Fix trailing spaces Rider generates in code

app/Desktop/Main/Controls/AttachmentFilterPanelModel.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using DHT.Desktop.Common;
+using DHT.Server;
 using DHT.Server.Data.Filters;
 using DHT.Server.Database;
 using DHT.Utils.Models;
@@ -47,7 +48,7 @@ sealed class AttachmentFilterPanelModel : BaseModel, IDisposable {
 
 	public IEnumerable<Unit> Units => AllUnits;
 
-	private readonly IDatabaseFile db;
+	private readonly State state;
 	private readonly string verb;
 
 	private readonly AsyncValueComputer<long> matchingAttachmentCountComputer;
@@ -55,10 +56,10 @@ sealed class AttachmentFilterPanelModel : BaseModel, IDisposable {
 	private long? totalAttachmentCount;
 
 	[Obsolete("Designer")]
-	public AttachmentFilterPanelModel() : this(DummyDatabaseFile.Instance) {}
+	public AttachmentFilterPanelModel() : this(State.Dummy) {}
 
-	public AttachmentFilterPanelModel(IDatabaseFile db, string verb = "Matches") {
-		this.db = db;
+	public AttachmentFilterPanelModel(State state, string verb = "Matches") {
+		this.state = state;
 		this.verb = verb;
 
 		this.matchingAttachmentCountComputer = AsyncValueComputer<long>.WithResultProcessor(SetAttachmentCounts).Build();
@@ -66,11 +67,11 @@ sealed class AttachmentFilterPanelModel : BaseModel, IDisposable {
 		UpdateFilterStatistics();
 
 		PropertyChanged += OnPropertyChanged;
-		db.Statistics.PropertyChanged += OnDbStatisticsChanged;
+		state.Db.Statistics.PropertyChanged += OnDbStatisticsChanged;
 	}
 
 	public void Dispose() {
-		db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
+		state.Db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
 	}
 
 	private void OnPropertyChanged(object? sender, PropertyChangedEventArgs e) {
@@ -81,7 +82,7 @@ sealed class AttachmentFilterPanelModel : BaseModel, IDisposable {
 
 	private void OnDbStatisticsChanged(object? sender, PropertyChangedEventArgs e) {
 		if (e.PropertyName == nameof(DatabaseStatistics.TotalAttachments)) {
-			totalAttachmentCount = db.Statistics.TotalAttachments;
+			totalAttachmentCount = state.Db.Statistics.TotalAttachments;
 			UpdateFilterStatistics();
 		}
 	}
@@ -96,7 +97,7 @@ sealed class AttachmentFilterPanelModel : BaseModel, IDisposable {
 		else {
 			matchingAttachmentCount = null;
 			UpdateFilterStatisticsText();
-			matchingAttachmentCountComputer.Compute(() => db.CountAttachments(filter));
+			matchingAttachmentCountComputer.Compute(() => state.Db.CountAttachments(filter));
 		}
 	}
 

app/Desktop/Main/Controls/MessageFilterPanelModel.cs

@@ -8,6 +8,7 @@ using Avalonia.Controls;
 using DHT.Desktop.Common;
 using DHT.Desktop.Dialogs.CheckBox;
 using DHT.Desktop.Dialogs.Message;
+using DHT.Server;
 using DHT.Server.Data;
 using DHT.Server.Data.Filters;
 using DHT.Server.Database;
@@ -62,7 +63,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	}
 
 	public HashSet<ulong> IncludedChannels {
-		get => includedChannels ?? db.GetAllChannels().Select(static channel => channel.Id).ToHashSet();
+		get => includedChannels ?? state.Db.GetAllChannels().Select(static channel => channel.Id).ToHashSet();
 		set => Change(ref includedChannels, value);
 	}
 
@@ -72,7 +73,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	}
 
 	public HashSet<ulong> IncludedUsers {
-		get => includedUsers ?? db.GetAllUsers().Select(static user => user.Id).ToHashSet();
+		get => includedUsers ?? state.Db.GetAllUsers().Select(static user => user.Id).ToHashSet();
 		set => Change(ref includedUsers, value);
 	}
 
@@ -91,7 +92,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	}
 
 	private readonly Window window;
-	private readonly IDatabaseFile db;
+	private readonly State state;
 	private readonly string verb;
 
 	private readonly AsyncValueComputer<long> exportedMessageCountComputer;
@@ -99,11 +100,11 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	private long? totalMessageCount;
 
 	[Obsolete("Designer")]
-	public MessageFilterPanelModel() : this(null!, DummyDatabaseFile.Instance) {}
+	public MessageFilterPanelModel() : this(null!, State.Dummy) {}
 
