Document the scrobblerlog package

pkg/scrobblerlog/parser.go

@@ -20,11 +20,18 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 */
 
-// Package to parse and writer .scrobbler.log files as written by Rockbox.
+// Package to parse and write .scrobbler.log files as written by Rockbox.
+//
+// The parser supports reading version 1.1 and 1.0 of the scrobbler log file
+// format. The latter is only supported if encoded in UTF-8.
+//
+// When written it always writes version 1.1 of the scrobbler log file format,
+// which includes the MusicBrainz recording ID as the last field of each row.
 //
 // See
 // - https://www.rockbox.org/wiki/LastFMLog
 // - https://git.rockbox.org/cgit/rockbox.git/tree/apps/plugins/lastfm_scrobbler.c
+// - https://web.archive.org/web/20110110053056/http://www.audioscrobbler.net/wiki/Portable_Player_Logging
 package scrobblerlog
 
 import (
@@ -79,6 +86,10 @@ type ScrobblerLog struct {
 	FallbackTimezone *time.Location
 }
 
+// Parses a scrobbler log file from the given reader.
+//
+// The reader must provide a valid scrobbler log file with a valid header.
+// This function implicitly calls [ScrobblerLog.ReadHeader].
 func (l *ScrobblerLog) Parse(data io.Reader, ignoreSkipped bool) error {
 	l.Records = make([]Record, 0)
 
@@ -106,6 +117,7 @@ func (l *ScrobblerLog) Parse(data io.Reader, ignoreSkipped bool) error {
 		// fmt.Printf("row: %v\n", row)
 
 		// We consider only the last field (recording MBID) optional
+		// This was added in the 1.1 file format.
 		if len(row) < 7 {
 			line, _ := tsvReader.FieldPos(0)
 			return fmt.Errorf("invalid record in scrobblerlog line %v", line)
@@ -126,6 +138,11 @@ func (l *ScrobblerLog) Parse(data io.Reader, ignoreSkipped bool) error {
 	return nil
 }
 
+// Append writes the given records to the writer.
+//
+// The writer should be for an existing scrobbler log file or
+// [ScrobblerLog.WriteHeader] should be called before this function.
+// Returns the last timestamp of the records written.
 func (l *ScrobblerLog) Append(data io.Writer, records []Record) (lastTimestamp time.Time, err error) {
 	tsvWriter := csv.NewWriter(data)
 	tsvWriter.Comma = '\t'
@@ -153,6 +170,9 @@ func (l *ScrobblerLog) Append(data io.Writer, records []Record) (lastTimestamp t
 	return
 }
 
+// Parses just the header of a scrobbler log file from the given reader.
+//
+// This function sets [ScrobblerLog.TZ] and [ScrobblerLog.Client].
 func (l *ScrobblerLog) ReadHeader(reader *bufio.Reader) error {
 	// Skip header
 	for i := 0; i < 3; i++ {
@@ -191,6 +211,7 @@ func (l *ScrobblerLog) ReadHeader(reader *bufio.Reader) error {
 	return nil
 }
 
+// Writes the header of a scrobbler log file to the given writer.
 func (l *ScrobblerLog) WriteHeader(writer io.Writer) error {
 	headers := []string{
 		"#AUDIOSCROBBLER/1.1\n",