// 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();

// Fallback link when we have no direct Spotify page: a Google search biased at Bandcamp,
// which surfaces the artist's Bandcamp page (when it exists) plus general results.
export const googleSearch = (n) => `https://www.google.com/search?q=${encodeURIComponent(`${n} bandcamp`)}`;

// The precision lever: return the item whose name matches the candidate
// case-insensitively, else null. Tolerates null/garbage items. Used for both
// Spotify artist items and album items — the exact-name match is the same gate.
export function pickArtist(name, items) {
  const want = norm(name);
  return (items ?? []).find((a) => a && norm(a.name) === want) ?? null;
}

// Same exact-name gate, named for the album path's readability.
export const pickAlbum = pickArtist;

// 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");

// True for http/https URLs only — reject javascript:, ftp:, garbage. The Spotify
// external_url flows into an injected link's href, so validate it defensively.
export function isHttpUrl(u) {
  try {
    const p = new URL(u).protocol;
    return p === "https:" || p === "http:";
  } catch {
    return false;
  }
}

// Build the single link to show for a confirmed name. Prefer the direct Spotify
// url (validated http(s), not a /search url); otherwise fall back to a Google→Bandcamp
// search. `primary` is what the extension renders ({ platform, url }); `kind`
// ("artist" | "album") tells it which affordance to show. `kind` is additive — the
// extension defaults to "artist" when absent, so older clients keep working.
export function linkResult(name, spotifyUrl, kind = "artist") {
  const k = kind === "album" ? "album" : "artist";
  const direct = spotifyUrl && isHttpUrl(spotifyUrl) && !isSearchUrl(spotifyUrl) ? spotifyUrl : null;
  if (direct) {
    return { name, kind: k, spotify: direct, primary: { platform: "spotify", url: direct } };
  }
  const url = googleSearch(name);
  return { name, kind: k, google: url, primary: { platform: "google", url } };
}