import type { Metadata } from 'next';
import Link from 'next/link';
import { notFound } from 'next/navigation';
import { getCachedPayload } from '@/lib/payload';
import { absoluteUrl } from '@/lib/site';
import { getFlags } from '@/lib/flags';
import styles from './Blog.module.css';

/*
 * Dynamic, not ISR.
 *
 * This route has no dynamic params, so Next prerenders it at build time — and
 * CI builds the image with no database reachable, which fails the build. It is
 * a single indexed query against Postgres on the same Docker network, so
 * rendering per request is cheap, and it means a newly published post appears
 * here immediately rather than waiting on a revalidation.
 */
export const dynamic = 'force-dynamic';

export const metadata: Metadata = {
  title: 'Blog',
  description:
    'Notes on what school performance data shows, and what it does not.',
  alternates: { canonical: absoluteUrl('/blog') },
};

function formatDate(value: string) {
  return new Date(value).toLocaleDateString('en-GB', {
    day: 'numeric',
    month: 'long',
    year: 'numeric',
  });
}

export default async function BlogIndexPage() {
  const flags = await getFlags();
  if (flags.blog !== true) notFound();

  const payload = await getCachedPayload();
  const { docs } = await payload.find({
    collection: 'posts',
    where: { _status: { equals: 'published' } },
    sort: '-publishedAt',
    limit: 50,
    depth: 0,
  });

  return (
    <div className={styles.page}>
      <header className={styles.header}>
        <p className={styles.kicker}>Blog</p>
        <h1 className={styles.heading}>Notes on the numbers</h1>
        <p className={styles.standfirst}>
          What school performance data shows, what it doesn&apos;t, and how to
          read it without being misled. Written by{' '}
          {/* Plain text when about_page is dark: the two flags are
              independent, so this link would otherwise point at a 404. */}
          {flags.about_page === true
            ? <Link href="/about" className={styles.link}>Tudor</Link>
            : 'Tudor'}.
        </p>
      </header>

      {docs.length === 0 ? (
        <p className={styles.empty}>No posts yet.</p>
      ) : (
        <ul className={styles.list}>
          {docs.map((post) => (
            <li key={post.id} className={styles.item}>
              <time className={styles.date} dateTime={String(post.publishedAt)}>
                {formatDate(String(post.publishedAt))}
              </time>
              <h2 className={styles.itemTitle}>
                <Link href={`/blog/${post.slug}`} className={styles.itemLink}>
                  {post.title}
                </Link>
              </h2>
              <p className={styles.excerpt}>{post.excerpt}</p>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}