createInFake ref r = modifyIORef' ref (Map.insert (reservationId r) r)

readOneFromFake :: IORef DB -> UUID -> IO (Maybe Reservation)
readOneFromFake ref rid = Map.lookup rid <$> readIORef ref

readManyFromFake :: IORef DB -> LocalTime -> IO [Reservation]
readManyFromFake ref (LocalTime d _) = do
  db <- readIORef ref
  let allReservations = Map.elems db