Add bulk forum export with configurable asset handling

- add bulk export of active and archived forum threads
- add opt-in multi-channel selection mode
- separate forum and regular channel export settings
- save forum exports as JSON
- add configurable asset folder structure and file naming
- allow shared, per-thread, or skipped common resources
- allow attachments to be grouped by media type or message
- make avatar downloads optional and disabled by default
- add configurable parallel forum export workers
- disable token persistence and auto-updates for the custom build

DiscordChatExporter.Core/Exporting/ExportAssetDownloader.cs

@@ -17,30 +17,43 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
 {
     private static readonly AsyncKeyedLocker<string> Locker = new();
 
-    // File paths of the previously downloaded assets
+    // File paths of the previously downloaded assets. The same URL can intentionally be stored
-    private readonly Dictionary<string, string> _previousPathsByUrl = new(StringComparer.Ordinal);
+    // in different forum folders, so the destination path is part of the cache key.
+    private readonly Dictionary<string, string> _previousPathsByRequest = new(
+        StringComparer.Ordinal
+    );
 
     public async ValueTask<string> DownloadAsync(
         string url,
+        string? relativeDirPath = null,
+        string? preferredFileName = null,
         CancellationToken cancellationToken = default
     )
     {
-        var fileName = GetFileNameFromUrl(url);
+        var actualWorkingDirPath = !string.IsNullOrWhiteSpace(relativeDirPath)
-        var filePath = Path.Combine(workingDirPath, fileName);
+            ? Path.Combine(workingDirPath, relativeDirPath)
+            : workingDirPath;
+
+        var fileName = !string.IsNullOrWhiteSpace(preferredFileName)
+            ? Path.EscapeFileName(preferredFileName)
+            : GetFileNameFromUrl(url);
+
+        var filePath = Path.Combine(actualWorkingDirPath, fileName);
+        var requestKey = url + '\n' + filePath;
 
         using var _ = await Locker.LockAsync(filePath, cancellationToken);
 
-        if (_previousPathsByUrl.TryGetValue(url, out var cachedFilePath))
+        if (_previousPathsByRequest.TryGetValue(requestKey, out var cachedFilePath))
             return cachedFilePath;
 
         // Reuse existing files if we're allowed to
         if (reuse && File.Exists(filePath))
-            return _previousPathsByUrl[url] = filePath;
+            return _previousPathsByRequest[requestKey] = 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.
         // This will catch both the 5-char lowercase hash and the 5-char uppercase hash variants.
-        if (reuse)
+        if (reuse && string.IsNullOrWhiteSpace(preferredFileName))
         {
             var legacyFileNames = GetLegacyFileNamesFromUrl(url);
             foreach (var legacyFileName in legacyFileNames)
@@ -53,7 +66,7 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
                     try
                     {
                         File.Move(legacyFilePath, filePath, true);
-                        return _previousPathsByUrl[url] = filePath;
+                        return _previousPathsByRequest[requestKey] = filePath;
                     }
                     catch (IOException)
                     {
@@ -64,7 +77,7 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
             }
         }
 
-        Directory.CreateDirectory(workingDirPath);
+        Directory.CreateDirectory(actualWorkingDirPath);
 
         await Http.ResiliencePipeline.ExecuteAsync(
             async innerCancellationToken =>
@@ -84,7 +97,7 @@ internal partial class ExportAssetDownloader(string workingDirPath, bool reuse)
             cancellationToken
         );
 
-        return _previousPathsByUrl[url] = filePath;
+        return _previousPathsByRequest[requestKey] = filePath;
     }
 }
 

DiscordChatExporter.Core/Exporting/ExportContext.cs

@@ -120,17 +120,69 @@ internal class ExportContext(DiscordClient discord, ExportRequest request)
     public Color? TryGetUserColor(Snowflake id) =>
         GetUserRoles(id).Where(r => r.Color is not null).Select(r => r.Color).FirstOrDefault();
 
-    public async ValueTask<string> ResolveAssetUrlAsync(
+    private string GetForumThreadDirPath()
+    {
+        var channelName = Path.EscapeFileName(Request.Channel.Name).Truncate(60);
+        return Path.Combine("threads", $"{Request.Channel.Id}-{channelName}");
+    }
+
+    private string? GetForumCommonAssetDirPath() =>
+        Request.ForumCommonAssetMode switch
+        {
+            ForumCommonAssetMode.SharedFolder => "common",
+            ForumCommonAssetMode.PerThreadFolder => Path.Combine(GetForumThreadDirPath(), "common"),
+            ForumCommonAssetMode.Skip => null,
+            _ => throw new ArgumentOutOfRangeException(),
+        };
+
+    private string GetForumAttachmentDirPath(Attachment attachment, Snowflake messageId)
+    {
+        var baseDirPath = Path.Combine(GetForumThreadDirPath(), "attachments");
+
+        return Request.ForumAttachmentFolderMode switch
+        {
+            ForumAttachmentFolderMode.PerThread => baseDirPath,
+            ForumAttachmentFolderMode.ByMediaType => Path.Combine(
+                baseDirPath,
+                attachment.IsImage ? "images"
+                    : attachment.IsVideo ? "videos"
+                    : attachment.IsAudio ? "audio"
+                    : "files"
+            ),
+            ForumAttachmentFolderMode.ByMessage => Path.Combine(
+                baseDirPath,
+                "messages",
+                messageId.ToString()
+            ),
+            _ => throw new ArgumentOutOfRangeException(),
+        };
+    }
+
+    private string? GetForumAttachmentFileName(Attachment attachment, Snowflake messageId) =>
+        Request.ForumAttachmentNamingMode switch
+        {
+            ForumAttachmentNamingMode.OriginalWithHash => null,
+            ForumAttachmentNamingMode.AttachmentIdAndOriginal =>
+                $"{attachment.Id}_{attachment.FileName}",
+            ForumAttachmentNamingMode.MessageAndAttachmentIdsAndOriginal =>
+                $"{messageId}_{attachment.Id}_{attachment.FileName}",
+            _ => throw new ArgumentOutOfRangeException(),
+        };
+
+    private async ValueTask<string> ResolveDownloadedAssetUrlAsync(
         string url,
-        CancellationToken cancellationToken = default
+        string? relativeDirPath,
+        string? preferredFileName,
+        CancellationToken cancellationToken
     )
     {
-        if (!Request.ShouldDownloadAssets)
+        var filePath = await _assetDownloader.DownloadAsync(
-            return url;
+            url,
+            relativeDirPath,
+            preferredFileName,
+            cancellationToken
+        );
 
