namespace MSCO.Server;

/// <summary>Die letzten Log-Zeilen im Speicher - für die Live-Konsole im Web-Panel.</summary>
public static class LogBuffer
{
    public readonly record struct Line(long Seq, string Time, string Text);

    const int Capacity = 3000;
    static readonly Queue<Line> lines = new();
    static readonly object gate = new();
    static long seq;

    public static long LastSeq { get { lock (gate) return seq; } }

    public static void Add(string time, string text)
    {
        lock (gate)
        {
            lines.Enqueue(new Line(++seq, time, text));
            while (lines.Count > Capacity) lines.Dequeue();
        }
    }

    /// <summary>Zeilen nach der angegebenen Nummer (höchstens max, die neuesten).</summary>
    public static List<Line> Since(long after, int max)
    {
        lock (gate)
        {
            var result = lines.Where(l => l.Seq > after).ToList();
            return result.Count > max ? result.GetRange(result.Count - max, max) : result;
        }
    }
}