How to add Script Params and Language using SortDescriptor in ElasticSearch Nest client

[aashini (Aashini J)]

I am using Elasticsearch Nest client in .Net application and looking for a syntax to add Params and Language in script based sorting with Sort Descriptor.

Below is the code with SortDescriptor :

string shortestDistance =
                "def hqDistance = 0;" +
                "if(!doc[params.headquartersCoordinatesField].empty)" +
                "{" +
                "hqDistance = (doc[params.headquartersCoordinatesField].arcDistance(params.latitude, params.longitude) * 0.000621371);" +
                "}" +
                "return hqDistance" ;

 var sortDesc = new SortDescriptor<Provider>();
 sortDesc.Script(s => s
            .Script(o => o.Source("shortestDistance"))
            .Order(SortOrder.Ascending)
            .Type("Number"));  

Here are my Params and Language code that I need to convert :

Lang = "painless", 
Params = new Dictionary<string, object>
{                                                
  {"headquartersCoordinatesField", Field<Provider>(f => f.Headquarters.Coordinates)},
  {"latitude", _latitude},
  {"longitude", _longitude}
}

Can anyone please response on how to add Params and Painless language in SortDescriptor Script ?
I would really appreciate the help!