using System;

namespace AcDream.App.Streaming;

/// <summary>
/// TEMP diagnostic (#138-B avatar-vanish). Env-gated (<c>ACDREAM_PROBE_ENT=1</c>)
/// trace of the persistent player entity across teleport streaming churn:
/// whether it is present in the render draw-DATA (<see cref="GpuWorldState"/>
/// flat view) and whether it survives the dynamics CULL
/// (<c>RetailPViewRenderer.DrawDynamicsLast</c>).
///
/// <para>The two halves answer the decisive question: is the avatar
/// "missing for a moment" because it is <b>absent from the draw set</b>
/// (re-injected into the pending bucket while its landblock re-streams), or
/// because it is <b>present but culled</b> (in the dynamics list, dropped by
/// the outside-stage / viewcone gate)?</para>
///
/// <para>STRIP once #138-B is root-caused (throwaway, like the dense-town FPS
/// apparatus). Observation-only — emits no behavior change.</para>
/// </summary>
internal static class EntityVanishProbe
{
    public static readonly bool Enabled =
        Environment.GetEnvironmentVariable("ACDREAM_PROBE_ENT") == "1";

    /// <summary>Player server guid, set once at world entry so the draw-side
    /// <c>[dyn]</c> line can single out the avatar without plumbing the guid
    /// through the render stack.</summary>
    public static uint PlayerGuid;

    public static void Log(string msg)
    {
        if (Enabled) Console.WriteLine(msg);
    }

    private static string _lastPlayerDyn = "";

    /// <summary>Emit a <c>[dyn] player</c> line only when the outcome string
    /// changes — a stationary, drawn avatar must not spam one line per frame
    /// (that console+Tee I/O would itself depress FPS and bury the signal).
    /// Fires on cell change or DRAWN↔CULLED transition.</summary>
    public static void LogPlayerDynOnChange(string status)
    {
        if (!Enabled) return;
        if (status == _lastPlayerDyn) return;
        _lastPlayerDyn = status;
        Console.WriteLine("[dyn] player " + status);
    }
}