namespace Azaion.Missions.E2E.Helpers;

/// <summary>
/// Median + percentile helper for the NFT-PERF-* and NFT-RES-LIM-01
/// scenarios. Inputs are wall-clock latency samples (or RSS samples)
/// in any orderable numeric type; the helper sorts a defensive copy
/// and uses the "nearest-rank" definition of percentile (matching the
/// percentile defaults used in `docker stats` and most CI dashboards).
/// </summary>
public static class LatencyPercentiles
{
    public static double P50(IReadOnlyList<double> samples) => Percentile(samples, 50);
    public static double P95(IReadOnlyList<double> samples) => Percentile(samples, 95);

    public static double Percentile(IReadOnlyList<double> samples, int percentile)
    {
        if (samples.Count == 0)
            throw new ArgumentException("samples must contain at least one value", nameof(samples));
        if (percentile < 0 || percentile > 100)
            throw new ArgumentOutOfRangeException(nameof(percentile), "percentile must be in [0, 100]");

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

        // Nearest-rank: rank = ceil(p/100 * N); index = rank - 1.
        var rank = (int)Math.Ceiling(percentile / 100.0 * sorted.Length);
        if (rank < 1) rank = 1;
        if (rank > sorted.Length) rank = sorted.Length;
        return sorted[rank - 1];
    }

    public static double Mean(IReadOnlyList<double> samples)
    {
        if (samples.Count == 0)
            throw new ArgumentException("samples must contain at least one value", nameof(samples));
        return samples.Average();
    }
}