From 89332244e3b1b6cc8ebe47ac81f40eb77ad6d685 Mon Sep 17 00:00:00 2001
From: "TCSBANK\\e.khudik" <e.khudik@tinkoff.ru>
Date: Mon, 4 Dec 2023 15:10:28 +0300
Subject: [PATCH 1/2] Added the ReceiveError event to MessageClient to provide
 the ability to handle exceptions in client code

---
 TelegramBotBase/Base/ErrorResult.cs   | 14 ++++++++
 TelegramBotBase/Base/MessageClient.cs | 50 ++++++++++++++++++++-------
 2 files changed, 51 insertions(+), 13 deletions(-)
 create mode 100644 TelegramBotBase/Base/ErrorResult.cs

diff --git a/TelegramBotBase/Base/ErrorResult.cs b/TelegramBotBase/Base/ErrorResult.cs
new file mode 100644
index 0000000..00d7c04
--- /dev/null
+++ b/TelegramBotBase/Base/ErrorResult.cs
@@ -0,0 +1,14 @@
+using System;
+
+namespace TelegramBotBase.Base
+{
+    public class ErrorResult : EventArgs
+    {
+        public ErrorResult(Exception exception)
+        {
+            Exception = exception;
+        }
+
+        public Exception Exception { get; }
+    }
+}
diff --git a/TelegramBotBase/Base/MessageClient.cs b/TelegramBotBase/Base/MessageClient.cs
index b5f9b3a..b95131f 100644
--- a/TelegramBotBase/Base/MessageClient.cs
+++ b/TelegramBotBase/Base/MessageClient.cs
@@ -18,6 +18,7 @@ namespace TelegramBotBase.Base;
 public class MessageClient
 {
     private static readonly object EvOnMessageLoop = new();
+    private static readonly object EvOnReceiveError = new();
 
     private static object __evOnMessage = new();
 
@@ -128,22 +129,12 @@ public class MessageClient
         await OnMessageLoop(new UpdateResult(update, null));
     }
 
-    public Task HandleErrorAsync(ITelegramBotClient botClient, Exception exception,
+    public async Task HandleErrorAsync(ITelegramBotClient botClient, Exception exception,
                                  CancellationToken cancellationToken)
     {
-        if (exception is ApiRequestException exApi)
-        {
-            Console.WriteLine($"Telegram API Error:\n[{exApi.ErrorCode}]\n{exApi.Message}");
-        }
-        else
-        {
-            Console.WriteLine(exception.ToString());
-        }
-
-        return Task.CompletedTask;
+        await OnReceiveError(new ErrorResult(exception));
     }
 
-
     /// <summary>
     ///     This will return the current list of bot commands.
     /// </summary>
@@ -186,7 +177,40 @@ public class MessageClient
 
     public async Task OnMessageLoop(UpdateResult update)
     {
-        await (Events[EvOnMessageLoop] as Async.AsyncEventHandler<UpdateResult>)?.Invoke(this, update);
+        var eventHandlers = (Events[EvOnMessageLoop] as Async.AsyncEventHandler<UpdateResult>)?.Invoke(this, update);
+
+        if (eventHandlers != null)
+        {
+            await eventHandlers;
+        }
+    }
+
+
+    public event Async.AsyncEventHandler<ErrorResult> ReceiveError
+    {
+        add => Events.AddHandler(EvOnReceiveError, value);
+        remove => Events.RemoveHandler(EvOnReceiveError, value);
+    }
+
+    public async Task OnReceiveError(ErrorResult update)
+    {
+        var eventHandlers = (Events[EvOnReceiveError] as Async.AsyncEventHandler<ErrorResult>)?.Invoke(this, update);
+
+        if (eventHandlers != null)
+        {
+            await eventHandlers;
+        }
+        else
+        {
+            if (update.Exception is ApiRequestException exApi)
+            {
+                Console.WriteLine($"Telegram API Error:\n[{exApi.ErrorCode}]\n{exApi.Message}");
+            }
+            else
+            {
+                Console.WriteLine(update.Exception.ToString());
+            }
+        }
     }
 
     #endregion

From 794dee7f580e7788d859ae5289dcce44d58702dc Mon Sep 17 00:00:00 2001
From: Florian Zevedei <florian.dahn@fdsoftware.de>
Date: Thu, 7 Dec 2023 17:49:35 +0100
Subject: [PATCH 2/2] improved readability

---
 TelegramBotBase/Base/MessageClient.cs | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/TelegramBotBase/Base/MessageClient.cs b/TelegramBotBase/Base/MessageClient.cs
index b95131f..17ec7f3 100644
--- a/TelegramBotBase/Base/MessageClient.cs
+++ b/TelegramBotBase/Base/MessageClient.cs
@@ -199,18 +199,19 @@ public class MessageClient
         if (eventHandlers != null)
         {
             await eventHandlers;
+            return;
+        }
+
+        //Fallback when no event handler is used.
+        if (update.Exception is ApiRequestException exApi)
+        {
+            Console.WriteLine($"Telegram API Error:\n[{exApi.ErrorCode}]\n{exApi.Message}");
         }
         else
         {
-            if (update.Exception is ApiRequestException exApi)
-            {
-                Console.WriteLine($"Telegram API Error:\n[{exApi.ErrorCode}]\n{exApi.Message}");
-            }
-            else
-            {
-                Console.WriteLine(update.Exception.ToString());
-            }
+            Console.WriteLine(update.Exception.ToString());
         }
+
     }
 
     #endregion