-        try
-        {
-            var filePath = await _assetDownloader.DownloadAsync(url, cancellationToken);
         var relativeFilePath = Path.GetRelativePath(Request.OutputDirPath, filePath);
 
         // Prefer the relative path so that the export package can be copied around without breaking references.
@@ -153,6 +205,28 @@ internal class ExportContext(DiscordClient discord, ExportRequest request)
 
         return optimalFilePath;
     }
+
+    public async ValueTask<string> ResolveAssetUrlAsync(
+        string url,
+        CancellationToken cancellationToken = default
+    )
+    {
+        if (!Request.ShouldDownloadAssets)
+            return url;
+
+        var relativeDirPath = Request.IsForumExport ? GetForumCommonAssetDirPath() : null;
+        if (Request.IsForumExport && relativeDirPath is null)
+            return url;
+
+        try
+        {
+            return await ResolveDownloadedAssetUrlAsync(
+                url,
+                relativeDirPath,
+                null,
+                cancellationToken
+            );
+        }
         // Try to catch only exceptions related to failed HTTP requests
         // https://github.com/Tyrrrz/DiscordChatExporter/issues/332
         // https://github.com/Tyrrrz/DiscordChatExporter/issues/372
@@ -163,4 +237,36 @@ internal class ExportContext(DiscordClient discord, ExportRequest request)
             return url;
         }
     }
+
+    public ValueTask<string> ResolveAvatarUrlAsync(
+        string url,
+        CancellationToken cancellationToken = default
+    ) =>
+        Request.IsForumExport && !Request.ShouldDownloadForumAvatars
+            ? ValueTask.FromResult(url)
+            : ResolveAssetUrlAsync(url, cancellationToken);
+
+    public async ValueTask<string> ResolveAttachmentUrlAsync(
+        Attachment attachment,
+        Snowflake messageId,
+        CancellationToken cancellationToken = default
+    )
+    {
+        if (!Request.ShouldDownloadAssets || !Request.IsForumExport)
+            return await ResolveAssetUrlAsync(attachment.Url, cancellationToken);
+
+        try
+        {
+            return await ResolveDownloadedAssetUrlAsync(
+                attachment.Url,
+                GetForumAttachmentDirPath(attachment, messageId),
+                GetForumAttachmentFileName(attachment, messageId),
+                cancellationToken
+            );
+        }
+        catch (Exception ex) when (ex is HttpRequestException or OperationCanceledException)
+        {
+            return attachment.Url;
+        }
+    }
 }

DiscordChatExporter.Core/Exporting/ExportRequest.cs

@@ -41,6 +41,16 @@ public partial class ExportRequest
 
     public bool ShouldReuseAssets { get; }
 
+    public bool IsForumExport { get; }
+
+    public bool ShouldDownloadForumAvatars { get; }
+
+    public ForumCommonAssetMode ForumCommonAssetMode { get; }
+
+    public ForumAttachmentFolderMode ForumAttachmentFolderMode { get; }
+
+    public ForumAttachmentNamingMode ForumAttachmentNamingMode { get; }
+
     public string? Locale { get; }
 
     public CultureInfo? CultureInfo { get; }
@@ -62,7 +72,13 @@ public partial class ExportRequest
         bool shouldDownloadAssets,
         bool shouldReuseAssets,
         string? locale,
-        bool isUtcNormalizationEnabled
+        bool isUtcNormalizationEnabled,
+        bool isForumExport = false,
+        bool shouldDownloadForumAvatars = false,
+        ForumCommonAssetMode forumCommonAssetMode = ForumCommonAssetMode.SharedFolder,
+        ForumAttachmentFolderMode forumAttachmentFolderMode = ForumAttachmentFolderMode.PerThread,
+        ForumAttachmentNamingMode forumAttachmentNamingMode =
+            ForumAttachmentNamingMode.AttachmentIdAndOriginal
     )
     {
         Guild = guild;
@@ -76,6 +92,11 @@ public partial class ExportRequest
         ShouldFormatMarkdown = shouldFormatMarkdown;
         ShouldDownloadAssets = shouldDownloadAssets;
         ShouldReuseAssets = shouldReuseAssets;
+        IsForumExport = isForumExport;
+        ShouldDownloadForumAvatars = shouldDownloadForumAvatars;
+        ForumCommonAssetMode = forumCommonAssetMode;
+        ForumAttachmentFolderMode = forumAttachmentFolderMode;
+        ForumAttachmentNamingMode = forumAttachmentNamingMode;
         Locale = locale;
         IsUtcNormalizationEnabled = isUtcNormalizationEnabled;
 
@@ -83,8 +104,10 @@ public partial class ExportRequest
 
         OutputDirPath = Path.GetDirectoryName(OutputFilePath)!;
 
-        AssetsDirPath = !string.IsNullOrWhiteSpace(assetsDirPath)
+        AssetsDirPath =
+            !string.IsNullOrWhiteSpace(assetsDirPath)
                 ? FormatPath(assetsDirPath, Guild, Channel, After, Before)
+            : IsForumExport ? Path.Combine(OutputDirPath, "_forum_assets")
             : $"{OutputFilePath}_Files{Path.DirectorySeparatorChar}";
 
