Add a notification modal when some users could not be selected from a list

OF DL.Cli/Program.cs

@@ -294,8 +294,9 @@ public class Program(IServiceProvider serviceProvider)
             }
             else if (config.NonInteractiveMode && !string.IsNullOrEmpty(config.NonInteractiveModeListName))
             {
-                Dictionary<string, long> selectedUsers =
+                ListUserSelectionResult listSelectionResult =
                     await orchestrationService.GetUsersForListAsync(config.NonInteractiveModeListName, users, lists);
+                Dictionary<string, long> selectedUsers = listSelectionResult.SelectedUsers;
                 hasSelectedUsersKVP = new KeyValuePair<bool, Dictionary<string, long>>(true, selectedUsers);
             }
             else

OF DL.Core/Models/Downloads/CreatorDownloadResult.cs

@@ -27,3 +27,10 @@ public class UserListResult
 
     public string? IgnoredListError { get; set; }
 }
+
+public class ListUserSelectionResult
+{
+    public Dictionary<string, long> SelectedUsers { get; set; } = new();
+
+    public List<string> UnavailableUsernames { get; set; } = [];
+}

OF DL.Core/Services/DownloadOrchestrationService.cs

@@ -110,13 +110,26 @@ public class DownloadOrchestrationService(
     /// <param name="allUsers">All available users.</param>
     /// <param name="lists">Known lists keyed by name.</param>
     /// <returns>The users that belong to the list.</returns>
-    public async Task<Dictionary<string, long>> GetUsersForListAsync(
+    public async Task<ListUserSelectionResult> GetUsersForListAsync(
         string listName, Dictionary<string, long> allUsers, Dictionary<string, long> lists)
     {
+        ListUserSelectionResult result = new();
         long listId = lists[listName];
         List<string> listUsernames = await apiService.GetListUsers($"/lists/{listId}/users") ?? [];
-        return allUsers.Where(x => listUsernames.Contains(x.Key))
+        HashSet<string> listUsernamesSet = listUsernames.ToHashSet(StringComparer.OrdinalIgnoreCase);
+        HashSet<string> allUsernamesSet = allUsers.Keys.ToHashSet(StringComparer.OrdinalIgnoreCase);
+
+        result.SelectedUsers = allUsers
+            .Where(x => listUsernamesSet.Contains(x.Key))
             .ToDictionary(x => x.Key, x => x.Value);
+
+        result.UnavailableUsernames = listUsernames
+            .Where(username => !allUsernamesSet.Contains(username))
+            .Distinct(StringComparer.OrdinalIgnoreCase)
+            .OrderBy(username => username, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+
+        return result;
     }
 
     /// <summary>

OF DL.Core/Services/IDownloadOrchestrationService.cs

@@ -17,7 +17,7 @@ public interface IDownloadOrchestrationService
     /// <summary>
     ///     Get users for a specific list by name.
     /// </summary>
-    Task<Dictionary<string, long>> GetUsersForListAsync(
+    Task<ListUserSelectionResult> GetUsersForListAsync(
         string listName, Dictionary<string, long> allUsers, Dictionary<string, long> lists);
 
     /// <summary>

OF DL.Gui/ViewModels/MainWindowViewModel.cs

@@ -371,10 +371,23 @@ public partial class MainWindowViewModel(
     [NotifyCanExecuteChangedFor(nameof(SubmitSinglePostOrMessageCommand))]
     [NotifyCanExecuteChangedFor(nameof(DownloadSelectedCommand))]
     [NotifyCanExecuteChangedFor(nameof(DownloadPurchasedTabCommand))]
+    [NotifyCanExecuteChangedFor(nameof(SelectUsersFromListCommand))]
     private bool _isDownloadSelectionWarningModalOpen;
 
     [ObservableProperty] private string _downloadSelectionWarningMessage = string.Empty;
 
