works perfectly

Author: ChekeredList71

.gitignore

@@ -1,2 +1,3 @@
 /build/
 /lib/
+/testing_files/

main.go

@@ -19,91 +19,103 @@ var command = []string{"custom"}
 var rsgainSemaphore chan int
 
 func main() {
-	albumMode := flag.Bool("a", false, "Calculate album gain and peak.")
-	skipExisting := flag.Bool("S", false, "Don't scan files with existing ReplayGain information.")
-	tagMode := flag.String("s", "s", "Tagmode:\ns: scan only\ni: write tags\nd: delete tags")
-	targetLoudness := flag.Int("l", -18, "Use n LUFS as target loudness (-30 ≤ n ≤ -5), default: -18")
-	clipMode := flag.String("c", "n", "n: no clipping protection (default),\np: clipping protection enabled for positive gain values only,\na: Use max peak level n dB for clipping protection")
-	quiet := flag.Bool("q", false, "(rsgain) Don't print scanning status messages.")
-	rsgainLimit := flag.Int("r", 100, "Limit, how many rsgain instances can run at a time.")
+	albumMode := *flag.Bool("a", false, "Calculate album gain and peak.")
+	skipExisting := *flag.Bool("S", false, "Don't scan files with existing ReplayGain information.")
+	tagMode := *flag.String("s", "s", "Tagmode:\ns: scan only\ni: write tags\nd: delete tags")
+	targetLoudness := *flag.Int("l", -18, "Use n LUFS as target loudness (-30 ≤ n ≤ -5), default: -18")
+	clipMode := *flag.String("c", "n", "n: no clipping protection (default),\np: clipping protection enabled for positive gain values only,\na: Use max peak level n dB for clipping protection")
+	quiet := *flag.Bool("q", false, "(rsgain) Don't print scanning status messages.")
+	rsgainLimit := *flag.Int("r", 100, "Limit, how many rsgain instances can run at a time.")
 	flag.Parse()
 
 	libraryRoot := flag.Arg(0)
 
 	// build the rsgain custom command and check values
 
-	if *albumMode {
+	if albumMode {
 		command = append(command, "-a")
 	}
 
-	if *skipExisting {
+	if skipExisting {
 		command = append(command, "-S")
 	}
 
-	if !slices.Contains([]string{"s", "d", "i"}, *tagMode) {
-		fmt.Printf("Invalid tagmode: %s", *tagMode)
+	if !slices.Contains([]string{"s", "d", "i"}, tagMode) {
+		fmt.Printf("Invalid tagmode: %s", tagMode)
 		os.Exit(2)
 	}
-	command = append(command, "-s", *tagMode)
+	command = append(command, "-s", tagMode)
 
-	if !(-30 <= *targetLoudness && *targetLoudness <= -5) {
+	if !(-30 <= targetLoudness && targetLoudness <= -5) {
 		fmt.Println("Target loudness n needs to be -30 ≤ n ≤ -5")
 		os.Exit(2)
 	}
-	command = append(command, "-l", strconv.Itoa(*targetLoudness))
+	command = append(command, "-l", strconv.Itoa(targetLoudness))
 
-	if !slices.Contains([]string{"n", "p", "a"}, *clipMode) {
-		fmt.Printf("Invalid clip mode: %s", *clipMode)
+	if !slices.Contains([]string{"n", "p", "a"}, clipMode) {
+		fmt.Printf("Invalid clip mode: %s", clipMode)
 		os.Exit(2)
 	}
-	command = append(command, "-c", *clipMode)
+	command = append(command, "-c", clipMode)
 
 	if libraryRoot == "" {
 		fmt.Println("No library path specified.")
 		os.Exit(2)
 	}
 
-	if *quiet {
+	if quiet {
 		command = append(command, "-q")
 	}
 
-	rsgainSemaphore = make(chan int, *rsgainLimit)
+	rsgainSemaphore = make(chan int, rsgainLimit)
 
 	/* Used for debugging
 	ctx, cancel := context.WithCancel(context.Background())
 	go monitorRsgainProcesses(ctx, 500*time.Millisecond)
 	*/
 
-	// scan for album folders
-	wg.Add(1)
-	err := walker(libraryRoot)
+	// if root is just a file
+	if isSupportedMusicFile(libraryRoot) {
+		err := runRSGain([]string{libraryRoot}, quiet)
+		if err != nil {
+			errLog.Printf("Something went wrong scanning %s: '%s\n'", libraryRoot, err)
+		}
+	} else { // if we have a folder, scan them with WalkDir
+		wg.Add(1)
+		err := walker(libraryRoot, quiet)
 
-	if err != nil {
-		errLog.Printf("Error walking library folder: %s\n", err)
-	}
+		if err != nil {
+			errLog.Printf("Error walking library folder: %s\n", err)
+		}
 
-	wg.Wait()
+		wg.Wait()
+	}
 
 	/*cancel()*/
 }
 
-func walker(root string) error {
+func walker(root string, isQuiet bool) error {
 	defer wg.Done()
 	return filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return err
 		}
 
-		// skip creating walkers on the initial directory (it would create infinite threads lol)
-		if d.IsDir() && path != root {
-			// when walked into a directory, launch a new walker on that
-			wg.Add(1)
-			go func() {
-				err := walker(path)
-				if err != nil {
-					errLog.Printf("Error walking %s: %s\n", path, err)
-				}
-			}()
+		if d.IsDir() {
+			// skip creating walkers on the initial directory (it would create infinite threads lol)
+			if path != root {
+				// when walked into a directory, launch a new walker on that
+				wg.Add(1)
+				go func() {
+					err := walker(path, isQuiet)
+					if err != nil {
+						errLog.Printf("Error walking %s: %s\n", path, err)
+					}
+				}()
+
+				// skip the current directory (the newly summoned walker is dealing with it)
+				return fs.SkipDir
+			}
 
 			// process supported files (separate thread)
 			wg.Add(1)
@@ -128,29 +140,35 @@ func walker(root string) error {
 					rsgainSemaphore <- 0 //add a slot to the semaphore
 					defer func() { <-rsgainSemaphore }()
 
-					cmd := exec.Command("rsgain", append(command, audioFiles...)...)
-
-					// Stream output to console
-					cmd.Stdout = os.Stdout
-					cmd.Stderr = os.Stderr
-					err := cmd.Run()
-
-					if err != nil {
-						errLog.Printf("Error calling rsgain on these files: '%v'\n", audioFiles)
-						errLog.Printf("Command failed: %s\nError: %v\n", cmd.String(), err)
-
-					}
+					err = runRSGain(audioFiles, isQuiet)
 				}
 			}()
-
-			// skip the current directory (the newly summoned walker is dealing with it)
-			return fs.SkipDir
 		}
 
-		return nil
+		return err
 	})
 }
 
+func runRSGain(audioFiles []string, isQuiet bool) error {
+	cmd := exec.Command("rsgain", append(command, audioFiles...)...)
+
+	// Stream output to console if set
+	if !isQuiet {
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+	}
+
+	err := cmd.Run()
+
+	if err != nil {
+		errLog.Printf("Error calling rsgain on these files: '%v'\n", audioFiles)
+		errLog.Printf("Command failed: %s\nError: %v\n", cmd.String(), err)
+
+	}
+
+	return err
+}
+
 func isSupportedMusicFile(path string) bool {
 	supportedFiles := []string{
 		".aiff", ".flac", ".flac",