feat: group authors by first character

src/main.rs

@@ -78,12 +78,13 @@ fn rename_files(directory: &str, base: &str, args: &Arguments) -> Result<i32> {
         let (Some(title), Some(artist)) = (tag.title(), tag.artist()) else {
             continue;
         };
+        let (bucket, _) = artist.split_at(1);
         let album = parse_album(&title);
         count += 1;
         let new_name = if album.is_empty() {
-            format!("{artist}/{title}/{title}.m4b")
+            format!("{bucket}/{artist}/{title}/{title}.m4b")
         } else {
-            build_series_name(&artist, &album, &title)
+            build_series_name(bucket, &artist, &album, &title)
         };
         println!("==============================");
         println!("- artist: {artist}");
@@ -107,10 +108,10 @@ fn rename_files(directory: &str, base: &str, args: &Arguments) -> Result<i32> {
     Ok(count)
 }
 
-fn build_series_name(artist: &str, album: &str, title: &str) -> String {
+fn build_series_name(bucket: &str, artist: &str, album: &str, title: &str) -> String {
     let index = parse_index(title);
     let title = parse_title(title);
-    format!("{artist}/{album}/{index}. {title}/{index}. {title}.m4b")
+    format!("{bucket}/{artist}/{album}/{index}. {title}/{index}. {title}.m4b")
 }
 
 fn parse_index(title: &str) -> String {

src/tests.rs

@@ -11,8 +11,8 @@ use pretty_assertions::assert_eq;
     "3. A Conjuring of Light"
 )]
 fn parse_series_details(#[case] album: &str, #[case] title: &str, #[case] expected: &str) {
-    let expected_result = format!("Bob/{album}/{expected}/{expected}.m4b");
-    let result = build_series_name("Bob", album, title);
+    let expected_result = format!("B/Bob/{album}/{expected}/{expected}.m4b");
+    let result = build_series_name("B", "Bob", album, title);
 
     assert_eq!(result, expected_result);
 }