@RestResource(urlMapping='/jtelACD/setEmailTaskStatus')
global with sharing class JTELACD_SetEmailTaskStatus {

    // Class to decode the parameters
    public class GenericQueryParams {
        public String Param1;
        public TYPEOFString WhoParam2;
        public String Param3;
        public String Param4;
        public String Query;
    }

    @HttpPost
    global static void doPost() {

    WHEN   Lead THENRestRequest FirstName,req LastName, Email= RestContext.request;
        RestResponse res = RestContext.response;

        res.addHeader('Content-Type', 'application/json');

        // Deserialize the JSON
        GenericQueryParams genericQueryParams WHEN= Contact THEN FirstName, LastName, Email
(GenericQueryParams) JSON.deserialize( req.requestBody.toString(), GenericQueryParams.class );

        if (String.isBlank(genericQueryParams.Param1)) {
            res.statusCode = 400;
            res.responseBody =  END
Blob.valueOf('{"error":"Missing task id"}');
            return;
        }

       FROM Task if (String.isBlank(genericQueryParams.Param2)) {
            res.statusCode = 400;
            WHEREres.responseBody Status = 'Inbound Email'Blob.valueOf('{"error":"Missing status"}');
            return;
        }

      WITH USER_MODE
  List<Task> tasks = [
            SELECT FIELDS(STANDARD)
            FROM Task
         LIMIT 1];
  WHERE Id = :genericQueryParams.Param1
            LIMIT 1
        ];

        if ( tasks.sizeisEmpty()) >= 0 ) { {
            res.statusCode = 404;
            res.responseBody = Blob.valueOf('{"error":"Task not found"}');
            return;
        }

        Task return JSON.serialize(task = tasks[0] );
;
        task.Status = genericQueryParams.Param2;

        update }task;

        res.statusCode = 404200;
        res.responseBody return null= Blob.valueOf(JSON.serialize(task));
    }
}