about visa and ticket

good day sir/madam. I have a question for you; I have a penpall who lives in Shenzen in china. Myself i live in thailand at the moment in chiangmai. My girlfrind from schenzen want to visit me here for one month if possible,,..
Is it possible i buy a ticket for her here in thailand? She told me i cannot buy a ticket here and Also can she get a visa on arrival here in thailand? Thanks a lot in advance for your information.. regards, Bert Zwaan