Format Chilean Rut in Postgresql

Here is a very practical method to format Chilean Rut (xx.xxx.xxx-x)

The only requirement is to have the following function previously.
PadIndex Postgresql

CREATE OR REPLACE FUNCTION public.fn_format_rut(var_rut varchar(12))
 RETURNS varchar(12) as $
declare
	v_cont integer;
	v_i integer;
	v_new_rut VARCHAR(12); 
begin
	v_cont := 0;
	v_i := 0;
	
	var_rut := substring(var_rut, patindex('%[^0]%',var_rut || '.'), length(var_rut));
	
	if(length(var_rut) = 0) then
		return '';
	else
		var_rut := replace(var_rut::text, '.','');
		var_rut := replace(var_rut::text, '-','');
		
		v_new_rut := '-' || right(var_rut::text, 1);
		
		v_i := length(var_rut);
		
		while v_i >= 2 loop
		
			v_i := v_i -1;
			v_new_rut := substring(var_rut, v_i, 1) || v_new_rut;
			v_cont := v_cont + 1;
			
			if(v_cont = 3 and v_i <> 0) then
				v_new_rut := '.' || v_new_rut;
				v_cont := 0;
			end if; 
		
        end loop;
		
	end if;
 	
 	return v_new_rut;
END; 
$ language 'plpgsql';