         CultureInfo = Locale?.Pipe(CultureInfo.GetCultureInfo);

DiscordChatExporter.Core/Exporting/ForumAssetOptions.cs

@@ -0,0 +1,22 @@
+namespace DiscordChatExporter.Core.Exporting;
+
+public enum ForumCommonAssetMode
+{
+    SharedFolder,
+    PerThreadFolder,
+    Skip,
+}
+
+public enum ForumAttachmentFolderMode
+{
+    PerThread,
+    ByMediaType,
+    ByMessage,
+}
+
+public enum ForumAttachmentNamingMode
+{
+    OriginalWithHash,
+    AttachmentIdAndOriginal,
+    MessageAndAttachmentIdsAndOriginal,
+}

DiscordChatExporter.Core/Exporting/JsonMessageWriter.cs

@@ -6,6 +6,7 @@ using System.Text.Encodings.Web;
 using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
+using DiscordChatExporter.Core.Discord;
 using DiscordChatExporter.Core.Discord.Data;
 using DiscordChatExporter.Core.Discord.Data.Embeds;
 using DiscordChatExporter.Core.Markdown.Parsing;
@@ -66,7 +67,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
 
         _writer.WriteString(
             "avatarUrl",
-            await Context.ResolveAssetUrlAsync(
+            await Context.ResolveAvatarUrlAsync(
                 Context.TryGetMember(user.Id)?.AvatarUrl ?? user.AvatarUrl,
                 cancellationToken
             )
@@ -121,6 +122,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
 
     private async ValueTask WriteAttachmentAsync(
         Attachment attachment,
+        Snowflake messageId,
         CancellationToken cancellationToken = default
     )
     {
@@ -129,7 +131,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
         _writer.WriteString("id", attachment.Id.ToString());
         _writer.WriteString(
             "url",
-            await Context.ResolveAssetUrlAsync(attachment.Url, cancellationToken)
+            await Context.ResolveAttachmentUrlAsync(attachment, messageId, cancellationToken)
         );
         _writer.WriteString("fileName", attachment.FileName);
         _writer.WriteNumber("fileSizeBytes", attachment.FileSize.TotalBytes);
@@ -473,7 +475,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
         _writer.WriteStartArray("attachments");
 
         foreach (var attachment in message.Attachments)
-            await WriteAttachmentAsync(attachment, cancellationToken);
+            await WriteAttachmentAsync(attachment, message.Id, cancellationToken);
 
         _writer.WriteEndArray();
 
@@ -570,7 +572,7 @@ internal class JsonMessageWriter(Stream stream, ExportContext context)
             _writer.WriteStartArray("attachments");
 
             foreach (var attachment in message.ForwardedMessage.Attachments)
-                await WriteAttachmentAsync(attachment, cancellationToken);
+                await WriteAttachmentAsync(attachment, message.Id, cancellationToken);
 
             _writer.WriteEndArray();
 

DiscordChatExporter.Gui/Converters/ForumAssetOptionToStringConverter.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Globalization;
+using Avalonia.Data.Converters;
+using DiscordChatExporter.Core.Exporting;
+
+namespace DiscordChatExporter.Gui.Converters;
+
+public class ForumAssetOptionToStringConverter : IValueConverter
+{
+    public static ForumAssetOptionToStringConverter Instance { get; } = new();
+
+    public object? Convert(
+        object? value,
+        Type targetType,
+        object? parameter,
+        CultureInfo culture
+    ) =>
+        value switch
+        {
+            ForumCommonAssetMode.SharedFolder => "One shared folder for the whole export",
+            ForumCommonAssetMode.PerThreadFolder => "Separate common folder inside every post",
+            ForumCommonAssetMode.Skip => "Do not download common resources",
+
+            ForumAttachmentFolderMode.PerThread => "One attachments folder per post",
+            ForumAttachmentFolderMode.ByMediaType => "Split into images, videos, audio and files",
+            ForumAttachmentFolderMode.ByMessage => "Separate folder for every message",
+
+            ForumAttachmentNamingMode.OriginalWithHash => "Original name + safety hash",
+            ForumAttachmentNamingMode.AttachmentIdAndOriginal => "Attachment ID + original name",
+            ForumAttachmentNamingMode.MessageAndAttachmentIdsAndOriginal =>
+                "Message ID + attachment ID + original name",
+            _ => value?.ToString(),
+        };
+
+    public object ConvertBack(
+        object? value,
+        Type targetType,
+        object? parameter,
+        CultureInfo culture
+    ) => throw new NotSupportedException();
+}

DiscordChatExporter.Gui/Framework/ViewModelManager.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using DiscordChatExporter.Core.Discord;
 using DiscordChatExporter.Core.Discord.Data;
 using DiscordChatExporter.Gui.Localization;
 using DiscordChatExporter.Gui.ViewModels;
@@ -18,13 +19,15 @@ public class ViewModelManager(IServiceProvider services, LocalizationManager loc
 
     public ExportSetupViewModel GetExportSetupViewModel(
         Guild guild,
-        IReadOnlyList<Channel> channels
+        IReadOnlyList<Channel> channels,
+        IReadOnlySet<Snowflake> forumChannelIds
     )
     {
         var viewModel = services.GetRequiredService<ExportSetupViewModel>();
 
         viewModel.Guild = guild;
         viewModel.Channels = channels;
+        viewModel.ForumChannelIds = forumChannelIds;
 
         return viewModel;
     }

DiscordChatExporter.Gui/Services/SettingsService.cs

@@ -23,10 +23,10 @@ public partial class SettingsService()
     public partial Language Language { get; set; }
 
