Implement force delete for languages and categories.

This commit introduces the ability to forcibly delete a language or a category, including all of its associated child items (categories and/or snippets).

Author: mx7b7

src/CodeSnip/MainViewModel.cs

@@ -554,10 +554,34 @@ private void OpenLanguageCategory()
                 LoadSnippets();
                 if (tmpSnippet != null)
                 {
-                    ExpandAndSelectSnippet(
-                        tmpSnippet.Category?.Language?.Id ?? 0,
-                        tmpSnippet.CategoryId,
-                        tmpSnippet.Id);
+                    // This block handles the edge case where the currently active snippet
+                    // might have been deleted (e.g., via "Force Delete Category") inside the Language/Category editor.
+
+                    // Flatten the entire collection of snippets from the newly loaded data and check if our snippet's ID is still present.
+                    bool snippetStillExists = Languages
+                        .SelectMany(l => l.Categories)
+                        .SelectMany(c => c.Snippets)
+                        .Any(s => s.Id == tmpSnippet.Id);
+
+                    if (snippetStillExists)
+                    {
+                        // The snippet was not deleted. Restore the selection in the TreeView
+                        ExpandAndSelectSnippet(
+                            tmpSnippet.Category?.Language?.Id ?? 0,
+                            tmpSnippet.CategoryId,
+                            tmpSnippet.Id);
+                    }
+                    else
+                    {
+                        // The snippet was deleted. To prevent data inconsistency and potential crashes
+                        // from actions on a "phantom" snippet, we must reset the editor state completely.
+                        SelectedSnippet = null;
+                        EditingSnippet = null;
+                        EditorText = string.Empty;
+                        IsEditorModified = false;
+                        UpdateWindowTitle();
+                        StatusMessage = "The previously selected snippet was deleted.";
+                    }
                 }
 
             });

src/CodeSnip/Resources/Icons.xaml

@@ -120,6 +120,8 @@
 
     <PathGeometry x:Key="ImageSave">M22.71,6.29a1,1,0,0,0-1.42,0L20,7.59V2a1,1,0,0,0-2,0V7.59l-1.29-1.3a1,1,0,0,0-1.42,1.42l3,3a1,1,0,0,0,.33.21.94.94,0,0,0,.76,0,1,1,0,0,0,.33-.21l3-3A1,1,0,0,0,22.71,6.29ZM19,13a1,1,0,0,0-1,1v.38L16.52,12.9a2.79,2.79,0,0,0-3.93,0l-.7.7L9.41,11.12a2.85,2.85,0,0,0-3.93,0L4,12.6V7A1,1,0,0,1,5,6h8a1,1,0,0,0,0-2H5A3,3,0,0,0,2,7V19a3,3,0,0,0,3,3H17a3,3,0,0,0,3-3V14A1,1,0,0,0,19,13ZM5,20a1,1,0,0,1-1-1V15.43l2.9-2.9a.79.79,0,0,1,1.09,0l3.17,3.17,0,0L15.46,20Zm13-1a.89.89,0,0,1-.18.53L13.31,15l.7-.7a.77.77,0,0,1,1.1,0L18,17.21Z</PathGeometry>
 
+    <PathGeometry x:Key="DeleteAlert">M17 4V6H3V4H6.5L7.5 3H12.5L13.5 4H17M4 19V7H16V19C16 20.1 15.1 21 14 21H6C4.9 21 4 20.1 4 19M19 15H21V17H19V15M19 7H21V13H19V7Z</PathGeometry>
+
 
 
     <Geometry x:Key="ContentCopy">M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z</Geometry>

src/CodeSnip/Services/DatabaseService.cs

@@ -358,6 +358,64 @@ public void DeleteCategory(int id)
             conn.Execute("DELETE FROM Categories WHERE ID = @Id", new { Id = id });
         }
 
+        public int CountSnippetsInCategory(int categoryId)
+        {
+            using var conn = CreateConnection();
+            return conn.ExecuteScalar<int>("SELECT COUNT(*) FROM Snippets WHERE CategoryId = @CategoryId", new { CategoryId = categoryId });
+        }
+
+        public int CountSnippetsInLanguage(int languageId)
+        {
+            using var conn = CreateConnection();
+            return conn.ExecuteScalar<int>(@"
+                SELECT COUNT(*) 
+                FROM Snippets s
+                JOIN Categories c ON s.CategoryId = c.ID
+                WHERE c.LanguageId = @LanguageId", new { LanguageId = languageId });
+        }
+
+        public void ForceDeleteCategory(int categoryId)
+        {
+            using var conn = CreateConnection();
+            conn.Open();
+            using var transaction = conn.BeginTransaction();
+            try
+            {
+                // Delete all snippete in category
+                conn.Execute("DELETE FROM Snippets WHERE CategoryId = @CategoryId", new { CategoryId = categoryId }, transaction);
+                // Delete the category itself
+                conn.Execute("DELETE FROM Categories WHERE ID = @Id", new { Id = categoryId }, transaction);
+                transaction.Commit();
+            }
+            catch
+            {
+                transaction.Rollback();
+                throw;
+            }
+        }
+
+        public void ForceDeleteLanguage(int languageId)
+        {
+            using var conn = CreateConnection();
+            conn.Open();
+            using var transaction = conn.BeginTransaction();
+            try
+            {
+                // Delete all snippets in categories of this language
+                conn.Execute("DELETE FROM Snippets WHERE CategoryId IN (SELECT ID FROM Categories WHERE LanguageId = @LanguageId)", new { LanguageId = languageId }, transaction);
+                //  Delete all categories of this language
+                conn.Execute("DELETE FROM Categories WHERE LanguageId = @LanguageId", new { LanguageId = languageId }, transaction);
+                // Delete the language itself
+                conn.Execute("DELETE FROM Languages WHERE ID = @Id", new { Id = languageId }, transaction);
+                transaction.Commit();
+            }
+            catch
+            {
+                transaction.Rollback();
+                throw;
+            }
+        }
+
         public async Task<bool> RunIntegrityCheckAsync()
         {
             try

