Clark Aiport to Ninoy Aquino airpot?

Hi, this is my first time travelling in philippines so i have some quesitions. Is there a direct non-stop bus from Clark to NAA? If there is one, what is it and how much does it cost? If there is none, suggest what kind of transportaion i should use and how much does it cost. I prefer bus, so i will only take expensive taxi as last resort. thx.