From efde9931c94d652896194cdbaf6f93d4148c1b0a Mon Sep 17 00:00:00 2001
From: Alexey Golub <tyrrrz@gmail.com>
Date: Fri, 7 Aug 2020 21:00:43 +0300
Subject: [PATCH] Refactor & optimize changes in last commit

---
 DiscordChatExporter.Gui/App.xaml              | 83 +++++++++++++++++++
 .../ViewModels/RootViewModel.cs               | 33 +-------
 DiscordChatExporter.Gui/Views/RootView.xaml   | 46 +++++-----
 3 files changed, 111 insertions(+), 51 deletions(-)

diff --git a/DiscordChatExporter.Gui/App.xaml b/DiscordChatExporter.Gui/App.xaml
index d22bbc8..e7a9e15 100644
--- a/DiscordChatExporter.Gui/App.xaml
+++ b/DiscordChatExporter.Gui/App.xaml
@@ -136,6 +136,89 @@
                     </Trigger>
                 </Style.Triggers>
             </Style>
+
+            <!--  Default MD Expander is incredibly slow (https://github.com/MaterialDesignInXAML/MaterialDesignInXamlToolkit/issues/1307)  -->
+            <Style BasedOn="{StaticResource MaterialDesignExpander}" TargetType="{x:Type Expander}">
+                <Setter Property="Template">
+                    <Setter.Value>
+                        <ControlTemplate TargetType="Expander">
+                            <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
+                                <DockPanel Background="{TemplateBinding Background}">
+                                    <ToggleButton
+                                        Name="HeaderSite"
+                                        BorderThickness="0"
+                                        Content="{TemplateBinding Header}"
+                                        ContentStringFormat="{TemplateBinding HeaderStringFormat}"
+                                        ContentTemplate="{TemplateBinding HeaderTemplate}"
+                                        ContentTemplateSelector="{TemplateBinding HeaderTemplateSelector}"
+                                        Cursor="Hand"
+                                        DockPanel.Dock="Top"
+                                        Focusable="False"
+                                        Foreground="{TemplateBinding Foreground}"
+                                        IsChecked="{Binding Path=IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
+                                        IsTabStop="False"
+                                        Opacity=".87"
+                                        Style="{StaticResource MaterialDesignExpanderDownHeaderStyle}"
+                                        TextElement.FontSize="15" />
+                                    <Border
+                                        Name="ContentSite"
+                                        DockPanel.Dock="Bottom"
+                                        Visibility="Collapsed">
+                                        <StackPanel
+                                            Name="ContentPanel"
+                                            Margin="{TemplateBinding Padding}"
+                                            HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                            VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
+                                            <ContentPresenter
+                                                Name="PART_Content"
+                                                ContentStringFormat="{TemplateBinding ContentStringFormat}"
+                                                ContentTemplate="{TemplateBinding ContentTemplate}"
+                                                ContentTemplateSelector="{TemplateBinding ContentTemplateSelector}"
+                                                Focusable="False" />
+                                        </StackPanel>
+                                    </Border>
+                                </DockPanel>
+                            </Border>
+                            <ControlTemplate.Triggers>
+                                <Trigger Property="IsExpanded" Value="true">
+                                    <Setter TargetName="ContentSite" Property="Visibility" Value="Visible" />
+                                </Trigger>
+                                <Trigger Property="ExpandDirection" Value="Right">
+                                    <Setter TargetName="HeaderSite" Property="DockPanel.Dock" Value="Left" />
+                                    <Setter TargetName="ContentSite" Property="DockPanel.Dock" Value="Right" />
+                                    <Setter TargetName="ContentPanel" Property="Orientation" Value="Horizontal" />
+                                    <Setter TargetName="ContentPanel" Property="Height" Value="Auto" />
+                                    <Setter TargetName="HeaderSite" Property="Style" Value="{StaticResource MaterialDesignExpanderRightHeaderStyle}" />
+                                </Trigger>
+
+                                <Trigger Property="ExpandDirection" Value="Left">
+                                    <Setter TargetName="HeaderSite" Property="DockPanel.Dock" Value="Right" />
+                                    <Setter TargetName="ContentSite" Property="DockPanel.Dock" Value="Left" />
+                                    <Setter TargetName="ContentPanel" Property="Orientation" Value="Horizontal" />
+                                    <Setter TargetName="ContentPanel" Property="Height" Value="Auto" />
+                                    <Setter TargetName="HeaderSite" Property="Style" Value="{StaticResource MaterialDesignExpanderLeftHeaderStyle}" />
+                                </Trigger>
+
+                                <Trigger Property="ExpandDirection" Value="Up">
+                                    <Setter TargetName="HeaderSite" Property="DockPanel.Dock" Value="Bottom" />
+                                    <Setter TargetName="ContentSite" Property="DockPanel.Dock" Value="Top" />
+                                    <Setter TargetName="ContentPanel" Property="Orientation" Value="Vertical" />
+                                    <Setter TargetName="ContentPanel" Property="Width" Value="Auto" />
+                                    <Setter TargetName="HeaderSite" Property="Style" Value="{StaticResource MaterialDesignExpanderUpHeaderStyle}" />
+                                </Trigger>
+
+                                <Trigger Property="ExpandDirection" Value="Down">
+                                    <Setter TargetName="HeaderSite" Property="DockPanel.Dock" Value="Top" />
+                                    <Setter TargetName="ContentSite" Property="DockPanel.Dock" Value="Bottom" />
+                                    <Setter TargetName="ContentPanel" Property="Orientation" Value="Vertical" />
+                                    <Setter TargetName="ContentPanel" Property="Width" Value="Auto" />
+                                    <Setter TargetName="HeaderSite" Property="Style" Value="{StaticResource MaterialDesignExpanderDownHeaderStyle}" />
+                                </Trigger>
+                            </ControlTemplate.Triggers>
+                        </ControlTemplate>
+                    </Setter.Value>
+                </Setter>
+            </Style>
         </s:ApplicationLoader>
     </Application.Resources>
 </Application>
\ No newline at end of file
diff --git a/DiscordChatExporter.Gui/ViewModels/RootViewModel.cs b/DiscordChatExporter.Gui/ViewModels/RootViewModel.cs
index e82fa6c..75a9fb5 100644
--- a/DiscordChatExporter.Gui/ViewModels/RootViewModel.cs
+++ b/DiscordChatExporter.Gui/ViewModels/RootViewModel.cs
@@ -1,10 +1,8 @@
 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;
@@ -44,34 +42,9 @@ namespace DiscordChatExporter.Gui.ViewModels
 
