using System;
using System.Collections.Generic;
using LeafWeb.Core.Entities;
using MathNet.Numerics;

namespace LeafWeb.Core.Utility
{
	public class TimeInProgressEstimater
	{
		private readonly double[] _xData;
		private readonly double[] _yData;

		public TimeInProgressEstimater(IEnumerable<ILeafInput> leafInputs)
		{
			var xData = new List<double>();
			var yData = new List<double>();
			foreach (var leafInput in leafInputs)
			{
				xData.Add(leafInput.InputFiles.Count);
				yData.Add(ConvertFromTimeSpan(leafInput.TimeInProgress));
			}
			_xData = xData.ToArray();
			_yData = yData.ToArray();
		}

		public TimeSpan EstimateTimeInProgress(ILeafInput leafInput)
		{
			//var lineFunc = Fit.LineFunc(_xData, _yData);
			var lineFunc = Fit.PolynomialFunc(_xData, _yData, 3);
			var estimate = lineFunc(leafInput.InputFiles.Count);
			return ConvertToTimeSpan(estimate);
		}

		private static double ConvertFromTimeSpan(TimeSpan timeSpan)
		{
			return timeSpan.TotalSeconds;
		}

		private static TimeSpan ConvertToTimeSpan(double estimate)
		{
			int int32;
			try
			{
				int32 = Convert.ToInt32(estimate);
			}
			catch (OverflowException)
			{
				int32 = int.MaxValue;
			}
			return TimeSpan.FromSeconds(int32);
		}
	}
}