Moved scrobblerlog parsing to separate package

internal/backends/scrobblerlog/scrobblerlog.go

@@ -25,6 +25,7 @@ import (
 	"go.uploadedlobster.com/scotty/internal/config"
 	"go.uploadedlobster.com/scotty/internal/i18n"
 	"go.uploadedlobster.com/scotty/internal/models"
+	"go.uploadedlobster.com/scotty/pkg/scrobblerlog"
 )
 
 type ScrobblerLogBackend struct {
@@ -32,7 +33,7 @@ type ScrobblerLogBackend struct {
 	includeSkipped bool
 	append         bool
 	file           *os.File
-	log            ScrobblerLog
+	log            scrobblerlog.ScrobblerLog
 }
 
 func (b *ScrobblerLogBackend) Name() string { return "scrobbler-log" }
@@ -58,8 +59,8 @@ func (b *ScrobblerLogBackend) FromConfig(config *config.ServiceConfig) models.Ba
 	b.filePath = config.GetString("file-path")
 	b.includeSkipped = config.GetBool("include-skipped", false)
 	b.append = config.GetBool("append", true)
-	b.log = ScrobblerLog{
+	b.log = scrobblerlog.ScrobblerLog{
-		Timezone: "UNKNOWN",
+		TZ:     scrobblerlog.TZ_UTC,
 		Client: "Rockbox unknown $Revision$",
 	}
 	return b
@@ -88,7 +89,7 @@ func (b *ScrobblerLogBackend) StartImport() error {
 		} else {
 			// Verify existing file is a scrobbler log
 			reader := bufio.NewReader(file)
-			if err = ReadHeader(reader, &b.log); err != nil {
+			if err = b.log.ReadHeader(reader); err != nil {
 				file.Close()
 				return err
 			}
@@ -99,7 +100,7 @@ func (b *ScrobblerLogBackend) StartImport() error {
 	}
 
 	if !b.append {
-		if err = WriteHeader(file, &b.log); err != nil {
+		if err = b.log.WriteHeader(file); err != nil {
 			file.Close()
 			return err
 		}
@@ -124,21 +125,21 @@ func (b *ScrobblerLogBackend) ExportListens(oldestTimestamp time.Time, results c
 
 	defer file.Close()
 
-	log, err := Parse(file, b.includeSkipped)
+	err = b.log.Parse(file, b.includeSkipped)
 	if err != nil {
 		progress <- models.Progress{}.Complete()
 		results <- models.ListensResult{Error: err}
 		return
 	}
 
-	listens := log.Listens.NewerThan(oldestTimestamp)
+	listens := b.log.Listens.NewerThan(oldestTimestamp)
 	sort.Sort(listens)
 	progress <- models.Progress{Elapsed: int64(len(listens))}.Complete()
 	results <- models.ListensResult{Items: listens}
 }
 
 func (b *ScrobblerLogBackend) ImportListens(export models.ListensResult, importResult models.ImportResult, progress chan models.Progress) (models.ImportResult, error) {
-	lastTimestamp, err := Write(b.file, export.Items)
+	lastTimestamp, err := b.log.Append(b.file, export.Items)
 	if err != nil {
 		return importResult, err
 	}

pkg/scrobblerlog/parser.go

@@ -19,6 +19,12 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 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.
+//
+// See
+// - https://www.rockbox.org/wiki/LastFMLog
+// - https://git.rockbox.org/cgit/rockbox.git/tree/apps/plugins/lastfm_scrobbler.c
 package scrobblerlog
 
 import (
@@ -34,22 +40,31 @@ import (
 	"go.uploadedlobster.com/scotty/internal/models"
 )
 
+// TZInfo is the timezone information in the header of the scrobbler log file.
+// It can be "UTC" or "UNKNOWN", if the device writing the scrobbler log file
+// knows the time, but not the timezone.
+type TZInfo string
+
+const (
+	TZ_UNKNOWN TZInfo = "UNKNOWN"
+	TZ_UTC     TZInfo = "UTC"
+)
+
+// Represents a scrobbler log file.
 type ScrobblerLog struct {
-	Timezone string
+	TZ       TZInfo
 	Client   string
 	Listens  models.ListensList
 	location *time.Location
 }
 