         public Guild? SelectedGuild { get; set; }
 
-
-        //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>? AvailableChannels => SelectedGuild != null
+            ? GuildChannelMap?[SelectedGuild]
+            : null;
 
         public IReadOnlyList<Channel>? SelectedChannels { get; set; }
 
diff --git a/DiscordChatExporter.Gui/Views/RootView.xaml b/DiscordChatExporter.Gui/Views/RootView.xaml
index e2a9c41..7072d2c 100644
--- a/DiscordChatExporter.Gui/Views/RootView.xaml
+++ b/DiscordChatExporter.Gui/Views/RootView.xaml
@@ -3,6 +3,7 @@
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:behaviors="clr-namespace:DiscordChatExporter.Gui.Behaviors"
+    xmlns:componentModel="clr-namespace:System.ComponentModel;assembly=WindowsBase"
     xmlns:converters="clr-namespace:DiscordChatExporter.Gui.Converters"
     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
     xmlns:i="http://schemas.microsoft.com/xaml/behaviors"
@@ -23,6 +24,17 @@
     <Window.TaskbarItemInfo>
         <TaskbarItemInfo ProgressState="Normal" ProgressValue="{Binding ProgressManager.Progress}" />
     </Window.TaskbarItemInfo>
+    <Window.Resources>
+        <CollectionViewSource x:Key="AvailableChannelsViewSource" Source="{Binding AvailableChannels, Mode=OneWay}">
+            <CollectionViewSource.GroupDescriptions>
+                <PropertyGroupDescription PropertyName="Category" />
+            </CollectionViewSource.GroupDescriptions>
+            <CollectionViewSource.SortDescriptions>
+                <componentModel:SortDescription Direction="Ascending" PropertyName="Category" />
+            </CollectionViewSource.SortDescriptions>
+        </CollectionViewSource>
+    </Window.Resources>
+
     <materialDesign:DialogHost SnackbarMessageQueue="{Binding Notifications}" Style="{DynamicResource MaterialDesignEmbeddedDialogHost}">
         <Grid>
             <Grid.RowDefinitions>
@@ -253,35 +265,29 @@
                     <Border Grid.Column="1">
                         <ListBox
                             HorizontalContentAlignment="Stretch"
-                            ItemsSource="{Binding AvailableChannels}"
+                            ItemsSource="{Binding Source={StaticResource AvailableChannelsViewSource}}"
                             SelectionMode="Extended"
-                            TextSearch.TextPath="Model.Name">
+                            TextSearch.TextPath="Model.Name"
+                            VirtualizingPanel.IsVirtualizingWhenGrouping="True">
                             <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>
+                                                    <ControlTemplate d:DataContext="{x:Type CollectionViewGroup}">
                                                         <Expander
+                                                            Margin="0"
                                                             Padding="0"
-                                                            BorderThickness="0"
+                                                            Background="Transparent"
+                                                            BorderBrush="{DynamicResource DividerBrush}"
+                                                            BorderThickness="0,1,0,0"
+                                                            Header="{Binding Name}"
                                                             IsExpanded="False">
                                                             <ItemsPresenter />
-                                                            <Expander.Header>
-                                                                <Run
-                                                                    FontWeight="Bold"
-                                                                    Foreground="{DynamicResource SecondaryTextBrush}"
-                                                                    Text="{Binding Name, Mode=OneWay}" />
-                                                            </Expander.Header>
                                                         </Expander>
                                                     </ControlTemplate>
                                                 </Setter.Value>
@@ -309,16 +315,14 @@
                                             VerticalAlignment="Center"
                                             Kind="Pound" />
 
-                                        <!--  Channel category / name  -->
+                                        <!--  Channel name  -->
                                         <TextBlock
                                             Grid.Column="1"
                                             Margin="3,8,8,8"
                                             VerticalAlignment="Center"
-                                            FontSize="14">
-                                            <Run Foreground="{DynamicResource SecondaryTextBrush}" Text="{Binding Category, Mode=OneWay}" />
-                                            <Run Text="/" />
-                                            <Run Foreground="{DynamicResource PrimaryTextBrush}" Text="{Binding Name, Mode=OneWay}" />
-                                        </TextBlock>
+                                            FontSize="14"
+                                            Foreground="{DynamicResource PrimaryTextBrush}"
+                                            Text="{Binding Name, Mode=OneWay}" />
 
                                         <!--  Is selected checkmark  -->
                                         <materialDesign:PackIcon