-	public MessageFilterPanelModel(Window window, IDatabaseFile db, string verb = "Matches") {
+	public MessageFilterPanelModel(Window window, State state, string verb = "Matches") {
 		this.window = window;
-		this.db = db;
+		this.state = state;
 		this.verb = verb;
 
 		this.exportedMessageCountComputer = AsyncValueComputer<long>.WithResultProcessor(SetExportedMessageCount).Build();
@@ -113,11 +114,11 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 		UpdateUserFilterLabel();
 
 		PropertyChanged += OnPropertyChanged;
-		db.Statistics.PropertyChanged += OnDbStatisticsChanged;
+		state.Db.Statistics.PropertyChanged += OnDbStatisticsChanged;
 	}
 
 	public void Dispose() {
-		db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
+		state.Db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
 	}
 
 	private void OnPropertyChanged(object? sender, PropertyChangedEventArgs e) {
@@ -136,7 +137,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 
 	private void OnDbStatisticsChanged(object? sender, PropertyChangedEventArgs e) {
 		if (e.PropertyName == nameof(DatabaseStatistics.TotalMessages)) {
-			totalMessageCount = db.Statistics.TotalMessages;
+			totalMessageCount = state.Db.Statistics.TotalMessages;
 			UpdateFilterStatistics();
 		}
 		else if (e.PropertyName == nameof(DatabaseStatistics.TotalChannels)) {
@@ -157,7 +158,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 		else {
 			exportedMessageCount = null;
 			UpdateFilterStatisticsText();
-			exportedMessageCountComputer.Compute(() => db.CountMessages(filter));
+			exportedMessageCountComputer.Compute(() => state.Db.CountMessages(filter));
 		}
 	}
 
@@ -175,11 +176,11 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	}
 
 	public async void OpenChannelFilterDialog() {
-		var servers = db.GetAllServers().ToDictionary(static server => server.Id);
+		var servers = state.Db.GetAllServers().ToDictionary(static server => server.Id);
 		var items = new List<CheckBoxItem<ulong>>();
 		var included = IncludedChannels;
 
-		foreach (var channel in db.GetAllChannels()) {
+		foreach (var channel in state.Db.GetAllChannels()) {
 			var channelId = channel.Id;
 			var channelName = channel.Name;
 
@@ -223,7 +224,7 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 		var items = new List<CheckBoxItem<ulong>>();
 		var included = IncludedUsers;
 
-		foreach (var user in db.GetAllUsers()) {
+		foreach (var user in state.Db.GetAllUsers()) {
 			var name = user.Name;
 			var discriminator = user.Discriminator;
 
@@ -240,13 +241,13 @@ sealed class MessageFilterPanelModel : BaseModel, IDisposable {
 	}
 
 	private void UpdateChannelFilterLabel() {
-		long total = db.Statistics.TotalChannels;
+		long total = state.Db.Statistics.TotalChannels;
 		long included = FilterByChannel ? IncludedChannels.Count : total;
 		ChannelFilterLabel = "Selected " + included.Format() + " / " + total.Pluralize("channel") + ".";
 	}
 
 	private void UpdateUserFilterLabel() {
-		long total = db.Statistics.TotalUsers;
+		long total = state.Db.Statistics.TotalUsers;
 		long included = FilterByUser ? IncludedUsers.Count : total;
 		UserFilterLabel = "Selected " + included.Format() + " / " + total.Pluralize("user") + ".";
 	}

app/Desktop/Main/Controls/ServerConfigurationPanelModel.cs

@@ -2,7 +2,7 @@ using System;
 using Avalonia.Controls;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Server;
-using DHT.Server.Database;
+using DHT.Server;
 using DHT.Server.Service;
 using DHT.Utils.Models;
 
@@ -46,7 +46,7 @@ sealed class ServerConfigurationPanelModel : BaseModel, IDisposable {
 	private readonly ServerManager serverManager;
 
 	[Obsolete("Designer")]
-	public ServerConfigurationPanelModel() : this(null!, new ServerManager(DummyDatabaseFile.Instance)) {}
+	public ServerConfigurationPanelModel() : this(null!, new ServerManager(State.Dummy)) {}
 
 	public ServerConfigurationPanelModel(Window window, ServerManager serverManager) {
 		this.window = window;

app/Desktop/Main/MainWindow.axaml

@@ -11,7 +11,7 @@
         Width="800" Height="500"
         MinWidth="520" MinHeight="300"
         WindowStartupLocation="CenterScreen"
-        Closed="OnClosed">
+        Closing="OnClosing">
 
     <Design.DataContext>
         <main:MainWindowModel />

app/Desktop/Main/MainWindow.axaml.cs

@@ -1,14 +1,18 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
+using System.Threading.Tasks;
 using Avalonia.Controls;
 using DHT.Desktop.Main.Pages;
+using DHT.Utils.Logging;
 using JetBrains.Annotations;
 
 namespace DHT.Desktop.Main;
 
