namespace StellaOps.Bench.LinkNotMerge.Vex;

internal readonly record struct DurationStatistics(double MeanMs, double P95Ms, double MaxMs)
{
    public static DurationStatistics From(IReadOnlyList<double> values)
    {
        if (values.Count == 0)
        {
            return new DurationStatistics(0, 0, 0);
        }

        var sorted = values.ToArray();
        Array.Sort(sorted);

        var total = 0d;
        foreach (var value in values)
        {
            total += value;
        }

        var mean = total / values.Count;
        var p95 = Percentile(sorted, 95);
        var max = sorted[^1];

        return new DurationStatistics(mean, p95, max);
    }

    private static double Percentile(IReadOnlyList<double> sorted, double percentile)
    {
        if (sorted.Count == 0)
        {
            return 0;
        }

        var rank = (percentile / 100d) * (sorted.Count - 1);
        var lower = (int)Math.Floor(rank);
        var upper = (int)Math.Ceiling(rank);
        var weight = rank - lower;

        if (upper >= sorted.Count)
        {
            return sorted[lower];
        }

        return sorted[lower] + weight * (sorted[upper] - sorted[lower]);
    }
}

internal readonly record struct ThroughputStatistics(double MeanPerSecond, double MinPerSecond)
{
    public static ThroughputStatistics From(IReadOnlyList<double> values)
    {
        if (values.Count == 0)
        {
            return new ThroughputStatistics(0, 0);
        }

        var total = 0d;
        var min = double.MaxValue;

        foreach (var value in values)
        {
            total += value;
            min = Math.Min(min, value);
        }

        var mean = total / values.Count;
        return new ThroughputStatistics(mean, min);
    }
}

internal readonly record struct AllocationStatistics(double MaxAllocatedMb)
{
    public static AllocationStatistics From(IReadOnlyList<double> values)
    {
        var max = 0d;
        foreach (var value in values)
        {
            max = Math.Max(max, value);
        }

        return new AllocationStatistics(max);
    }
}