+    [ObservableProperty]
+    [NotifyCanExecuteChangedFor(nameof(OpenSinglePostOrMessageModalCommand))]
+    [NotifyCanExecuteChangedFor(nameof(SubmitSinglePostOrMessageCommand))]
+    [NotifyCanExecuteChangedFor(nameof(DownloadSelectedCommand))]
+    [NotifyCanExecuteChangedFor(nameof(DownloadPurchasedTabCommand))]
+    [NotifyCanExecuteChangedFor(nameof(SelectUsersFromListCommand))]
+    private bool _isListSelectionWarningModalOpen;
+
+    [ObservableProperty] private string _listSelectionWarningMessage = string.Empty;
+
+    public ObservableCollection<string> ListSelectionUnavailableUsers { get; } = [];
+
     [ObservableProperty] [NotifyCanExecuteChangedFor(nameof(SubmitSinglePostOrMessageCommand))]
     private string _singlePostOrMessageUrl = string.Empty;
 
@@ -827,20 +840,24 @@ public partial class MainWindowViewModel(
                 user.IsSelected = false;
             }
 
-            Dictionary<string, long> listUsers = await downloadOrchestrationService.GetUsersForListAsync(
+            ListUserSelectionResult listSelectionResult = await downloadOrchestrationService.GetUsersForListAsync(
                 SelectedListName,
                 _allUsers,
                 _allLists);
-            HashSet<string> selectedUsernames = listUsers.Keys.ToHashSet(StringComparer.Ordinal);
+            HashSet<string> selectedUsernames = listSelectionResult.SelectedUsers.Keys
+                .ToHashSet(StringComparer.OrdinalIgnoreCase);
 
             foreach (SelectableUserViewModel user in AvailableUsers)
             {
                 user.IsSelected = selectedUsernames.Contains(user.Username);
             }
 
+            ShowListSelectionWarningIfNeeded(listSelectionResult.UnavailableUsernames);
+
             OnPropertyChanged(nameof(SelectedUsersSummary));
             OnPropertyChanged(nameof(AllUsersSelected));
             DownloadSelectedCommand.NotifyCanExecuteChanged();
+            SelectUsersFromListCommand.NotifyCanExecuteChanged();
         }
         finally
         {
@@ -935,6 +952,13 @@ public partial class MainWindowViewModel(
         EditConfig();
     }
 
+    [RelayCommand]
+    private void CloseListSelectionWarning()
+    {
+        IsListSelectionWarningModalOpen = false;
+        ListSelectionUnavailableUsers.Clear();
+    }
+
     [RelayCommand(CanExecute = nameof(CanStopWork))]
     private void StopWork()
     {
@@ -1075,6 +1099,7 @@ public partial class MainWindowViewModel(
     private bool CanApplySelectedList() =>
         CurrentScreen == AppScreen.UserSelection &&
         !string.IsNullOrWhiteSpace(SelectedListName) &&
+        !IsListSelectionWarningModalOpen &&
         !IsDownloading;
 
     private bool CanDownloadSelected() =>
@@ -1083,6 +1108,7 @@ public partial class MainWindowViewModel(
         !IsDownloadSelectionWarningModalOpen &&
         !IsMissingCdmWarningModalOpen &&
         !IsShowScrapeSizeWarningModalOpen &&
+        !IsListSelectionWarningModalOpen &&
         !IsDownloading;
 
     private bool CanDownloadPurchasedTab() =>
@@ -1091,6 +1117,7 @@ public partial class MainWindowViewModel(
         !IsDownloadSelectionWarningModalOpen &&
         !IsMissingCdmWarningModalOpen &&
         !IsShowScrapeSizeWarningModalOpen &&
+        !IsListSelectionWarningModalOpen &&
         !IsDownloading;
 
     private bool CanOpenSinglePostOrMessageModal() =>
@@ -1099,6 +1126,7 @@ public partial class MainWindowViewModel(
         !IsDownloadSelectionWarningModalOpen &&
         !IsMissingCdmWarningModalOpen &&
         !IsShowScrapeSizeWarningModalOpen &&
+        !IsListSelectionWarningModalOpen &&
         !IsSinglePostOrMessageModalOpen;
 