src/CodeSnip/Views/LanguageCategoryView/LanguageCategoryView.xaml

@@ -6,8 +6,8 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
              xmlns:local="clr-namespace:CodeSnip.Views.LanguageCategoryView"
              xmlns:helpers="clr-namespace:CodeSnip.Helpers"
-             mc:Ignorable="d"
-              >
+             d:DataContext="{d:DesignInstance Type={x:Type local:LanguageCategoryViewModel}}"
+             mc:Ignorable="d" >
     <UserControl.Resources>
         <helpers:BoolToAddCancelConverter x:Key="BoolToAddCancelConverter"/>
     </UserControl.Resources>
@@ -37,13 +37,22 @@
                     <ColumnDefinition Width="*"/>
                     <ColumnDefinition Width="*" />
                     <ColumnDefinition Width="*" />
+                    <ColumnDefinition Width="Auto" />
                 </Grid.ColumnDefinitions>
                 <Button Content="{Binding IsAddingLanguage, Converter={StaticResource BoolToAddCancelConverter}}"
                         Command="{Binding ToggleAddLanguageCommand}" Grid.Column="0" Margin="0,0,10,0"/>
 
                 <Button Content="Save" Command="{Binding SaveLanguageCommand}" IsEnabled="{Binding SaveLanguageCommand.CanExecute}" Grid.Column="1" Margin="0,0,10,0" />
-                <Button Content="Delete Language" Grid.Column="2"
+                <Button Content="Delete Language" Grid.Column="2" Margin="0,0,10,0"
                     Command="{Binding DeleteLanguageCommand}" />
+                <Button Grid.Column="3" Command="{Binding ForceDeleteLanguageCommand}" 
+                        ToolTip="Deletes the language and ALL its categories and snippets"
+                        ToolTipService.InitialShowDelay="300"
+                        ToolTipService.ShowDuration="3000"
+                        ToolTipService.BetweenShowDelay="100" >
+                    <Path Data="{StaticResource DeleteAlert}" Fill="Red"
+                         Width="16" Height="16" Stretch="Uniform" />
+                </Button>
             </Grid>
 
             <Separator Margin="0,40,0,40"/>
@@ -72,13 +81,22 @@
                     <ColumnDefinition Width="*" />
                     <ColumnDefinition Width="*" />
                     <ColumnDefinition Width="*" />
+                    <ColumnDefinition Width="Auto" />
                 </Grid.ColumnDefinitions>
                 <Button Content="{Binding IsAddingCategory, Converter={StaticResource BoolToAddCancelConverter}}"
                         Command="{Binding ToggleAddCategoryCommand}" Grid.Column="0" Margin="0,0,10,0" />
 
                 <Button Content="Save" Command="{Binding SaveCategoryCommand}" IsEnabled="{Binding SaveCategoryCommand.CanExecute}" Grid.Column="1" Margin="0,0,10,0"/>
-                <Button Content="Delete Category" Grid.Column="2"
+                <Button Content="Delete Category" Grid.Column="2" Margin="0,0,10,0"
                     Command="{Binding DeleteCategoryCommand}" />
+                <Button Grid.Column="3" Command="{Binding ForceDeleteCategoryCommand}" 
+                        ToolTip="Deletes the category and ALL its snippets"
+                        ToolTipService.InitialShowDelay="300"
+                        ToolTipService.ShowDuration="3000"
+                        ToolTipService.BetweenShowDelay="100" >
+                    <Path Data="{StaticResource DeleteAlert}" Fill="Red"
+                          Width="16" Height="16" Stretch="Uniform" />
+                </Button>
             </Grid>
             <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Margin="0,30,0,0">
                 <Button Content="Close" Width="80" Margin="0,0,10,0" Command="{Binding CloseCommand}" />

src/CodeSnip/Views/LanguageCategoryView/LanguageCategoryViewModel.cs

@@ -228,6 +228,7 @@ partial void OnSelectedLanguageChanged(Language? value)
             {
                 NewLanguageCode = value.Code ?? "";
                 NewLanguageName = value.Name ?? "";
+                SelectedLanguageForCategory = value;
             }
         }
 
