refactor: Improve exception handling and logging in authentication and playlist services; enhance code readability and structure

app/services/auth.py

@@ -467,11 +467,13 @@ class AuthService:
         # If user has existing password, verify it
         if had_existing_password:
             if not current_password:
-                raise ValueError("Current password is required when changing existing password")
+                msg = "Current password is required when changing existing password"
+                raise ValueError(msg)
             if not PasswordUtils.verify_password(current_password, user.password_hash):
-                raise ValueError("Current password is incorrect")
+                msg = "Current password is incorrect"
+                raise ValueError(msg)
         else:
-            # User doesn't have a password (OAuth-only user), so we're setting their first password
+            # User doesn't have a password (OAuth-only user), setting first password
             logger.info("Setting first password for OAuth user: %s", user_email)
 
         # Hash new password
@@ -509,6 +511,6 @@ class AuthService:
             updated_at=user.updated_at,
         )
 
-    async def get_user_oauth_providers(self, user: User):
+    async def get_user_oauth_providers(self, user: User) -> list:
         """Get OAuth providers connected to the user."""
         return await self.oauth_repo.get_by_user_id(user.id)

app/services/credit.py

@@ -223,11 +223,11 @@ class CreditService:
                     user_id,
                 )
 
-            return transaction
-
         except Exception:
             await session.rollback()
             raise
+        else:
+            return transaction
         finally:
             await session.close()
 
@@ -316,11 +316,11 @@ class CreditService:
                     user_id,
                 )
 
-            return transaction
-
         except Exception:
             await session.rollback()
             raise
+        else:
+            return transaction
         finally:
             await session.close()
 
@@ -503,11 +503,11 @@ class CreditService:
                     user_id,
                 )
 
-            return transaction
-
         except Exception:
             await session.rollback()
             raise
+        else:
+            return transaction
         finally:
             await session.close()
 

app/services/dashboard.py

@@ -87,7 +87,7 @@ class DashboardService:
             )
             raise
 
-    def _get_date_filter(self, period: str) -> datetime | None:
+    def _get_date_filter(self, period: str) -> datetime | None:  # noqa: PLR0911
         """Calculate the date filter based on the period."""
         now = datetime.now(UTC)
 

app/services/playlist.py

@@ -212,12 +212,13 @@ class PlaylistService:
         """Search all playlists by name."""
         return await self.playlist_repo.search_by_name(query)
 
-    async def search_and_sort_playlists(
+    async def search_and_sort_playlists(  # noqa: PLR0913
         self,
         search_query: str | None = None,
         sort_by: PlaylistSortField | None = None,
         sort_order: SortOrder = SortOrder.ASC,
         user_id: int | None = None,
+        *,
         include_stats: bool = False,
         limit: int | None = None,
         offset: int = 0,
@@ -269,7 +270,7 @@ class PlaylistService:
             current_sounds = await self.playlist_repo.get_playlist_sounds(playlist_id)
             position = len(current_sounds)
         else:
-            # Ensure position doesn't create gaps - if position is too high, place at end
+            # Ensure position doesn't create gaps - if too high, place at end
             current_sounds = await self.playlist_repo.get_playlist_sounds(playlist_id)
             max_position = len(current_sounds)
             position = min(position, max_position)
@@ -329,7 +330,11 @@ class PlaylistService:
         # Create sequential positions: 0, 1, 2, 3...
         sound_positions = [(sound.id, index) for index, sound in enumerate(sounds)]
         await self.playlist_repo.reorder_playlist_sounds(playlist_id, sound_positions)
-        logger.debug("Reordered %s sounds in playlist %s to eliminate gaps", len(sounds), playlist_id)
+        logger.debug(
+            "Reordered %s sounds in playlist %s to eliminate gaps",
+            len(sounds),
+            playlist_id,
+        )
 
     async def reorder_playlist_sounds(
         self,