I'm not the one you asked from, but I have read something on the subject. As far as I know, this has been speculated but never really proven. Then again, it tends to be so in history that you can consider something proven by something and yet someone will "prove" you are wrong. Unanimous points of view tend to be rare, but I think the majority of the researchers don't believe in this theory. I think Viktor Suvorov is the most prominent supporter of this theory, but I haven't read any of his books, so I can't say how good or bad they are.

As for what I believe myself: Stalin saw enemies everywhere and that wasn't only due to his paranoia. His whole "socialism in one country" on the contrary to Marx's and Lenin's ideal of world revolution was fundamentally an attempt to make Soviet Union a strong nation that could hold its own against foreign invasion. The Soviet Union was preparing for a war already in the end of 1920s and that was a major point in the industrialization campaign of the early 1930s.

Stalin certainly expected Hitler, or someone else for that matter, to attack at some point. That is why he first ended his policy of semi-isolation with the Western countries and sought collective security from the League of nations. When the Spanish civil war began, however, he became disappointed when apparently his new friends didn't react strongly enough. So he concluded that if the Germans attacked Eastern Europe, he couldn't count on the help of them there either. Hence the non-aggression treaty to buy time.

And this is where it becomes mere speculation. If Stalin was preparing for a war for a long time, and not only against Germany, it is possible that he eventually wanted to make a "pre-emptive strike" himself. But I don't think in 1941. He had only recently consolidated his power as the absolute ruler of the party and the state in 1936 - 1938. The second five year plan had to abandon some of its great dreams just to fix what the first one left undone. The third one had been started, yes, but it is questionable how much it could have achieved, if it hadn't been interrupted by Hitler's invasion. All in all I think Soviet Union wasn't by then ready for an offensive war, but functioned well for a defensive one. And I think Stalin knew that too. Being one of the most notorious dictators of the 20th century isn't synonymous to being stupid.