using System.Collections.Generic;

namespace yield
{
    public class Averager
    {
        DataPoint point;
        Queue<double> queue;
        double sum;
        int windowWidth;
        public Averager(DataPoint point, int windowWidth)
        {
            this.windowWidth = windowWidth;
            this.point = point;
            queue = new Queue<double>();
        }

        public double Measure()
        {
            var value = point.OriginalY;
            queue.Enqueue(value);
            sum += value;

            if (queue.Count > windowWidth)
                sum -= queue.Dequeue();

            return sum / queue.Count;
        }
    }
    public static class MovingAverageTask
    {
        public static IEnumerable<DataPoint> MovingAverage(this IEnumerable<DataPoint> data, int windowWidth)
        {
            var counter = data.GetEnumerator();
            var t = 0;

            while (counter.MoveNext())
            {
                var point = counter.Current;
                if (t > 0) // здесь всё плохо. Как мне получить значение новое у точки?
                {
                    var averager = new Averager(point, windowWidth);
                    point.OriginalY = point.AvgSmoothedY;
                }
                else // а тут вроде норм
                {
                    point.AvgSmoothedY = point.OriginalY;
                    t++;
                }
                yield return point;
            }
        }
    }
}