not be thinking straight

to not be thinking clearly or using good judgment

没想清楚，没好好动脑筋

I'm sorry, that was a stupid thing to do - I wasn't thinking straight.

对不起，那样做太愚蠢了——我当时没有想好。

I'm sorry about Elena. I wasn't thinking straight. I didn't know she had a death wish.

埃琳娜的事，我很抱歉。我当时没想清楚。不知道她是要去送死。