Refactor

DiscordChatExporter.Core/Exceptions/ChannelEmptyException.cs

@@ -1,8 +1,3 @@
-using System;
-
 namespace DiscordChatExporter.Core.Exceptions;
 
-// Thrown when there is circumstancially no message to export with given parameters,
-// though it should not be treated as a runtime error; simply warn instead
-public class ChannelEmptyException(string message)
-    : DiscordChatExporterException(message, false, null) { }
+public class ChannelEmptyException(string message) : DiscordChatExporterException(message);

DiscordChatExporter.Core/Exporting/ChannelExporter.cs

@@ -31,7 +31,8 @@ public class ChannelExporter(DiscordClient discord)
         var context = new ExportContext(discord, request);
         await context.PopulateChannelsAndRolesAsync(cancellationToken);
 
-        // Export messages
+        // Initialize the exporter before further checks to ensure the file is created even if
+        // an exception is thrown after this point.
         await using var messageExporter = new MessageExporter(context);
 
         // Check if the channel is empty

DiscordChatExporter.Core/Exporting/MessageExporter.cs

@@ -13,24 +13,7 @@ internal partial class MessageExporter(ExportContext context) : IAsyncDisposable
 
     public long MessagesExported { get; private set; }
 
-    private async ValueTask ResetWriterAsync(CancellationToken cancellationToken = default)
-    {
-        if (_writer is not null)
-        {
-            try
-            {
-                await _writer.WritePostambleAsync(cancellationToken);
-            }
-            // Writer must be disposed, even if it fails to write the postamble
-            finally
-            {
-                await _writer.DisposeAsync();
-                _writer = null;
-            }
-        }
-    }
-
-    private async ValueTask<MessageWriter> GetWriterAsync(
+    private async ValueTask<MessageWriter> InitializeWriterAsync(
         CancellationToken cancellationToken = default
     )
     {
@@ -43,7 +26,7 @@ internal partial class MessageExporter(ExportContext context) : IAsyncDisposable
             )
         )
         {
-            await ResetWriterAsync(cancellationToken);
+            await UninitializeWriterAsync(cancellationToken);
             _partitionIndex++;
         }
 
@@ -60,21 +43,40 @@ internal partial class MessageExporter(ExportContext context) : IAsyncDisposable
         return _writer = writer;
     }
 
+    private async ValueTask UninitializeWriterAsync(CancellationToken cancellationToken = default)
+    {
+        if (_writer is not null)
+        {
+            try
+            {
+                await _writer.WritePostambleAsync(cancellationToken);
+            }
+            // Writer must be disposed, even if it fails to write the postamble
+            finally
+            {
+                await _writer.DisposeAsync();
+                _writer = null;
+            }
+        }
+    }
+
     public async ValueTask ExportMessageAsync(
         Message message,
         CancellationToken cancellationToken = default
     )
     {
-        var writer = await GetWriterAsync(cancellationToken);
+        var writer = await InitializeWriterAsync(cancellationToken);
         await writer.WriteMessageAsync(message, cancellationToken);
         MessagesExported++;
     }
 
     public async ValueTask DisposeAsync()
     {
-        // causes the file to be created whether there were messages written or not
-        await GetWriterAsync();
-        await ResetWriterAsync();
+        // If not messages were written, force the creation of an empty file
+        if (MessagesExported <= 0)
+            _ = await InitializeWriterAsync();
+
+        await UninitializeWriterAsync();
     }
 }