Integration of payment system

The aim of the project:

Development of the functions of receiving payments and payments for a site (in php).

Payment system: Unitpay (dot) ru
(there is an API manual on the website)

Requirements:

Payments

Make a payment API (Unitpay)

To check the status of payment API (Unitpay)

If successful, update the users balance (DB*)

Payment

To check the users balance (DB*)

If sufficient funds to deduct the amount from balance (DB*)

To pay to the specified WebMoney purse (API Unitpay)

*Database login and register ready

Be sure to specify the cost and time of execution rates.

PS the website in-house