A neighbour punched a passer by without provocation and KO'd him. Witnesses saw the entire thing and confirmed this to the police. The guy who was hit has made an official complaint to the police. If the police press charges and the neighbour goes to court, what will he likely get if found guilty. As far as I know he has no previous.
it's also going to depend on whether he has a criminal record for a "like" offence, his mental health and whether he pleads guilty rather than being found guilty.