-- Treat an invitation room as the account's initial room rather than an
-- immutable lifetime binding. Room IDs remain unique across accounts so two
-- listeners cannot accidentally claim the same upstream room.

DROP TRIGGER IF EXISTS users_room_id_immutable ON users;
DROP FUNCTION IF EXISTS prevent_user_room_id_change();

CREATE OR REPLACE FUNCTION enforce_live_source_account_room()
RETURNS trigger
LANGUAGE plpgsql
SET search_path = pg_catalog, public
AS $$
BEGIN
  IF NOT EXISTS (
    SELECT 1 FROM public.users
    WHERE id = NEW.owner_user_id AND room_id = NEW.room_id
  ) THEN
    RAISE EXCEPTION 'live source room_id must equal its owning account room_id';
  END IF;
  IF TG_OP = 'UPDATE'
     AND NEW.owner_user_id IS DISTINCT FROM OLD.owner_user_id THEN
    RAISE EXCEPTION 'live source ownership is immutable';
  END IF;
  RETURN NEW;
END;
$$;

COMMENT ON COLUMN users.room_id IS
  'Current account-level Bilibili room; initialized by invitation and user-switchable.';
COMMENT ON COLUMN live_sources.room_id IS
  'Current room of the owning account; updated atomically with users.room_id.';