using System.Collections.ObjectModel;
using System.Linq;

namespace FrostFS.SDK.Client.Models.Netmap.Placement;

internal struct MeanIQRAgg : IAggregator
{
    private const int minLn = 4;
    internal Collection<double> arr = [];

    public MeanIQRAgg()
    {
    }

    public readonly void Add(double d)
    {
        arr.Add(d);
    }

    public readonly double Compute()
    {
        var length = arr.Count;
        if (length == 0)
        {
            return 0;
        }

        var sorted = arr.OrderBy(p => p).ToArray();

        double minV, maxV;

        if (arr.Count < minLn)
        {
            minV = sorted[0];
            maxV = sorted[length - 1];
        }
        else
        {
            var start = length / minLn;
            var end = length * 3 / minLn - 1;

            minV = sorted[start];
            maxV = sorted[end];
        }

        var count = 0;
        double sum = 0;

        foreach (var e in sorted)
        {
            if (e >= minV && e <= maxV)
            {
                sum += e;
                count++;
            }
        }

        return sum / count;
    }

    internal readonly void Clear()
    {
        arr.Clear();
    }
}