I want to build a complex access control system just like Facebook.

How should I design my database so that:

• A user may select which streams to see (via liking a page) and may further select to see all or only important streams.
• Also he get to see posts of a friend, but if a friend changes visibility he may or may not see it.
• A user may be an owner or member of a group and accordingly he have access.
  So for a user there is so many access related information and also for each data point.

I use Perl/MySQL/Apache. Any help will be appreciated.