/**
 * Blog RSS feed — GET /blog/rss.xml
 *
 * Syndication for the store's articles (many of them auto-published by the
 * SEO Autopilot): feed readers, newsletter tools, and aggregators can follow
 * the blog without polling HTML. The root layout advertises it via
 * <link rel="alternate" type="application/rss+xml">.
 *
 * NOTE (multi-locale scaffolds): the URL contains a dot, so the locale
 * middleware never rewrites it, and a copy nested under [locale]/blog/ would
 * 404. The scaffolder moves this route back to the app ROOT
 * (app/blog/rss.xml) after the [locale] move — the literal `blog` segment
 * wins over `[locale]` for /blog/rss.xml, while /he/blog/... keeps matching
 * the locale tree. See scaffold.ts.
 */
import { getServerClient } from '@/core/lib/brainerce.server';
import { getCanonicalSiteUrl } from '@/core/lib/site-url';

export const revalidate = 3600;

function esc(value: string): string {
  return value
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;');
}

export async function GET() {
  const baseUrl = await getCanonicalSiteUrl();
  const client = await getServerClient();

  const [info, posts] = await Promise.all([
    client.getStoreInfo().catch(() => null),
    client.blog.getPosts({ limit: 50 }).catch(() => null),
  ]);

  const items = (posts?.data ?? [])
    .map((post) => {
      const url = `${baseUrl}/blog/${post.slug}`;
      const description = post.seoDescription ?? post.excerpt ?? '';
      const pubDate = post.publishedAt ? new Date(post.publishedAt).toUTCString() : undefined;
      return [
        '    <item>',
        `      <title>${esc(post.title)}</title>`,
        `      <link>${esc(url)}</link>`,
        `      <guid isPermaLink="true">${esc(url)}</guid>`,
        ...(pubDate ? [`      <pubDate>${pubDate}</pubDate>`] : []),
        ...(description ? [`      <description>${esc(description)}</description>`] : []),
        '    </item>',
      ].join('\n');
    })
    .join('\n');

  const xml = [
    '<?xml version="1.0" encoding="UTF-8"?>',
    '<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">',
    '  <channel>',
    `    <title>${esc(info?.name ?? 'Blog')}</title>`,
    `    <link>${esc(`${baseUrl}/blog`)}</link>`,
    `    <description>${esc(info?.metaDescription ?? `${info?.name ?? 'Store'} blog`)}</description>`,
    `    <atom:link href="${esc(`${baseUrl}/blog/rss.xml`)}" rel="self" type="application/rss+xml"/>`,
    items,
    '  </channel>',
    '</rss>',
  ].join('\n');

  return new Response(xml, {
    headers: { 'Content-Type': 'application/rss+xml; charset=utf-8' },
  });
}