     private bool CanSubmitSinglePostOrMessage() =>
@@ -1106,6 +1134,7 @@ public partial class MainWindowViewModel(
         !IsDownloadSelectionWarningModalOpen &&
         !IsMissingCdmWarningModalOpen &&
         !IsShowScrapeSizeWarningModalOpen &&
+        !IsListSelectionWarningModalOpen &&
         !IsDownloading &&
         !string.IsNullOrWhiteSpace(SinglePostOrMessageUrl);
 
@@ -1195,7 +1224,8 @@ public partial class MainWindowViewModel(
     partial void OnSelectedListNameChanged(string? value)
     {
         SelectUsersFromListCommand.NotifyCanExecuteChanged();
-        if (_isApplyingListSelection || IsDownloading || CurrentScreen != AppScreen.UserSelection ||
+        if (_isApplyingListSelection || IsDownloading || IsListSelectionWarningModalOpen ||
+            CurrentScreen != AppScreen.UserSelection ||
             string.IsNullOrWhiteSpace(value))
         {
             return;
@@ -1533,6 +1563,42 @@ public partial class MainWindowViewModel(
         return confirmed;
     }
 
+    private void ShowListSelectionWarningIfNeeded(IReadOnlyCollection<string> unavailableUsers)
+    {
+        if (unavailableUsers.Count == 0)
+        {
+            return;
+        }
+
+        ListSelectionUnavailableUsers.Clear();
+        foreach (string username in unavailableUsers.OrderBy(name => name, StringComparer.OrdinalIgnoreCase))
+        {
+            ListSelectionUnavailableUsers.Add(username);
+        }
+
+        List<string> recommendations = [];
+        if (!configService.CurrentConfig.IncludeExpiredSubscriptions)
+        {
+            recommendations.Add("Include Expired Subscriptions");
+        }
+
+        if (!configService.CurrentConfig.IncludeRestrictedSubscriptions)
+        {
+            recommendations.Add("Include Restricted Subscriptions");
+        }
+
+        string recommendationText = recommendations.Count > 0
+            ? $"Recommendation:\nEnable {string.Join(" and ", recommendations.Select(option => $"\"{option}\""))} in the subscriptions section of the configuration page. After doing so, select \"Refresh\" from the file menu."
+            : "These users may be unavailable or inaccessible with your current account.";
+
+        ListSelectionWarningMessage =
+            $"{unavailableUsers.Count} user(s) from \"{SelectedListName}\" could not be selected.\n\n" +
+            $"{recommendationText}\n\n" +
+            "Users that could not be selected:";
+
+        IsListSelectionWarningModalOpen = true;
+    }
+
     private static bool TryParseSinglePostOrMessageUrl(
         string url,
         out SingleDownloadRequest request,

