SQL & PL/SQL

Hello,

I want to create a view like:

create or replace view oferte_la_culegere_vw(pcod_lucrare  varchar2, pcod_tipprodso varchar2) is
 select ol.cod_oferta from oferte_lucrare ol 
    join oferte o on o.cod_oferta = ol.cod_oferta
   where ol.cod_tip_lucrare = pcod_lucrare
     and (ol.activ = 'D' or 
 case when ol.activ = 'I' then
    if os_util.are_atributie(o.atributie_exceptie) then  ... -- add condition or ol.activ = 'N' to the query    
)
 intersect
 select t.cod_oferta from tipinstprodso_oferta
   where t.cod_tipprodso = pcod_tipprodso
 order by 1;

show errors view oferte_la_culegere_vw;

So in the 1st select i have to filter only for ol.activ = 'D', but i can select records with ol.activ = 'N', only if that condition matches (os_util.are_atributie...).
How can i specify this in a view?

Thanks