Google Play Store Sign + Buy Application with cURL

We working on "buy & earn" templated web project. We need php class for Google Play Store. User login on play store with using google account. Check device id added this Google Play account. If have any defined payment method buy use with this. (Must read and check payment methods on google play, credit-card, account balance etc.) If not defined any payment method or not success buy action return error. Development notes, - We completed all action to "[login to view URL]" But comppurch have a "rmd" parameter and this generate from minified javascript.