 [SuppressMessage("ReSharper", "MemberCanBeInternal")]
 public sealed partial class MainWindow : Window {
+	private static readonly Log Log = Log.ForType<MainWindow>();
+	
 	[UsedImplicitly]
 	public MainWindow() {
 		InitializeComponent();
@@ -20,9 +24,24 @@ public sealed partial class MainWindow : Window {
 		DataContext = new MainWindowModel(this, args);
 	}
 
-	public async void OnClosed(object? sender, EventArgs e) {
+	public async void OnClosing(object? sender, WindowClosingEventArgs e) {
+		e.Cancel = true;
+		Closing -= OnClosing;
+
+		try {
+			await Dispose();
+		} finally {
+			Close();
+		}
+	}
+
+	private async Task Dispose() {
 		if (DataContext is MainWindowModel model) {
+			try {
 				await model.DisposeAsync();
+			} catch (Exception ex) {
+				Log.Error("Caught exception while disposing window: " + ex);
+			}
 		}
 
 		foreach (var temporaryFile in ViewerPageModel.TemporaryFiles) {

app/Desktop/Main/MainWindowModel.cs

@@ -7,7 +7,7 @@ using Avalonia.Controls;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Main.Screens;
 using DHT.Desktop.Server;
-using DHT.Server.Database;
+using DHT.Server;
 using DHT.Utils.Models;
 
 namespace DHT.Desktop.Main;
@@ -27,7 +27,7 @@ sealed class MainWindowModel : BaseModel, IAsyncDisposable {
 
 	private readonly Window window;
 
-	private IDatabaseFile? db;
+	private State? state;
 
 	[Obsolete("Designer")]
 	public MainWindowModel() : this(null!, Arguments.Empty) {}
@@ -75,21 +75,24 @@ sealed class MainWindowModel : BaseModel, IAsyncDisposable {
 		if (e.PropertyName == nameof(welcomeScreenModel.Db)) {
 			if (mainContentScreenModel != null) {
 				mainContentScreenModel.DatabaseClosed -= MainContentScreenModelOnDatabaseClosed;
-				await mainContentScreenModel.DisposeAsync();
+				mainContentScreenModel.Dispose();
 			}
 
-			db?.Dispose();
-			db = welcomeScreenModel.Db;
+			if (state != null) {
+				await state.DisposeAsync();
+			}
 			
-			if (db == null) {
+			state = welcomeScreenModel.Db == null ? null : new State(welcomeScreenModel.Db);
+
+			if (state == null) {
 				Title = DefaultTitle;
 				mainContentScreenModel = null;
 				mainContentScreen = null;
 				CurrentScreen = welcomeScreen;
 			}
 			else {
-				Title = Path.GetFileName(db.Path) + " - " + DefaultTitle;
-				mainContentScreenModel = new MainContentScreenModel(window, db);
+				Title = Path.GetFileName(state.Db.Path) + " - " + DefaultTitle;
+				mainContentScreenModel = new MainContentScreenModel(window, state);
 				await mainContentScreenModel.Initialize();
 				mainContentScreenModel.DatabaseClosed += MainContentScreenModelOnDatabaseClosed;
 				mainContentScreen = new MainContentScreen { DataContext = mainContentScreenModel };
@@ -108,13 +111,13 @@ sealed class MainWindowModel : BaseModel, IAsyncDisposable {
 	}
 
 	public async ValueTask DisposeAsync() {
+		mainContentScreenModel?.Dispose();
+
+		if (state != null) {
+			await state.DisposeAsync();
+			state = null;
+		}
+		
 		welcomeScreenModel.Dispose();
-		
-		if (mainContentScreenModel != null) {
-			await mainContentScreenModel.DisposeAsync();
-		}
-		
-		db?.Dispose();
-		db = null;
 	}
 }

app/Desktop/Main/Pages/AdvancedPageModel.cs

@@ -3,7 +3,7 @@ using Avalonia.Controls;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Main.Controls;
 using DHT.Desktop.Server;
-using DHT.Server.Database;
+using DHT.Server;
 using DHT.Utils.Models;
 
 namespace DHT.Desktop.Main.Pages;
@@ -12,14 +12,14 @@ sealed class AdvancedPageModel : BaseModel, IDisposable {
 	public ServerConfigurationPanelModel ServerConfigurationModel { get; }
 
 	private readonly Window window;
-	private readonly IDatabaseFile db;
+	private readonly State state;
 
 	[Obsolete("Designer")]
-	public AdvancedPageModel() : this(null!, DummyDatabaseFile.Instance, new ServerManager(DummyDatabaseFile.Instance)) {}
+	public AdvancedPageModel() : this(null!, State.Dummy, new ServerManager(State.Dummy)) {}
 
