Prefer message timestamp over the `last-modified` header for asset file dates (#1321)

DiscordChatExporter.Core/Exporting/ExportAssetDownloader.cs

@@ -23,7 +23,8 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
 
     public async ValueTask<string> DownloadAsync(
         string url,
-        CancellationToken cancellationToken = default
+        CancellationToken cancellationToken = default,
+        DateTimeOffset? timestamp = null
     )
     {
         var fileName = GetFileNameFromUrl(url);
@@ -48,34 +49,12 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
                 await using (var output = File.Create(filePath))
                     await response.Content.CopyToAsync(output, innerCancellationToken);
 
-                // Try to set the file date according to the last-modified header
-                try
+                // Try to set the file date according to the message timestamp
+                if (timestamp is not null)
                 {
-                    var lastModified = response
-                        .Content.Headers.TryGetValue("Last-Modified")
-                        ?.Pipe(s =>
-                            DateTimeOffset.TryParse(
-                                s,
-                                CultureInfo.InvariantCulture,
-                                DateTimeStyles.None,
-                                out var instant
-                            )
-                                ? instant
-                                : (DateTimeOffset?)null
-                        );
-
-                    if (lastModified is not null)
-                    {
-                        File.SetCreationTimeUtc(filePath, lastModified.Value.UtcDateTime);
-                        File.SetLastWriteTimeUtc(filePath, lastModified.Value.UtcDateTime);
-                        File.SetLastAccessTimeUtc(filePath, lastModified.Value.UtcDateTime);
-                    }
-                }
-                catch
-                {
-                    // This can apparently fail for some reason.
-                    // Updating the file date is not a critical task, so we'll just ignore exceptions thrown here.
-                    // https://github.com/Tyrrrz/DiscordChatExporter/issues/585
+                    File.SetCreationTimeUtc(filePath, timestamp.Value.UtcDateTime);
+                    File.SetLastWriteTimeUtc(filePath, timestamp.Value.UtcDateTime);
+                    File.SetLastAccessTimeUtc(filePath, timestamp.Value.UtcDateTime);
                 }
             },
             cancellationToken

DiscordChatExporter.Core/Exporting/ExportContext.cs

@@ -103,7 +103,8 @@ internal class ExportContext(DiscordClient discord, ExportRequest request)
 
     public async ValueTask<string> ResolveAssetUrlAsync(
         string url,
-        CancellationToken cancellationToken = default
+        CancellationToken cancellationToken = default,
+        DateTimeOffset? timestamp = null
     )
     {
         if (!Request.ShouldDownloadAssets)
@@ -111,7 +112,7 @@ internal class ExportContext(DiscordClient discord, ExportRequest request)
 
         try
         {
-            var filePath = await _assetDownloader.DownloadAsync(url, cancellationToken);
+            var filePath = await _assetDownloader.DownloadAsync(url, cancellationToken, timestamp);
             var relativeFilePath = Path.GetRelativePath(Request.OutputDirPath, filePath);
 
             // Prefer the relative path so that the export package can be copied around without breaking references.

DiscordChatExporter.Core/Exporting/JsonMessageWriter.cs

@@ -436,7 +436,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
             _writer.WriteString("id", attachment.Id.ToString());
             _writer.WriteString(
                 "url",
-                await Context.ResolveAssetUrlAsync(attachment.Url, cancellationToken)
+                await Context.ResolveAssetUrlAsync(attachment.Url, cancellationToken, message.Timestamp)
             );
             _writer.WriteString("fileName", attachment.FileName);
             _writer.WriteNumber("fileSizeBytes", attachment.FileSize.TotalBytes);
@@ -466,7 +466,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
             _writer.WriteString("format", sticker.Format.ToString());
             _writer.WriteString(
                 "sourceUrl",
-                await Context.ResolveAssetUrlAsync(sticker.SourceUrl, cancellationToken)
+                await Context.ResolveAssetUrlAsync(sticker.SourceUrl, cancellationToken, message.Timestamp)
             );
 
             _writer.WriteEndObject();