-func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
+func (l *ScrobblerLog) Parse(data io.Reader, includeSkipped bool) error {
-	result := ScrobblerLog{
+	l.Listens = make(models.ListensList, 0)
-		Listens: make(models.ListensList, 0),
-	}
 
 	reader := bufio.NewReader(data)
-	err := ReadHeader(reader, &result)
+	err := l.ReadHeader(reader)
 	if err != nil {
-		return result, err
+		return err
 	}
 
 	tsvReader := csv.NewReader(reader)
@@ -64,7 +79,7 @@ func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
 		if err == io.EOF {
 			break
 		} else if err != nil {
-			return result, err
+			return err
 		}
 
 		// fmt.Printf("row: %v\n", row)
@@ -72,7 +87,7 @@ func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
 		// We consider only the last field (recording MBID) optional
 		if len(row) < 7 {
 			line, _ := tsvReader.FieldPos(0)
-			return result, fmt.Errorf("invalid record in scrobblerlog line %v", line)
+			return fmt.Errorf("invalid record in scrobblerlog line %v", line)
 		}
 
 		rating := row[5]
@@ -80,18 +95,18 @@ func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
 			continue
 		}
 
-		listen, err := result.rowToListen(row)
+		listen, err := l.rowToListen(row)
 		if err != nil {
-			return result, err
+			return err
 		}
 
-		result.Listens = append(result.Listens, listen)
+		l.Listens = append(l.Listens, listen)
 	}
 
-	return result, nil
+	return nil
 }
 
-func Write(data io.Writer, listens models.ListensList) (lastTimestamp time.Time, err error) {
+func (l *ScrobblerLog) Append(data io.Writer, listens models.ListensList) (lastTimestamp time.Time, err error) {
 	tsvWriter := csv.NewWriter(data)
 	tsvWriter.Comma = '\t'
 
@@ -122,7 +137,7 @@ func Write(data io.Writer, listens models.ListensList) (lastTimestamp time.Time,
 	return
 }
 
-func ReadHeader(reader *bufio.Reader, log *ScrobblerLog) error {
+func (l *ScrobblerLog) ReadHeader(reader *bufio.Reader) error {
 	// Skip header
 	for i := 0; i < 3; i++ {
 		line, _, err := reader.ReadLine()
@@ -142,14 +157,14 @@ func ReadHeader(reader *bufio.Reader, log *ScrobblerLog) error {
 			// the log knows the time, but not the timezone.
 			timezone, found := strings.CutPrefix(text, "#TZ/")
 			if found {
-				log.Timezone = timezone
+				l.TZ = TZInfo(timezone)
-				log.location = locationFromTimezone(log.Timezone)
+				l.location = locationFromTimezone(l.TZ)
 				continue
 			}
 
 			client, found := strings.CutPrefix(text, "#CLIENT/")
 			if found {
-				log.Client = client
+				l.Client = client
 				continue
 			}
 		}
@@ -161,11 +176,11 @@ func ReadHeader(reader *bufio.Reader, log *ScrobblerLog) error {
 	return nil
 }
 
-func WriteHeader(writer io.Writer, log *ScrobblerLog) error {
+func (l *ScrobblerLog) WriteHeader(writer io.Writer) error {
 	headers := []string{
 		"#AUDIOSCROBBLER/1.1\n",
-		"#TZ/" + log.Timezone + "\n",
+		"#TZ/" + string(l.TZ) + "\n",
-		"#CLIENT/" + log.Client + "\n",
+		"#CLIENT/" + l.Client + "\n",
 	}
 	for _, line := range headers {
 		_, err := writer.Write([]byte(line))
@@ -219,8 +234,8 @@ func (l ScrobblerLog) rowToListen(row []string) (models.Listen, error) {
 // Convert the timezone string from the header to a time.Location.
 // Often this is set to "UNKNOWN" in the log file, in which case it defaults
 // to UTC.
-func locationFromTimezone(timezone string) *time.Location {
+func locationFromTimezone(timezone TZInfo) *time.Location {
-	location, err := time.LoadLocation(timezone)
+	location, err := time.LoadLocation(string(timezone))
 	if err != nil {
 		return time.UTC
 	}

pkg/scrobblerlog/parser_test.go

@@ -31,8 +31,8 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.uploadedlobster.com/mbtypes"
-	"go.uploadedlobster.com/scotty/internal/backends/scrobblerlog"
 	"go.uploadedlobster.com/scotty/internal/models"
+	"go.uploadedlobster.com/scotty/pkg/scrobblerlog"
 )
 
