Libation/Source/LibationUiBase/GridView/RowComparerBase.cs

97 lines
2.9 KiB
C#

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)
{
//Podcast episodes usually all have the same PurchaseDate and DateAdded property:
//the date that the series was added to the library. So when sorting by PurchaseDate
//and DateAdded, compare SeriesOrder instead..
return PropertyName switch
{
nameof(IGridEntry.DateAdded) or nameof (IGridEntry.PurchaseDate) => geA.SeriesOrder.CompareTo(geB.SeriesOrder),
_ => 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);
var compare = x.GetMemberComparer(val1.GetType()).Compare(val1, val2);
return compare == 0 && x.Liberate.IsSeries && y.Liberate.IsSeries
//Both a and b are series parents and compare as equal, so break the tie.
? x.AudibleProductId.CompareTo(y.AudibleProductId)
: compare;
}
public int Compare(IGridEntry x, IGridEntry y)
{
return Compare((object)x, y);
}
}
}