[GUI] Make categories collapsible in channel list (#354)

DiscordChatExporter.Gui/ViewModels/RootViewModel.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.ComponentModel;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Windows.Data;
 using DiscordChatExporter.Domain.Discord;
 using DiscordChatExporter.Domain.Discord.Models;
 using DiscordChatExporter.Domain.Exceptions;
@@ -42,9 +44,34 @@ namespace DiscordChatExporter.Gui.ViewModels
 
         public Guild? SelectedGuild { get; set; }
 
-        public IReadOnlyList<Channel>? AvailableChannels => SelectedGuild != null
-            ? GuildChannelMap?[SelectedGuild]
-            : null;
+
+        //Here for Legacy Purposes
+        public IReadOnlyList<Channel>? AvailableChannelsList
+        {
+            get
+            {
+                return SelectedGuild != null ? GuildChannelMap?[SelectedGuild] : null;
+            }
+        }
+
+        public ICollectionView? AvailableChannels 
+        {
+            get 
+            {
+                var result = SelectedGuild != null ? GuildChannelMap?[SelectedGuild] : null;
+                if (result != null)
+                {
+                    var GroupedResults = CollectionViewSource.GetDefaultView(result);
+                    GroupedResults.GroupDescriptions.Clear();
+                    GroupedResults.SortDescriptions.Clear();
+                    GroupedResults.GroupDescriptions.Add(new PropertyGroupDescription("Category"));
+                    GroupedResults.SortDescriptions.Add(new SortDescription("Category", ListSortDirection.Descending));
+                    return GroupedResults;
+                }
+                else return null;
+            }
+        }
+
 
         public IReadOnlyList<Channel>? SelectedChannels { get; set; }
 

DiscordChatExporter.Gui/Views/RootView.xaml

@@ -259,6 +259,37 @@
                             <i:Interaction.Behaviors>
                                 <behaviors:ChannelMultiSelectionListBoxBehavior SelectedItems="{Binding SelectedChannels}" />
                             </i:Interaction.Behaviors>
+                            <ListBox.GroupStyle>
+                                <GroupStyle>
+                                    <GroupStyle.Panel>
+                                        <ItemsPanelTemplate>
+                                            <VirtualizingStackPanel Orientation="Vertical" />
+                                        </ItemsPanelTemplate>
+                                    </GroupStyle.Panel>
+                                    <GroupStyle.ContainerStyle>
+                                        <Style TargetType="{x:Type GroupItem}">
+                                            <Setter Property="Template">
+                                                <Setter.Value>
+                                                    <ControlTemplate>
+                                                        <Expander
+                                                            Padding="0"
+                                                            BorderThickness="0"
+                                                            IsExpanded="False">
+                                                            <ItemsPresenter />
+                                                            <Expander.Header>
+                                                                <Run
+                                                                    FontWeight="Bold"
+                                                                    Foreground="{DynamicResource SecondaryTextBrush}"
+                                                                    Text="{Binding Name, Mode=OneWay}" />
+                                                            </Expander.Header>
+                                                        </Expander>
+                                                    </ControlTemplate>
+                                                </Setter.Value>
+                                            </Setter>
+                                        </Style>
+                                    </GroupStyle.ContainerStyle>
+                                </GroupStyle>
+                            </ListBox.GroupStyle>
                             <ListBox.ItemTemplate>
                                 <DataTemplate>
                                     <Grid Margin="-8" Background="Transparent">