Move track information into struct

This adds a NewTrack func that creates the struct, and we now use this in RenameTrack().

sanitize.go

@@ -13,29 +13,41 @@ import (
 
 var trackNameReg = regexp.MustCompile("^([0-9]{2}).+")
 
-// RenameTrack takes a filename, opens it, reads the metadata, and returns both
-// the old and new filename.
-func RenameTrack(file string) string {
+func NewTrack(file string) *Track {
 	f, err := os.Open(file)
 	if err != nil {
 		fmt.Printf("error loading file: %v", err)
-		return ""
+		return nil
 	}
 	defer f.Close()
 
-	fName := f.Name()
-	fMatch := trackNameReg.FindStringSubmatch(fName)
+	m, err := tag.ReadFrom(f)
+	if err != nil {
+		return nil
+	}
+
+	return &Track{
+		Title:    m.Title(),
+		Artist:   m.Artist(),
+		Filename: f.Name(),
+	}
+}
+
+// RenameTrack takes a filename, opens it, reads the metadata, and returns both
+// the old and new filename.
+func RenameTrack(file string) string {
+	t := NewTrack(file)
+
+	// Extract playlist track number from filename
+	fMatch := trackNameReg.FindStringSubmatch(t.Filename)
 	if len(fMatch) < 2 {
 		log.Fatal("Unexpect filename format")
 	}
 	trackNum := fMatch[1]
-	ext := fName[strings.LastIndex(fName, "."):]
 
-	m, err := tag.ReadFrom(f)
-	if err != nil {
-		log.Fatal(err)
-	}
-	return fmt.Sprintf("%s-%s-%s%s", trackNum, Sanitize(m.Artist()), Sanitize(m.Title()), ext)
+	ext := t.Filename[strings.LastIndex(t.Filename, "."):]
+
+	return fmt.Sprintf("%s-%s-%s%s", trackNum, Sanitize(t.Artist), Sanitize(t.Title), ext)
 }
 
 // Sanitize takes a string and removes problematic characters from it.

track.go

@@ -0,0 +1,14 @@
+package cdr
+
+type (
+	Mixtape struct {
+		Tracks []Track
+	}
+
+	Track struct {
+		Title  string
+		Artist string
+
+		Filename string
+	}
+)