Entering the store URL with customer data and dedicated product portfolio

For a special action with a partner we are seeking following functionality:

Customer has User ID , log in credentials and its details stored with Partner website.

We want the customer to give access to our shopify shop by using a URL on the partner website, which will include all customer details ( name, address, etc…) and give the routed customer special discounts on selected products.

The intend is that the customer does not have to provide his details neither enter a discount code.

At check out we want all details to be parsed from the URL and discount code applied.

If at all possible a different discount per product or collection would be beneficial.

As this is a One off activity we need to keep the cost down to make it worth while. Does anyone have a ready to go solution that just needs parametrised or is this not feasible at all.

Thank you

Erik