ZumoTokenClientFlowPlugin.cs

namespace Postcode.Performance.Plugins
{
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Globalization;
    using System.Net.Http;
    using System.Threading;
    using System.Threading.Tasks;

    using Microsoft.VisualStudio.TestTools.WebTesting;
    using Newtonsoft.Json.Linq;

    [Description("Generates ZuMo token for Azure Api & Mobile Apps in client flow scenario.")]
    [DisplayName("Generate ZuMo Token (Client Flow)")]
    public class ZumoTokenClientFlowPlugin : WebTestPlugin
    {
        private ReaderWriterLockSlim _cacheLock = new ReaderWriterLockSlim();
        private static Dictionary<string, string> zumoTokenCache = new Dictionary<string, string>();

        [DisplayName("Target Context Parameter Name")]
        [Description("Name of the context parameter that will receive the retrieved ZuMo token.")]
        public string ContextParamTarget { get; set; }

        [DisplayName("Azure AD Authority Base URL")]
        [Description("Example: https://login.microsoftonline.com")]
        public string AzureADAuthorityBaseUrl { get; set; }

        [DisplayName("App Service Gateway URL")]
        [Description("Example: https://xxxxxxx.azurewebsites.net/")]
        public string AppServiceGatewayURL { get; set; }

        [DisplayName("Azure AD Tenant")]
        [Description("You can use a domain name or tenant Id Example: abc.com OR 1de4b508-d463-4547-7cee-dcaac3501123")]
        public string AzureADTenant { get; set; }

        [DisplayName("Azure AD App Client Id")]
        [Description("Example: fde5f9bf-df94-42af-ba44-391453a0b333")]
        public string ClientId { get; set; }

        [DisplayName("Azure AD App Key/Secret")]
        [Description("Example: +9PBng0ZO1xU2dfshR23dweQPx1Cs6+3joSMAh1/sE=")]
        public string SecretKey { get; set; }

        public override void PreWebTest(object sender, PreWebTestEventArgs e)
        {
            if (!zumoTokenCache.ContainsKey(this.AppServiceGatewayURL))
            {
                var tokenTask = this.GetZumoAccessToken();
                tokenTask.Wait();

                try
                {
                    this._cacheLock.EnterWriteLock();
                    if (!zumoTokenCache.ContainsKey(this.AppServiceGatewayURL))
                    {
                        zumoTokenCache.Add(this.AppServiceGatewayURL, tokenTask.Result);
                    }
                }
                finally
                {
                    this._cacheLock.ExitWriteLock();
                }

            }

            e.WebTest.Context.Add(this.ContextParamTarget, zumoTokenCache[this.AppServiceGatewayURL]);
            base.PreWebTest(sender, e);
        }

        public async Task<string> GetZumoAccessToken()
        {
            var aadAuthorityUrl = this.AzureADAuthorityBaseUrl;
            var gatewayUrl = this.AppServiceGatewayURL;

            using (var accessTokenClient = new HttpClient())
            {
                var accessTokenContent = new FormUrlEncodedContent(
                                            new[] {
                                                new KeyValuePair<string, string>(
                                                        "resource", 
                                                        string.Format(
                                                            CultureInfo.InvariantCulture, 
                                                            "{0}{1}", this.AppServiceGatewayURL, "/login/aad")),
                                                new KeyValuePair<string, string>("client_id", this.ClientId),
                                                new KeyValuePair<string, string>("client_secret", this.SecretKey),
                                                new KeyValuePair<string, string>("grant_type", "client_credentials")
                                                });

                accessTokenClient.BaseAddress = new Uri(aadAuthorityUrl);
                var accessTokenReplyContent = await accessTokenClient.PostAsync(
                                            string.Format(CultureInfo.InvariantCulture, 
                                            "/{0}/oauth2/token", this.AzureADTenant), accessTokenContent);

                if (accessTokenReplyContent.IsSuccessStatusCode)
                {
                    var accessTokenReplyJson = JToken.Parse(await accessTokenReplyContent.Content.ReadAsStringAsync());
                    using (var zumoTokenClient = new HttpClient())
                    {
                        var jsonObject = new JObject();
                        jsonObject.Add("access_token", accessTokenReplyJson["access_token"]);
                        var zumoTokenContent = new StringContent(jsonObject.ToString());

                        zumoTokenClient.BaseAddress = new Uri(gatewayUrl);
                        var zumoTokenReplyContent = await zumoTokenClient.PostAsync("/login/aad", zumoTokenContent);

                        if (zumoTokenReplyContent.IsSuccessStatusCode)
                        {
                            var zumoTokenReplyJson = JToken.Parse(await zumoTokenReplyContent.Content.ReadAsStringAsync());
                            return zumoTokenReplyJson["authenticationToken"].ToString();
                        }
                    }
                }
            }

            return null;
        }
    }
}