Adding payment processor as a plugin

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
Content-Type: application/json; charset=utf-8
Accept: application/json
Content-Length: length
"test": false,
"language": "en",
"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!!