Was Roosevelt warned of the attack?

Like so many other episodes in history, the attack on Pearl Harbor is fraught with a nebulous conspiracy theory. Roosevelt would have known about the attack and would have done nothing to prevent it.
Or he would have done little: just giving orders for the American aircraft carriers to leave the naval base of Hawaii, saving them from destruction. Why would the President of the United States have acted in this way? Because he needed a pretext to enter the war. And nothing better than a treacherous attack, causing important but not decisive losses, to turn American public opinion in favor of participation in the war.