drop function if exists get_referers(param_user_id bigint, param_user_bm_id smallint) cascade;
create function get_referers(param_user_id bigint, param_user_bm_id smallint) 
returns table  (
        referer_id bigint,
        referer_level integer
)  
as $end$
    begin
		return query with recursive tree as (
			select 
				users.referer_id as referer_id, 
				(
					select count(*) % 5 + 1 
					from user_bms 
					where 
						user_bms.user_id=users.referer_id 
					and 
						user_bms.bm_id=param_user_bm_id
				)::integer as referer_level
 			from users
			where users.user_id = param_user_id
			
			union
			
			select 
				users.referer_id as referer_id, 
				tree.referer_level::integer - case when user_bms is null then 0 else 1 end as referer_level
		    from users
		    left join user_bms  
		    	on user_bms.user_id = users.user_id and user_bms.bm_id = param_user_bm_id
		    join tree
		        on tree.referer_id = users.user_id  and users.user_id != users.referer_id
		    where 
		    	tree.referer_level - case when user_bms is null then 0 else 1 end > 0
			)
			select * from tree order by referer_level limit 1;
    end;
$end$ 
language plpgsql;


select * from get_referers(1122::bigint, 1::smallint);