Implement filtering in the sortable binding list.

Source/LibationWinForms/SyncBindingSource.cs

@@ -21,31 +21,7 @@ namespace LibationWinForms
             => syncContext = SynchronizationContext.Current;
 
         public override bool SupportsFiltering => true;
-        public override string Filter { get => FilterString; set => SetFilter(value); }
 
-        private string FilterString;
-
-        private void SetFilter(string filterString)
-		{
-            if (filterString != FilterString)
-                RemoveFilter();
-
-            FilterString = filterString;
-
-            var searchResults = SearchEngineCommands.Search(filterString);
-            var productIds = searchResults.Docs.Select(d => d.ProductId).ToList();
-
-            var allItems = ((SortableBindingList<GridEntry>)DataSource).InnerList;
-            var filterList = productIds.Join(allItems, s => s, ge => ge.AudibleProductId, (pid, ge) => ge).ToList();
-
-            ((SortableBindingList<GridEntry>)DataSource).SetFilteredItems(filterList);
-        }
-
-		public override void RemoveFilter()
-        {
-            ((SortableBindingList<GridEntry>)DataSource).RemoveFilter();
-            base.RemoveFilter();
-		}
 		protected override void OnListChanged(ListChangedEventArgs e)
         {
             if (syncContext is not null)

Source/LibationWinForms/grid/ProductsGrid.cs

@@ -159,7 +159,7 @@ namespace LibationWinForms
 
 		#region UI display functions
 
-		private SortableBindingList<GridEntry> bindingList;
+		private SortableFilterableBindingList bindingList;
 
 		private bool hasBeenDisplayed;
 		public event EventHandler InitialLoaded;
@@ -168,69 +168,56 @@ namespace LibationWinForms
 			// don't return early if lib size == 0. this will not update correctly if all books are removed
 			var lib = DbContexts.GetLibrary_Flat_NoTracking();
 
-			var orderedBooks = lib
-				// default load order
-				.OrderByDescending(lb => lb.DateAdded)
-				//// more advanced example: sort by author, then series, then title
-				//.OrderBy(lb => lb.Book.AuthorNames)
-				//    .ThenBy(lb => lb.Book.SeriesSortable)
-				//    .ThenBy(lb => lb.Book.TitleSortable)
-				.ToList();
-
-			// bind
-			if (bindingList?.Count > 0)
-				updateGrid(orderedBooks);
-			else
-				bindToGrid(orderedBooks);
-
-
 			if (!hasBeenDisplayed)
 			{
+				// bind
+				bindToGrid(lib);
 				hasBeenDisplayed = true;
 				InitialLoaded?.Invoke(this, new());
+				VisibleCountChanged?.Invoke(this, bindingList.Count);
 			}
+			else
+				updateGrid(lib);
 
 		}
 
-		private void bindToGrid(List<DataLayer.LibraryBook> orderedBooks)
+		private void bindToGrid(List<LibraryBook> orderedBooks)
 		{
-			bindingList = new SortableBindingList<GridEntry>(orderedBooks.Select(lb => toGridEntry(lb)));
+			bindingList = new SortableFilterableBindingList(orderedBooks.OrderByDescending(lb => lb.DateAdded).Select(lb => new GridEntry(lb)));
 			gridEntryBindingSource.DataSource = bindingList;
 		}
 
-		private void updateGrid(List<DataLayer.LibraryBook> orderedBooks)
+		private void updateGrid(List<LibraryBook> dbBooks)
 		{
-			for (var i = orderedBooks.Count - 1; i >= 0; i--)
+			int visibleCount = bindingList.Count;
+
+			//Add absent books to grid, or update current books
+			for (var i = dbBooks.Count - 1; i >= 0; i--)
 			{
-				var libraryBook = orderedBooks[i];
-				var existingItem = bindingList.FirstOrDefault(i => i.AudibleProductId == libraryBook.Book.AudibleProductId);
+				var libraryBook = dbBooks[i];
+				var existingItem = bindingList.AllItems.FirstOrDefault(i => i.AudibleProductId == libraryBook.Book.AudibleProductId);
 
 				// add new to top
 				if (existingItem is null)
-					bindingList.Insert(0, toGridEntry(libraryBook));
+					bindingList.Insert(0, new GridEntry(libraryBook));
 				// update existing
 				else
 					existingItem.UpdateLibraryBook(libraryBook);
 			}
 
-			// remove deleted from grid. note: actual deletion from db must still occur via the RemoveBook feature. deleting from audible will not trigger this
-			var oldIds = bindingList.Select(ge => ge.AudibleProductId).ToList();
-			var newIds = orderedBooks.Select(lb => lb.Book.AudibleProductId).ToList();
-			var remove = oldIds.Except(newIds).ToList();
-			foreach (var id in remove)
-			{
-				var oldItem = bindingList.FirstOrDefault(ge => ge.AudibleProductId == id);
-				if (oldItem is not null)
-					bindingList.Remove(oldItem);
-			}
-		}
+			// remove deleted from grid.
+			// note: actual deletion from db must still occur via the RemoveBook feature. deleting from audible will not trigger this
+			var removedBooks = 
+				bindingList
+				.AllItems
+				.ExceptBy(dbBooks.Select(lb => lb.Book.AudibleProductId), ge => ge.AudibleProductId)
+				.ToList();
 
