using System.Globalization;

namespace Godosa.Core.Diagnostics;

/// <summary>Per-frame CSV rows for perf-log stall hunts. Fixed columns first, then the
/// caller's own (<see cref="Header"/> names, <see cref="Row"/> values, same order).
/// Invariant culture; times in ms with 3 decimals; blank = unknown (e.g. GPU before a
/// timer query reports).</summary>
public static class PerfCsv
{
    public const string BaseHeader = "t_s,frame_ms,work_ms,sim_ticks,sim_ms,gpu_ms";

    public static string Header(params string[] extraColumns) =>
        extraColumns.Length == 0 ? BaseHeader : BaseHeader + "," + string.Join(',', extraColumns);

    public static string Row(double timeSeconds, double frameSeconds, double workSeconds, int simTicks,
        double simSeconds, double? gpuSeconds, params string[] extraValues)
    {
        string row = string.Create(CultureInfo.InvariantCulture,
            $"{timeSeconds:F3},{frameSeconds * 1000:F3},{workSeconds * 1000:F3},{simTicks},{simSeconds * 1000:F3},{Ms(gpuSeconds)}");
        return extraValues.Length == 0 ? row : row + "," + string.Join(',', extraValues);
    }

    /// <summary>Seconds → ms with 3 decimals (invariant); blank for null.</summary>
    public static string Ms(double? seconds) =>
        seconds is { } s ? (s * 1000).ToString("F3", CultureInfo.InvariantCulture) : "";
}