I18NCommander/I18N Commander/UI WinForms/Components/SectionTree.cs

using DataModel.Database;
using DataModel.Database.Common;
using Microsoft.Extensions.DependencyInjection;
using Processor;
using UI_WinForms.Dialogs;
using UI_WinForms.Resources;

namespace UI_WinForms.Components;

public partial class SectionTree : UserControl
{
    private readonly DataContext db;
    
    public SectionTree()
    {
        this.InitializeComponent();

        // Get the DI context from the main form:
        this.db = Program.SERVICE_PROVIDER.GetService<DataContext>()!;
        
        // Dispose of the context when the control is disposed:
        this.Disposed += (_, _) => this.db.Dispose();

        // Create an image list from a resource:
        var imgList = new ImageList();
        imgList.ImageSize = new Size(45, 45);
        imgList.ColorDepth = ColorDepth.Depth32Bit;
        imgList.Images.Add(Icons.icons8_documents_folder_512);

        // Set the image list to the tree view:
        this.treeView.ImageList = imgList;

        // Subscribe to the load event:
        this.Load += this.OnLoad;
    }

    private async void OnLoad(object? sender, EventArgs e)
    {
        // A dictionary to cache all known tree nodes:
        var treeNodes = new Dictionary<string, TreeNode>();

        // Get the max. depth of the tree:
        var maxDepth = await SectionProcessor.GetDepth(this.db);
        
        // Store nodes, where we cannot find the parents:
        var missingParents = new List<TreeNode>();

        // Populate the tree view out of the database, layer by layer:
        for (var i = 0; i <= maxDepth; i++)
        {
            await foreach (var section in SectionProcessor.LoadLayer(this.db, i))
            {
                // Create the tree node:
                var node = new TreeNode
                {
                    Name = section.DataKey, // [sic] name is the key
                    Text = section.Name,
                    StateImageIndex = 1,
                };
                
                // Cache the node:
                treeNodes.Add(section.DataKey, node);
                
                // Is this a root node?
                if (section.Depth is 0)
                    
                    // Set the root node:
                    this.treeView.Nodes.Add(node);
                
                // Otherwise, attach this section to its parent node:
                else
                {
                    // Get the parent from our cache within O(1):
                    treeNodes.TryGetValue(section.Parent?.DataKey ?? string.Empty, out var parent);

                    // If the parent node is not found, skip this section:
                    if (parent is null)
                    {
                        missingParents.Add(node);
                        continue;
                    }

                    // Add the node to the parent:
                    parent.Nodes.Add(node);
                }
            }
        }
        
        // If we found any missing parents, show a dialog:
        if (missingParents.Any())
        {
            MessageBox.Show($"In {missingParents.Count} case(s) we could not found the matching parent. We added these nodes to a special root node, though.", "Parent not found", MessageBoxButtons.OK, MessageBoxIcon.Error);
            
            // Create a root node for all missing parents:
            var rootMissedParents = new TreeNode
            {
                Name = "MISSING_PARENTS",
                Text = "Missing Parents",
                StateImageIndex = 1,
            };
            
            // Add the root node to the tree:
            this.treeView.Nodes.Add(rootMissedParents);
            
            // Add all missing parents to the root node:
            foreach (var node in missingParents)
                rootMissedParents.Nodes.Add(node);
        }
    }

    private async void buttonAdd_Click(object sender, EventArgs e)
    {
        var result = InputDialog.Show(new InputDialog.Options(
            Message: "Please type the desired section name.",
            Title: "Add a section",
            Placeholder: "My next section",
            ShowQuestionCheckbox: true,
            QuestionCheckboxText: "Add a root node (i.e. ignoring the selected node)"
        ));
        
        if(result.DialogResult == DialogResult.Cancel)
            return;

        var addRootNode = result.AnswerToQuestion;
        
        // Get the currently selected section as parent:
        var selectedNode = this.treeView.SelectedNode;

        // Add the new section to the database:
        var addedSection = await SectionProcessor.AddSection(this.db, result.Text,  addRootNode ? null : selectedNode?.Name);
        
        // Add the new section to the tree control:
        var node = new TreeNode
        {
            Name = addedSection.DataKey, // [sic] name is the key
            Text = addedSection.Name,
            StateImageIndex = 1,
        };

        if(!addRootNode && selectedNode is not null)
            selectedNode.Nodes.Add(node);
        else
            this.treeView.Nodes.Add(node);
        
        // Ensure, that the added node is visible and gets the focus:
        node.EnsureVisible();
        this.treeView.SelectedNode = node;
    }
}