-	public AdvancedPageModel(Window window, IDatabaseFile db, ServerManager serverManager) {
+	public AdvancedPageModel(Window window, State state, ServerManager serverManager) {
 		this.window = window;
-		this.db = db;
+		this.state = state;
 
 		ServerConfigurationModel = new ServerConfigurationPanelModel(window, serverManager);
 	}
@@ -33,7 +33,7 @@ sealed class AdvancedPageModel : BaseModel, IDisposable {
 	}
 
 	public async void VacuumDatabase() {
-		db.Vacuum();
+		state.Db.Vacuum();
 		await Dialog.ShowOk(window, "Vacuum Database", "Done.");
 	}
 }

app/Desktop/Main/Pages/AttachmentsPageModel.cs

@@ -6,6 +6,7 @@ using System.Threading.Tasks;
 using Avalonia.Threading;
 using DHT.Desktop.Common;
 using DHT.Desktop.Main.Controls;
+using DHT.Server;
 using DHT.Server.Data;
 using DHT.Server.Data.Aggregations;
 using DHT.Server.Data.Filters;
@@ -16,7 +17,7 @@ using DHT.Utils.Tasks;
 
 namespace DHT.Desktop.Main.Pages;
 
-sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
+sealed class AttachmentsPageModel : BaseModel, IDisposable {
 	private static readonly DownloadItemFilter EnqueuedItemFilter = new () {
 		IncludeStatuses = new HashSet<DownloadStatus> {
 			DownloadStatus.Enqueued,
@@ -26,7 +27,7 @@ sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
 
 	private bool isThreadDownloadButtonEnabled = true;
 
-	public string ToggleDownloadButtonText => downloader == null ? "Start Downloading" : "Stop Downloading";
+	public string ToggleDownloadButtonText => IsDownloading ? "Stop Downloading" : "Start Downloading";
 
 	public bool IsToggleDownloadButtonEnabled {
 		get => isThreadDownloadButtonEnabled;
@@ -54,34 +55,34 @@ sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
 		}
 	}
 
-	public bool IsDownloading => downloader != null;
+	public bool IsDownloading => state.Downloader.IsDownloading;
 	public bool HasFailedDownloads => statisticsFailed.Items > 0;
 
-	private readonly IDatabaseFile db;
+	private readonly State state;
 	private readonly AsyncValueComputer<DownloadStatusStatistics>.Single downloadStatisticsComputer;
-	private BackgroundDownloader? downloader;
 
 	private int doneItemsCount;
 	private int initialFinishedCount;
 	private int? totalItemsToDownloadCount;
 
-	public AttachmentsPageModel() : this(DummyDatabaseFile.Instance) {}
+	public AttachmentsPageModel() : this(State.Dummy) {}
 
-	public AttachmentsPageModel(IDatabaseFile db) {
-		this.db = db;
-		this.FilterModel = new AttachmentFilterPanelModel(db);
+	public AttachmentsPageModel(State state) {
+		this.state = state;
 		
-		this.downloadStatisticsComputer = AsyncValueComputer<DownloadStatusStatistics>.WithResultProcessor(UpdateStatistics).WithOutdatedResults().BuildWithComputer(db.GetDownloadStatusStatistics);
-		this.downloadStatisticsComputer.Recompute();
+		FilterModel = new AttachmentFilterPanelModel(state);
 
-		db.Statistics.PropertyChanged += OnDbStatisticsChanged;
+		downloadStatisticsComputer = AsyncValueComputer<DownloadStatusStatistics>.WithResultProcessor(UpdateStatistics).WithOutdatedResults().BuildWithComputer(state.Db.GetDownloadStatusStatistics);
+		downloadStatisticsComputer.Recompute();
+
+		state.Db.Statistics.PropertyChanged += OnDbStatisticsChanged;
+		state.Downloader.OnItemFinished += DownloaderOnOnItemFinished;
 	}
 
-	public async ValueTask DisposeAsync() {
-		db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
-
+	public void Dispose() {
+		state.Db.Statistics.PropertyChanged -= OnDbStatisticsChanged;
+		state.Downloader.OnItemFinished -= DownloaderOnOnItemFinished;
 		FilterModel.Dispose();
-		await DisposeDownloader();
 	}
 
 	private void OnDbStatisticsChanged(object? sender, PropertyChangedEventArgs e) {
@@ -101,7 +102,7 @@ sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
 	private void EnqueueDownloadItems() {
 		var filter = FilterModel.CreateFilter();
 		filter.DownloadItemRule = AttachmentFilter.DownloadItemRules.OnlyNotPresent;
-		db.EnqueueDownloadItems(filter);
+		state.Db.EnqueueDownloadItems(filter);
 
 		downloadStatisticsComputer.Recompute();
 	}
@@ -146,25 +147,24 @@ sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
 	}
 
 	public async Task OnClickToggleDownload() {
-		if (downloader == null) {
-			initialFinishedCount = statisticsDownloaded.Items + statisticsFailed.Items;
-			EnqueueDownloadItems();
-			downloader = new BackgroundDownloader(db);
-			downloader.OnItemFinished += DownloaderOnOnItemFinished;
-		}
-		else {
+		if (IsDownloading) {
 			IsToggleDownloadButtonEnabled = false;
-			await DisposeDownloader();
+			await state.Downloader.Stop();
 			downloadStatisticsComputer.Recompute();
 			IsToggleDownloadButtonEnabled = true;
 
