Per Per Product Payment Gateway API Integration

I need a core php developer to integrate a Per Per Product Payment Gateway API to my existing website - [login to view URL] - Task To Complete: * You need to add a PAY NOW button, which will show on My Investment section, once an order request has been created. The PAY NOW button must appear with the order. * When a user click on the PAY NOW button - the Bitcoin Pay Per Product Crypto Payment Invoice must appear. * the invoice must show the details of the order that's being created and due for payment. Details must be same as the created order, on My Investment section. NOTE: * UNPAID and PAID order transaction must be recorded on users Transaction History table - UNPAID text colour must be RED and PAID text must be GREEN. The colors of text indicate the transaction status. NEW ORDER INVOICE TERM & CONDITIONS * User can create as many investment orders as he/she wants, but user can not create a new investment order, if there is still an UNPAID order invoice that is pending payment. * Once all invoices are paid in full, system will allow user to Create New Investment. * When there is an UNPAID invoice, system will deny user access to Create New Investment, when user clicks on Invest In Bitcoin button.