// Single-track metadata resolver — the ONE place callers use to enrich a downloaded single.
// Order: Deezer (artist-verified) → MusicBrainz (artist-verified) → nothing.
// Returning {} is intentional and safe: the download then uses its clean fallback
// (album_artist = song artist, album = "Singles", cover = source thumbnail, year/genre untouched).
//
// Both sources apply the SAME discipline — the artist must correspond — so a same-titled song by a
// different artist can never contaminate album/cover/year again.

const dz = require('./deezer');
const mb = require('./musicbrainz');

async function lookupTrackMeta(artist, title) {
  const d = await dz.lookupTrackMeta(artist, title).catch(() => ({}));
  if (d && d.album) return d;                         // Deezer matched (artist-verified)

  const m = await mb.lookupTrackMeta(artist, title).catch(() => ({}));
  if (m && m.album) return m;                         // MusicBrainz matched (artist-verified)

  return d || {};                                     // nothing convincing → clean fallback
}

module.exports = { lookupTrackMeta };