new payment gateway in opencart 2.0

Hello everybody Now I have created some payment in open cart 1.5.6 but it's the dawn of the new era and I have been asked to create a new payment gateway for diamond web pay there is an extension for 1.5.6 but not for 2.0 how do I go about it.
I know some things have been deprecated in 2.0 like $data so should I look at an existing module in 2.0 and build a similar one.