feat: Implement main playlist restrictions; add internal method for sound addition and update tests

app/services/playlist.py

@@ -51,6 +51,16 @@ class PlaylistService:
         self.playlist_repo = PlaylistRepository(session)
         self.sound_repo = SoundRepository(session)
 
+    async def _is_main_playlist(self, playlist_id: int) -> bool:
+        """Check if the given playlist is the main playlist."""
+        try:
+            playlist = await self.playlist_repo.get_by_id(playlist_id)
+        except Exception:
+            logger.exception("Failed to check if playlist is main: %s", playlist_id)
+            return False
+        else:
+            return playlist is not None and playlist.is_main
+
     async def get_playlist_by_id(self, playlist_id: int) -> Playlist:
         """Get a playlist by ID."""
         playlist = await self.playlist_repo.get_by_id(playlist_id)
@@ -145,6 +155,13 @@ class PlaylistService:
         is_current: bool | None = None,
     ) -> Playlist:
         """Update a playlist."""
+        # Check if this is the main playlist
+        if await self._is_main_playlist(playlist_id):
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail="The main playlist cannot be edited",
+            )
+
         playlist = await self.get_playlist_by_id(playlist_id)
 
         update_data: dict[str, Any] = {}
@@ -186,6 +203,13 @@ class PlaylistService:
 
     async def delete_playlist(self, playlist_id: int, user_id: int) -> None:
         """Delete a playlist."""
+        # Check if this is the main playlist
+        if await self._is_main_playlist(playlist_id):
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail="The main playlist cannot be deleted",
+            )
+
         playlist = await self.get_playlist_by_id(playlist_id)
 
         if not playlist.is_deletable:
@@ -247,6 +271,13 @@ class PlaylistService:
         position: int | None = None,
     ) -> None:
         """Add a sound to a playlist."""
+        # Check if this is the main playlist
+        if await self._is_main_playlist(playlist_id):
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail="Sounds cannot be added to the main playlist",
+            )
+
         # Verify playlist exists
         await self.get_playlist_by_id(playlist_id)
 
@@ -295,6 +326,13 @@ class PlaylistService:
         user_id: int,
     ) -> None:
         """Remove a sound from a playlist."""
+        # Check if this is the main playlist
+        if await self._is_main_playlist(playlist_id):
+            raise HTTPException(
+                status_code=status.HTTP_403_FORBIDDEN,
+                detail="Sounds cannot be removed from the main playlist",
+            )
+
         # Verify playlist exists
         await self.get_playlist_by_id(playlist_id)
 
@@ -377,8 +415,23 @@ class PlaylistService:
             "total_play_count": total_plays,
         }
 
-    async def add_sound_to_main_playlist(self, sound_id: int, user_id: int) -> None:
+    async def add_sound_to_main_playlist(
+        self, sound_id: int, user_id: int,  # noqa: ARG002
+    ) -> None:
         """Add a sound to the global main playlist."""
+        raise HTTPException(
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail="Sounds cannot be added to the main playlist",
+        )
+
+    async def _add_sound_to_main_playlist_internal(
+        self, sound_id: int, user_id: int,
+    ) -> None:
+        """Add sound to main playlist bypassing restrictions.
+
+        This method is intended for internal system use only (e.g., extraction service).
+        It bypasses the main playlist modification restrictions.
+        """
         main_playlist = await self.get_main_playlist()
 
         if main_playlist.id is None:
@@ -395,7 +448,7 @@ class PlaylistService:
         ):
             await self.playlist_repo.add_sound_to_playlist(main_playlist_id, sound_id)
             logger.info(
-                "Added sound %s to main playlist for user %s",
+                "Added sound %s to main playlist for user %s (internal)",
                 sound_id,
                 user_id,
             )