scrobblerlog: implemented append mode

backends/scrobblerlog/parser.go

@@ -46,7 +46,7 @@ func Parse(data io.Reader, includeSkipped bool) (ScrobblerLog, error) {
 	}
 
 	reader := bufio.NewReader(data)
-	err := readHeader(reader, &result)
+	err := ReadHeader(reader, &result)
 	if err != nil {
 		return result, err
 	}
@@ -123,7 +123,7 @@ func Write(data io.Writer, listens models.ListensList) (lastTimestamp time.Time,
 	return
 }
 
-func readHeader(reader *bufio.Reader, log *ScrobblerLog) error {
+func ReadHeader(reader *bufio.Reader, log *ScrobblerLog) error {
 	// Skip header
 	for i := 0; i < 3; i++ {
 		line, _, err := reader.ReadLine()

backends/scrobblerlog/parser_test.go

@@ -22,6 +22,7 @@ THE SOFTWARE.
 package scrobblerlog_test
 
 import (
+	"bufio"
 	"bytes"
 	"strings"
 	"testing"
@@ -114,3 +115,14 @@ func TestWrite(t *testing.T) {
 	assert.Equal("", lines[4])
 	assert.Equal(time.Unix(1699572072, 0), lastTimestamp)
 }
+
+func TestReadHeader(t *testing.T) {
+	data := bytes.NewBufferString(testScrobblerLog)
+	reader := bufio.NewReader(data)
+	log := scrobblerlog.ScrobblerLog{}
+	err := scrobblerlog.ReadHeader(reader, &log)
+	assert.NoError(t, err)
+	assert.Equal(t, log.Timezone, "UNKNOWN")
+	assert.Equal(t, log.Client, "Rockbox sansaclipplus $Revision$")
+	assert.Empty(t, log.Listens)
+}

backends/scrobblerlog/scrobblerlog.go

@@ -22,6 +22,7 @@ THE SOFTWARE.
 package scrobblerlog
 
 import (
+	"bufio"
 	"os"
 	"sort"
 	"time"
@@ -33,6 +34,7 @@ import (
 type ScrobblerLogBackend struct {
 	filePath       string
 	includeSkipped bool
+	append         bool
 	file           *os.File
 	log            ScrobblerLog
 }
@@ -42,25 +44,56 @@ func (b *ScrobblerLogBackend) Name() string { return "scrobbler-log" }
 func (b *ScrobblerLogBackend) FromConfig(config *viper.Viper) models.Backend {
 	b.filePath = config.GetString("file-path")
 	b.includeSkipped = config.GetBool("include-skipped")
-	return b
+	b.append = true
+	if config.IsSet("append") {
+		b.append = config.GetBool("append")
 	}
-
-func (b *ScrobblerLogBackend) StartImport() error {
-	file, err := os.Create(b.filePath)
-	if err != nil {
-		return err
-	}
-
 	b.log = ScrobblerLog{
 		Timezone: "UNKNOWN",
 		Client:   "Rockbox unknown $Revision$",
 	}
+	return b
+}
 
+func (b *ScrobblerLogBackend) StartImport() error {
+	flags := os.O_RDWR | os.O_CREATE
+	if !b.append {
+		flags |= os.O_TRUNC
+	}
+	file, err := os.OpenFile(b.filePath, flags, 0666)
+	if err != nil {
+		return err
+	}
+
+	if b.append {
+		stat, err := file.Stat()
+		if err != nil {
+			file.Close()
+			return err
+		}
+
+		if stat.Size() == 0 {
+			// Zero length file, treat as a new file
+			b.append = false
+		} else {
+			// Verify existing file is a scrobbler log
+			reader := bufio.NewReader(file)
+			err = ReadHeader(reader, &b.log)
+			if err != nil {
+				file.Close()
+				return err
+			}
+			file.Seek(0, 2)
+		}
+	}
+
+	if !b.append {
 		err = WriteHeader(file, &b.log)
 		if err != nil {
 			file.Close()
 			return err
 		}
+	}
 
 	b.file = file
 	return nil

scotty.example.toml

@@ -50,6 +50,9 @@ backend         = "scrobbler-log"
 file-path       = "data/.scrobbler.log"
 # If true, reading listens from the file also returns listens marked as "skipped"
 include-skipped = true
+# If true (default), new listens will be appended to the existing file. Set to
+# false to overwrite the file and create a new scrobbler log on every run.
+append          = true
 
 [service.jspf]
 # Write listens and loves to JSPF playlist files (https://xspf.org/jspf)