stuff

app/api/schemas/playlist.py

@@ -29,3 +29,7 @@ class PlaylistUpdate(BaseModel):
 class PlaylistAddTrack(BaseModel):
     track_id: uuid.UUID
     position: float | None = None
+
+
+class PlaylistReorder(BaseModel):
+    track_ids: list[uuid.UUID]

app/api/v1/playlists.py

@@ -13,11 +13,17 @@ from app.api.deps import (
     TrackRepoDep,
 )
 from app.api.schemas.pagination import PagedResponse
-from app.api.schemas.playlist import PlaylistAddTrack, PlaylistCreate, PlaylistOut, PlaylistUpdate
+from app.api.schemas.playlist import (
+    PlaylistAddTrack,
+    PlaylistCreate,
+    PlaylistOut,
+    PlaylistReorder,
+    PlaylistUpdate,
+)
 from app.api.schemas.track import TrackOut
 from app.api.v1.tracks import _build_track_out
 from app.domain.entities.playlist import Playlist
-from app.domain.errors import NotFoundError, PermissionDeniedError
+from app.domain.errors import NotFoundError, PermissionDeniedError, ValidationError
 from app.infrastructure.db.repositories.playlist_repository import SqlAlchemyPlaylistRepository
 
 router = APIRouter(prefix="/playlists", tags=["playlists"])
@@ -182,7 +188,32 @@ async def remove_playlist_track(
 
 
 @router.put("/{playlist_id}/tracks/reorder")
-async def reorder_playlist_tracks(playlist_id: uuid.UUID, _: CurrentUser) -> Any: ...
+async def reorder_playlist_tracks(
+    playlist_id: uuid.UUID,
+    body: PlaylistReorder,
+    playlist_repo: PlaylistRepoDep,
+    user: CurrentUser,
+) -> PlaylistOut:
+    playlist = await playlist_repo.get_by_id(playlist_id)
+    if playlist is None:
+        raise NotFoundError(f"Playlist {playlist_id} not found.")
+    if playlist.owner_id != user.id:
+        raise PermissionDeniedError("You don't own this playlist.")
+
+    total = await playlist_repo.get_track_total(playlist_id)
+    current_tracks = (
+        await playlist_repo.get_tracks(playlist_id, limit=total, offset=0) if total else []
+    )
+    current_ids = {t.id for t in current_tracks}
+    given_ids = body.track_ids
+    if len(given_ids) != len(set(given_ids)) or set(given_ids) != current_ids:
+        raise ValidationError("track_ids must be a permutation of the playlist's current tracks.")
+
+    await playlist_repo.reorder_tracks(playlist_id, given_ids)
+    updated = await playlist_repo.get_by_id(playlist_id)
+    assert updated is not None
+    items = await _build_playlist_out([updated], playlist_repo)
+    return items[0]
 
 
 @router.get("/{playlist_id}/cover")

app/domain/ports.py

@@ -278,11 +278,15 @@ class PlaylistRepository(Protocol):
         self, playlist_id: uuid.UUID, *, limit: int, offset: int
     ) -> list[Track]: ...
     async def get_track_total(self, playlist_id: uuid.UUID) -> int: ...
+    async def has_track(self, playlist_id: uuid.UUID, track_id: uuid.UUID) -> bool: ...
     async def add_track(
         self, playlist_id: uuid.UUID, track_id: uuid.UUID, *, position: float
     ) -> None: ...
     async def remove_track(self, playlist_id: uuid.UUID, track_id: uuid.UUID) -> None: ...
     async def max_position(self, playlist_id: uuid.UUID) -> float: ...
+    async def reorder_tracks(
+        self, playlist_id: uuid.UUID, ordered_track_ids: list[uuid.UUID]
+    ) -> None: ...
     # list must come after any method using list[...] in its signature (name shadowing)
     async def list(self, *, owner_id: uuid.UUID, limit: int, offset: int) -> list[Playlist]: ...
 

app/infrastructure/db/repositories/playlist_repository.py

@@ -138,9 +138,22 @@ class SqlAlchemyPlaylistRepository:
     async def get_track_total(self, playlist_id: uuid.UUID) -> int:
         return await self.track_count(playlist_id)
 
+    async def has_track(self, playlist_id: uuid.UUID, track_id: uuid.UUID) -> bool:
+        row = (
+            await self._session.execute(
+                select(PlaylistTrackModel.id).where(
+                    PlaylistTrackModel.playlist_id == playlist_id,
+                    PlaylistTrackModel.track_id == track_id,
+                )
+            )
+        ).scalar_one_or_none()
+        return row is not None
+
     async def add_track(
         self, playlist_id: uuid.UUID, track_id: uuid.UUID, *, position: float
     ) -> None:
+        if await self.has_track(playlist_id, track_id):
+            return
         row = PlaylistTrackModel(playlist_id=playlist_id, track_id=track_id, position=position)
         self._session.add(row)
         playlist = await self._session.get(PlaylistModel, playlist_id)
@@ -148,6 +161,26 @@ class SqlAlchemyPlaylistRepository:
             playlist.version = playlist.version + 1
         await self._session.flush()
 
+    async def reorder_tracks(
+        self, playlist_id: uuid.UUID, ordered_track_ids: list[uuid.UUID]
+    ) -> None:
+        rows = (
+            (
+                await self._session.execute(
+                    select(PlaylistTrackModel).where(PlaylistTrackModel.playlist_id == playlist_id)
+                )
+            )
+            .scalars()
+            .all()
+        )
+        by_track_id = {row.track_id: row for row in rows}
+        for position, track_id in enumerate(ordered_track_ids, start=1):
+            by_track_id[track_id].position = float(position)
+        playlist = await self._session.get(PlaylistModel, playlist_id)
+        if playlist is not None:
+            playlist.version = playlist.version + 1
+        await self._session.flush()
+
     async def remove_track(self, playlist_id: uuid.UUID, track_id: uuid.UUID) -> None:
         row = (
             await self._session.execute(