CmdPal: Add filter by Terminal channel (#41582)

## Summary of the Pull Request

- Introduces a new filter on the Profiles page to filter by Terminal
channel.
- Adds a new option to remember the last select Terminal channel (or
automatically reset to All Channels).
- Adds new classes `AppSettings` and `AppSettingsManager` to hold
non-user settings.

Pictures? Pictures!

<img width="1485" height="931" alt="image"
src="https://github.com/user-attachments/assets/2cec7a8d-efe6-4692-a7ba-9608fb181624"
/>

<img width="1730" height="1014" alt="image"
src="https://github.com/user-attachments/assets/87984b82-e085-42a5-b71c-5ddc71ff52ec"
/>

<img width="1722" height="1063" alt="image"
src="https://github.com/user-attachments/assets/97baff23-3db0-404b-8a8d-622f841b344b"
/>

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

- [x] Closes: #41432 
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowsTerminal/Pages/ProfilesListPage.cs

@@ -2,40 +2,73 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
+using System;
 using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using ManagedCommon;
 using Microsoft.CmdPal.Ext.WindowsTerminal.Commands;
 using Microsoft.CmdPal.Ext.WindowsTerminal.Helpers;
 using Microsoft.CmdPal.Ext.WindowsTerminal.Properties;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
+using Windows.Foundation;
 
 namespace Microsoft.CmdPal.Ext.WindowsTerminal.Pages;
 
-internal sealed partial class ProfilesListPage : ListPage
+internal sealed partial class ProfilesListPage : ListPage, INotifyItemsChanged
 {
+    event TypedEventHandler<object, IItemsChangedEventArgs> INotifyItemsChanged.ItemsChanged
+    {
+        add
+        {
+            ItemsChanged += value;
+            EnsureInitialized();
+            SelectTerminalFilter();
+        }
+
+        remove
+        {
+            ItemsChanged -= value;
+        }
+    }
+
     private readonly TerminalQuery _terminalQuery = new();
     private readonly SettingsManager _terminalSettings;
+    private readonly AppSettingsManager _appSettingsManager;
 
     private bool showHiddenProfiles;
     private bool openNewTab;
     private bool openQuake;
 
-    public ProfilesListPage(SettingsManager terminalSettings)
+    private bool initialized;
+    private TerminalChannelFilters? terminalFilters;
+
+    public ProfilesListPage(SettingsManager terminalSettings, AppSettingsManager appSettingsManager)
     {
         Icon = Icons.TerminalIcon;
         Name = Resources.profiles_list_page_name;
         _terminalSettings = terminalSettings;
+        _appSettingsManager = appSettingsManager;
     }
 
-#pragma warning disable SA1108
-    public List<ListItem> Query()
+    private List<ListItem> Query()
     {
+        EnsureInitialized();
+
         showHiddenProfiles = _terminalSettings.ShowHiddenProfiles;
         openNewTab = _terminalSettings.OpenNewTab;
         openQuake = _terminalSettings.OpenQuake;
 
         var profiles = _terminalQuery.GetProfiles();
 
+        if (terminalFilters?.IsAllSelected == false)
+        {
+            profiles = profiles.Where(profile => profile.Terminal.AppUserModelId == terminalFilters.CurrentFilterId);
+        }
+
         var result = new List<ListItem>();
 
         foreach (var profile in profiles)
@@ -52,12 +85,66 @@ internal sealed partial class ProfilesListPage : ListPage
                 MoreCommands = [
                     new CommandContextItem(new LaunchProfileAsAdminCommand(profile.Terminal.AppUserModelId, profile.Name, openNewTab, openQuake)),
                 ],
-#pragma warning restore SA1108
             });
         }
 
         return result;
     }
 
-    public override IListItem[] GetItems() => Query().ToArray();
+    private void EnsureInitialized()
+    {
+        if (initialized)
+        {
+            return;
+        }
+
+        var terminals = _terminalQuery.GetTerminals();
+        terminalFilters = new TerminalChannelFilters(terminals);
+        terminalFilters.PropChanged += TerminalFiltersOnPropChanged;
+        SelectTerminalFilter();
+        Filters = terminalFilters;
+        initialized = true;
+    }
+
+    private void SelectTerminalFilter()
+    {
+        Trace.Assert(terminalFilters != null);
+
+        // Select the preferred channel if it exists; we always select the preferred channel,
+        // but user have an option to save the preferred channel when he changes the filter
+        if (_terminalSettings.SaveLastSelectedChannel)
+        {
+            if (!string.IsNullOrWhiteSpace(_appSettingsManager.Current.LastSelectedChannel) &&
+                terminalFilters.ContainsFilter(_appSettingsManager.Current.LastSelectedChannel))
+            {
+                terminalFilters.CurrentFilterId = _appSettingsManager.Current.LastSelectedChannel;
+            }
+        }
+        else
+        {
+            terminalFilters.CurrentFilterId = TerminalChannelFilters.AllTerminalsFilterId;
+        }
+    }
+
+    private void TerminalFiltersOnPropChanged(object sender, IPropChangedEventArgs args)
+    {
+        Trace.Assert(terminalFilters != null);
+
+        RaiseItemsChanged();
+        _appSettingsManager.Current.LastSelectedChannel = terminalFilters.CurrentFilterId;
+        _appSettingsManager.Save();
+    }
+
+    public override IListItem[] GetItems()
+    {
+        try
+        {
+            return [.. Query()];
+        }
+        catch (Exception ex)
+        {
+            Logger.LogError("Failed to list Windows Terminal profiles", ex);
+            throw;
+        }
+    }
 }

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WindowsTerminal/Pages/TerminalChannelFilters.cs

@@ -0,0 +1,56 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using Microsoft.CmdPal.Ext.WindowsTerminal.Properties;
+using Microsoft.CommandPalette.Extensions;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+
+namespace Microsoft.CmdPal.Ext.WindowsTerminal.Pages;
+
+internal sealed partial class TerminalChannelFilters : Filters
+{
+    internal const string AllTerminalsFilterId = "all";
+
+    private readonly List<TerminalPackage> _terminals;
+
+    public bool IsAllSelected => CurrentFilterId == AllTerminalsFilterId;
+
+    public TerminalChannelFilters(IEnumerable<TerminalPackage> terminals, string preselectedFilterId = AllTerminalsFilterId)
+    {
+        CurrentFilterId = preselectedFilterId;
+        _terminals = [.. terminals];
+    }
+
+    public override IFilterItem[] GetFilters()
+    {
+        var items = new List<IFilterItem>
+        {
+            new Filter()
+            {
+                Id = AllTerminalsFilterId,
+                Name = Resources.all_channels,
+                Icon = Icons.FilterIcon,
+            },
+            new Separator(),
+        };
+
+        foreach (var terminalPackage in _terminals)
+        {
+            items.Add(new Filter()
+            {
+                Id = terminalPackage.AppUserModelId,
+                Name = terminalPackage.DisplayName,
+                Icon = new IconInfo(terminalPackage.LogoPath),
+            });
+        }
+
+        return [.. items];
+    }
+
+    public bool ContainsFilter(string id)
+    {
+        return _terminals.FindIndex(terminal => terminal.AppUserModelId == id) > -1;
+    }
+}