Create auto switch between desktop and mobile website

I have 2 versions of the website. The main desktop version is done in flash, and the other one is the mobile version. I need you to create auto-switch between them....So the script can detect the browser and auto detect for visitors which version to load (most likely use "user agent” method). Needs to be setup for all screen sizes and to be compatible with most mobile devices (android, iphone, etc) PLEASE bid only if you are expert in resolving this. Thanks!