60 lines
1.6 KiB
Go
60 lines
1.6 KiB
Go
package library
|
|
|
|
// MusicBrainz tag keys vary by audio format. dhowden/tag's Raw() map exposes
|
|
// the format-specific entries as-is — so we look up multiple candidates and
|
|
// take the first non-empty match.
|
|
//
|
|
// References:
|
|
// - ID3v2 (MP3): TXXX frames keyed by description.
|
|
// - Vorbis (FLAC/OGG): all-caps comment names.
|
|
// - MP4 (M4A): iTunes freeform atoms ("----:com.apple.iTunes:...").
|
|
|
|
var albumMBIDKeys = []string{
|
|
"TXXX:MusicBrainz Album Id",
|
|
"MUSICBRAINZ_ALBUMID",
|
|
"----:com.apple.iTunes:MusicBrainz Album Id",
|
|
}
|
|
|
|
var artistMBIDKeys = []string{
|
|
"TXXX:MusicBrainz Artist Id",
|
|
"MUSICBRAINZ_ARTISTID",
|
|
"----:com.apple.iTunes:MusicBrainz Artist Id",
|
|
}
|
|
|
|
// extractMBIDs reads MusicBrainz album and artist IDs from a tag.Metadata
|
|
// Raw() map. Returns ("", "") when the keys are absent. Multi-value keys
|
|
// (some formats list multiple artist IDs for collaborations) take only the
|
|
// first value — Minstrel uses the primary release artist for MBCAA lookup.
|
|
func extractMBIDs(raw map[string]interface{}) (albumMBID, artistMBID string) {
|
|
albumMBID = firstStringValue(raw, albumMBIDKeys)
|
|
artistMBID = firstStringValue(raw, artistMBIDKeys)
|
|
return
|
|
}
|
|
|
|
func firstStringValue(raw map[string]interface{}, keys []string) string {
|
|
for _, k := range keys {
|
|
v, ok := raw[k]
|
|
if !ok || v == nil {
|
|
continue
|
|
}
|
|
switch x := v.(type) {
|
|
case string:
|
|
if x != "" {
|
|
return x
|
|
}
|
|
case []string:
|
|
if len(x) > 0 && x[0] != "" {
|
|
return x[0]
|
|
}
|
|
case []interface{}:
|
|
if len(x) == 0 {
|
|
continue
|
|
}
|
|
if s, ok := x[0].(string); ok && s != "" {
|
|
return s
|
|
}
|
|
}
|
|
}
|
|
return ""
|
|
}
|