CREATE OR REPLACE FUNCTION import.is_new_key(
        tablename varchar,
        kv anyelement)
    RETURNS boolean
AS $$
DECLARE columnname varchar;
DECLARE ret boolean;
BEGIN
    columnname = (SELECT column_name
        FROM information_schema.constraint_column_usage k
        JOIN information_schema.table_constraints USING (constraint_name)
        WHERE k.table_name = tablename and constraint_type = 'PRIMARY KEY');
    EXECUTE format('SELECT NOT EXISTS(SELECT 1 FROM import.%I WHERE %I = $1)',
            tablename, columnname)
        INTO ret
        USING kv;
    RETURN ret;
END;
$$
    LANGUAGE plpgsql
    SECURITY DEFINER
    STABLE PARALLEL SAFE;

DROP POLICY parent_allowed ON import.import_logs;
CREATE POLICY parent_allowed ON import.import_logs
    FOR ALL TO waterway_admin
    USING (EXISTS(SELECT 1 FROM import.imports WHERE id = import_id))
    WITH CHECK (import.is_new_key('imports', import_id)
        OR EXISTS(SELECT 1 FROM import.imports WHERE id = import_id));

DROP POLICY parent_allowed ON import.track_imports;
CREATE POLICY parent_allowed ON import.track_imports
    FOR ALL TO waterway_admin
    USING (EXISTS(SELECT 1 FROM import.imports WHERE id = import_id))
    WITH CHECK (import.is_new_key('imports', import_id)
        OR EXISTS(SELECT 1 FROM import.imports WHERE id = import_id));

DROP POLICY import_configuration_policy ON import.import_configuration;
CREATE POLICY import_configuration_policy ON import.import_configuration
    FOR ALL TO waterway_admin
    USING (EXISTS(SELECT 1 FROM users.list_users lu
            WHERE lu.username = import_configuration.username));

DROP POLICY parent_allowed ON import.import_configuration_attributes;
CREATE POLICY parent_allowed ON import.import_configuration_attributes
    FOR ALL TO waterway_admin
    USING (EXISTS(SELECT 1 FROM import.import_configuration
            WHERE id = import_configuration_id))
    WITH CHECK (
        import.is_new_key('import_configuration', import_configuration_id)
        OR EXISTS(SELECT 1 FROM import.import_configuration
            WHERE id = import_configuration_id));