Adding payment processor as a plugin

Hello!
I want to add a payment processor to marketpress. Is this possible? And can this be made as a plugin for example?

I've been reading some documentation regarding this processor, and all of them are capable of handling rest api calls:
for example:

POST /payments-api/4.0/service.cgi HTTP/1.1
Host: stg.api.pay.com
Content-Type: application/json; charset=utf-8
Accept: application/json
Content-Length: length
{
"test": false,
"language": "en",
"command": "GET_PAYMENT_METHODS",
"merchant": {
"apiLogin": "xxxxxxxxxxxxx",
"apiKey": "xxxxxxxxxxxxx"
}
}

Is this possible and is there documentation about it?
I've been looking in the forums, but posts I've found are very old and not very clear. Thanks!!