// Pure, side-effect-free helpers for the resolver. Kept separate from resolver.js
// (which has the HTTP-server side effect) so they can be unit-tested with `node --test`
// without starting a server. The artist-match precision lever lives here.

export const norm = (s) => String(s).normalize("NFKC").trim().toLowerCase();

export const bandcampSearch = (n) => `https://bandcamp.com/search?q=${encodeURIComponent(n)}&item_type=b`;
export const spotifySearch = (n) => `https://open.spotify.com/search/${encodeURIComponent(n)}`;

// The precision lever: return the result whose name matches the candidate
// case-insensitively, else null. `minScore` (MusicBrainz) additionally requires a
// confidence score. Tolerates null/garbage items.
export function pickArtist(name, items, { minScore = null } = {}) {
  const want = norm(name);
  return (
    (items ?? []).find(
      (a) => a && norm(a.name) === want && (minScore == null || (a.score ?? 0) >= minScore),
    ) ?? null
  );
}

// Link object for a confirmed Spotify hit (direct artist url when present, else search).
export const spotifyResult = (hit) => ({
  name: hit.name,
  spotify: hit.external_urls?.spotify ?? spotifySearch(hit.name),
  bandcamp: bandcampSearch(hit.name),
});

// Extract direct links from a MusicBrainz artist's url-relations (zero-cred: MB stores
// official Bandcamp / streaming URLs). Either field may be null.
export function relUrls(relations) {
  const urls = (relations ?? []).map((r) => r && r.url && r.url.resource).filter(Boolean);
  const find = (host) => urls.find((u) => u.includes(host)) ?? null;
  return { bandcamp: find("bandcamp.com"), spotify: find("open.spotify.com") };
}

// Link object for a confirmed MusicBrainz hit: prefer the direct url-rel links, fall back
// to search urls when MB has no relation for that platform.
export function mbResult(hit, links) {
  return {
    name: hit.name,
    spotify: links?.spotify ?? spotifySearch(hit.name),
    bandcamp: links?.bandcamp ?? bandcampSearch(hit.name),
  };
}