Rotating values of a flagged System.Enum in C#

RotateFlagEnum.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

// Requires C# 7.3 or later (Roslyn 3.0 or later) for where TEnum : System.Enum
public class Program
{
	public static void Main()
	{
		CompassDirections dirs = CompassDirections.NORTH | CompassDirections.SOUTHEAST;
		
		#region Test functionality
		Console.WriteLine("Valid directions are: {0}\n", dirs);
		
		// Rotation as a standard method
		dirs = Rotate(dirs, 2);
		
		Console.WriteLine("Updated directions are: {0}\n", dirs);
		
		// Rotation as an extension method to TEnum
		dirs.Rotate(6);
		
		Console.WriteLine("Updated directions are: {0}\n", dirs);
		#endregion
	}
	
	// Standard method
	public static TEnum Rotate<TEnum>(TEnum inEnum, int positions = 1) where TEnum : System.Enum
	{
		if (positions == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate 0 positions.  No rotation will occur.");
			return inEnum;
		}
			
		// Currently doesn't support any underlying enum type but int
		if (Enum.GetUnderlyingType(inEnum.GetType()) != typeof(int))
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valud on integer underlying types.  The System,Enum '" + inEnum.GetType().Name + "' does not use such an underlying value.");
			
		if (!typeof(TEnum).GetCustomAttributes<FlagsAttribute>().Any())
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valid for enums that have the [System.Flags] attribute set. The System.Enum '" + inEnum.GetType().Name + "' does not use that attribute.");
		
		List<int> values = new List<int>((int[])Enum.GetValues(inEnum.GetType()));
		
		if (values.Any(a => a < 0))
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valid for enums that contain no negative integer values. The System.Enum '" + inEnum.GetType().Name + "' includes negative values.");
		
		if (((int)(object)inEnum ^ 0) == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate an enum that is set to 'NONE = 0'. No rotation will occur.");
			return inEnum;
		}
		
		int allValuesMask = values.Max();
		
		if (((int)(object)inEnum ^ allValuesMask) == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate an enum that is set to 'ALL', 'OMNI', or a similar status including all flags. No rotation will occur.");
			return inEnum;
		}
		
		// Remove 0/NONE and OMNI/ALL
		values.Remove(0);
		values.Remove(values.Max());
		
		if (positions % values.Count == 0)
		{
			Console.WriteLine("Rotate<ENum>() called with perfect roundness positions % possiblePositions == 0. No rotation will occur.");
			return inEnum;
		}
		
		int maxRotation = Convert.ToString(values.Max(), 2).Length;
		
		while (Math.Abs(positions) > maxRotation)
		{
			if (positions > 0)
				positions -= maxRotation;
			else
				positions += maxRotation;
		}
		
		if (positions > 0)
		{
			return (TEnum)(object)(((int)(object)inEnum << positions | (int)(object)inEnum >> (maxRotation - positions)) & allValuesMask);
		}
		else if (positions < 0)
		{
			positions = Math.Abs(positions);
			return (TEnum)(object)(((int)(object)inEnum >> positions | (int)(object)inEnum << (maxRotation - positions)) & allValuesMask);
		}
		
		Console.WriteLine("Rotate<TEnum>() Unable to rotate - unknown condition.");
		return inEnum;
	}
}

public static class EnumExtensions
{
	// Extension of TEnum
	public static void Rotate<TEnum>(this ref TEnum inEnum, int positions = 1) where TEnum : struct, System.Enum
	{
		if (positions == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate 0 positions.  No rotation will occur.");
			return;
		}
		
		// Currently doesn't support any underlying enum type but int
		if (Enum.GetUnderlyingType(inEnum.GetType()) != typeof(int))
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valud on integer underlying types.  The System,Enum '" + inEnum.GetType().Name + "' does not use such an underlying value.");
			
		if (!typeof(TEnum).GetCustomAttributes<FlagsAttribute>().Any())
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valid for enums that have the [System.Flags] attribute set. The System.Enum '" + inEnum.GetType().Name + "' does not use that attribute.");
			
		List<int> values = new List<int>((int[])Enum.GetValues(inEnum.GetType()));
		
		if (values.Any(a => a < 0))
			throw new NotSupportedException("This method, Rotate<TEnum>(), is only valid for enums that contain no negative integer values. The System.Enum '" + inEnum.GetType().Name + "' includes negative values.");
		
		if (((int)(object)inEnum ^ 0) == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate an enum that is set to 'NONE = 0'. No rotation will occur.");
			return;
		}
		
		int allValuesMask = values.Max();
		
		if (((int)(object)inEnum ^ allValuesMask) == 0)
		{
			Console.WriteLine("Rotate<TEnum>() called to rotate an enum that is set to 'ALL', 'OMNI', or a similar status including all flags. No rotation will occur.");
			return;
		}
		
		// Remove 0/NONE and OMNI/ALL
		values.Remove(0);
		values.Remove(values.Max());
		
		if (positions % values.Count == 0)
		{
			Console.WriteLine("Rotate<ENum>() called with perfect roundness positions % possiblePositions == 0. No rotation will occur.");
			return;
		}
		
		int maxRotation = Convert.ToString(values.Max(), 2).Length;

		while (Math.Abs(positions) > maxRotation)
		{
			if (positions > 0)
				positions -= maxRotation;
			else
				positions += maxRotation;
		}

		if (positions > 0)
		{
			inEnum = (TEnum)(object)(((int)(object)inEnum << positions | (int)(object)inEnum >> (maxRotation - positions)) & allValuesMask);
			return;
		}
		else if (positions < 0)
		{
			positions = Math.Abs(positions);
			inEnum = (TEnum)(object)(((int)(object)inEnum >> positions | (int)(object)inEnum << (maxRotation - positions)) & allValuesMask);
			return;
		}
		
		Console.WriteLine("Rotate<TEnum>() Unable to rotate - unknown condition.");
		return;
	}
}

[System.Flags]
public enum CompassDirections
{
	NONE		=		0,
	NORTH		=		1 << 0,
	NORTHEAST	=		1 << 1,
	EAST		=		1 << 2,
	SOUTHEAST	=		1 << 3,
	SOUTH		=		1 << 4,
	SOUTHWEST	=		1 << 5,
	WEST		=		1 << 6,
	NORTHWEST	=		1 << 7,
	OMNI		=		~(~0 << 8)
}