I have a design that can do both. The basic core of it is what I use for my smoker, and I occasionally build small temporary earthen ovens in place of the smoker. I use it in an unfinished state, but it could certainly be used as the "engine" inside a masonry built unit that could be used as both oven or smoker, with excellent temperature control. As well, the heat you don't use to cook can be shunted into heated seating if desired. It's a bit detailed to explain here, but if you are interested I'd be happy to walk you through the design. I'm not selling anything, btw.
Cooking on a crazy contraption...