Write PHP code to process credit card payments via Square API

We want to transfer our credit card processing from an older system to the Square API ([login to view URL]) We would pass credit card number, expiration date, CID, billing address to your php code that would interact with Square's API to process the payment and return "accepted" or "declined". The Square API docs mention use of Composer to install components, but we are on a shared hosting system that does not provide this privilege, so you would have to figure out how to alternatively install the required Square libraries. Should be a plain-vanilla PHP script.