Create customer/cart/order programatically - Create checkout module

[KoreLewi]

Hi!

I want to create a "quick checkout" functionality for my 1.7.7 Prestashop.
I have added a button to the product page which, which opens a popup where I enter some information to place my order.

The problem I ran into was that nowhere do I find what steps I should follow.

As I think:

1. Add product to cart on button click
2. Open popup: enter customer data -> create customer (i have call an ajax frontcontroller)
   1. how can i add the new customer to context and context->cart?
   2. how do i link the cart to the customer? is enough this line: $this->context->cart->id_customer = $customer->id?
3. Same for the address. What should the new address be connected with? And how? Is it enough to add to the address the $address->id_customer?

Not to mention the delivery methods and the shipping methods .. 

Based on my memories, there was a module called ps_checkout in an older version where they were in one place. But now I can't find it anywhere.

I hope someone can help, even someone who has already created a checkout module on the order in which the steps should be performed.

Thank you!

[Knowband Plugins]

We suggest using a module to add the mentioned functionality at your store.
Modules Links for your reference: https://addons.prestashop.com/en/search?search_query=smart checkout