CREATE FUNCTION users.user_country(user_name name DEFAULT current_user)
    RETURNS internal.user_profiles.country%TYPE
    AS $$
        SELECT country FROM users.list_users
            WHERE username = user_name
    $$
    LANGUAGE SQL
    STABLE PARALLEL SAFE;

ALTER TABLE waterway.sections ADD country char(2) REFERENCES countries
    DEFAULT users.user_country();

-- Try to find out the country of existing sections:
UPDATE waterway.sections s SET country = (
    SELECT COALESCE(
        users.user_country((
            SELECT i.username
                FROM import.imports i
                    JOIN import.import_logs ON i.id = import_id
                WHERE i.kind = 'sec'
                    AND (state = 'accepted' AND s.staging_done
                        OR state = 'pending' AND NOT s.staging_done)
                    AND msg = 'Storing section ''' || s.name || ''''
                ORDER BY i.enqueued DESC FETCH FIRST ROW ONLY)),
        '--'));

ALTER TABLE waterway.sections ALTER country SET NOT NULL;

DROP POLICY responsibility_area ON waterway.sections;
CREATE POLICY same_country ON waterway.sections
    FOR ALL TO waterway_admin
    USING (country = (
        SELECT country FROM users.list_users WHERE username = current_user));