Moodle expert for creating a plugin for restricting access

I need a plugin "RESTRICT ON GENERIC CONDITION" that can be used any place where the user access to an activity or resource can be restricted. The plugin should be able to run a select statement that will return a true/false value (1/0) against an external database, and give access to the activity/resource is the value is true. If the value is false (or there is some error with the execution of the call), the activity/resource should not be visible. It must be possible to use the current userid and at least the course id as parameters in the call. E.g. "SELECT (username = "admin") FROM mdl_user WHERE id = &current_user_id" (or whatever the parameter for the currently logged in user is..)