Pull channels lazily in the GUI

Closes #1005

DiscordChatExporter.Gui/ViewModels/Components/DashboardViewModel.cs

@@ -38,17 +38,13 @@ public class DashboardViewModel : PropertyChangedBase
 
     public string? Token { get; set; }
 
-    private IReadOnlyDictionary<Guild, IReadOnlyList<Channel>>? ChannelsByGuild { get; set; }
-
-    public IReadOnlyList<Guild>? AvailableGuilds => ChannelsByGuild?.Keys.ToArray();
+    public IReadOnlyList<Guild>? AvailableGuilds { get; private set; }
 
     public Guild? SelectedGuild { get; set; }
 
     public bool IsDirectMessageGuildSelected => SelectedGuild?.Id == Guild.DirectMessages.Id;
 
-    public IReadOnlyList<Channel>? AvailableChannels => SelectedGuild is not null
-        ? ChannelsByGuild?[SelectedGuild]
-        : null;
+    public IReadOnlyList<Channel>? AvailableChannels { get; private set; }
 
     public IReadOnlyList<Channel>? SelectedChannels { get; set; }
 
@@ -82,7 +78,7 @@ public class DashboardViewModel : PropertyChangedBase
             Token = _settingsService.LastToken;
     }
 
-    public async void ShowSettings()
+    public async Task ShowSettingsAsync()
     {
         var dialog = _viewModelFactory.CreateSettingsViewModel();
         await _dialogManager.ShowDialogAsync(dialog);
@@ -90,9 +86,9 @@ public class DashboardViewModel : PropertyChangedBase
 
     public void ShowHelp() => ProcessEx.StartShellExecute(App.DocumentationUrl);
 
-    public bool CanPopulate => !IsBusy && !string.IsNullOrWhiteSpace(Token);
+    public bool CanPullGuildsAsync => !IsBusy && !string.IsNullOrWhiteSpace(Token);
 
-    public async void Populate()
+    public async Task PullGuildsAsync()
     {
         IsBusy = true;
         var progress = _progressMuxer.CreateInput();
@@ -103,21 +99,71 @@ public class DashboardViewModel : PropertyChangedBase
             if (string.IsNullOrWhiteSpace(token))
                 return;
 
+            AvailableGuilds = null;
+            SelectedGuild = null;
+            AvailableChannels = null;
+            SelectedChannels = null;
+
+            _discord = new DiscordClient(token);
             _settingsService.LastToken = token;
 
-            var discord = new DiscordClient(token);
+            var guilds = await _discord.GetUserGuildsAsync();
+
+            AvailableGuilds = guilds;
+            SelectedGuild = guilds.FirstOrDefault();
 
-            var channelsByGuild = new Dictionary<Guild, IReadOnlyList<Channel>>();
-            await foreach (var guild in discord.GetUserGuildsAsync())
+            // Pull channels for the selected guild
+            await PullChannelsAsync();
+        }
+        catch (DiscordChatExporterException ex) when (!ex.IsFatal)
+        {
+            _eventAggregator.Publish(
+                new NotificationMessage(ex.Message.TrimEnd('.'))
+            );
+        }
+        catch (Exception ex)
+        {
+            var dialog = _viewModelFactory.CreateMessageBoxViewModel(
+                "Error pulling guilds",
+                ex.ToString()
+            );
+
+            await _dialogManager.ShowDialogAsync(dialog);
+        }
+        finally
+        {
+            progress.ReportCompletion();
+            IsBusy = false;
+        }
+    }
+
+    public bool CanPullChannelsAsync => !IsBusy && _discord is not null && SelectedGuild is not null;
+
+    public async Task PullChannelsAsync()
+    {
+        IsBusy = true;
+        var progress = _progressMuxer.CreateInput();
+
+        try
+        {
+            if (_discord is null || SelectedGuild is null)
+                return;
+
+            AvailableChannels = null;
+            SelectedChannels = null;
+
+            var channels = new List<Channel>();
+
+            await foreach (var channel in _discord.GetGuildChannelsAsync(SelectedGuild.Id))
             {
-                channelsByGuild[guild] = (await discord.GetGuildChannelsAsync(guild.Id))
-                    .Where(c => c.Kind != ChannelKind.GuildCategory)
-                    .ToArray();
+                if (channel.Kind == ChannelKind.GuildCategory)
+                    continue;
+
+                channels.Add(channel);
             }
 
