feat: Implement playlist sound deletion and update current playlist logic on deletion

app/services/playlist.py

@@ -3,10 +3,12 @@
 from typing import Any, TypedDict
 
 from fastapi import HTTPException, status
+from sqlmodel import select
 from sqlmodel.ext.asyncio.session import AsyncSession
 
 from app.core.logging import get_logger
 from app.models.playlist import Playlist
+from app.models.playlist_sound import PlaylistSound
 from app.models.sound import Sound
 from app.repositories.playlist import PlaylistRepository, PlaylistSortField, SortOrder
 from app.repositories.sound import SoundRepository
@@ -231,11 +233,20 @@ class PlaylistService:
         # Check if this was the current playlist before deleting
         was_current = playlist.is_current
 
+        # First, delete all playlist_sound relationships
+        await self._delete_playlist_sounds(playlist_id)
+
+        # Then delete the playlist itself
         await self.playlist_repo.delete(playlist)
         logger.info("Deleted playlist %s for user %s", playlist_id, user_id)
 
-        # If the deleted playlist was current, reload player to use main fallback
+        # If the deleted playlist was current, set main playlist as current
         if was_current:
+            main_playlist = await self.get_main_playlist()
+            await self.playlist_repo.update(main_playlist, {"is_current": True})
+            logger.info("Set main playlist as current after deleting current playlist %s", playlist_id)
+
+            # Reload player to reflect the change
             await _reload_player_playlist()
 
     async def search_playlists(self, query: str, user_id: int) -> list[Playlist]:
@@ -539,6 +550,20 @@ class PlaylistService:
         # Reload player playlist to reflect the change (will fallback to main)
         await _reload_player_playlist()
 
+    async def _delete_playlist_sounds(self, playlist_id: int) -> None:
+        """Delete all playlist_sound records for a given playlist."""
+        # Get all playlist_sound records for this playlist
+        stmt = select(PlaylistSound).where(PlaylistSound.playlist_id == playlist_id)
+        result = await self.session.exec(stmt)
+        playlist_sounds = result.all()
+
+        # Delete each playlist_sound record
+        for playlist_sound in playlist_sounds:
+            await self.session.delete(playlist_sound)
+
+        await self.session.commit()
+        logger.info("Deleted %d playlist_sound records for playlist %s", len(playlist_sounds), playlist_id)
+
     async def _unset_current_playlist(self) -> None:
         """Unset any current playlist globally."""
         current_playlist = await self.playlist_repo.get_current_playlist()