 var testScrobblerLog = `#AUDIOSCROBBLER/1.1
@@ -48,9 +48,10 @@ Teeth Agency	You Don't Have To Live In Pain	Wolfs Jam	2	107	L	1260359404	1262bea
 func TestParser(t *testing.T) {
 	assert := assert.New(t)
 	data := bytes.NewBufferString(testScrobblerLog)
-	result, err := scrobblerlog.Parse(data, true)
+	result := scrobblerlog.ScrobblerLog{}
+	err := result.Parse(data, true)
 	require.NoError(t, err)
-	assert.Equal("UNKNOWN", result.Timezone)
+	assert.Equal(scrobblerlog.TZ_UNKNOWN, result.TZ)
 	assert.Equal("Rockbox sansaclipplus $Revision$", result.Client)
 	assert.Len(result.Listens, 5)
 	listen1 := result.Listens[0]
@@ -70,7 +71,8 @@ func TestParser(t *testing.T) {
 func TestParserExcludeSkipped(t *testing.T) {
 	assert := assert.New(t)
 	data := bytes.NewBufferString(testScrobblerLog)
-	result, err := scrobblerlog.Parse(data, false)
+	result := scrobblerlog.ScrobblerLog{}
+	err := result.Parse(data, false)
 	require.NoError(t, err)
 	assert.Len(result.Listens, 4)
 	listen4 := result.Listens[3]
@@ -78,14 +80,15 @@ func TestParserExcludeSkipped(t *testing.T) {
 	assert.Equal(mbtypes.MBID("1262beaf-19f8-4534-b9ed-7eef9ca8e83f"), listen4.RecordingMBID)
 }
 
-func TestWrite(t *testing.T) {
+func TestAppend(t *testing.T) {
 	assert := assert.New(t)
 	data := make([]byte, 0, 10)
 	buffer := bytes.NewBuffer(data)
 	log := scrobblerlog.ScrobblerLog{
-		Timezone: "Unknown",
+		TZ:     scrobblerlog.TZ_UNKNOWN,
 		Client: "Rockbox foo $Revision$",
-		Listens: []models.Listen{
+	}
+	listens := []models.Listen{
 		{
 			ListenedAt: time.Unix(1699572072, 0),
 			Track: models.Track{
@@ -98,17 +101,16 @@ func TestWrite(t *testing.T) {
 				AdditionalInfo: models.AdditionalInfo{"rockbox_rating": "L"},
 			},
 		},
-		},
 	}
-	err := scrobblerlog.WriteHeader(buffer, &log)
+	err := log.WriteHeader(buffer)
 	require.NoError(t, err)
-	lastTimestamp, err := scrobblerlog.Write(buffer, log.Listens)
+	lastTimestamp, err := log.Append(buffer, listens)
 	require.NoError(t, err)
 	result := buffer.String()
 	lines := strings.Split(result, "\n")
 	assert.Equal(5, len(lines))
 	assert.Equal("#AUDIOSCROBBLER/1.1", lines[0])
-	assert.Equal("#TZ/Unknown", lines[1])
+	assert.Equal("#TZ/UNKNOWN", lines[1])
 	assert.Equal("#CLIENT/Rockbox foo $Revision$", lines[2])
 	assert.Equal(
 		"Prinzhorn Dance School\tHome Economics\tReign\t1\t271\tL\t1699572072\tb59cf4e7-caee-4019-a844-79d2c58d4dff",
@@ -121,9 +123,9 @@ func TestReadHeader(t *testing.T) {
 	data := bytes.NewBufferString(testScrobblerLog)
 	reader := bufio.NewReader(data)
 	log := scrobblerlog.ScrobblerLog{}
-	err := scrobblerlog.ReadHeader(reader, &log)
+	err := log.ReadHeader(reader)
 	assert.NoError(t, err)
-	assert.Equal(t, log.Timezone, "UNKNOWN")
+	assert.Equal(t, log.TZ, scrobblerlog.TZ_UNKNOWN)
 	assert.Equal(t, log.Client, "Rockbox sansaclipplus $Revision$")
 	assert.Empty(t, log.Listens)
 }