Help with wp_list_pages

I am looking to have a custom list of pages on a sidebar based on a specific set of criteria.

My structure is as follows
/ (homepage)
/products
/products/category/
/products/category/product_name/

What I am looking to do, is on the Products page, show only a list of Categories in the sidebar.

If you are on the Category page, i want to show all the Categories plus also show the products for the current category

so the side menu would look like this on the Products main level:
Category 1
Category 2
Category 3

Click on a category, say 2 and then the sidebar should show this:

Category 1
Category 2
-Product 1
-Product 2
-Product 3
Category 3

I would need the same menu for Category as Product detail page.

Anyone have any ideas? I’m stumped.

TIA,
ETI