C# hjälp class för Swish API för e-handel, fungerande

gistfile1.txt

using System;
using System.IO;
using System.Net;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Web;

namespace WebShop.Helpers
{
    public class SwishAPIHelper
    {
        public static string StartSwishPayment(string phonenumber, int amount, string message)
        {
            try
            {
                string DataToPost = "{ \"payeePaymentReference\": \"0123456789\", " +
                                        "\"callbackUrl\": \"https://datorbutik.se/Swish/Callback/\", " +
                                         "\"payerAlias\": \"" + phonenumber + "\", " +
                                         "\"payeeAlias\": \"1231181189\", " +
                                         "\"amount\": \"" + amount + "\", " +
                                         "\"currency\": \"SEK\", " +
                                         "\"message\": \"" + message + "\" }";

                string URL = "https://mss.swicpc.bankgirot.se/swish-cpcapi/api/v1/paymentrequests/";

                //ServicePointManager.Expect100Continue = true;

                ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11;

                //Cert Challenge URL 
                Uri requestURI = new Uri(URL);

                //Create the Request Object
                HttpWebRequest req = (HttpWebRequest)WebRequest.Create(requestURI);

                //Set the Request Object parameters
                req.ContentType = "application/json; charset=UTF-8";
                req.Method = "POST";
                req.ProtocolVersion = HttpVersion.Version10;

                // turn our request string into a byte stream
                byte[] postBytes = Encoding.UTF8.GetBytes(DataToPost);

                req.ContentLength = postBytes.Length;

                string path = HttpContext.Current.Server.MapPath("~/App_Data/SwishMerchantTestCertificate1231181189.p12");

                X509Certificate cert = new X509Certificate2(path, "swish", X509KeyStorageFlags.Exportable | X509KeyStorageFlags.PersistKeySet);

                req.ClientCertificates.Add(cert);

                Stream requestStream = req.GetRequestStream();

                // now send it
                requestStream.Write(postBytes, 0, postBytes.Length);
                requestStream.Close();

                try
                {
                    WebResponse response = req.GetResponse();

                    String result = "";

                    using (StreamReader rdr = new StreamReader(response.GetResponseStream()))
                    {
                        result = rdr.ReadToEnd();
                    }

                    HttpWebResponse httpResponse = (HttpWebResponse)response;

                    return "Status code: " + httpResponse.StatusCode + " - Content: " + result;
                }
                catch (WebException e)
                {
                    using (WebResponse response = e.Response)
                    {
                        HttpWebResponse httpResponse = (HttpWebResponse)response;

                        //Log.Information("Error code: {0}", httpResponse.StatusCode);

                        using (Stream data = response.GetResponseStream())
                        {
                            string text = new StreamReader(data).ReadToEnd();

                            return "Error code: " + httpResponse.StatusCode + " - Content: " + text;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                return "Exception: " + ex.ToString();
            }
        }
    }
}