How to auto generate the product reference

[desoxire]

Hello!  I would like to auto generate the product reference with the following format:

Always 8 digits:

• 01+02: Week of the year (php date "W")
• 03+04: Year (php date "y")
• 05-08: upcounting number, starting at 0001 (reset at the beginning of every week)

E.g. First product of 2018 would be 01180001

How can I manage to do so? Where do I have to have a look?
It would be also enough, if this reference ist predefined in a new product and editable...

Thank you for your help!!!