1 files changed, 31 insertions, 0 deletions
diff --git a/internal/service/filename.go b/internal/service/filename.go
new file mode 100644
index 0000000..9303de6
--- /dev/null
+++ b/internal/service/filename.go
@@ -0,0 +1,31 @@
+package service
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// uniqueFilename returns a non-conflicting full path by appending (n)
+// if a file with the same name already exists in dir.
+func uniqueFilename(dir, filename string) string {
+	filename = filepath.Base(filename)
+	if filename == "." || filename == ".." || filename == "" {
+		return ""
+	}
+	ext := filepath.Ext(filename)
+	base := strings.TrimSuffix(filename, ext)
+
+	candidate := filepath.Join(dir, filename)
+	if _, err := os.Stat(candidate); os.IsNotExist(err) {
+		return candidate
+	}
+
+	for i := 1; ; i++ {
+		candidate = filepath.Join(dir, fmt.Sprintf("%s(%d)%s", base, i, ext))
+		if _, err := os.Stat(candidate); os.IsNotExist(err) {
+			return candidate
+		}
+	}
+}