@@ -402,12 +403,11 @@ private async Task DeleteLanguageAsync()
                     return;
 
                 _databaseService.DeleteLanguage(SelectedLanguage.Id);
-                Languages.Remove(SelectedLanguage);
-                SelectedLanguage = Languages.FirstOrDefault();
+                HandleLanguageDeletion(SelectedLanguage);
             }
             catch (Exception ex)
             {
-                await DialogService.Instance.ShowMessageAsync("Error", ex.Message);
+                await DialogService.Instance.ShowMessageAsync("Error", $"Failed to delete language '{SelectedLanguage?.Name}'.\n\nDetails: {ex.Message}");
             }
         }
 
@@ -426,8 +426,7 @@ private async Task DeleteCategoryAsync()
                     return;
 
                 _databaseService.DeleteCategory(SelectedCategory.Id);
-                SelectedLanguageForCategory.Categories.Remove(SelectedCategory);
-                SelectedCategory = FilteredCategories.FirstOrDefault();
+                HandleCategoryDeletion(SelectedCategory);
 
             }
             catch (Exception ex)
@@ -438,11 +437,110 @@ private async Task DeleteCategoryAsync()
                 }
                 else
                 {
-                    await DialogService.Instance.ShowMessageAsync("Error", ex.Message);
+                    await DialogService.Instance.ShowMessageAsync("Error", $"Failed to delete category '{SelectedCategory?.Name}'.\n\nDetails: {ex.Message}");
                 }
             }
         }
 
+        [RelayCommand]
+        private async Task ForceDeleteLanguage()
+        {
+            if (SelectedLanguage == null)
+            {
+                await DialogService.Instance.ShowMessageAsync("Action Skipped", "Please select a language to delete.");
+                return;
+            }
+
+            int snippetCount = _databaseService.CountSnippetsInLanguage(SelectedLanguage.Id);
+            string message = $"Are you sure you want to permanently delete the language '{SelectedLanguage.Name}'?";
+
+            if (snippetCount > 0)
+            {
+                message += $"\n\nThis will also delete all of its categories and {snippetCount} associated snippets. This action cannot be undone.";
+            }
+            else
+            {
+                message += "\n\nThis will also delete all of its (empty) categories. This action cannot be undone.";
+            }
+
+            bool confirm = await DialogService.Instance.ShowConfirmAsync("Force Delete Confirmation", message);
+
+            if (!confirm)
+                return;
+
+            try
+            {
+                _databaseService.ForceDeleteLanguage(SelectedLanguage.Id);
+                HandleLanguageDeletion(SelectedLanguage);
+            }
+            catch (Exception ex)
+            {
+                await DialogService.Instance.ShowMessageAsync("Error", $"Failed to delete language '{SelectedLanguage?.Name}'.\n\nDetails: {ex.Message}");
+            }
+        }
+
+        [RelayCommand]
+        private async Task ForceDeleteCategory()
+        {
+            if (SelectedCategory == null || SelectedLanguageForCategory == null)
+            {
+                await DialogService.Instance.ShowMessageAsync("Action Skipped", "Please select a category to delete.");
+                return;
+            }
+
+            int snippetCount = _databaseService.CountSnippetsInCategory(SelectedCategory.Id);
+            string message = $"Are you sure you want to permanently delete the category '{SelectedCategory.Name}'?";
+
+            if (snippetCount > 0)
+            {
+                message += $"\n\nThis will also delete {snippetCount} associated snippets. This action cannot be undone.";
+            }
+            else
+            {
+                message += "\n\nThis action cannot be undone.";
+            }
+
+            bool confirm = await DialogService.Instance.ShowConfirmAsync("Force Delete Confirmation", message);
+
+            if (!confirm)
+                return;
+
+            try
+            {
+                _databaseService.ForceDeleteCategory(SelectedCategory.Id);
+                HandleCategoryDeletion(SelectedCategory);
+            }
+            catch (Exception ex)
+            {
+                await DialogService.Instance.ShowMessageAsync("Error", $"Failed to delete category '{SelectedCategory?.Name}'.\n\nDetails: {ex.Message}");
+            }
+        }
+
+        private void HandleLanguageDeletion(Language languageToDelete)
+        {
+            if (languageToDelete == null) return;
+
+            Languages.Remove(languageToDelete);
+            SelectedLanguage = Languages.FirstOrDefault();
+
+            if (SelectedLanguage == null)
+            {
+                NewLanguageCode = string.Empty;
+                NewLanguageName = string.Empty;
+                SelectedLanguageForCategory = null;
+            }
+        }
+
+        private void HandleCategoryDeletion(Category categoryToDelete)
+        {
+            SelectedLanguageForCategory?.Categories.Remove(categoryToDelete);
+            SelectedCategory = FilteredCategories.FirstOrDefault();
+            if (SelectedCategory == null)
+            {
+                NewCategoryName = string.Empty;
+            }
+        }
+
         [RelayCommand]
         private void Close()
         {