What is best way to implement the facet display name (A to Z) for lexical sorting

Hi,

I am trying to implement in my web shop the facet which can filter the products in a section via their first letter in product names. For example like here: A to Z - A to D (3) - E to H (1) - I to M (2) - N to S (4) - T to Z (0)

If I klick on "A -D", I should get the sorted list of products containing names beginning with letters A, B, C or D.

What ist the best way t do this?