Multiple installation for each user

Hi I am thinking of using Piwik for my current under development website,

A brieft about My website: it is more or less like ebay kind of marketplace where users come and buy different products and each seller has an internal webshop, something like

I would like to give a small dashboard to each of the seller for looking at the web analytics and allow them to modify there shop based upon the reports from piwik.

Now the problem is :
Each of the seller will have web analytics dashboard something like:
I dont want each of the seller to have analytics reports from other seller and would like them to have customized analytics dashboard showing them some features specific to their webshop.
Every time a seller registers a profile, they automatically gets an analytics dashboard
How should I proceed with multiple installation with common code and how to structure the database.

Create one website per user. See:

I want it to happen automatically, and dont want to have multiple code base .

This is what I am trying to do: One code base of piwik and everytime a user creates the login credential for seller account they automatically gets a dashboard for analytics,

You can do that automatically with the api. create just a “website” for the user inside of piwik. Its not multiple code bases.