Fix formatting

Co-authored-by: Oleksii Holub <1935960+Tyrrrz@users.noreply.github.com>

DiscordChatExporter.Core/Exporting/ExportAssetDownloader.cs

@@ -38,23 +38,28 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
             return _previousPathsByUrl[url] = filePath;
 
         // Check for a file cached by the legacy naming scheme (5-char hash) and rename it
-        // to the new naming scheme to preserve backwards compatibility with existing exports
+        // to the new naming scheme to preserve backwards compatibility with existing exports.
+        // This will catch both the 5-char lowercase hash and the 5-char uppercase hash variants.
         if (reuse)
         {
-            var legacyFilePath = Path.Combine(workingDirPath, GetLegacyFileNameFromUrl(url));
-            if (File.Exists(legacyFilePath))
+            var legacyFileNames = GetLegacyFileNamesFromUrl(url);
+            foreach (var legacyFileName in legacyFileNames)
             {
-                // Overwrite in case the destination file was created concurrently between our
-                // earlier existence check and this move operation
-                try
+                var legacyFilePath = Path.Combine(workingDirPath, legacyFileName);
+                if (File.Exists(legacyFilePath))
                 {
-                    File.Move(legacyFilePath, filePath, overwrite: true);
-                    return _previousPathsByUrl[url] = filePath;
-                }
-                catch (IOException)
-                {
-                    // The legacy file was moved or deleted concurrently or something else happened.
-                    // Upgrading old files is not crucial, so we can just move on.
+                    // Overwrite in case the destination file was created concurrently between our
+                    // earlier existence check and this move operation
+                    try
+                    {
+                        File.Move(legacyFilePath, filePath, true);
+                        return _previousPathsByUrl[url] = filePath;
+                    }
+                    catch (IOException)
+                    {
+                        // The legacy file was moved or deleted concurrently or something else happened.
+                        // Upgrading old files is not crucial, so we can just move on.
+                    }
                 }
             }
         }
@@ -87,10 +92,16 @@ internal partial class ExportAssetDownloader
 {
     private static string NormalizeUrl(string url)
     {
-        // Remove signature parameters from Discord CDN URLs to normalize them
+        // Remove signature parameters from Discord CDN/media URLs to normalize them
         var uri = new Uri(url);
-        if (!string.Equals(uri.Host, "cdn.discordapp.com", StringComparison.OrdinalIgnoreCase))
+
+        if (
+            !string.Equals(uri.Host, "cdn.discordapp.com", StringComparison.OrdinalIgnoreCase)
+            && !string.Equals(uri.Host, "media.discordapp.net", StringComparison.OrdinalIgnoreCase)
+        )
+        {
             return url;
+        }
 
         var query = HttpUtility.ParseQueryString(uri.Query);
         query.Remove("ex");
@@ -137,13 +148,16 @@ internal partial class ExportAssetDownloader
         );
 
     // Legacy naming used a 5-char hash, kept for backwards compatibility with existing exports
-    private static string GetLegacyFileNameFromUrl(string url) =>
-        GetFileNameFromUrl(
-            url,
-            SHA256
-                .HashData(Encoding.UTF8.GetBytes(NormalizeUrl(url)))
-                .Pipe(Convert.ToHexStringLower)
-                // 5 chars = 20 bits, reaches 1% collision probability at ~145 files
-                .Truncate(5)
-        );
+    private static IReadOnlyList<string> GetLegacyFileNamesFromUrl(string url)
+    {
+        var hashData = SHA256.HashData(Encoding.UTF8.GetBytes(NormalizeUrl(url)));
+
+        return
+        [
+            // Lowercase variant (introduced in 2.46.1)
+            GetFileNameFromUrl(url, Convert.ToHexStringLower(hashData).Truncate(5)),
+            // Uppercase variant (original)
+            GetFileNameFromUrl(url, Convert.ToHexString(hashData).Truncate(5)),
+        ];
+    }
 }

DiscordChatExporter.Core/Exporting/ExportRequest.cs

@@ -206,10 +206,15 @@ public partial class ExportRequest
     {
         var actualOutputPath = FormatPath(outputPath, guild, channel, after, before);
 
-        // Output is a directory
+        // Determine whether the output path refers to a directory or a file.
+        // The extension-based heuristic is evaluated on the original, unsubstituted path,
+        // because the value of a template token (e.g. a guild or channel name) may contain
+        // a period that would otherwise be mistaken for a file extension, incorrectly causing
+        // a directory path to be treated as a file.
+        // https://github.com/Tyrrrz/DiscordChatExporter/issues/1502
         if (
             Directory.Exists(actualOutputPath)
-            || string.IsNullOrWhiteSpace(Path.GetExtension(actualOutputPath))
+            || string.IsNullOrWhiteSpace(Path.GetExtension(outputPath))
         )
         {
             var fileName = GetDefaultOutputFileName(guild, channel, format, after, before);