Connected.Components/Utilities/SortingAssistent.cs

// Copyright (c) MudBlazor 2021
// MudBlazor licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Linq.Expressions;
using System.Reflection;
using Connected.Components;

namespace Connected.Utilities;

public static class SortingAssistent
{
	public static void UpdateOrder<T>(this IEnumerable<T> items, ItemDropInfo<T> dropInfo, Expression<Func<T, int>> valueUpdater, int zoneOffset = 0)
	{
		var memberSelectorExpression = valueUpdater.Body as MemberExpression;
		if (memberSelectorExpression == null) { throw new InvalidOperationException(); }

		var property = memberSelectorExpression.Member as PropertyInfo;

		if (property == null) { throw new InvalidOperationException(); }

		var newIndex = dropInfo.IndexInZone + zoneOffset;

		var item = dropInfo.Item;

		int index = 0;
		foreach (var _item in items.OrderBy(x => (int)property.GetValue(x)))
		{
			if (_item.Equals(item) == true)
			{
				property.SetValue(item, newIndex);
			}
			else
			{
				if (index == newIndex)
				{
					index++;
				}

				property.SetValue(_item, index);

				index++;
			}
		}
	}
}