-		private GridEntry toGridEntry(DataLayer.LibraryBook libraryBook)
-		{
-			var entry = new GridEntry(libraryBook);
-			// see also notes in Libation/Source/__ARCHITECTURE NOTES.txt :: MVVM
-			entry.LibraryBookUpdated += (sender, _) => _dataGridView.InvalidateRow(_dataGridView.GetRowIdOfBoundItem((GridEntry)sender));
-			return entry;
+			foreach (var removed in removedBooks)
+				bindingList.Remove(removed);
+
+			if (bindingList.Count != visibleCount)
+				VisibleCountChanged?.Invoke(this, bindingList.Count);
 		}
 
 		#endregion
@@ -239,23 +226,21 @@ namespace LibationWinForms
 
 		public void Filter(string searchString)
 		{
-			if (_dataGridView.Rows.Count == 0)
-				return;
+			int visibleCount = bindingList.Count;
 
 			if (string.IsNullOrEmpty(searchString))
 				gridEntryBindingSource.RemoveFilter();
 			else
 				gridEntryBindingSource.Filter = searchString;
 
-
-			VisibleCountChanged?.Invoke(this, bindingList.Count);
+			if (visibleCount != bindingList.Count)
+				VisibleCountChanged?.Invoke(this, bindingList.Count);
 		}
 
 		#endregion
 
 		internal List<LibraryBook> GetVisible()
 			=> bindingList
-			.InnerList
 			.Select(row => row.LibraryBook)
 			.ToList();
 

Source/LibationWinForms/grid/SortableFilterableBindingList.cs

@@ -0,0 +1,126 @@
+using ApplicationServices;
+using Dinah.Core.DataBinding;
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+
+namespace LibationWinForms
+{
+	/*
+     * Allows filtering of the underlying SortableBindingList<GridEntry>
+     * by implementing IBindingListView aud using SearchEngineCommands 
+     * 
+     * When filtering is applied, the filtered-out items are removed
+     * from the base list and added to the private FilterRemoved list.
+     * All items, filtered or not, are stored in the private AllItems
+     * list. When filtering is removed, items in the FilterRemoved list
+     * are added back to the base list.
+     * 
+     * Remove and InsertItem are overridden to ensure that the current
+     * filter remains applied when items are removed/added to the list.
+     */
+	internal class SortableFilterableBindingList : SortableBindingList<GridEntry>, IBindingListView
+	{
+		/// <summary>
+		/// Items that were removed from the list due to filtering
+		/// </summary>
+		private readonly List<GridEntry> FilterRemoved = new();
+		/// <summary>
+		/// Tracks all items in the list, both filtered and not.
+		/// </summary>
+		public readonly List<GridEntry> AllItems;
+		private string FilterString;
+		private Action Sort;
+		public SortableFilterableBindingList(IEnumerable<GridEntry> enumeration) : base(enumeration)
+		{
+			AllItems = new List<GridEntry>(Items);
+
+			//This is only necessary because SortableBindingList doesn't expose Sort()
+			//You should make SortableBindingList.Sort protected and remove reflection
+			var method = typeof(SortableBindingList<GridEntry>).GetMethod("Sort", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+			Sort = method.CreateDelegate<Action>(this);
+		}
+
+		public bool SupportsFiltering => true;
+		public string Filter { get => FilterString; set => ApplyFilter(value); }
+
+		#region Unused - Advanced Filtering
+		public bool SupportsAdvancedSorting => false;
+
+
+		//This ApplySort overload is only called is SupportsAdvancedSorting is true.
+		//Otherwise BindingList.ApplySort() is used
+		public void ApplySort(ListSortDescriptionCollection sorts) => throw new NotImplementedException();
+
+		public ListSortDescriptionCollection SortDescriptions => throw new NotImplementedException();
+		#endregion
+
+		public new void Remove(GridEntry entry)
+		{
+			AllItems.Remove(entry);
+			FilterRemoved.Remove(entry);
+			base.Remove(entry);
+		}
+
+		protected override void InsertItem(int index, GridEntry item)
+		{
+			AllItems.Insert(index, item);
+
+			if (FilterString is not null)
+			{
+				var searchResults = SearchEngineCommands.Search(FilterString);
+				//Decide if the new item matches the filter, and either insert it in the
+				//displayed items or the filtered out items list
+				if (searchResults.Docs.Any(d => d.ProductId == item.AudibleProductId))
+					base.InsertItem(index, item);
+				else
+					FilterRemoved.Add(item);
+			}
+			else
+				base.InsertItem(index, item);
+		}
+
+		private void ApplyFilter(string filterString)
+		{
+			if (filterString != FilterString)
+				RemoveFilter();
+
+			FilterString = filterString;
+
+			var searchResults = SearchEngineCommands.Search(filterString);
+			var productIds = searchResults.Docs.Select(d => d.ProductId).ToList();
+
+			for (int i = Items.Count - 1; i >= 0; i--)
+			{
+				if (!productIds.Contains(Items[i].AudibleProductId))
+				{
+					FilterRemoved.Add(Items[i]);
+					Items.RemoveAt(i);
+					base.OnListChanged(new ListChangedEventArgs(ListChangedType.ItemDeleted, i));
+				}
+			}
+		}
+
+		public void RemoveFilter()
+		{
+			if (FilterString is null) return;
+
+			for (int i = 0; i < FilterRemoved.Count; i++)
+			{
+				Items.Insert(i, FilterRemoved[i]);
+				base.OnListChanged(new ListChangedEventArgs(ListChangedType.ItemAdded, i));
+			}
+
+			FilterRemoved.Clear();
+
+			if (IsSortedCore)
+				Sort();
+			else
+				//No user-defined sort is applied, so do default sorting by date added, descending
+				((List<GridEntry>)Items).Sort((i1,i2) =>i2.LibraryBook.DateAdded.CompareTo(i1.LibraryBook.DateAdded));
+
+			FilterString = null;
+		}
+	}
+}