smartaction-spt4/Patch/MovementPatchUtil.cs

using System.Reflection;
using EFT;
using HarmonyLib;

namespace SmartAction.Patch;

internal static class MovementPatchUtil
{
    // MovementContext._player is protected, so it needs reflection. Resolved once at
    // type-init rather than per call — these postfixes run on every movement query.
    private static readonly FieldInfo PlayerField = AccessTools.Field(typeof(MovementContext), "_player");

    /// <summary>
    /// True only for the player this client controls.
    ///
    /// Every bot and, under Fika, every remote player owns its own MovementContext, and these
    /// postfixes fire for all of them. Gating on IsYourPlayer is what keeps the patches inert
    /// for everyone else — it is the entire multiplayer-safety story for Stage 1.
    /// </summary>
    internal static bool IsLocalPlayer(MovementContext context)
    {
        var value = PlayerField?.GetValue(context);

        // Fast path when instrumentation is off: no counters, no branches beyond the check.
        if (!Diagnostics.Enabled)
        {
            return value is Player { IsYourPlayer: true };
        }

        if (value is not Player player)
        {
            // Predicted failure mode: a MovementContext whose _player is not yet assigned
            // (bot mid-spawn). The pattern match absorbs it rather than throwing an NRE.
            Diagnostics.NullPlayerCalls++;
            Diagnostics.OnceNullPlayer();
            Diagnostics.Tick();
            return false;
        }

        var isLocal = player.IsYourPlayer;
        if (isLocal) Diagnostics.LocalCalls++;
        else Diagnostics.NonLocalCalls++;

        Diagnostics.Tick();
        return isLocal;
    }
}