skip directory create if already exists, return PathBuf, convert to string outside

src/main.rs

@@ -128,7 +128,9 @@ async fn main() -> Result<()> {
                                 config.preload_max_filecount.unwrap_or_default(),
                             )),
                             // the folder to preload temporary files (e.g. images for the audio albums)
-                            output_folder: Some(preload.output_folder(&i)?),
+                            output_folder: Some(
+                                preload.output_folder(&i)?.to_string_lossy().to_string(),
+                            ),
                             ..Default::default()
                         }),
                     ),

src/preload.rs

@@ -31,11 +31,14 @@ impl Preload {
         Ok(())
     }
 
-    pub fn output_folder(&self, info_hash: &str) -> Result<String> {
+    /// * create new directory if not exists
+    pub fn output_folder(&self, info_hash: &str) -> Result<PathBuf> {
         let mut p = PathBuf::from(&self.directory);
         p.push(info_hash);
-        fs::create_dir(&p)?;
-        Ok(p.to_string_lossy().to_string())
+        if !p.exists() {
+            fs::create_dir(&p)?
+        }
+        Ok(p)
     }
 
     pub fn root(&self) -> PathBuf {