import type { APIRoute } from 'astro';

interface PostInfo {
  slug: string;
  date: string;
  title?: string;
  summary?: string;
  excerpt?: string;
  tags: string[];
  draft: boolean;
}

interface SiteConfig {
  title: string;
  subtitle: string;
}

// Strip C0/DEL control chars that are illegal in XML 1.0 (allow tab, LF, CR).
// eslint-disable-next-line no-control-regex
const XML_INVALID = /[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]/g;

function escapeXml(s: string): string {
  return s.replace(XML_INVALID, '').replace(/[<>&'"]/g, c => ({
    '<': '&lt;',
    '>': '&gt;',
    '&': '&amp;',
    "'": '&apos;',
    '"': '&quot;',
  }[c]!));
}

function formatSlug(slug: string): string {
  return slug
    .split('-')
    .map(w => w.charAt(0).toUpperCase() + w.slice(1))
    .join(' ');
}

export const GET: APIRoute = async ({ site }) => {
  const API_URL = process.env.PUBLIC_API_URL || 'http://backend:3000';
  const origin = site?.toString().replace(/\/$/, '') || '';

  let posts: PostInfo[] = [];
  let config: SiteConfig = { title: "Ela's Atelier", subtitle: 'Works on paper, canvas, and elsewhere' };
  try {
    const [pr, cr] = await Promise.all([
      fetch(`${API_URL}/api/posts`),
      fetch(`${API_URL}/api/config`),
    ]);
    if (pr.ok) posts = await pr.json();
    if (cr.ok) config = await cr.json();
  } catch (e) {
    console.error('feed.xml backend fetch failed', e);
  }

  const items = posts
    .filter(p => !p.draft)
    .map(p => {
      const url = `${origin}/posts/${encodeURIComponent(p.slug)}`;
      const description = p.summary || p.excerpt || '';
      const pubDate = new Date(p.date).toUTCString();
      const categories = p.tags.map(t => `      <category>${escapeXml(t)}</category>`).join('\n');
      return `    <item>
      <title>${escapeXml(p.title || formatSlug(p.slug))}</title>
      <link>${escapeXml(url)}</link>
      <guid isPermaLink="true">${escapeXml(url)}</guid>
      <pubDate>${pubDate}</pubDate>
      <description>${escapeXml(description)}</description>
${categories}
    </item>`;
    })
    .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>${escapeXml(config.title)}</title>
    <link>${escapeXml(origin)}</link>
    <description>${escapeXml(config.subtitle)}</description>
    <language>en</language>
    <atom:link href="${escapeXml(origin)}/feed.xml" rel="self" type="application/rss+xml" />
${items}
  </channel>
</rss>`;

  return new Response(xml, {
    headers: {
      'Content-Type': 'application/xml; charset=utf-8',
      'Cache-Control': 'public, max-age=600',
    },
  });
};