OF DL.Gui/Views/MainWindow.axaml

@@ -1573,6 +1573,58 @@
             </Border>
         </Grid>
 
+        <Grid Grid.Row="0" Grid.RowSpan="3"
+              IsVisible="{Binding IsListSelectionWarningModalOpen}"
+              Background="{DynamicResource OverlayBackgroundBrush}"
+              ZIndex="1002"
+              PointerPressed="OnModalOverlayClicked">
+            <Border Background="{DynamicResource ModalBackgroundBrush}"
+                    BorderBrush="{DynamicResource ModalBorderBrush}"
+                    BorderThickness="1"
+                    CornerRadius="16"
+                    Padding="28"
+                    Width="720"
+                    MaxHeight="560"
+                    HorizontalAlignment="Center"
+                    VerticalAlignment="Center"
+                    BoxShadow="0 20 25 -5 #19000000, 0 10 10 -5 #0F000000"
+                    PointerPressed="OnModalContentClicked">
+                <StackPanel Spacing="16">
+                    <TextBlock FontSize="20"
+                               FontWeight="Bold"
+                               Foreground="{DynamicResource TextPrimaryBrush}"
+                               Text="Some Users Could Not Be Selected" />
+
+                    <TextBlock Foreground="{DynamicResource TextSecondaryBrush}"
+                               TextWrapping="Wrap"
+                               Text="{Binding ListSelectionWarningMessage}" />
+
+                    <Border BorderBrush="{DynamicResource SurfaceBorderBrush}"
+                            BorderThickness="1"
+                            CornerRadius="8"
+                            Background="{DynamicResource SurfaceBackgroundBrush}"
+                            Padding="8"
+                            MaxHeight="240">
+                        <ListBox ItemsSource="{Binding ListSelectionUnavailableUsers}"
+                                 BorderThickness="0"
+                                 Background="Transparent">
+                            <ListBox.ItemTemplate>
+                                <DataTemplate>
+                                    <TextBlock Text="{Binding}" />
+                                </DataTemplate>
+                            </ListBox.ItemTemplate>
+                        </ListBox>
+                    </Border>
+
+                    <StackPanel Orientation="Horizontal" Spacing="10" HorizontalAlignment="Right">
+                        <Button Content="Close"
+                                Classes="primary"
+                                Command="{Binding CloseListSelectionWarningCommand}" />
+                    </StackPanel>
+                </StackPanel>
+            </Border>
+        </Grid>
+
         <Grid Grid.Row="0" Grid.RowSpan="3"
               IsVisible="{Binding IsMissingCdmWarningModalOpen}"
               Background="{DynamicResource OverlayBackgroundBrush}"

OF DL.Gui/Views/MainWindow.axaml.cs

@@ -283,6 +283,7 @@ public partial class MainWindow : Window
         vm.CreatorConfigEditor.ModalViewModel.CancelCommand.Execute(null);
         vm.CancelSinglePostOrMessageCommand.Execute(null);
         vm.CancelDownloadSelectionWarningCommand.Execute(null);
+        vm.CloseListSelectionWarningCommand.Execute(null);
         vm.CancelMissingCdmWarningCommand.Execute(null);
         vm.CancelShowScrapeSizeWarningCommand.Execute(null);
     }

OF DL.Tests/Services/DownloadOrchestrationServiceTests.cs

@@ -79,10 +79,30 @@ public class DownloadOrchestrationServiceTests
         Dictionary<string, long> allUsers = new() { { "alice", 1 }, { "bob", 2 } };
         Dictionary<string, long> lists = new() { { "mylist", 5 } };
 
-        Dictionary<string, long> result = await service.GetUsersForListAsync("mylist", allUsers, lists);
+        ListUserSelectionResult result = await service.GetUsersForListAsync("mylist", allUsers, lists);
 
-        Assert.Single(result);
+        Assert.Single(result.SelectedUsers);
-        Assert.Equal(2, result["bob"]);
+        Assert.Equal(2, result.SelectedUsers["bob"]);
+        Assert.Empty(result.UnavailableUsernames);
+    }
+
+    [Fact]
+    public async Task GetUsersForListAsync_ReturnsUnavailableUsers()
+    {
+        FakeConfigService configService = new(CreateConfig());
+        ConfigurableApiService apiService = new()
+        {
+            ListUsersHandler = _ => Task.FromResult<List<string>?>(["bob", "carol"])
+        };
+        DownloadOrchestrationService service =
+            new(apiService, configService, new OrchestrationDownloadServiceStub(), new UserTrackingDbService());
+        Dictionary<string, long> allUsers = new() { { "alice", 1 }, { "bob", 2 } };
+        Dictionary<string, long> lists = new() { { "mylist", 5 } };
+
+        ListUserSelectionResult result = await service.GetUsersForListAsync("mylist", allUsers, lists);
+
+        Assert.Single(result.SelectedUsers);
+        Assert.Equal("carol", Assert.Single(result.UnavailableUsernames));
     }
 
     [Fact]