// 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
  );
}

// A "/search" url means we don't have a direct artist page (just a search fallback).
export const isSearchUrl = (url) => typeof url === "string" && url.includes("/search");

// Choose the single best link to show: prefer Spotify when the artist is actually ON
// Spotify (a direct, non-search url); else a direct Bandcamp; else the Spotify search.
export function primaryOf({ spotify, bandcamp }) {
  if (spotify && !isSearchUrl(spotify)) return { platform: "spotify", url: spotify };
  if (bandcamp && !isSearchUrl(bandcamp)) return { platform: "bandcamp", url: bandcamp };
  return { platform: "spotify", url: spotify };
}

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

// True for http/https URLs only — reject javascript:, ftp:, garbage. These values flow
// into an injected link's href, so validate the third-party MB data defensively.
export function isHttpUrl(u) {
  try {
    const p = new URL(u).protocol;
    return p === "https:" || p === "http:";
  } catch {
    return false;
  }
}

// Extract direct links from a MusicBrainz artist's url-relations (zero-cred: MB stores
// official Bandcamp / streaming URLs). Accepts only http(s) and matches by parsed hostname
// (not substring, so "evilbandcamp.com" / "javascript:…bandcamp.com…" don't slip through).
// Either field may be null.
export function relUrls(relations) {
  const urls = (relations ?? []).map((r) => r && r.url && r.url.resource).filter(isHttpUrl);
  const byHost = (host) =>
    urls.find((u) => {
      try {
        const h = new URL(u).hostname;
        return h === host || h.endsWith("." + host);
      } catch {
        return false;
      }
    }) ?? null;
  return { bandcamp: byHost("bandcamp.com"), spotify: byHost("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) {
  const r = {
    name: hit.name,
    spotify: links?.spotify ?? spotifySearch(hit.name),
    bandcamp: links?.bandcamp ?? bandcampSearch(hit.name),
  };
  return { ...r, primary: primaryOf(r) };
}