Convert Joomla 2.5 Virtuemart Plugin to Joomla 3 & VM 3

Dear Freelancers I want to convert the attached plugin to work with Joomla 3 and of course VM 3 The attached script is a plugin for Virtuemart payment method it's for joomla 2.5 I want a PHP expert to read it and make it workable with Joomla 3 and want to work like as joomla 2.5 Please describe if you read and precept the current code Thanks