-			db.RemoveDownloadItems(EnqueuedItemFilter, FilterRemovalMode.RemoveMatching);
+			state.Db.RemoveDownloadItems(EnqueuedItemFilter, FilterRemovalMode.RemoveMatching);
 
 			doneItemsCount = 0;
 			initialFinishedCount = 0;
 			totalItemsToDownloadCount = null;
 			UpdateDownloadMessage();
 		}
+		else {
+			initialFinishedCount = statisticsDownloaded.Items + statisticsFailed.Items;
+			await state.Downloader.Start();
+			EnqueueDownloadItems();
+		}
 
 		OnPropertyChanged(nameof(ToggleDownloadButtonText));
 		OnPropertyChanged(nameof(IsDownloading));
@@ -179,22 +179,13 @@ sealed class AttachmentsPageModel : BaseModel, IAsyncDisposable {
 			}
 		};
 
-		db.RemoveDownloadItems(allExceptFailedFilter, FilterRemovalMode.KeepMatching);
+		state.Db.RemoveDownloadItems(allExceptFailedFilter, FilterRemovalMode.KeepMatching);
 
 		if (IsDownloading) {
 			EnqueueDownloadItems();
 		}
 	}
 
-	private async Task DisposeDownloader() {
-		if (downloader != null) {
-			downloader.OnItemFinished -= DownloaderOnOnItemFinished;
-			await downloader.Stop();
-		}
-
-		downloader = null;
-	}
-
 	public sealed class StatisticsRow {
 		public string State { get; }
 		public int Items { get; set; }

app/Desktop/Main/Pages/DatabasePageModel.cs

@@ -14,6 +14,7 @@ using DHT.Desktop.Dialogs.File;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Dialogs.Progress;
 using DHT.Desktop.Dialogs.TextBox;
+using DHT.Server;
 using DHT.Server.Data;
 using DHT.Server.Database;
 using DHT.Server.Database.Import;
@@ -33,11 +34,11 @@ sealed class DatabasePageModel : BaseModel {
 	private readonly Window window;
 
 	[Obsolete("Designer")]
-	public DatabasePageModel() : this(null!, DummyDatabaseFile.Instance) {}
+	public DatabasePageModel() : this(null!, State.Dummy) {}
 
-	public DatabasePageModel(Window window, IDatabaseFile db) {
+	public DatabasePageModel(Window window, State state) {
 		this.window = window;
-		this.Db = db;
+		this.Db = state.Db;
 	}
 
 	public async void OpenDatabaseFolder() {

app/Desktop/Main/Pages/DebugPageModel.cs

@@ -6,8 +6,8 @@ using System.Threading.Tasks;
 using Avalonia.Controls;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Dialogs.Progress;
+using DHT.Server;
 using DHT.Server.Data;
-using DHT.Server.Database;
 using DHT.Server.Service;
 using DHT.Utils.Models;
 
@@ -18,14 +18,14 @@ namespace DHT.Desktop.Main.Pages {
 		public string GenerateMessages { get; set; } = "0";
 
 		private readonly Window window;
-		private readonly IDatabaseFile db;
+		private readonly State state;
 
 		[Obsolete("Designer")]
-		public DebugPageModel() : this(null!, DummyDatabaseFile.Instance) {}
+		public DebugPageModel() : this(null!, State.Dummy) {}
 
-		public DebugPageModel(Window window, IDatabaseFile db) {
+		public DebugPageModel(Window window, State state) {
 			this.window = window;
-			this.db = db;
+			this.state = state;
 		}
 
 		public async void OnClickAddRandomDataToDatabase() {
@@ -83,11 +83,11 @@ namespace DHT.Desktop.Main.Pages {
 				Discriminator = rand.Next(0, 9999).ToString(),
 			}).ToArray();
 
-			db.AddServer(server);
-			db.AddUsers(users);
+			state.Db.AddServer(server);
+			state.Db.AddUsers(users);
 
 			foreach (var channel in channels) {
-				db.AddChannel(channel);
+				state.Db.AddChannel(channel);
 			}
 
 			var now = DateTimeOffset.Now;
@@ -117,7 +117,7 @@ namespace DHT.Desktop.Main.Pages {
 					};
 				}).ToArray();
 
