Active Record Join Subquery

[eluser]Unknown[/eluser]
i need to write this mysql query in active record which include query inside join

select p.id, sn.upgrade, ssnn.MaxUpgrade, sn.package_id, p.category_id, p.sub_category_id, p.name as product_name,
p.from_date, p.to_date, c.name as category_name, sc.name as sub_category_name,cus.first_name, cus.last_name, cus.email, cus.company_phone1, pd.city_id, city.name as city_name,
area.name as area_name
from product p
inner join category c on c.id = p.category_id
inner join sub_category sc on sc.id = p.sub_category_id
inner join customer cus on cus.product_id = p.id
inner join product_desc pd on pd.product_id = p.id
inner join city on city.id = pd.city_id
inner join area on area.id = pd.area_id
inner join subscription sn on sn.product_id = p.id
inner join (select product_id, max(upgrade) as MaxUpgrade from subscription group by product_id) as ssnn
on sn.product_id = ssnn.product_id and sn.upgrade = ssnn.MaxUpgrade
group by p.id