using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Microsoft.Research.DynamicDataDisplay.Charts.Axes.DateTime.Strategies
{
	public class DelegateDateTimeStrategy : DefaultDateTimeTicksStrategy
	{
		private readonly Func<TimeSpan, DifferenceIn?> function;
		public DelegateDateTimeStrategy(Func<TimeSpan, DifferenceIn?> function)
		{
			if (function == null)
				throw new ArgumentNullException("function");

			this.function = function;
		}

		public override DifferenceIn GetDifference(TimeSpan span)
		{
			DifferenceIn? customResult = function(span);

			DifferenceIn result = customResult.HasValue ?
				customResult.Value :
				base.GetDifference(span);

			return result;
		}
	}
}