     [ObservableProperty]
-    public partial bool IsAutoUpdateEnabled { get; set; } = true;
+    public partial bool IsAutoUpdateEnabled { get; set; }
 
     [ObservableProperty]
-    public partial bool IsTokenPersisted { get; set; } = true;
+    public partial bool IsTokenPersisted { get; set; }
 
     [ObservableProperty]
     public partial RateLimitPreference RateLimitPreference { get; set; } =
@@ -49,7 +49,7 @@ public partial class SettingsService()
     public partial string? LastToken { get; set; }
 
     [ObservableProperty]
-    public partial ExportFormat LastExportFormat { get; set; } = ExportFormat.HtmlDark;
+    public partial ExportFormat LastExportFormat { get; set; } = ExportFormat.Json;
 
     [ObservableProperty]
     public partial string? LastPartitionLimitValue { get; set; }
@@ -64,14 +64,41 @@ public partial class SettingsService()
     public partial bool LastShouldFormatMarkdown { get; set; } = true;
 
     [ObservableProperty]
-    public partial bool LastShouldDownloadAssets { get; set; }
+    public partial bool LastShouldDownloadAssets { get; set; } = true;
 
     [ObservableProperty]
-    public partial bool LastShouldReuseAssets { get; set; }
+    public partial bool LastShouldReuseAssets { get; set; } = true;
 
     [ObservableProperty]
     public partial string? LastAssetsDirPath { get; set; }
 
+    [ObservableProperty]
+    public partial bool LastForumShouldDownloadAssets { get; set; } = true;
+
+    [ObservableProperty]
+    public partial bool LastForumShouldReuseAssets { get; set; } = true;
+
+    [ObservableProperty]
+    public partial string? LastForumAssetsDirPath { get; set; }
+
+    [ObservableProperty]
+    public partial bool LastForumShouldDownloadAvatars { get; set; }
+
+    [ObservableProperty]
+    public partial ForumCommonAssetMode LastForumCommonAssetMode { get; set; } =
+        ForumCommonAssetMode.SharedFolder;
+
+    [ObservableProperty]
+    public partial ForumAttachmentFolderMode LastForumAttachmentFolderMode { get; set; } =
+        ForumAttachmentFolderMode.ByMediaType;
+
+    [ObservableProperty]
+    public partial ForumAttachmentNamingMode LastForumAttachmentNamingMode { get; set; } =
+        ForumAttachmentNamingMode.AttachmentIdAndOriginal;
+
+    [ObservableProperty]
+    public partial int LastForumParallelLimit { get; set; } = 4;
+
     public override void Save()
     {
         // Clear the token if it's not supposed to be persisted

DiscordChatExporter.Gui/ViewModels/Components/DashboardViewModel.cs

@@ -4,6 +4,7 @@ using System.Collections.ObjectModel;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
+using Avalonia.Controls;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
 using DiscordChatExporter.Core.Discord;
@@ -91,6 +92,25 @@ public partial class DashboardViewModel : ViewModelBase
 
     public ObservableCollection<ChannelConnection> SelectedChannels { get; } = [];
 
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(ChannelSelectionMode))]
+    public partial bool IsMultiSelectionEnabled { get; set; }
+
+    public SelectionMode ChannelSelectionMode =>
+        IsMultiSelectionEnabled
+            ? SelectionMode.Multiple | SelectionMode.Toggle
+            : SelectionMode.Single;
+
+    partial void OnIsMultiSelectionEnabledChanged(bool value)
+    {
+        if (value || SelectedChannels.Count <= 1)
+            return;
+
+        var lastSelectedChannel = SelectedChannels[^1];
+        SelectedChannels.Clear();
+        SelectedChannels.Add(lastSelectedChannel);
+    }
+
     public override Task InitializeAsync()
     {
         if (!string.IsNullOrWhiteSpace(_settingsService.LastToken))
@@ -222,6 +242,47 @@ public partial class DashboardViewModel : ViewModelBase
     private bool CanExport() =>
         !IsBusy && _discord is not null && SelectedGuild is not null && SelectedChannels.Any();
 
+    private async Task<IReadOnlyList<Channel>> ExpandForumChannelsAsync(
+        IReadOnlyList<Channel> channels,
+        CancellationToken cancellationToken = default
+    )
+    {
+        if (_discord is null)
+            return channels;
+
+        var expandedChannels = new List<Channel>();
+        var seenChannelIds = new HashSet<Snowflake>();
+
+        // Keep regular channels and explicitly selected threads as-is. Forum channels are
+        // containers without their own message history, so they are replaced with all of
+        // their accessible active and archived threads below.
+        foreach (var channel in channels.Where(c => c.Kind != ChannelKind.GuildForum))
+        {
+            if (seenChannelIds.Add(channel.Id))
+                expandedChannels.Add(channel);
+        }
+
+        var forums = channels.Where(c => c.Kind == ChannelKind.GuildForum).ToArray();
+        if (forums.Length <= 0)
+            return expandedChannels;
+
+        await foreach (
+            var thread in _discord.GetChannelThreadsAsync(
+                forums,
+                includeArchived: true,
+                cancellationToken: cancellationToken
+            )
+        )
+        {
+            // A thread may already be selected explicitly or may transition from active to
+            // archived while it is being discovered. Export every thread only once.
+            if (seenChannelIds.Add(thread.Id))
+                expandedChannels.Add(thread);
+        }
+
+        return expandedChannels;
+    }
+
     [RelayCommand(CanExecute = nameof(CanExport))]
     private async Task ExportAsync()
     {
@@ -232,9 +293,31 @@ public partial class DashboardViewModel : ViewModelBase
             if (_discord is null || SelectedGuild is null || !SelectedChannels.Any())
                 return;
 
