Now actually fix race condition

.gitignore

@@ -0,0 +1 @@
+main.exe

main.go

@@ -12,71 +12,32 @@ import (
 )
 
 func init() {
-	log.SetFlags(log.Lmicroseconds)
+	log.SetFlags(log.Lmicroseconds | log.Lshortfile)
 }
 
 func main() {
-	recreate := flag.Bool("f", false, "First rename all files to <name>.bak and then rename them to iter (to prevent conflicts of already existing files)")
 	flag.Parse()
-
-	originalExtensions := make(map[string]string)
-	var mapMutex sync.RWMutex
 	var wg sync.WaitGroup
+	var renamedFiles sync.Map
 	extensionRegex := regexp.MustCompile(`\.[a-zA-Z0-9]+$`)
 
-	if *recreate {
-		log.Printf("Recreating all files first")
-		for _, file := range flag.Args() {
-			wg.Add(1)
-			go func(file string) {
-				defer wg.Done()
-				_, err := os.Stat(file)
-				if os.IsNotExist(err) {
-					log.Printf("File %s does not exist", file)
-					return
-				}
-
-				res := extensionRegex.FindAllString(file, -1)
-				if len(res) == 0 {
-					log.Printf("No extension found for file %s", file)
-					return
-				}
-				dir := path.Dir(file)
-				extension := res[0]
-				bckpFile := fmt.Sprintf("%s/%s.bak", dir, file)
-
-				_, err = os.Stat(bckpFile)
-				if !os.IsNotExist(err) {
-					log.Printf("File %s already exists", bckpFile)
-					return
-				}
-
-				log.Printf("%s -> %s", file, bckpFile)
-				err = os.Rename(file, bckpFile)
-				if err != nil {
-					log.Printf("Error renaming file %s to %s: %s", file, bckpFile, err)
-				}
-
-				mapMutex.Lock()
-				originalExtensions[bckpFile] = extension
-				mapMutex.Unlock()
-			}(file)
-		}
-	}
-
 	wg.Wait()
 	wg = sync.WaitGroup{}
 	for _, file := range flag.Args() {
 		wg.Add(1)
 		go func(file string) {
 			defer wg.Done()
-			if *recreate {
-				file = file + ".bak"
+			file = path.Clean(file)
+			log.Printf("Checking file %s", file)
+
+			if !DoesFileExist(file) {
+				log.Printf("File %s does not exist", file)
+				return
 			}
 
 			info, err := os.Stat(file)
-			if os.IsNotExist(err) {
-				log.Printf("File %s does not exist", file)
+			if info == nil {
+				log.Printf("Error checking file %s: %s", file, err)
 				return
 			}
 
@@ -89,35 +50,35 @@ func main() {
 			modtimeString := modtime.Local().Format("2006-01-02T15-04-05")
 			newFile := modtimeString
 
-			bakless := strings.TrimRight(file, ".bak")
-			res := extensionRegex.FindAllString(bakless, -1)
+			res := extensionRegex.FindAllString(file, -1)
 			if len(res) == 0 {
 				log.Printf("No extension found for file %s", file)
 				return
 			}
 			extension := res[0]
 
-			mapMutex.RLock()
-			prevExtension, ok := originalExtensions[file]
-			mapMutex.RUnlock()
-			if ok {
-				extension = prevExtension
-			}
-
 			dir := path.Dir(file)
 			newFile = fmt.Sprintf("%s/%s%s", dir, newFile, extension)
 			newFile = path.Clean(newFile)
 			newFile = strings.TrimRight(newFile, ".bak")
+			log.Printf("New file name for %s: %s", file, newFile)
 
-			_, err = os.Stat(newFile)
-			if os.IsExist(err) {
+			if DoesFileExist(newFile) {
 				log.Printf("File %s already exists", newFile)
 				return
-			} else if !os.IsNotExist(err) {
-				log.Printf("An unexpected error occurred: %v", err)
-				return
 			}
 
+			_, ok := renamedFiles.Load(newFile)
+			if ok {
+				log.Printf("File %s already renamed", newFile)
+				return
+			}
+
+			if file == newFile {
+				log.Printf("File %s already has the correct name", file)
+				return
+			}
+			renamedFiles.Store(newFile, struct{}{})
 			log.Printf("%s -> %s", file, newFile)
 			err = os.Rename(file, newFile)
 			if err != nil {
@@ -128,3 +89,12 @@ func main() {
 	}
 	wg.Wait()
 }
+
+func DoesFileExist(input string) bool {
+	file, err := os.Open(input)
+	if err != nil {
+		return false
+	}
+	file.Close()
+	return true
+}