Heavily front ended, averaged out to what hes on now for 3 years with a 4th and 5th trigger. Incentives for BnF etc etc.
I'd question whether his current form warrants the same level of contract he's on now. Especially if there are no other clubs knocking down his door. But I suppose it's not like we have a whole bunch of players with form warranting fat new contracts, so might as well front load him for a year or two to keep everybody happy.