import { httpAction } from "./_generated/server";
import { api } from "./_generated/api";

// Site configuration for RSS feed
const SITE_URL = process.env.SITE_URL || "https://markdown.fast";
const SITE_TITLE = "markdown sync framework";
const SITE_DESCRIPTION =
  "An open-source publishing framework for AI agents and developers. Write markdown, sync from the terminal. Your content is instantly available to browsers, LLMs, and AI agents. Built on Convex and Netlify.";

// Escape XML special characters
function escapeXml(text: string): string {
  return text
    .replace(/&/g, "&")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;")
    .replace(/'/g, "&apos;");
}

// Generate RSS XML from posts (description only)
function generateRssXml(
  posts: Array<{
    title: string;
    description: string;
    slug: string;
    date: string;
  }>,
  feedPath: string = "/rss.xml",
): string {
  const items = posts
    .map((post) => {
      const pubDate = new Date(post.date).toUTCString();
      const url = `${SITE_URL}/${post.slug}`;

      return `
    <item>
      <title>${escapeXml(post.title)}</title>
      <link>${url}</link>
      <guid>${url}</guid>
      <pubDate>${pubDate}</pubDate>
      <description>${escapeXml(post.description)}</description>
    </item>`;
    })
    .join("");

  return `<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:content="http://purl.org/rss/1.0/modules/content/">
  <channel>
    <title>${escapeXml(SITE_TITLE)}</title>
    <link>${SITE_URL}</link>
    <description>${escapeXml(SITE_DESCRIPTION)}</description>
    <language>en-us</language>
    <lastBuildDate>${new Date().toUTCString()}</lastBuildDate>
    <atom:link href="${SITE_URL}${feedPath}" rel="self" type="application/rss+xml"/>
    ${items}
  </channel>
</rss>`;
}

// Generate RSS XML with full content (for LLMs and readers)
function generateFullRssXml(
  posts: Array<{
    title: string;
    description: string;
    slug: string;
    date: string;
    content: string;
    readTime?: string;
    tags: string[];
  }>,
): string {
  const items = posts
    .map((post) => {
      const pubDate = new Date(post.date).toUTCString();
      const url = `${SITE_URL}/${post.slug}`;

      return `
    <item>
      <title>${escapeXml(post.title)}</title>
      <link>${url}</link>
      <guid>${url}</guid>
      <pubDate>${pubDate}</pubDate>
      <description>${escapeXml(post.description)}</description>
      <content:encoded><![CDATA[${post.content}]]></content:encoded>
      ${post.tags.map((tag) => `<category>${escapeXml(tag)}</category>`).join("\n      ")}
    </item>`;
    })
    .join("");

  return `<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:content="http://purl.org/rss/1.0/modules/content/">
  <channel>
    <title>${escapeXml(SITE_TITLE)} - Full Content</title>
    <link>${SITE_URL}</link>
    <description>${escapeXml(SITE_DESCRIPTION)} Full article content for readers and AI.</description>
    <language>en-us</language>
    <lastBuildDate>${new Date().toUTCString()}</lastBuildDate>
    <atom:link href="${SITE_URL}/rss-full.xml" rel="self" type="application/rss+xml"/>
    ${items}
  </channel>
</rss>`;
}

// HTTP action to serve RSS feed (descriptions only)
export const rssFeed = httpAction(async (ctx) => {
  const posts = await ctx.runQuery(api.posts.getAllPosts);

  const xml = generateRssXml(
    posts.map((post) => ({
      title: post.title,
      description: post.description,
      slug: post.slug,
      date: post.date,
    })),
  );

  return new Response(xml, {
    headers: {
      "Content-Type": "application/rss+xml; charset=utf-8",
      "Cache-Control": "public, max-age=3600, s-maxage=7200",
    },
  });
});

// HTTP action to serve full RSS feed (with complete content)
export const rssFullFeed = httpAction(async (ctx) => {
  const posts = await ctx.runQuery(api.posts.getAllPosts);

  // Fetch full content for each post
  const fullPosts = await Promise.all(
    posts.map(async (post) => {
      const fullPost = await ctx.runQuery(api.posts.getPostBySlug, {
        slug: post.slug,
      });
      return {
        title: post.title,
        description: post.description,
        slug: post.slug,
        date: post.date,
        content: fullPost?.content || "",
        readTime: post.readTime,
        tags: post.tags,
      };
    }),
  );

  const xml = generateFullRssXml(fullPosts);

  return new Response(xml, {
    headers: {
      "Content-Type": "application/rss+xml; charset=utf-8",
      "Cache-Control": "public, max-age=3600, s-maxage=7200",
    },
  });
});