Variables for automating invoices?

Is it possible currently or planned for the future, to support variables to help automate invoicing, by programmatically generating invoices using variable rules for invoice input fields?

Could I populate the “customer” and “amount” values automatically by referencing those fields with a variable, with the variable referring to specific pieces of data available in site admin dashboards, such as username, role, posts, comments, friends, etc.?

I would like to generate invoices for all users (customer) with role “X”, and have the “amount” be derived from “post count”, or something similar. This would be helpful for recurring/subscription billing, where the invoices are automatically generated based on the input-variable rules.

Is there variable mapping available or planned?

Thanks again!