Looking to have a "Slug" for "Files"

[Schaken]

I am looking to be able to have a custom slug for the Files application on my webpage. 
My goal is to have it auto generate when you publish the file, BUT have the option to enter your own SLUG instead if you wish. Maybe a button next to publish, or a toggle somewhere, just something obvious for my community to be able to see it and know what it does. Also a way to detect the slug has also not been used yet as well. I would have for someone to overwrite another persons work (If that is possible) 
Here is a simple picture of what I am looking for as an example. this design is not something I am married to, just used it as an example.

[DawPi]

Interested. 🙂

[Schaken]

This commission has been taken by @DawPi

 

[DawPi]

And it's done: