I was searching for resources on how to make a payment gateway for Shopify to build as a public app. I've seen tutorials on public app making but no solid tutorial for creating a payment gateway app. Can anyone suggests or guide me, or is there any skeleton-like WooCommerce provides. I'm from a PHP stack & would appreciate it if anyone could give any example app or guideline from which I'll be able to create mine. I want to use the Laravel PHP SDK if it's possible to do with it. Thanks in advance.