Add basic caching for authentication tokens

ChaosBot/Services/ICache.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace ChaosBot.Services
+{
+    public interface ICache<T, TU>
+    {
+        void Invalidate();
+        void Add(T key, TU value, DateTime expires);
+        void Remove(T key);
+        TU Get(T key);
+        bool HasKey(T key);
+    }
+}

ChaosBot/WebServer/AccessTokenCache.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using ChaosBot.Services;
+
+namespace ChaosBot.WebServer
+{
+    public class AccessTokenCache : ICache<string, string>
+    {
+        private Dictionary<string, Tuple<string, DateTime>> _cache = new Dictionary<string, Tuple<string, DateTime>>();
+        
+        public void Invalidate()
+        {
+            DateTime now = DateTime.Now;
+
+            _cache = _cache
+                .Where(v => v.Value.Item2 > now)
+                .ToDictionary(x => x.Key, x => x.Value);
+        }
+
+        public void Add(string key, string value, DateTime expires)
+        {
+            _cache.Add(key, new Tuple<string, DateTime>(value, expires));
+        }
+
+        public void Remove(string key)
+        {
+            _cache.Remove(key);
+        }
+
+        public string Get(string key)
+        {
+            if (!_cache.TryGetValue(key, out Tuple<string, DateTime> data))
+                throw new KeyNotFoundException();
+
+            return data.Item1;
+        }
+
+        public bool HasKey(string key)
+        {
+            return _cache.ContainsKey(key);
+        }
+
+        public List<string> GetKeys()
+        {
+            return _cache.Keys.ToList();
+        }
+    }
+}

ChaosBot/WebServer/App/DiscordController.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Net.Http;
@@ -15,6 +16,7 @@ namespace ChaosBot.WebServer.App
     [Route("/api/discord")]
     public class DiscordController : Controller
     {
+        private static readonly AccessTokenCache Cache = WebServer.Cache;
         private static readonly HttpClient client = new HttpClient();
         private static readonly ILogger Logger = Program.Logger;
         
@@ -43,6 +45,9 @@ namespace ChaosBot.WebServer.App
             string responseString = await response.Content.ReadAsStringAsync();
             DiscordOauthResponse responseObject = JsonConvert.DeserializeObject<DiscordOauthResponse>(responseString);
 
+            DiscordUserResponse userResponse = GetDiscordUser(responseObject.access_token);
+            Cache.Add(responseObject.access_token, userResponse.id, DateTime.Now.AddSeconds(responseObject.expires_in));
+
             return LocalRedirect($"/#/?access_token={responseObject.access_token}");
         }
 
@@ -52,16 +57,7 @@ namespace ChaosBot.WebServer.App
             if (!Request.Cookies.TryGetValue("access_token", out string accessToken))
                 accessToken = null;
 
-            HttpResponseMessage response;
-            using (HttpRequestMessage requestMessage =
-                new HttpRequestMessage(HttpMethod.Get, "https://discord.com/api/v7/users/@me"))
-            {
-                requestMessage.Headers.Authorization =
-                    new AuthenticationHeaderValue("Bearer", accessToken);
-                response = client.SendAsync(requestMessage).GetAwaiter().GetResult();
-            }
-            string responseString = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
-            DiscordUserResponse userResponse = JsonConvert.DeserializeObject<DiscordUserResponse>(responseString);
+            DiscordUserResponse userResponse = GetDiscordUser(accessToken);
 
             return Json(userResponse);
         }
@@ -85,6 +81,22 @@ namespace ChaosBot.WebServer.App
 
             return Json(userResponse);
         }
+
+        private static DiscordUserResponse GetDiscordUser(string accessToken)
+        {
+            HttpResponseMessage response;
+            using (HttpRequestMessage requestMessage =
+                new HttpRequestMessage(HttpMethod.Get, "https://discord.com/api/v7/users/@me"))
+            {
+                requestMessage.Headers.Authorization =
+                    new AuthenticationHeaderValue("Bearer", accessToken);
+                response = client.SendAsync(requestMessage).GetAwaiter().GetResult();
+            }
+
+            string responseString = response.Content.ReadAsStringAsync().GetAwaiter().GetResult();
+            DiscordUserResponse userResponse = JsonConvert.DeserializeObject<DiscordUserResponse>(responseString);
+            return userResponse;
+        }
     }
 
     internal class DiscordOauthResponse

ChaosBot/WebServer/Startup.cs

@@ -30,6 +30,9 @@ namespace ChaosBot.WebServer
                 options.ForwardedHeaders =
                     ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
             });
+
+            services
+                .AddSingleton(sp => new AccessTokenCache());
         }
         
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline

ChaosBot/WebServer/WebServer.cs

@@ -11,6 +11,8 @@ namespace ChaosBot.WebServer
 {
     public static class WebServer
     {
+        public static readonly AccessTokenCache Cache = new AccessTokenCache();
+        
         public static void Start(string[] args)
         {
             CreateHostBuilder(args).Build().Run();