C4IT-F4SD-Client/FasdDesktopUi/Basics/UserControls/HierarchicalSelectionControl.xaml.cs

using FasdDesktopUi.Basics.Models;
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;

namespace FasdDesktopUi.Basics.UserControls
{
    public partial class HierarchicalSelectionControl : UserControl
    {
        private readonly ObservableCollection<HierarchicalSelectionItem> visibleItems = new ObservableCollection<HierarchicalSelectionItem>();
        private readonly Dictionary<string, HierarchicalSelectionItem> itemLookup = new Dictionary<string, HierarchicalSelectionItem>();
        private readonly DispatcherTimer searchDelayTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(250) };
        private string lastSearchText = string.Empty;
        public ObservableCollection<HierarchicalSelectionItem> VisibleItems => visibleItems;

        public event EventHandler DropDownOpened;
        public event EventHandler DropDownClosed;

        public HierarchicalSelectionControl()
        {
            InitializeComponent();
            TreeViewControl.ItemsSource = visibleItems;
            searchDelayTimer.Tick += SearchDelayTimer_Tick;
        }

        #region DependencyProperties

        public ObservableCollection<HierarchicalSelectionItem> ItemsSource
        {
            get => (ObservableCollection<HierarchicalSelectionItem>)GetValue(ItemsSourceProperty);
            set => SetValue(ItemsSourceProperty, value);
        }

        public static readonly DependencyProperty ItemsSourceProperty = DependencyProperty.Register(
            nameof(ItemsSource),
            typeof(ObservableCollection<HierarchicalSelectionItem>),
            typeof(HierarchicalSelectionControl),
            new PropertyMetadata(null, OnItemsSourceChanged));

        private static void OnItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is HierarchicalSelectionControl control)
            {
                control.RebuildLookup();
                control.ApplyFilter(control.lastSearchText);
                control.TryExpandToSelectedItem();
            }
        }

        public HierarchicalSelectionItem SelectedItem
        {
            get => (HierarchicalSelectionItem)GetValue(SelectedItemProperty);
            set => SetValue(SelectedItemProperty, value);
        }

        public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.Register(
            nameof(SelectedItem),
            typeof(HierarchicalSelectionItem),
            typeof(HierarchicalSelectionControl),
            new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSelectedItemChanged));

        private static void OnSelectedItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is HierarchicalSelectionControl control)
            {
                control.TryExpandToSelectedItem();
            }
        }

        public Brush ComboBoxBackground
        {
            get => (Brush)GetValue(ComboBoxBackgroundProperty);
            set => SetValue(ComboBoxBackgroundProperty, value);
        }

        public static readonly DependencyProperty ComboBoxBackgroundProperty =
            DependencyProperty.Register(nameof(ComboBoxBackground), typeof(Brush), typeof(HierarchicalSelectionControl), new PropertyMetadata(Brushes.Transparent));

        public string SearchPlaceholderText
        {
            get => (string)GetValue(SearchPlaceholderTextProperty);
            set => SetValue(SearchPlaceholderTextProperty, value);
        }

        public static readonly DependencyProperty SearchPlaceholderTextProperty =
            DependencyProperty.Register(nameof(SearchPlaceholderText), typeof(string), typeof(HierarchicalSelectionControl), new PropertyMetadata(string.Empty));

        #endregion

        private void DropDownPopup_Opened(object sender, EventArgs e)
        {
            SearchTextBox.Focus();
            SearchTextBox.SelectAll();
            DropDownOpened?.Invoke(this, e);
        }

        private void DropDownPopup_Closed(object sender, EventArgs e)
        {
            searchDelayTimer.Stop();
            DropDownClosed?.Invoke(this, e);
        }

        private void SearchTextBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            searchDelayTimer.Stop();
            searchDelayTimer.Start();
        }

        private void SearchDelayTimer_Tick(object sender, EventArgs e)
        {
            searchDelayTimer.Stop();
            lastSearchText = SearchTextBox.Text ?? string.Empty;
            ApplyFilter(lastSearchText);
        }

        private void TreeViewControl_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
        {
            if (e.NewValue is HierarchicalSelectionItem selected)
            {
                var original = ResolveOriginalItem(selected);
                if (original != null)
                    SelectedItem = original;

                DropDownPopup.IsOpen = false;
            }
        }

        private HierarchicalSelectionItem ResolveOriginalItem(HierarchicalSelectionItem item)
        {
            if (item == null)
                return null;

            if (!string.IsNullOrWhiteSpace(item.Id) && itemLookup.TryGetValue(item.Id, out var original))
                return original;

            return item;
        }

        private void RebuildLookup()
        {
            itemLookup.Clear();

            if (ItemsSource == null)
                return;

            foreach (var entry in ItemsSource.SelectMany(item => item.SelfAndDescendants()))
            {
                if (string.IsNullOrWhiteSpace(entry.Id))
                    continue;

                itemLookup[entry.Id] = entry;
            }
        }

        private void ApplyFilter(string searchText)
        {
            visibleItems.Clear();

            if (ItemsSource == null)
                return;

            if (string.IsNullOrWhiteSpace(searchText))
            {
                foreach (var item in ItemsSource)
                {
                    item.SetExpandedRecursive(false);
                    visibleItems.Add(item);
                }

                TryExpandToSelectedItem();
                return;
            }

            var comparison = StringComparison.CurrentCultureIgnoreCase;

            foreach (var root in ItemsSource)
            {
                var clone = root.CloneBranch(node =>
                    node.FullPath?.IndexOf(searchText, comparison) >= 0 ||
                    node.DisplayName?.IndexOf(searchText, comparison) >= 0);

                if (clone == null)
                    continue;

                clone.SetExpandedRecursive(true);
                visibleItems.Add(clone);
            }
        }

        private void TryExpandToSelectedItem()
        {
            if (SelectedItem == null || string.IsNullOrWhiteSpace(SelectedItem.Id))
                return;

            if (!string.IsNullOrWhiteSpace(lastSearchText))
                return;

            var chain = SelectedItem;
            while (chain != null)
            {
                chain.IsExpanded = true;
                chain = chain.Parent;
            }
        }

        private void DisplayBorder_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            if (!IsEnabled)
                return;

            e.Handled = true;
            DropDownPopup.IsOpen = !DropDownPopup.IsOpen;
        }

        protected override void OnPreviewKeyDown(KeyEventArgs e)
        {
            base.OnPreviewKeyDown(e);

            if (!IsEnabled)
                return;

            if (!DropDownPopup.IsOpen && (e.Key == Key.Enter || e.Key == Key.Down || e.Key == Key.Space))
            {
                DropDownPopup.IsOpen = true;
                e.Handled = true;
                return;
            }

            if (DropDownPopup.IsOpen && e.Key == Key.Escape)
            {
                DropDownPopup.IsOpen = false;
                e.Handled = true;
            }
        }
    }
}