How to refactor complicated logic in create_unique method?

I would like to simplify this complicated logic for creating unique Track
object.

def self.create_unique(p)
  f = Track.find :first, :conditions => ['user_id = ? AND target_id = ? AND
target_type = ?', p[:user_id], p[:target_id], p[:target_type]]
  x = ((p[:target_type] == 'User') and (p[:user_id] == p[:target_id]))
  Track.create(p) if (!f and !x)
end

For a start I would do the x=... first since it does not depend on f.
Then you only need to do the find if x true. Then in the find use
.count and test it for >0 rather then finding a record. Also extract
the find out into one or more scopes.
Are there relationships between user and track? If so then you may be
able to use current_user.tracks rather than testing user_id.

Colin