Adding Service Principal in Azure AD programmatically

Until now I have been adding my Azure ACS as a Service Principal in Azure AD through PowerShell. I need to automate the process through code but I am struggling to find a way to do it programmatically.

I can see that the PowerShell commandlets use https://provisioningapi.microsoftonline.com/ProvisioningWebService.svc for performing all tasks but there is no documentation around it. I was able to capture the traffic in Fiddler but was not able to recreate the tokens and the bindings being used.

Is there any other recommended way to do this kind of stuff?

Thanks!