-				db.AddMessages(messages);
+				state.Db.AddMessages(messages);
 
 				messageCount -= BatchSize;
 				await callback.Update("Adding messages in batches of " + BatchSize, ++batchIndex, batchCount);

app/Desktop/Main/Pages/ViewerPageModel.cs

@@ -13,8 +13,8 @@ using DHT.Desktop.Dialogs.File;
 using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Main.Controls;
 using DHT.Desktop.Server;
+using DHT.Server;
 using DHT.Server.Data.Filters;
-using DHT.Server.Database;
 using DHT.Server.Database.Export;
 using DHT.Server.Database.Export.Strategy;
 using DHT.Utils.Models;
@@ -38,16 +38,16 @@ sealed class ViewerPageModel : BaseModel, IDisposable {
 	public MessageFilterPanelModel FilterModel { get; }
 
 	private readonly Window window;
-	private readonly IDatabaseFile db;
+	private readonly State state;
 
 	[Obsolete("Designer")]
-	public ViewerPageModel() : this(null!, DummyDatabaseFile.Instance) {}
+	public ViewerPageModel() : this(null!, State.Dummy) {}
 
-	public ViewerPageModel(Window window, IDatabaseFile db) {
+	public ViewerPageModel(Window window, State state) {
 		this.window = window;
-		this.db = db;
+		this.state = state;
 
-		FilterModel = new MessageFilterPanelModel(window, db, "Will export");
+		FilterModel = new MessageFilterPanelModel(window, state, "Will export");
 		FilterModel.FilterPropertyChanged += OnFilterPropertyChanged;
 	}
 
@@ -72,7 +72,7 @@ sealed class ViewerPageModel : BaseModel, IDisposable {
 		string jsonTempFile = path + ".tmp";
 
 		await using (var jsonStream = new FileStream(jsonTempFile, FileMode.Create, FileAccess.ReadWrite, FileShare.Read)) {
-			await ViewerJsonExport.Generate(jsonStream, strategy, db, FilterModel.CreateFilter());
+			await ViewerJsonExport.Generate(jsonStream, strategy, state.Db, FilterModel.CreateFilter());
 
 			char[] jsonBuffer = new char[Math.Min(32768, jsonStream.Position)];
 			jsonStream.Position = 0;
@@ -98,7 +98,7 @@ sealed class ViewerPageModel : BaseModel, IDisposable {
 
 	public async void OnClickOpenViewer() {
 		string rootPath = Path.Combine(Path.GetTempPath(), "DiscordHistoryTracker");
-		string filenameBase = Path.GetFileNameWithoutExtension(db.Path) + "-" + DateTime.Now.ToString("yyyy-MM-dd");
+		string filenameBase = Path.GetFileNameWithoutExtension(state.Db.Path) + "-" + DateTime.Now.ToString("yyyy-MM-dd");
 		string fullPath = Path.Combine(rootPath, filenameBase + ".html");
 		int counter = 0;
 
@@ -123,8 +123,8 @@ sealed class ViewerPageModel : BaseModel, IDisposable {
 		string? path = await window.StorageProvider.SaveFile(new FilePickerSaveOptions {
 			Title = "Save Viewer",
 			FileTypeChoices = ViewerFileTypes,
-			SuggestedFileName = Path.GetFileNameWithoutExtension(db.Path) + ".html",
-			SuggestedStartLocation = await FileDialogs.GetSuggestedStartLocation(window, Path.GetDirectoryName(db.Path)),
+			SuggestedFileName = Path.GetFileNameWithoutExtension(state.Db.Path) + ".html",
+			SuggestedStartLocation = await FileDialogs.GetSuggestedStartLocation(window, Path.GetDirectoryName(state.Db.Path)),
 		});
 
 		if (path != null) {
@@ -136,13 +136,13 @@ sealed class ViewerPageModel : BaseModel, IDisposable {
 		var filter = FilterModel.CreateFilter();
 
 		if (DatabaseToolFilterModeKeep) {
-			if (DialogResult.YesNo.Yes == await Dialog.ShowYesNo(window, "Keep Matching Messages in This Database", db.CountMessages(filter).Pluralize("message") + " will be kept, and the rest will be removed from this database. This action cannot be undone. Proceed?")) {
-				db.RemoveMessages(filter, FilterRemovalMode.KeepMatching);
+			if (DialogResult.YesNo.Yes == await Dialog.ShowYesNo(window, "Keep Matching Messages in This Database", state.Db.CountMessages(filter).Pluralize("message") + " will be kept, and the rest will be removed from this database. This action cannot be undone. Proceed?")) {
+				state.Db.RemoveMessages(filter, FilterRemovalMode.KeepMatching);
 			}
 		}
 		else if (DatabaseToolFilterModeRemove) {
-			if (DialogResult.YesNo.Yes == await Dialog.ShowYesNo(window, "Remove Matching Messages in This Database", db.CountMessages(filter).Pluralize("message") + " will be removed from this database. This action cannot be undone. Proceed?")) {
-				db.RemoveMessages(filter, FilterRemovalMode.RemoveMatching);
+			if (DialogResult.YesNo.Yes == await Dialog.ShowYesNo(window, "Remove Matching Messages in This Database", state.Db.CountMessages(filter).Pluralize("message") + " will be removed from this database. This action cannot be undone. Proceed?")) {
+				state.Db.RemoveMessages(filter, FilterRemovalMode.RemoveMatching);
 			}
 		}
 	}

