Move filter query and RowComparer into UI base

Source/LibationUiBase/GridView/QueryExtensions.cs

@@ -1,4 +1,5 @@
-using DataLayer;
+using ApplicationServices;
+using DataLayer;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -39,6 +40,20 @@ namespace LibationUiBase.GridView
 				return null;
 			}
 		}
+
+		public static HashSet<IGridEntry>? FilterEntries(this IEnumerable<IGridEntry> entries, string searchString)
+		{
+			if (string.IsNullOrEmpty(searchString)) return null;
+
+			var searchResultSet = SearchEngineCommands.Search(searchString);
+
+			var booksFilteredIn = entries.BookEntries().Join(searchResultSet.Docs, lbe => lbe.AudibleProductId, d => d.ProductId, (lbe, d) => (IGridEntry)lbe);
+
+			//Find all series containing children that match the search criteria
+			var seriesFilteredIn = entries.SeriesEntries().Where(s => s.Children.Join(searchResultSet.Docs, lbe => lbe.AudibleProductId, d => d.ProductId, (lbe, d) => lbe).Any());
+
+			return booksFilteredIn.Concat(seriesFilteredIn).ToHashSet();
+		}
 	}
 #nullable disable
 }

Source/LibationUiBase/GridView/RowComparerBase.cs

@@ -0,0 +1,82 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.ComponentModel;
+
+namespace LibationUiBase.GridView
+{
+	/// <summary>
+	/// This compare class ensures that all top-level grid entries (standalone books or series parents)
+	/// are sorted by PropertyName while all episodes remain immediately beneath their parents and remain
+	/// sorted by series index, ascending.
+	/// </summary>
+	public abstract class RowComparerBase : IComparer, IComparer<IGridEntry>, IComparer<object>
+	{
+		public abstract string PropertyName { get; set; }
+
+		public int Compare(object x, object y)
+		{
+			if (x is null && y is not null) return -1;
+			if (x is not null && y is null) return 1;
+			if (x is null && y is null) return 0;
+
+			var geA = (IGridEntry)x;
+			var geB = (IGridEntry)y;
+
+			var sortDirection = GetSortOrder();
+
+			ISeriesEntry parentA = null;
+			ISeriesEntry parentB = null;
+
+			if (geA is ILibraryBookEntry lbA && lbA.Parent is ISeriesEntry seA)
+				parentA = seA;
+			if (geB is ILibraryBookEntry lbB && lbB.Parent is ISeriesEntry seB)
+				parentB = seB;
+
+			//both a and b are top-level grid entries
+			if (parentA is null && parentB is null)
+				return InternalCompare(geA, geB);
+
+			//a is top-level, b is a child
+			if (parentA is null && parentB is not null)
+			{
+				// b is a child of a, parent is always first
+				if (parentB == geA)
+					return sortDirection is ListSortDirection.Ascending ? -1 : 1;
+				else
+					return InternalCompare(geA, parentB);
+			}
+
+			//a is a child, b is a top-level
+			if (parentA is not null && parentB is null)
+			{
+				// a is a child of b, parent is always first
+				if (parentA == geB)
+					return sortDirection is ListSortDirection.Ascending ? 1 : -1;
+				else
+					return InternalCompare(parentA, geB);
+			}
+
+			//both are children of the same series
+			if (parentA == parentB)
+				return InternalCompare(geA, geB);
+
+			//a and b are children of different series.
+			return InternalCompare(parentA, parentB);
+		}
+
+		protected abstract ListSortDirection? GetSortOrder();
+
+		private int InternalCompare(IGridEntry x, IGridEntry y)
+		{
+			var val1 = x.GetMemberValue(PropertyName);
+			var val2 = y.GetMemberValue(PropertyName);
+
+			return x.GetMemberComparer(val1.GetType()).Compare(val1, val2); ;
+		}
+
+		public int Compare(IGridEntry x, IGridEntry y)
+		{
+			return Compare((object)x, y);
+		}
+	}
+}