You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,. How may I assist you?

USER: I am Joshua Martinez. I am planning to book a direct flight ticket to Oakland, CA-OAK. So can you please help me in that?

ASSISTANT: Please provide your departure airport code.

USER: My source airport is Austin, TX-AUS.

ASSISTANT: May I know your travelling dates?

USER: My journey dates are from 07/15 to 07/17.

ASSISTANT: No direct flight is available with your requirement.

USER: That's not a problem.

ASSISTANT: Thanks.

USER: Thank you.