Holy S$%^&*!
That's awful and extremely dangerous! You really need to ground your the bike!
Take care of those brakes ASAP! You may be able to get by with the chain for a little while longer if it is only surface rust
(pray that it is). Your focus really needs to be on your brakes. You are metal to metal on both brakes. The rear rotors are so sharp you can cut meat with it!
To be honest, the rear caliper piston may give you a problem from the looks of it. You are just a few millimeters from having the caliper grounded by the rotor.
If this is your daily driver, your are an accident that's going
(not waiting) to happen. You may be able to stop the bike today but tomorrow it may stop you. Please don't become a statistic.