lib/config.mjs';

import { collectDocs } from './lib/collect.mjs';

import { dim, green, red, yellow } from './lib/log.mjs';

/**

* Post-build prerender: writes one static index.html per page into the build

* output, with the article HTML baked in and full SEO metadata (title,

* description, canonical, Open Graph, Twitter card), plus sitemap.xml and

* robots.txt.

*

* No SSR involved — the SPA shell is reused as-is and the content is placed

* inside <app-root>, so crawlers and no-JS readers get the real page while

* Angular replaces it with the interactive app the moment it boots.

*

* Runs as part of `npm run build`, after `ng build`.

*/

const DIST = path.join(ROOT, 'dist', 'feastdocs', 'browser');

const config = await loadConfig();

const shellPath = path.join(DIST, 'index.html');

let shell;

try {

shell = await fs.readFile(shellPath, 'utf8');

} catch {

console.error(

`${red('✗')} prerender: ${path.relative(ROOT, shellPath)} not found — run ng build first.`,

);

process.exit(1);

}

if (!config.siteUrl) {

console.log(

`${yellow('!')} prerender skipped: set ${dim('siteUrl')} in feastdocs.config.mjs ` +

`(e.g. 'https://docs.example.com') to enable SEO output.`,

);

process.exit(0);

}

const siteUrl = config.siteUrl.replace(/\/+$/, '');

const { docs } = await collectDocs(config);

let pages = 0;

for (const doc of docs) {

const html = renderPage(shell, doc, config, siteUrl);

const target =

doc.slug === '' ? shellPath : path.join(DIST, ...doc.slug.split('/'), 'index.html');

await fs.mkdir(path.dirname(target), { recursive: true });

await fs.writeFile(target, html, 'utf8');

pages += 1;

}

// Sitemap: public, navigable pages only — hidden pages stay reachable but unlisted.

const sitemapEntries = docs

.filter((doc) => !doc.hidden)

.map(

(doc) =>

` <url><loc>${escapeXml(pageurl(/sitelet?url=https%3A%2F%2Fgithub.com%2FMindfeast%2Ffeastdocs%2Fblob%2Fmain%2Ftools%2FsiteUrl%2C%2520doc.slug))}</loc>` +

`<lastmod>${doc.lastUpdated.slice(0, 10)}</lastmod></url>`,

)

.join('\n');

await fs.writeFile(

path.join(DIST, 'sitemap.xml'),

`<?xml version="1.0" encoding="UTF-8"?>\n<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">\n${sitemapEntries}\n</urlset>\n`,

'utf8',

);

await fs.writeFile(

path.join(DIST, 'robots.txt'),

`User-agent: *\nAllow: /\nDisallow: /_editor\n\nSitemap: ${siteUrl}/sitemap.xml\n`,

'utf8',

);

console.log(

`${green('✓')} prerendered ${pages} pages, sitemap.xml, robots.txt ${dim(`→ ${path.relative(ROOT, DIST)}`)}`,

);

/**

* The URL a page is actually served at.

*

* Pages are written as `<slug>/index.html`, so a host that serves directories

* — Cloudflare Pages, GitHub Pages — answers `/slug` with a 308 to `/slug/`.

* Declaring the slash-less form pointed the sitemap and the canonical at that

* redirect instead of at the page: every sitemap URL came back from Search

* Console as "Discovered – currently not indexed", and the page served at

* `/slug/` claimed `/slug` as canonical, which redirects back to it.

*

* nginx (deploy/nginx.conf) answers both forms with a 200, so the trailing

* slash is the single form that is correct on every host we deploy to.

*/

function pageurl(/sitelet?url=https%3A%2F%2Fgithub.com%2FMindfeast%2Ffeastdocs%2Fblob%2Fmain%2Ftools%2FsiteUrl%2C%2520slug) {

return slug === '' ? `${siteUrl}/` : `${siteUrl}/${slug}/`;

}

function renderPage(shell, doc, config, siteUrl) {

const title = doc.slug === '' ? config.title : `${doc.title} · ${config.title}`;

const description = doc.description || config.tagline;

const url = pageurl(/sitelet?url=https%3A%2F%2Fgithub.com%2FMindfeast%2Ffeastdocs%2Fblob%2Fmain%2Ftools%2FsiteUrl%2C%2520doc.slug);

const meta = [

`<link rel="canonical" href="${escapeAttr(url)}" />`,

`<meta property="og:title" content="${escapeAttr(title)}" />`,

`<meta property="og:description" content="${escapeAttr(description)}" />`,

`<meta property="og:type" content="article" />`,

`<meta property="og:url" content="${escapeAttr(url)}" />`,

`<meta property="og:site_name" content="${escapeAttr(config.title)}" />`,

];

// Without an image, a shared link renders as a bare text card on LinkedIn,

// Slack and X. With one, the large-summary layout applies.

if (config.socialImage) {

const image = `${siteUrl}/${String(config.socialImage).replace(/^\/+/, '')}`;

meta.push(

`<meta property="og:image" content="${escapeAttr(image)}" />`,

`<meta property="og:image:alt" content="${escapeAttr(config.title)}" />`,

`<meta name="twitter:image" content="${escapeAttr(image)}" />`,

`<meta name="twitter:card" content="summary_large_image" />`,

);

} else {

meta.push(`<meta name="twitter:card" content="summary" />`);

}

const metaTags = meta.join('\n ');

// The static article inherits the shipped stylesheet (fd-markdown etc.), so

// even the no-JS rendering is presentable. Angular clears it on bootstrap.

const article =

`<main class="fd-prerender" style="max-width:820px;margin:0 auto;padding:2rem 1.5rem">` +

`<article class="fd-doc"><h1>${escapeHtml(doc.title)}</h1>` +

(doc.description ? `<p>${escapeHtml(doc.description)}</p>` : '') +

`<div class="fd-markdown">${doc.html}</div></article></main>`;

return shell

.replace(/<title>[\s\S]*?<\/title>/, `<title>${escapeHtml(title)}</title>`)

.replace(

/<meta name="description"[^>]*\/?>/,

`<meta name="description" content="${escapeAttr(description)}" />`,

)

.replace('</head>', ` ${metaTags}\n </head>`)

.replace(/<app-root><\/app-root>/, `<app-root>${article}</app-root>`);

}

function escapeHtml(value) {

return String(value).replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');

}

function escapeAttr(value) {

return escapeHtml(value).replace(/"/g, '&quot;');

}

function escapeXml(value) {

return escapeAttr(value).replace(/'/g, '&apos;');

}