Port Form1 to Avalonia

Source/LibationWinForms/AvaloniaUI/ViewModels/QueryExtensions.cs

@@ -0,0 +1,44 @@
+using DataLayer;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace LibationWinForms.AvaloniaUI.ViewModels
+{
+#nullable enable
+	internal static class QueryExtensions
+	{
+		public static IEnumerable<LibraryBookEntry2> BookEntries(this IEnumerable<GridEntry2> gridEntries)
+			=> gridEntries.OfType<LibraryBookEntry2>();
+
+		public static IEnumerable<SeriesEntrys2> SeriesEntries(this IEnumerable<GridEntry2> gridEntries)
+			=> gridEntries.OfType<SeriesEntrys2>();
+
+		public static T? FindByAsin<T>(this IEnumerable<T> gridEntries, string audibleProductID) where T : GridEntry2
+			=> gridEntries.FirstOrDefault(i => i.AudibleProductId == audibleProductID);
+
+		public static IEnumerable<SeriesEntrys2> EmptySeries(this IEnumerable<GridEntry2> gridEntries)
+			=> gridEntries.SeriesEntries().Where(i => i.Children.Count == 0);
+
+		public static SeriesEntrys2? FindSeriesParent(this IEnumerable<GridEntry2> gridEntries, LibraryBook seriesEpisode)
+		{
+			if (seriesEpisode.Book.SeriesLink is null) return null;
+
+			try
+			{
+				//Parent books will always have exactly 1 SeriesBook due to how
+				//they are imported in ApiExtended.getChildEpisodesAsync()
+				return gridEntries.SeriesEntries().FirstOrDefault(
+					lb =>
+					seriesEpisode.Book.SeriesLink.Any(
+						s => s.Series.AudibleSeriesId == lb.LibraryBook.Book.SeriesLink.Single().Series.AudibleSeriesId));
+			}
+			catch (Exception ex)
+			{
+				Serilog.Log.Error(ex, "Query error in {0}", nameof(FindSeriesParent));
+				return null;
+			}
+		}
+	}
+#nullable disable
+}