Add "queue to waitingroom" feature

syng/queue.py

@@ -120,6 +120,20 @@ class Queue:
                 return item
         return None
 
+    def find_all_by_name(self, name: str) -> Iterable[Entry]:
+        """
+        Find all entries by their performer and return them as an iterable.
+
+        :param name: The name of the performer to search for.
+        :type name: str
+        :returns: The entries with the performer.
+        :rtype: Iterable[Entry]
+        """
+
+        for item in self._queue:
+            if item.shares_performer(name):
+                yield item
+
     def find_by_uuid(self, uuid: UUID | str) -> Optional[Entry]:
         """
         Find an entry by its uuid and return it.

syng/server.py

@@ -682,6 +682,33 @@ class Server:
 
         await self.sio.emit("play", current, room=sid)
 
+    @admin
+    @with_state
+    async def handle_queue_to_waiting_room(
+        self, state: State, sid: str, data: dict[str, Any]
+    ) -> None:
+        """
+        Handle the "queue-to-waiting" message.
+
+        If on an admin-connection, removes a song from the queue and appends it to
+        the waiting room. If the performer has only one entry in the queue, it is
+        put back into the queue immediately.
+
+        :param sid: The session id of the requesting client
+        :type sid: str
+        :rtype: None
+        """
+
+        entry = state.queue.find_by_uuid(data["uuid"])
+        if entry is not None:
+            performer_entries = list(state.queue.find_all_by_name(entry.performer))
+            print(performer_entries)
+            if len(performer_entries) == 1:
+                return
+            await state.queue.remove(entry)
+            state.waiting_room.append(entry)
+            await self.broadcast_state(state, sid=sid)
+
     @admin
     @with_state
     async def handle_waiting_room_to_queue(