import Link from 'next/link';
import type { SchoolPlace, SchoolPhasePage } from '@/lib/jsonld';
import styles from './NearbyPlaces.module.css';

/**
 * Links from a school page into the location layer.
 *
 * This exists for a structural reason rather than a decorative one. Before
 * it, the only anchor on a school page pointed at the school's own website,
 * so the ~27k pages that carry most of the site's inbound authority passed it
 * straight off-site and none of it reached the place pages. These links are
 * what circulate it instead.
 *
 * Every entry comes from the place registry via the API, so a link is only
 * ever offered for a page that exists: a place below the publish threshold is
 * absent from the registry and therefore absent here.
 */

/** Narrowest first: a reader on a school page wants its town before its
 *  county. The API orders widest-first because that is what the breadcrumb
 *  reads, so the two orders are deliberately different. */
const ORDER: Record<string, number> = {
  town: 0, locality: 0, outcode: 1, authority: 2,
};

function label(place: SchoolPlace): string {
  const noun = place.count === 1 ? 'school' : 'schools';
  const preposition = place.kind === 'outcode' ? 'near' : 'in';
  return `${place.count} ${noun} ${preposition} ${place.name}`;
}

/** "22 primary schools in Brentwood" — the phrasing the query itself uses. */
function phaseLabel(place: SchoolPlace, page: SchoolPhasePage): string {
  const noun = page.count === 1 ? 'school' : 'schools';
  return `${page.count} ${page.phase} ${noun} in ${place.name}`;
}

export function NearbyPlaces({ places }: { places: SchoolPlace[] }) {
  if (places.length === 0) return null;

  const sorted = [...places].sort(
    (a, b) => (ORDER[a.kind] ?? 9) - (ORDER[b.kind] ?? 9),
  );

  return (
    <section className={styles.section} aria-labelledby="nearby-places">
      <h2 id="nearby-places" className={styles.heading}>More schools near here</h2>
      <ul className={styles.list}>
        {sorted.flatMap((place) => [
          <li key={`${place.kind}:${place.slug}`}>
            <Link href={place.url} className={styles.link}>{label(place)}</Link>
          </li>,
          /* Immediately after its own place, so "22 primary schools in
             Brentwood" reads as part of Brentwood rather than as an
             unrelated link further down the row. */
          ...place.phases.map((page) => (
            <li key={`${place.kind}:${place.slug}:${page.phase}`}>
              <Link href={page.url} className={styles.link}>
                {phaseLabel(place, page)}
              </Link>
            </li>
          )),
        ])}
      </ul>
    </section>
  );
}