Being 8 speed the swap is really easy. Easiest way would be to get some Claris ST-R240 flat bar combination brake and shifters in a 2x8. You'll need new brake cable inners with MTB cable ends on them. Gear cables can be re-used. Think about getting some flat bars with a few more hand positions like butterfly bars, Velo Orange Crazy bars, Jones Loop, Surly Moloko