I can do this fairly quickly for you using either python, java, or C# (whichever you prefer).
Should not take long
Relevant Skills and Experience
Python - 3 years
Java - 8 years
C# - 4 years
Proposed Milestones
$50 USD - project prototype
$77.78 USD - project complete
Additional Services Offered
$100 USD - Add vouch/claiming system for new users, to allow auditing of invites