+            var selectedChannels = SelectedChannels.Select(c => c.Channel).ToArray();
+            var channelsToExport = await ExpandForumChannelsAsync(selectedChannels);
+
+            if (channelsToExport.Count <= 0)
+            {
+                _snackbarManager.Notify(
+                    "No accessible active or archived threads were found in the selected forum."
+                );
+                return;
+            }
+
+            var selectedForumIds = selectedChannels
+                .Where(c => c.Kind == ChannelKind.GuildForum)
+                .Select(c => c.Id)
+                .ToHashSet();
+
+            var forumChannelIds = channelsToExport
+                .Where(c => c.Parent is not null && selectedForumIds.Contains(c.Parent.Id))
+                .Select(c => c.Id)
+                .ToHashSet();
+
             var dialog = _viewModelManager.GetExportSetupViewModel(
                 SelectedGuild,
-                SelectedChannels.Select(c => c.Channel).ToArray()
+                channelsToExport,
+                forumChannelIds
             );
 
             if (await _dialogManager.ShowDialogAsync(dialog) != true)
@@ -252,7 +335,12 @@ public partial class DashboardViewModel : ViewModelBase
                 channelProgressPairs,
                 new ParallelOptions
                 {
-                    MaxDegreeOfParallelism = Math.Max(1, _settingsService.ParallelLimit),
+                    MaxDegreeOfParallelism = Math.Max(
+                        1,
+                        dialog.HasForumChannels
+                            ? dialog.SelectedForumParallelLimit
+                            : _settingsService.ParallelLimit
+                    ),
                 },
                 async (pair, cancellationToken) =>
                 {
@@ -261,22 +349,33 @@ public partial class DashboardViewModel : ViewModelBase
 
                     try
                     {
+                        var isForumChannel = dialog.IsForumChannel(channel);
+
                         var request = new ExportRequest(
                             dialog.Guild!,
                             channel,
                             dialog.OutputPath!,
-                            dialog.AssetsDirPath,
+                            isForumChannel ? dialog.ForumAssetsDirPath : dialog.AssetsDirPath,
-                            dialog.SelectedFormat,
+                            isForumChannel ? ExportFormat.Json : dialog.SelectedFormat,
                             dialog.After?.Pipe(Snowflake.FromDate),
                             dialog.Before?.Pipe(Snowflake.FromDate),
                             dialog.PartitionLimit,
                             dialog.MessageFilter,
                             dialog.IsReverseMessageOrder,
                             dialog.ShouldFormatMarkdown,
-                            dialog.ShouldDownloadAssets,
+                            isForumChannel
-                            dialog.ShouldReuseAssets,
+                                ? dialog.ForumShouldDownloadAssets
+                                : dialog.ShouldDownloadAssets,
+                            isForumChannel
+                                ? dialog.ForumShouldReuseAssets
+                                : dialog.ShouldReuseAssets,
                             _settingsService.Locale,
-                            _settingsService.IsUtcNormalizationEnabled
+                            _settingsService.IsUtcNormalizationEnabled,
+                            isForumChannel,
+                            dialog.ForumShouldDownloadAvatars,
+                            dialog.SelectedForumCommonAssetMode,
+                            dialog.SelectedForumAttachmentFolderMode,
+                            dialog.SelectedForumAttachmentNamingMode
                         );
 
                         await exporter.ExportChannelAsync(request, progress, cancellationToken);

DiscordChatExporter.Gui/ViewModels/Dialogs/ExportSetupViewModel.cs

@@ -30,8 +30,20 @@ public partial class ExportSetupViewModel(
 
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(IsSingleChannel))]
+    [NotifyPropertyChangedFor(nameof(HasRegularChannels))]
+    [NotifyPropertyChangedFor(nameof(HasMixedChannelTypes))]
+    [NotifyPropertyChangedFor(nameof(HasOnlyForumChannels))]
+    [NotifyPropertyChangedFor(nameof(HasOnlyRegularChannels))]
     public partial IReadOnlyList<Channel>? Channels { get; set; }
 
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(HasForumChannels))]
+    [NotifyPropertyChangedFor(nameof(HasRegularChannels))]
+    [NotifyPropertyChangedFor(nameof(HasMixedChannelTypes))]
+    [NotifyPropertyChangedFor(nameof(HasOnlyForumChannels))]
+    [NotifyPropertyChangedFor(nameof(HasOnlyRegularChannels))]
+    public partial IReadOnlySet<Snowflake>? ForumChannelIds { get; set; }
+
     [ObservableProperty]
     public partial string? OutputPath { get; set; }
 
@@ -77,13 +89,61 @@ public partial class ExportSetupViewModel(
     [ObservableProperty]
     public partial string? AssetsDirPath { get; set; }
 
+    [ObservableProperty]
+    public partial bool ForumShouldDownloadAssets { get; set; }
+
+    [ObservableProperty]
+    public partial bool ForumShouldReuseAssets { get; set; }
+
+    [ObservableProperty]
+    public partial string? ForumAssetsDirPath { get; set; }
+
+    [ObservableProperty]
+    public partial bool ForumShouldDownloadAvatars { get; set; }
+
+    [ObservableProperty]
+    public partial ForumCommonAssetMode SelectedForumCommonAssetMode { get; set; }
+
+    [ObservableProperty]
+    public partial ForumAttachmentFolderMode SelectedForumAttachmentFolderMode { get; set; }
+
+    [ObservableProperty]
+    public partial ForumAttachmentNamingMode SelectedForumAttachmentNamingMode { get; set; }
+
+    [ObservableProperty]
+    public partial int SelectedForumParallelLimit { get; set; }
+
     [ObservableProperty]
     public partial bool IsAdvancedSectionDisplayed { get; set; }
 
     public bool IsSingleChannel => Channels?.Count == 1;
 
