chore: improve resource exhausted error message (#584)

* chore: improve resource exhausted error message

* remove unused imports

* make LimitExceededMessageWrapper a static class with static members instead

* create separate method CreateWithMessageWrapper

src/Momento.Sdk/Exceptions/CacheExceptionMapper.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Threading.Tasks;
 using Grpc.Core;
 using Microsoft.Extensions.Logging;
 
@@ -79,7 +78,7 @@ public SdkException Convert(Exception e, Metadata? transportMetadata = null)
                     return new AuthenticationException(ex.Message, transportDetails);
 
                 case StatusCode.ResourceExhausted:
-                    return new LimitExceededException(ex.Message, transportDetails);
+                    return LimitExceededException.CreateWithMessageWrapper(ex.Message, transportDetails, ex);
 
                 case StatusCode.NotFound:
                     return new NotFoundException(ex.Message, transportDetails);

src/Momento.Sdk/Exceptions/LimitExceededException.cs

@@ -1,15 +1,94 @@
 namespace Momento.Sdk.Exceptions;
 
-using System;
+using Grpc.Core;
 
 /// <summary>
 /// Requested operation couldn't be completed because system limits were hit.
 /// </summary>
 public class LimitExceededException : SdkException
 {
     /// <include file="../docs.xml" path='docs/class[@name="SdkException"]/constructor/*' />
-    public LimitExceededException(string message, MomentoErrorTransportDetails transportDetails, Exception? e = null) : base(MomentoErrorCode.LIMIT_EXCEEDED_ERROR, message, transportDetails, e)
+    public LimitExceededException(string messageWrapper, string message, MomentoErrorTransportDetails transportDetails, RpcException? e = null) : base(MomentoErrorCode.LIMIT_EXCEEDED_ERROR, message, transportDetails, e) {
+        this.MessageWrapper = messageWrapper;
+    }
+
+    /// <summary>
+    /// Creates a LimitExceededException with a message wrapper that specifies the limit that was exceeded.
+    /// </summary>
+    /// <param name="message"></param>
+    /// <param name="transportDetails"></param>
+    /// <param name="e"></param>
+    /// <returns></returns>
+    public static LimitExceededException CreateWithMessageWrapper(string message, MomentoErrorTransportDetails transportDetails, RpcException? e = null)
     {
-        this.MessageWrapper = "Request rate exceeded the limits for this account.  To resolve this error, reduce your request rate, or contact us at [email protected] to request a limit increase";
+        var messageWrapper = LimitExceededMessageWrapper.UnknownLimitExceeded;
+        var errMetadata = e?.Trailers.Get("err")?.Value;
+        if (errMetadata != null) {
+            messageWrapper = errMetadata switch
+            {
+                "topic_subscriptions_limit_exceeded" => LimitExceededMessageWrapper.TopicSubscriptionsLimitExceeded,
+                "operations_rate_limit_exceeded" => LimitExceededMessageWrapper.OperationsRateLimitExceeded,
+                "throughput_rate_limit_exceeded" => LimitExceededMessageWrapper.ThroughputRateLimitExceeded,
+                "request_size_limit_exceeded" => LimitExceededMessageWrapper.RequestSizeLimitExceeded,
+                "item_size_limit_exceeded" => LimitExceededMessageWrapper.ItemSizeLimitExceeded,
+                "element_size_limit_exceeded" => LimitExceededMessageWrapper.ElementSizeLimitExceeded,
+                _ => LimitExceededMessageWrapper.UnknownLimitExceeded,
+            };
+        } else {
+            var lowerCasedMessage = message.ToLower();
+            if (lowerCasedMessage.Contains("subscribers")) {
+                messageWrapper = LimitExceededMessageWrapper.TopicSubscriptionsLimitExceeded;
+            } else if (lowerCasedMessage.Contains("operations")) {
+                messageWrapper = LimitExceededMessageWrapper.OperationsRateLimitExceeded;
+            } else if (lowerCasedMessage.Contains("throughput")) {
+                messageWrapper = LimitExceededMessageWrapper.ThroughputRateLimitExceeded;
+            } else if (lowerCasedMessage.Contains("request limit")) {
+                messageWrapper = LimitExceededMessageWrapper.RequestSizeLimitExceeded;
+            } else if (lowerCasedMessage.Contains("item size")) {
+                messageWrapper = LimitExceededMessageWrapper.ItemSizeLimitExceeded;
+            } else if (lowerCasedMessage.Contains("element size")) {
+                messageWrapper = LimitExceededMessageWrapper.ElementSizeLimitExceeded;
+            } else {
+                messageWrapper = LimitExceededMessageWrapper.UnknownLimitExceeded;
+            }
+        }
+
+        return new LimitExceededException(messageWrapper, message, transportDetails, e);
     }
 }
+
+/// <summary>
+/// Provides a specific reason for the limit exceeded error.
+/// </summary>
+public static class LimitExceededMessageWrapper
+{
+    /// <summary>
+    /// Topic subscriptions limit exceeded for this account.
+    /// </summary>
+    public static string TopicSubscriptionsLimitExceeded = "Topic subscriptions limit exceeded for this account";
+    /// <summary>
+    /// Request rate limit exceeded for this account.
+    /// </summary>
+    public static string OperationsRateLimitExceeded = "Request rate limit exceeded for this account";
+
+    /// <summary>
+    /// Bandwidth limit exceeded for this account.
+    /// </summary>
+    public static string ThroughputRateLimitExceeded = "Bandwidth limit exceeded for this account";
+    /// <summary>
+    /// Request size limit exceeded for this account.
+    /// </summary>
+    public static string RequestSizeLimitExceeded = "Request size limit exceeded for this account";
+    /// <summary>
+    /// Item size limit exceeded for this account.
+    /// </summary>
+    public static string ItemSizeLimitExceeded = "Item size limit exceeded for this account";
+    /// <summary>
+    /// Element size limit exceeded for this account.
+    /// </summary>
+    public static string ElementSizeLimitExceeded = "Element size limit exceeded for this account";
+    /// <summary>
+    /// Unknown limit exceeded for this account.
+    /// </summary>
+    public static string UnknownLimitExceeded = "Limit exceeded for this account";
+}