More gracefully handle exceeding the API limit.

POEApi.Infrastructure/Events/ThottledEventArgs.cs

@@ -5,9 +5,15 @@ namespace POEApi.Infrastructure.Events
     public class ThottledEventArgs : EventArgs
     {
         public TimeSpan WaitTime { get; private set; }
-        public ThottledEventArgs(TimeSpan waitTime)
+        /// <summary>
+        /// Whether the throttling event was expected.  If it was not expected, there might be other agents or
+        /// untracked actions using up resources towards the limit.
+        /// </summary>
+        public bool Expected { get; private set; }
+        public ThottledEventArgs(TimeSpan waitTime, bool expected = true)
         {
             WaitTime = waitTime;
+            Expected = expected;
         }
     }
 }

POEApi.Transport/HttpTransport.cs

@@ -206,11 +206,26 @@ protected HttpWebResponse BuildHttpRequestAndGetResponse(HttpMethod method, stri
         protected MemoryStream PerformHttpRequest(HttpMethod method, string url, bool? allowAutoRedirects = null,
             string requestData = null)
         {
-            using (var response = BuildHttpRequestAndGetResponse(method, url, allowAutoRedirects, requestData))
+            HttpWebResponse response = null;
+            // TODO: Don't retry an infinite number of times.
+            bool retry = true;
+            while (retry)
             {
-                MemoryStream responseStream = GetMemoryStreamFromResponse(response);
-                return responseStream;
+                try
+                {
+                    response = BuildHttpRequestAndGetResponse(method, url, allowAutoRedirects, requestData);
+                    retry = false;
+                }
+                catch (System.Net.WebException ex) when (
+                    !string.IsNullOrWhiteSpace(ex.Message) && ex.Message.Contains("(429) Too Many Requests."))
+                {
+                    Logger.Log("Exceeded API limit while performing HTTP request: " + ex.ToString());
+                    _taskThrottle.HandleUnexpectedOverload();
+                }
             }
+
+            MemoryStream responseStream = GetMemoryStreamFromResponse(response);
+            return responseStream;
         }
 
         // The refresh parameter in this ITransport implementation is ignored.

POEApi.Transport/TaskThrottle.cs

@@ -88,5 +88,22 @@ protected void RemvoeExpiredTasks()
                 CurrentTasks.Dequeue();
             }
         }
+
+        public void HandleUnexpectedOverload()
+        {
+            lock (_lockObject)
+            {
+                // We've unexpectedly gone over the number of allowed requests in a time period.  Fill up the set of
+                // current tasks as if we had started tasks.
+                while (CurrentTasks.Count < WindowLimit)
+                    CurrentTasks.Enqueue(DateTime.Now);
+
+                // Wait at least as long as the WindowSize before trying another task.
+                var timeUntilNextTask = CurrentTasks.Peek() - DateTime.Now;
+                TimeSpan waitTime = timeUntilNextTask > WindowSize ? timeUntilNextTask : WindowSize;
+                Throttled?.Invoke(this, new ThottledEventArgs(waitTime, false));  // Not an expected throttle event.
+                System.Threading.Thread.Sleep(waitTime);
+            }
+        }
     }
 }

Procurement/View/RefreshView.xaml.cs

@@ -78,9 +78,14 @@ private void model_StashLoading(POEApi.Model.POEModel sender, POEApi.Model.Event
 
         void model_Throttled(object sender, ThottledEventArgs e)
         {
-            if (e.WaitTime.TotalSeconds > 4)
+            if (!e.Expected)
+                update(string.Format("Exceeded GGG Server request limit; throttling activated.  Waiting {0} " +
+                    "seconds.  Ensure you do not have other instances of Procurement running or other apps using " +
+                    "the GGG API with your account.", Convert.ToInt32(e.WaitTime.TotalSeconds)),
+                    new POEEventArgs(POEEventState.BeforeEvent));
+            else if (e.WaitTime.TotalSeconds > 4)
                 update(string.Format("GGG Server request limit hit, throttling activated. Please wait {0} seconds",
-                    e.WaitTime.Seconds), new POEEventArgs(POEEventState.BeforeEvent));
+                    Convert.ToInt32(e.WaitTime.TotalSeconds)), new POEEventArgs(POEEventState.BeforeEvent));
         }
 
         private void update(string message, POEEventArgs e)

Procurement/ViewModel/LoginWindowViewModel.cs

@@ -345,8 +345,14 @@ void Model_Authenticating(POEModel sender, AuthenticateEventArgs e)
 
         void Model_Throttled(object sender, ThottledEventArgs e)
         {
-            if (e.WaitTime.TotalSeconds > 4)
-                Update(string.Format("GGG Server request limit hit, throttling activated. Please wait {0} seconds", e.WaitTime.Seconds), new POEEventArgs(POEEventState.BeforeEvent));
+            if (!e.Expected)
+                Update(string.Format("Exceeded GGG Server request limit; throttling activated.  Waiting {0} " +
+                    "seconds.  Ensure you do not have other instances of Procurement running or other apps using " +
+                    "the GGG API with your account.", Convert.ToInt32(e.WaitTime.TotalSeconds)),
+                    new POEEventArgs(POEEventState.BeforeEvent));
+            else if (e.WaitTime.TotalSeconds > 4)
+                Update(string.Format("GGG Server request limit hit, throttling activated. Please wait {0} seconds",
+                    Convert.ToInt32(e.WaitTime.TotalSeconds)), new POEEventArgs(POEEventState.BeforeEvent));
         }
 
         private void Update(string message, POEEventArgs e)