+    public bool HasForumChannels => ForumChannelIds?.Count > 0;
+
+    public bool HasRegularChannels =>
+        Channels?.Any(c => ForumChannelIds?.Contains(c.Id) != true) == true;
+
+    public bool HasMixedChannelTypes => HasForumChannels && HasRegularChannels;
+
+    public bool HasOnlyForumChannels => HasForumChannels && !HasRegularChannels;
+
+    public bool HasOnlyRegularChannels => HasRegularChannels && !HasForumChannels;
+
+    public bool IsForumChannel(Channel channel) => ForumChannelIds?.Contains(channel.Id) == true;
+
     public IReadOnlyList<ExportFormat> AvailableFormats { get; } = Enum.GetValues<ExportFormat>();
 
+    public IReadOnlyList<ForumCommonAssetMode> AvailableForumCommonAssetModes { get; } =
+        Enum.GetValues<ForumCommonAssetMode>();
+
+    public IReadOnlyList<ForumAttachmentFolderMode> AvailableForumAttachmentFolderModes { get; } =
+        Enum.GetValues<ForumAttachmentFolderMode>();
+
+    public IReadOnlyList<ForumAttachmentNamingMode> AvailableForumAttachmentNamingModes { get; } =
+        Enum.GetValues<ForumAttachmentNamingMode>();
+
+    public IReadOnlyList<int> AvailableForumParallelLimits { get; } = [1, 2, 4, 8];
+
     public bool IsAfterDateSet => AfterDate is not null;
 
     public DateTimeOffset? After => AfterDate?.Add(AfterTime ?? TimeSpan.Zero);
@@ -113,6 +173,14 @@ public partial class ExportSetupViewModel(
         ShouldDownloadAssets = settingsService.LastShouldDownloadAssets;
         ShouldReuseAssets = settingsService.LastShouldReuseAssets;
         AssetsDirPath = settingsService.LastAssetsDirPath;
+        ForumShouldDownloadAssets = settingsService.LastForumShouldDownloadAssets;
+        ForumShouldReuseAssets = settingsService.LastForumShouldReuseAssets;
+        ForumAssetsDirPath = settingsService.LastForumAssetsDirPath;
+        ForumShouldDownloadAvatars = settingsService.LastForumShouldDownloadAvatars;
+        SelectedForumCommonAssetMode = settingsService.LastForumCommonAssetMode;
+        SelectedForumAttachmentFolderMode = settingsService.LastForumAttachmentFolderMode;
+        SelectedForumAttachmentNamingMode = settingsService.LastForumAttachmentNamingMode;
+        SelectedForumParallelLimit = settingsService.LastForumParallelLimit;
 
         // Show the "advanced options" section by default if any
         // of the advanced options are set to non-default values.
@@ -173,6 +241,14 @@ public partial class ExportSetupViewModel(
             AssetsDirPath = path;
     }
 
+    [RelayCommand]
+    private async Task ShowForumAssetsDirPathPromptAsync()
+    {
+        var path = await dialogManager.PromptDirectoryPathAsync();
+        if (!string.IsNullOrWhiteSpace(path))
+            ForumAssetsDirPath = path;
+    }
+
     [RelayCommand]
     private async Task ConfirmAsync()
     {
@@ -195,6 +271,14 @@ public partial class ExportSetupViewModel(
         settingsService.LastShouldDownloadAssets = ShouldDownloadAssets;
         settingsService.LastShouldReuseAssets = ShouldReuseAssets;
         settingsService.LastAssetsDirPath = AssetsDirPath;
+        settingsService.LastForumShouldDownloadAssets = ForumShouldDownloadAssets;
+        settingsService.LastForumShouldReuseAssets = ForumShouldReuseAssets;
+        settingsService.LastForumAssetsDirPath = ForumAssetsDirPath;
+        settingsService.LastForumShouldDownloadAvatars = ForumShouldDownloadAvatars;
+        settingsService.LastForumCommonAssetMode = SelectedForumCommonAssetMode;
+        settingsService.LastForumAttachmentFolderMode = SelectedForumAttachmentFolderMode;
+        settingsService.LastForumAttachmentNamingMode = SelectedForumAttachmentNamingMode;
+        settingsService.LastForumParallelLimit = SelectedForumParallelLimit;
 
         Close(true);
     }

DiscordChatExporter.Gui/Views/Components/DashboardView.axaml

@@ -147,7 +147,7 @@
             ItemsSource="{Binding AvailableChannels}"
             SelectedItems="{Binding SelectedChannels}"
             SelectionChanged="AvailableChannelsTreeView_OnSelectionChanged"
-            SelectionMode="Multiple"
+            SelectionMode="{Binding ChannelSelectionMode}"
             TextSearch.Text="Name"
           >
             <TreeView.Styles>
@@ -302,22 +302,39 @@
         </ScrollViewer>
       </Panel>
 
-      <!--  Export button  -->
+      <!--  Selection mode and export buttons  -->
+      <StackPanel
+        Margin="32,24"
+        HorizontalAlignment="Right"
+        VerticalAlignment="Bottom"
+        IsVisible="{Binding $self.IsEffectivelyEnabled}"
+        Orientation="Horizontal"
+        Spacing="12"
+      >
+        <ToggleButton
+          Width="56"
+          Height="56"
+          Padding="0"
+          IsChecked="{Binding IsMultiSelectionEnabled}"
+          Theme="{DynamicResource MaterialIconButton}"
+          ToolTip.Tip="Enable multi-select mode"
+        >
+          <materialIcons:MaterialIcon Width="28" Height="28" Kind="CheckboxMultipleMarked" />
+        </ToggleButton>
+
         <Button
           Width="56"
           Height="56"
-        Margin="32,24"
           Padding="0"
-        HorizontalAlignment="Right"
-        VerticalAlignment="Bottom"
           Background="{DynamicResource MaterialSecondaryMidBrush}"
           Command="{Binding ExportCommand}"
           Foreground="{DynamicResource MaterialSecondaryMidForegroundBrush}"
-        IsVisible="{Binding $self.IsEffectivelyEnabled}"
           Theme="{DynamicResource MaterialIconButton}"
+          ToolTip.Tip="Export selected channels"
         >
           <materialIcons:MaterialIcon Width="32" Height="32" Kind="Download" />
         </Button>
+      </StackPanel>
     </Panel>
   </DockPanel>
 </UserControl>

