import { categories } from "@/lib/blog/config";
import { absolute, lastChanged } from "@/lib/blog/feeds";
import { listPublishedPosts } from "@/lib/blog/loader";
import {
  BLOG_PATH,
  categoryPath,
  postPath,
  RECENT_PATH,
  UPDATED_PATH,
} from "@/lib/blog/routes";
import type { MetadataRoute } from "next";

export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const posts = await listPublishedPosts();
  const newest = (list: typeof posts) => list.map(lastChanged).sort().at(-1);
  const updated = posts.filter((p) => p.updatedAt);
  return [
    { url: absolute("/") },
    { url: absolute("/get-started") },
    { url: absolute(BLOG_PATH), lastModified: newest(posts) },
    { url: absolute(RECENT_PATH), lastModified: newest(posts) },
    ...(updated.length
      ? [{ url: absolute(UPDATED_PATH), lastModified: newest(updated) }]
      : []),
    ...categories
      .map((c) => ({ c, inCat: posts.filter((p) => p.category === c.slug) }))
      .filter(({ inCat }) => inCat.length > 0)
      .map(({ c, inCat }) => ({
        url: absolute(categoryPath(c.slug)),
        lastModified: newest(inCat),
      })),
    ...posts.map((p) => ({
      url: absolute(postPath(p.slug)),
      lastModified: lastChanged(p),
    })),
  ];
}