From 4aad2ad36b1f488f98e969bcc17ae2ca0f077d92 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franti=C5=A1ek=20Boh=C3=A1=C4=8Dek?=
 <fandabohacek@gmail.com>
Date: Fri, 31 Dec 2021 11:13:56 +0100
Subject: [PATCH] feat: add support for logging nested results

---
 .../Extensions/ResultExtensions.cs            | 47 +++++++++++++------
 1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/Core/NosSmooth.Core/Extensions/ResultExtensions.cs b/Core/NosSmooth.Core/Extensions/ResultExtensions.cs
index 41c2dae..24ae4e5 100644
--- a/Core/NosSmooth.Core/Extensions/ResultExtensions.cs
+++ b/Core/NosSmooth.Core/Extensions/ResultExtensions.cs
@@ -5,6 +5,8 @@
 //  Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.CodeDom.Compiler;
+using System.IO;
 using System.Text;
 using Microsoft.Extensions.Logging;
 using Remora.Results;
@@ -17,51 +19,68 @@ namespace NosSmooth.Core.Extensions;
 public static class ResultExtensions
 {
     /// <summary>
-    /// Logs the given result if it is errorful.
+    /// Logs the given result if it isn't successful.
     /// </summary>
-    /// <param name="logger">The logger.</param>
+    /// <param name="logger">The logger to log with.</param>
     /// <param name="result">The result to log.</param>
-    /// <exception cref="InvalidOperationException">Thrown if the result was unsuccessful.</exception>
+    /// <exception cref="InvalidOperationException">Thrown if the result was successful.</exception>
     public static void LogResultError(this ILogger logger, IResult result)
     {
         if (result.IsSuccess)
         {
-            throw new InvalidOperationException("The result was successful, it has to be unsuccessful to log it.");
+            throw new InvalidOperationException("The result was successful, only unsuccessful results are supported.");
         }
 
+        using StringWriter stringWriter = new StringWriter();
+        using IndentedTextWriter logTextWriter = new IndentedTextWriter(stringWriter, " ");
+        logTextWriter.Write("Encountered an error: ");
+
+        LogResultError(logTextWriter, result);
+        logger.LogError(stringWriter.ToString());
+    }
+
+    private static void LogResultError(IndentedTextWriter logTextWriter, IResult result)
+    {
         switch (result.Error)
         {
             case AggregateError aggregateError:
-                logger.LogAggreggateError(aggregateError);
+                LogAggreggateError(logTextWriter, aggregateError);
                 break;
             default:
-                logger.LogNestedError(result);
+                LogNestedError(logTextWriter, result);
                 break;
         }
     }
 
-    private static void LogAggreggateError(this ILogger logger, AggregateError error)
+    private static void LogAggreggateError(IndentedTextWriter logTextWriter, AggregateError error)
     {
         foreach (var result in error.Errors)
         {
-            logger.LogResultError(result);
+            LogResultError(logTextWriter, result);
         }
     }
 
-    private static void LogNestedError(this ILogger logger, IResult? result)
+    private static void LogNestedError(IndentedTextWriter logTextWriter, IResult? result)
     {
         if ((result?.IsSuccess ?? true) || result.Error is null)
         {
             throw new InvalidOperationException("The result was successful, it has to be unsuccessful to log it.");
         }
 
-        var stringBuilder = new StringBuilder(result.Error.Message);
-        int index = 0;
+        logTextWriter.WriteLine(result.Error.Message);
+        IResultError? lastError = result.Error;
         while ((result = result?.Inner) is not null && result.Error is not null)
         {
-            stringBuilder.Append($"\n  {index++}: {result.Error.Message}");
-        }
+            // ReSharper disable once PossibleUnintendedReferenceComparison
+            if (lastError == result.Error)
+            {
+                continue;
+            }
+            lastError = result.Error;
 
-        logger.LogError(stringBuilder.ToString());
+            logTextWriter.WriteLine("--- See the inner error ---");
+            logTextWriter.Indent++;
+            logTextWriter.WriteLine(result.Error.Message);
+        }
     }
 }
\ No newline at end of file
-- 
2.49.0