DiscordChatExporter.Gui/Views/Dialogs/ExportSetupView.axaml

@@ -9,9 +9,150 @@
   xmlns:materialIcons="clr-namespace:Material.Icons.Avalonia;assembly=Material.Icons.Avalonia"
   xmlns:utils="clr-namespace:DiscordChatExporter.Gui.Utils"
   x:Name="UserControl"
-  Width="380"
+  Width="520"
   x:DataType="dialogs:ExportSetupViewModel"
 >
+  <UserControl.Resources>
+    <DataTemplate x:Key="ForumAssetSettingsTemplate" x:DataType="dialogs:ExportSetupViewModel">
+      <StackPanel Margin="8" Orientation="Vertical" Spacing="14">
+        <TextBlock FontWeight="SemiBold" Text="Forum export (JSON)" />
+        <TextBlock
+          Opacity="0.75"
+          Text="These options apply only to posts expanded from selected forum channels."
+          TextWrapping="Wrap"
+        />
+
+        <DockPanel LastChildFill="False">
+          <TextBlock DockPanel.Dock="Left" Text="Download post files and resources" />
+          <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ForumShouldDownloadAssets}" />
+        </DockPanel>
+
+        <DockPanel IsEnabled="{Binding ForumShouldDownloadAssets}" LastChildFill="False">
+          <TextBlock DockPanel.Dock="Left" Text="Reuse files already downloaded" />
+          <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ForumShouldReuseAssets}" />
+        </DockPanel>
+
+        <DockPanel IsEnabled="{Binding ForumShouldDownloadAssets}" LastChildFill="False">
+          <TextBlock DockPanel.Dock="Left" Text="Download user avatars" />
+          <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ForumShouldDownloadAvatars}" />
+        </DockPanel>
+
+        <ComboBox
+          IsEnabled="{Binding ForumShouldDownloadAssets}"
+          ItemsSource="{Binding AvailableForumCommonAssetModes}"
+          materialAssists:ComboBoxAssist.Label="Common resources (emoji, icons, previews)"
+          SelectedItem="{Binding SelectedForumCommonAssetMode}"
+          Theme="{DynamicResource MaterialFilledComboBox}"
+        >
+          <ComboBox.ItemTemplate>
+            <DataTemplate>
+              <TextBlock Text="{Binding Converter={x:Static converters:ForumAssetOptionToStringConverter.Instance}}" />
+            </DataTemplate>
+          </ComboBox.ItemTemplate>
+        </ComboBox>
+
+        <ComboBox
+          IsEnabled="{Binding ForumShouldDownloadAssets}"
+          ItemsSource="{Binding AvailableForumAttachmentFolderModes}"
+          materialAssists:ComboBoxAssist.Label="Post attachment folders"
+          SelectedItem="{Binding SelectedForumAttachmentFolderMode}"
+          Theme="{DynamicResource MaterialFilledComboBox}"
+        >
+          <ComboBox.ItemTemplate>
+            <DataTemplate>
+              <TextBlock Text="{Binding Converter={x:Static converters:ForumAssetOptionToStringConverter.Instance}}" />
+            </DataTemplate>
+          </ComboBox.ItemTemplate>
+        </ComboBox>
+
+        <ComboBox
+          IsEnabled="{Binding ForumShouldDownloadAssets}"
+          ItemsSource="{Binding AvailableForumAttachmentNamingModes}"
+          materialAssists:ComboBoxAssist.Label="Post attachment names"
+          SelectedItem="{Binding SelectedForumAttachmentNamingMode}"
+          Theme="{DynamicResource MaterialFilledComboBox}"
+        >
+          <ComboBox.ItemTemplate>
+            <DataTemplate>
+              <TextBlock Text="{Binding Converter={x:Static converters:ForumAssetOptionToStringConverter.Instance}}" />
+            </DataTemplate>
+          </ComboBox.ItemTemplate>
+        </ComboBox>
+
+        <ComboBox
+          ItemsSource="{Binding AvailableForumParallelLimits}"
+          materialAssists:ComboBoxAssist.Label="Parallel forum export workers"
+          SelectedItem="{Binding SelectedForumParallelLimit}"
+          Theme="{DynamicResource MaterialFilledComboBox}"
+          ToolTip.Tip="4 is the recommended balance between speed and Discord rate limits."
+        />
+
+        <TextBox
+          IsEnabled="{Binding ForumShouldDownloadAssets}"
+          materialAssists:TextFieldAssist.Label="Forum assets root (optional)"
+          Text="{Binding ForumAssetsDirPath}"
+          Theme="{DynamicResource FilledTextBox}"
+        >
+          <TextBox.InnerRightContent>
+            <Button
+              Margin="8,8,8,6"
+              Padding="8"
+              Command="{Binding ShowForumAssetsDirPathPromptCommand}"
+              Theme="{DynamicResource MaterialFlatButton}"
+            >
+              <materialIcons:MaterialIcon Width="20" Height="20" Kind="FolderOpen" />
+            </Button>
+          </TextBox.InnerRightContent>
+        </TextBox>
+      </StackPanel>
+    </DataTemplate>
+
+    <DataTemplate x:Key="RegularAssetSettingsTemplate" x:DataType="dialogs:ExportSetupViewModel">
+      <StackPanel Margin="8" Orientation="Vertical" Spacing="14">
+        <TextBlock FontWeight="SemiBold" Text="Regular channel assets" />
+
+        <DockPanel
+          LastChildFill="False"
+          ToolTip.Tip="{Binding LocalizationManager.DownloadAssetsTooltip}"
+        >
+          <TextBlock
+            DockPanel.Dock="Left"
+            Text="{Binding LocalizationManager.DownloadAssetsLabel}"
+          />
+          <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ShouldDownloadAssets}" />
+        </DockPanel>
+
+        <DockPanel
+          IsEnabled="{Binding ShouldDownloadAssets}"
+          LastChildFill="False"
+          ToolTip.Tip="{Binding LocalizationManager.ReuseAssetsTooltip}"
+        >
+          <TextBlock DockPanel.Dock="Left" Text="{Binding LocalizationManager.ReuseAssetsLabel}" />
+          <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ShouldReuseAssets}" />
+        </DockPanel>
+
+        <TextBox
+          IsEnabled="{Binding ShouldDownloadAssets}"
+          materialAssists:TextFieldAssist.Label="{Binding LocalizationManager.AssetsDirPathLabel}"
+          Text="{Binding AssetsDirPath}"
+          Theme="{DynamicResource FilledTextBox}"
+          ToolTip.Tip="{Binding LocalizationManager.AssetsDirPathTooltip}"
+        >
+          <TextBox.InnerRightContent>
+            <Button
+              Margin="8,8,8,6"
+              Padding="8"
+              Command="{Binding ShowAssetsDirPathPromptCommand}"
+              Theme="{DynamicResource MaterialFlatButton}"
+            >
+              <materialIcons:MaterialIcon Width="20" Height="20" Kind="FolderOpen" />
+            </Button>
+          </TextBox.InnerRightContent>
+        </TextBox>
+      </StackPanel>
+    </DataTemplate>
+  </UserControl.Resources>
+
   <Grid RowDefinitions="Auto,*,Auto">
     <!--  Guild/channel info  -->
     <Grid Grid.Row="0" Margin="16" ColumnDefinitions="Auto,*">
@@ -89,6 +230,7 @@
 
