I have to redirect a sizable ant ecommerce site to a different domain with a brand new url structure. The present site doesn't have any notible ratings, but just over 1000 indexed pages and will get a great deal of longtail traffic.

The url structure is much like so:

world wide web.olddomain.com/beds-millbrook-c-36_43.html //category

world wide web.olddomain.com/chameleon-backcare-bed mattress-p-244.html //product

world wide web.newsite.com/category/beds/millbrook-beds //category

world wide web.newsite.com/beds/chameleon-backcare-2000-bed mattress //product, note numberhtml code extension

Because the web addresses are extremely different (old site didnt have all the product reputation for example) i cant use whatever other than writing 1000 individual redirects.

Is the fact that even achievable? Or perhaps is there some miracle way thats eluding me?

Any help much appreciated