package library

import (
	"github.com/dhowden/tag"
	"github.com/dhowden/tag/mbz"
)

// extractMBIDs reads MusicBrainz album and artist IDs from a tag.Metadata.
//
// Delegates to dhowden/tag/mbz, which knows the per-format Raw() conventions:
//   - Vorbis (FLAC/OGG) keys are lowercased by the parser.
//   - ID3v2 (MP3) TXXX frames are stored under "TXXX"/"TXXX_N" with
//     a *tag.Comm value whose Description holds the Picard tag name.
//   - MP4 (M4A) freeform iTunes atoms are stored under their bare sub-name.
//
// We previously hand-rolled this lookup against guessed keys
// ("MUSICBRAINZ_ALBUMID", "TXXX:MusicBrainz Album Id", ...), none of which
// dhowden actually produces — so every extraction returned ("",""), which
// fed an empty MBID into both the scanner and the boot-time backfill.
func extractMBIDs(m tag.Metadata) (albumMBID, artistMBID string) {
	info := mbz.Extract(m)
	return info.Get(mbz.Album), info.Get(mbz.Artist)
}