           <!--  Format  -->
           <ComboBox
+            IsVisible="{Binding HasRegularChannels}"
             Margin="16,8"
             materialAssists:ComboBoxAssist.Label="{Binding LocalizationManager.FormatLabel}"
             ItemsSource="{Binding AvailableFormats}"
@@ -103,6 +245,28 @@
             </ComboBox.ItemTemplate>
           </ComboBox>
 
+          <ContentControl
+            Margin="16,8"
+            Content="{Binding}"
+            ContentTemplate="{StaticResource ForumAssetSettingsTemplate}"
+            IsVisible="{Binding HasOnlyForumChannels}"
+          />
+
+          <TabControl Margin="16,8" IsVisible="{Binding HasMixedChannelTypes}">
+            <TabItem Header="FORUM POSTS">
+              <ContentControl
+                Content="{Binding}"
+                ContentTemplate="{StaticResource ForumAssetSettingsTemplate}"
+              />
+            </TabItem>
+            <TabItem Header="REGULAR CHANNELS">
+              <ContentControl
+                Content="{Binding}"
+                ContentTemplate="{StaticResource RegularAssetSettingsTemplate}"
+              />
+            </TabItem>
+          </TabControl>
+
           <!--  Advanced section  -->
           <StackPanel
             Margin="16,8"
@@ -220,51 +384,11 @@
               <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ShouldFormatMarkdown}" />
             </DockPanel>
 
-            <!--  Download assets  -->
+            <ContentControl
-            <DockPanel
+              Content="{Binding}"
-              LastChildFill="False"
+              ContentTemplate="{StaticResource RegularAssetSettingsTemplate}"
-              ToolTip.Tip="{Binding LocalizationManager.DownloadAssetsTooltip}"
+              IsVisible="{Binding HasOnlyRegularChannels}"
-            >
-              <TextBlock
-                DockPanel.Dock="Left"
-                Text="{Binding LocalizationManager.DownloadAssetsLabel}"
             />
-              <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ShouldDownloadAssets}" />
-            </DockPanel>
-
-            <!--  Reuse assets  -->
-            <DockPanel
-              IsEnabled="{Binding ShouldDownloadAssets}"
-              LastChildFill="False"
-              ToolTip.Tip="{Binding LocalizationManager.ReuseAssetsTooltip}"
-            >
-              <TextBlock
-                DockPanel.Dock="Left"
-                Text="{Binding LocalizationManager.ReuseAssetsLabel}"
-              />
-              <ToggleSwitch DockPanel.Dock="Right" IsChecked="{Binding ShouldReuseAssets}" />
-            </DockPanel>
-
-            <!--  Assets path  -->
-            <TextBox
-              materialAssists:TextFieldAssist.Label="{Binding LocalizationManager.AssetsDirPathLabel}"
-              IsEnabled="{Binding ShouldDownloadAssets}"
-              Text="{Binding AssetsDirPath}"
-              Theme="{DynamicResource FilledTextBox}"
-              ToolTip.Tip="{Binding LocalizationManager.AssetsDirPathTooltip}"
-            >
-              <TextBox.InnerRightContent>
-                <Button
-                  Margin="8,8,8,6"
-                  Padding="8"
-                  VerticalAlignment="Center"
-                  Command="{Binding ShowAssetsDirPathPromptCommand}"
-                  Theme="{DynamicResource MaterialFlatButton}"
-                >
-                  <materialIcons:MaterialIcon Width="20" Height="20" Kind="FolderOpen" />
-                </Button>
-              </TextBox.InnerRightContent>
-            </TextBox>
           </StackPanel>
         </StackPanel>
       </ScrollViewer>