Ken Rosenthal has it from a source:

Three-team trade, per source, will look like this: Choo, Jason Donald to #Reds, Gregorius to #Diamondbacks, Stubbs, AZ pitcher to #Indians.

I really, really like this deal for the Reds. Shin-Soo Choo gets on base like a monster and Jason Donald is a perfectly passable utility guy. This deal makes the Reds better for next season.

Losing Didi Gregorius is the big loss here. He has a tremendous glove at shortstop and has the raw tools to turn into a pretty good hitter. But those tools have not developed yet, and he seems to have a long way to go in that respect. Plus, Zack Cozart seems to have a decent hold on a position, so Didi was more or less expendable.