-            _discord = discord;
-            ChannelsByGuild = channelsByGuild;
-            SelectedGuild = channelsByGuild.Keys.FirstOrDefault();
+            AvailableChannels = channels;
+            SelectedChannels = null;
         }
         catch (DiscordChatExporterException ex) when (!ex.IsFatal)
         {
@@ -128,7 +174,7 @@ public class DashboardViewModel : PropertyChangedBase
         catch (Exception ex)
         {
             var dialog = _viewModelFactory.CreateMessageBoxViewModel(
-                "Error pulling guilds and channels",
+                "Error pulling channels",
                 ex.ToString()
             );
 
@@ -141,13 +187,13 @@ public class DashboardViewModel : PropertyChangedBase
         }
     }
 
-    public bool CanExport =>
+    public bool CanExportAsync =>
         !IsBusy &&
         _discord is not null &&
         SelectedGuild is not null &&
         SelectedChannels?.Any() is true;
 
-    public async void Export()
+    public async Task ExportAsync()
     {
         IsBusy = true;
 

DiscordChatExporter.Gui/Views/Components/DashboardView.xaml

@@ -99,12 +99,12 @@
                         </controls:RevealablePasswordBox.Style>
                     </controls:RevealablePasswordBox>
 
-                    <!--  Pull data button  -->
+                    <!--  Pull guilds button  -->
                     <Button
                         Grid.Column="2"
                         Margin="0,6,6,6"
                         Padding="4"
-                        Command="{s:Action Populate}"
+                        Command="{s:Action PullGuildsAsync}"
                         IsDefault="True"
                         Style="{DynamicResource MaterialDesignFlatButton}"
                         ToolTip="Pull available guilds and channels (Enter)">
@@ -121,7 +121,7 @@
                 Grid.Column="1"
                 Margin="6"
                 Padding="4"
-                Command="{s:Action ShowSettings}"
+                Command="{s:Action ShowSettingsAsync}"
                 Foreground="{DynamicResource MaterialDesignDarkForeground}"
                 Style="{DynamicResource MaterialDesignFlatButton}"
                 ToolTip="Settings">
@@ -273,6 +273,7 @@
                                     Margin="-8"
                                     Background="Transparent"
                                     Cursor="Hand"
+                                    MouseLeftButtonUp="{s:Action PullChannelsAsync}"
                                     ToolTip="{Binding Name}">
                                     <!--  Guild icon placeholder  -->
                                     <Ellipse
@@ -348,7 +349,7 @@
                             <DataTemplate DataType="{x:Type data:Channel}">
                                 <Grid Margin="-8" Background="Transparent">
                                     <Grid.InputBindings>
-                                        <MouseBinding Command="{s:Action Export}" MouseAction="LeftDoubleClick" />
+                                        <MouseBinding Command="{s:Action ExportAsync}" MouseAction="LeftDoubleClick" />
                                     </Grid.InputBindings>
                                     <Grid.ColumnDefinitions>
                                         <ColumnDefinition Width="Auto" />
@@ -410,9 +411,9 @@
                 Margin="32,24"
                 HorizontalAlignment="Right"
                 VerticalAlignment="Bottom"
-                Command="{s:Action Export}"
+                Command="{s:Action ExportAsync}"
                 Style="{DynamicResource MaterialDesignFloatingActionAccentButton}"
-                Visibility="{Binding CanExport, Converter={x:Static s:BoolToVisibilityConverter.Instance}}">
+                Visibility="{Binding CanExportAsync, Converter={x:Static s:BoolToVisibilityConverter.Instance}}">
                 <materialDesign:PackIcon
                     Width="32"
                     Height="32"