Power BI API for IMPORT pbix files

The problem is that I am developing in Delphi, not C #, Delphi unfortunately does not contain an integration API as C #, which already has the GetToken function.

RequestAuthToken.Params.ParameterByName('grant_type').Value := 'password';
RequestAuthToken.Params.ParameterByName('scope').Value         := 'openid';
RequestAuthToken.Params.ParameterByName('resource').Value    := ResourceURI;
RequestAuthToken.Params.ParameterByName('client_id').Value     := ClientID;

My app is a native app, so i dont have a client_secret, what should i do? Need to pass this param?
RequestAuthToken.Params.ParameterByName('client_secret').Value := ?

RequestAuthToken.Params.ParameterByName('username').Value := ':MY_USR+NAME';
RequestAuthToken.Params.ParameterByName('password').Value  := ':PASSWORD_OF_USER';

What params should i use to get the token? In C# example, the program just call one function and nothing else.