PHP and Joomla programmer

Hello, I'm creating a new website with Joomla and Digicom extension, and I need to add a feature on DigiCom. It's a shopping cart which support selling ebook, software etc. with subscription system. What I need is a redirect system with below condition: > If no product/subscription purchased and or subscription expired block "registered users" to access to URL "books" and it's sub categories like "books/category...", > if registered users (without active subscription) try to access to "books" or it's parent links then redirect users to "books-demo" link. > If customer/registered user purchased product/subscription and subscriptions is active, then allow access to "books" URL. > This feature isn't included in the extension, so you will need to develop within the extension. Candidate with low price will be awarded.