app/Desktop/Main/Screens/MainContentScreenModel.cs

@@ -5,13 +5,13 @@ using DHT.Desktop.Dialogs.Message;
 using DHT.Desktop.Main.Controls;
 using DHT.Desktop.Main.Pages;
 using DHT.Desktop.Server;
-using DHT.Server.Database;
+using DHT.Server;
 using DHT.Server.Service;
 using DHT.Utils.Logging;
 
 namespace DHT.Desktop.Main.Screens;
 
-sealed class MainContentScreenModel : IAsyncDisposable {
+sealed class MainContentScreenModel : IDisposable {
 	private static readonly Log Log = Log.ForType<MainContentScreenModel>();
 
 	public DatabasePage DatabasePage { get; }
@@ -53,37 +53,37 @@ sealed class MainContentScreenModel : IAsyncDisposable {
 	private readonly ServerManager serverManager;
 
 	[Obsolete("Designer")]
-	public MainContentScreenModel() : this(null!, DummyDatabaseFile.Instance) {}
+	public MainContentScreenModel() : this(null!, State.Dummy) {}
 
-	public MainContentScreenModel(Window window, IDatabaseFile db) {
+	public MainContentScreenModel(Window window, State state) {
 		this.window = window;
-		this.serverManager = new ServerManager(db);
+		this.serverManager = new ServerManager(state);
 
 		ServerLauncher.ServerManagementExceptionCaught += ServerLauncherOnServerManagementExceptionCaught;
 
-		DatabasePageModel = new DatabasePageModel(window, db);
+		DatabasePageModel = new DatabasePageModel(window, state);
 		DatabasePage = new DatabasePage { DataContext = DatabasePageModel };
 
 		TrackingPageModel = new TrackingPageModel(window);
 		TrackingPage = new TrackingPage { DataContext = TrackingPageModel };
 
-		AttachmentsPageModel = new AttachmentsPageModel(db);
+		AttachmentsPageModel = new AttachmentsPageModel(state);
 		AttachmentsPage = new AttachmentsPage { DataContext = AttachmentsPageModel };
 
-		ViewerPageModel = new ViewerPageModel(window, db);
+		ViewerPageModel = new ViewerPageModel(window, state);
 		ViewerPage = new ViewerPage { DataContext = ViewerPageModel };
 
-		AdvancedPageModel = new AdvancedPageModel(window, db, serverManager);
+		AdvancedPageModel = new AdvancedPageModel(window, state, serverManager);
 		AdvancedPage = new AdvancedPage { DataContext = AdvancedPageModel };
 
 		#if DEBUG
-		DebugPageModel = new DebugPageModel(window, db);
+		DebugPageModel = new DebugPageModel(window, state);
 		DebugPage = new DebugPage { DataContext = DebugPageModel };
 		#else
 		DebugPage = null;
 		#endif
 
-		StatusBarModel = new StatusBarModel(db.Statistics);
+		StatusBarModel = new StatusBarModel(state.Db.Statistics);
 
 		AdvancedPageModel.ServerConfigurationModel.ServerStatusChanged += OnServerStatusChanged;
 		DatabaseClosed += OnDatabaseClosed;
@@ -97,9 +97,9 @@ sealed class MainContentScreenModel : IAsyncDisposable {
 		serverManager.Launch();
 	}
 
-	public async ValueTask DisposeAsync() {
+	public void Dispose() {
 		ServerLauncher.ServerManagementExceptionCaught -= ServerLauncherOnServerManagementExceptionCaught;
-		await AttachmentsPageModel.DisposeAsync();
+		AttachmentsPageModel.Dispose();
 		ViewerPageModel.Dispose();
 		serverManager.Dispose();
 	}

app/Desktop/Server/ServerManager.cs

@@ -1,5 +1,5 @@
 using System;
-using DHT.Server.Database;
+using DHT.Server;
 using DHT.Server.Service;
 
 namespace DHT.Desktop.Server;
@@ -12,10 +12,10 @@ sealed class ServerManager : IDisposable {
 
 	public bool IsRunning => ServerLauncher.IsRunning;
 
