CombGuid

CombGuid.cs

public static class CombGuid
{
	public static readonly Guid Empty = Guid.Parse("00000000-0000-0000-0000-000000000000");
	
	private static readonly Func<Guid> GeneratorCore = () =>
	{
	    var destinationArray = Guid.NewGuid().ToByteArray();
	    var time = new DateTime(1900, 1, 1);
	    var now = DateTime.UtcNow;
	    var span = new TimeSpan(now.Ticks - time.Ticks);
	    var timeOfDay = now.TimeOfDay;
	    var bytes = BitConverter.GetBytes(span.Days);
	    var array = BitConverter.GetBytes((long)(timeOfDay.TotalMilliseconds / 3.333333));
	    Array.Reverse(bytes);
	    Array.Reverse(array);
	    Array.Copy(bytes, bytes.Length - 2, destinationArray, destinationArray.Length - 6, 2);
	    Array.Copy(array, array.Length - 4, destinationArray, destinationArray.Length - 4, 4);
	    return new Guid(destinationArray);
	};
	
	private static Func<Guid> _generator = GeneratorCore;
	
	public static Guid Generate()
	{
	    return _generator();
	}
	
	public static void Reset()
	{
	    _generator = GeneratorCore;
	}
	
	public static IDisposable Stub(Guid value)
	{
	    _generator = () => value;
	    return new DisposableAction(Reset);
	}
}