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

namespace AsbCloudInfrastructure.Services.Subsystems.Utils
{
#nullable enable
    internal class Interpolation
    {
        private IEnumerator<(DateTimeOffset dateMin, float? depthMin, DateTimeOffset dateMax, float? depthMax)> enumerator;
        (DateTimeOffset dateMin, float? depthMin, DateTimeOffset dateMax, float? depthMax) lastValue = default;

        public Interpolation(IOrderedEnumerable<(DateTimeOffset dateMin, float? depthMin, DateTimeOffset dateMax, float? depthMax)> collection)
        {
            enumerator = collection.GetEnumerator();
            enumerator.MoveNext();
        }

        public float GetDepth(DateTimeOffset date)
        {
            if (lastValue.depthMin is not null &&
                lastValue.depthMax is not null)
            {
                while (date > enumerator.Current.dateMax)
                {
                    if (isLess(date))
                        CalcValue(enumerator.Current, date.Second);
                    enumerator.MoveNext();
                }
            }
            return (float)lastValue.depthMin;
        }
        
        private bool isLess(DateTimeOffset date)
        {
           if (date <= enumerator.Current.dateMax && date >= enumerator.Current.dateMin)
                return true;
           return false;
        }
        private float CalcValue((DateTimeOffset dateMin, float? depthMin, DateTimeOffset dateMax, float? depthMax) item, int x)
        {
            
            var a = (item.depthMax - item.depthMin) / (item.dateMax.Second - item.dateMin.Second);
            var b = item.depthMin * (item.dateMax.Second - (item.depthMax - item.depthMin) / (item.dateMax.Second - item.dateMin.Second));
            var resultDepth = a * x + b;
            return (float)resultDepth;
        }

    }
#nullable disable
}