-	private readonly IDatabaseFile db;
+	private readonly State state;
 
-	public ServerManager(IDatabaseFile db) {
-		if (db != DummyDatabaseFile.Instance) {
+	public ServerManager(State state) {
+		if (state != State.Dummy) {
 			if (instance != null) {
 				throw new InvalidOperationException("Only one instance of ServerManager can exist at the same time!");
 			}
@@ -23,11 +23,11 @@ sealed class ServerManager : IDisposable {
 			instance = this;
 		}
 
-		this.db = db;
+		this.state = state;
 	}
 
 	public void Launch() {
-		ServerLauncher.Relaunch(Port, Token, db);
+		ServerLauncher.Relaunch(Port, Token, state.Db);
 	}
 
 	public void Relaunch(ushort port, string token) {

app/Server/Download/Downloader.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using DHT.Server.Database;
+
+namespace DHT.Server.Download;
+
+public sealed class Downloader {
+	private DownloaderTask? current;
+	public bool IsDownloading => current != null;
+	
+	public event EventHandler<DownloadItem>? OnItemFinished;
+	
+	private readonly IDatabaseFile db;
+	private readonly SemaphoreSlim semaphore = new (1, 1);
+	
+	internal Downloader(IDatabaseFile db) {
+		this.db = db;
+	}
+
+	public async Task Start() {
+		await semaphore.WaitAsync();
+		try {
+			if (current == null) {
+				current = new DownloaderTask(db);
+				current.OnItemFinished += DelegateOnItemFinished;
+			}
+		} finally {
+			semaphore.Release();
+		}
+	}
+
+	public async Task Stop() {
+		await semaphore.WaitAsync();
+		try {
+			if (current != null) {
+				await current.Stop();
+				current.OnItemFinished -= DelegateOnItemFinished;
+				current = null;
+			}
+		} finally {
+			semaphore.Release();
+		}
+	}
+
+	private void DelegateOnItemFinished(object? sender, DownloadItem e) {
+		OnItemFinished?.Invoke(this, e);
+	}
+}

app/Server/Download/DownloaderTask.cs

@@ -11,14 +11,14 @@ using DHT.Utils.Tasks;
 
 namespace DHT.Server.Download;
 
-public sealed class BackgroundDownloader : BaseModel {
-	private static readonly Log Log = Log.ForType<BackgroundDownloader>();
+sealed class DownloaderTask : BaseModel {
+	private static readonly Log Log = Log.ForType<DownloaderTask>();
 
 	private const int DownloadTasks = 4;
 	private const int QueueSize = 25;
 	private const string UserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36";
 
-	public event EventHandler<DownloadItem>? OnItemFinished;
+	internal event EventHandler<DownloadItem>? OnItemFinished;
 
 	private readonly Channel<DownloadItem> downloadQueue = Channel.CreateBounded<DownloadItem>(new BoundedChannelOptions(QueueSize) {
 		SingleReader = false,
@@ -34,7 +34,7 @@ public sealed class BackgroundDownloader : BaseModel {
 	private readonly Task queueWriterTask;
 	private readonly Task[] downloadTasks;
 
-	public BackgroundDownloader(IDatabaseFile db) {
+	internal DownloaderTask(IDatabaseFile db) {
 		this.cancellationToken = cancellationTokenSource.Token;
 		this.db = db;
 		this.queueWriterTask = Task.Run(RunQueueWriterTask);
@@ -56,7 +56,7 @@ public sealed class BackgroundDownloader : BaseModel {
 	}
 
 	private async Task RunDownloadTask(int taskIndex) {
-		var log = Log.ForType<BackgroundDownloader>("Task " + taskIndex);
+		var log = Log.ForType<DownloaderTask>("Task " + taskIndex);
 
 		var client = new HttpClient();
 		client.DefaultRequestHeaders.UserAgent.ParseAdd(UserAgent);
@@ -87,7 +87,7 @@ public sealed class BackgroundDownloader : BaseModel {
 		}
 	}
 
-	public async Task Stop() {
+	internal async Task Stop() {
 		try {
 			await cancellationTokenSource.CancelAsync();
 		} catch (Exception) {

app/Server/State.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Threading.Tasks;
+using DHT.Server.Database;
+using DHT.Server.Download;
+
+namespace DHT.Server;
+
+public sealed class State : IAsyncDisposable {
+	public static State Dummy { get; } = new (DummyDatabaseFile.Instance);
+	
+	public IDatabaseFile Db { get; }
+	public Downloader Downloader { get; }
+
+	public State(IDatabaseFile db) {
+		Db = db;
+		Downloader = new Downloader(db);
+	}
+
+	public async ValueTask DisposeAsync() {
+		await Downloader.Stop();
+		Db.Dispose();
+	}
+}