wwdpublic/Content.Client/Administration/Systems/AdminSystem.cs

using System.Linq;
using Content.Shared.Administration;
using Content.Shared.Administration.Events;
using Content.Shared.GameTicking;
using Robust.Shared.Network;

namespace Content.Client.Administration.Systems
{
    public sealed partial class AdminSystem : EntitySystem
    {
        public event Action<List<PlayerInfo>>? PlayerListChanged;

        public Dictionary<NetUserId, PlayerInfo> PlayerInfos = new();
        public IReadOnlyList<PlayerInfo> PlayerList =>
            PlayerInfos != null ? PlayerInfos.Values.ToList() : new List<PlayerInfo>();

        public override void Initialize()
        {
            base.Initialize();

            InitializeOverlay();
            SubscribeNetworkEvent<FullPlayerListEvent>(OnPlayerListChanged);
            SubscribeNetworkEvent<PlayerInfoChangedEvent>(OnPlayerInfoChanged);
        }

        public override void Shutdown()
        {
            base.Shutdown();
            ShutdownOverlay();
        }

        private void OnPlayerInfoChanged(PlayerInfoChangedEvent ev)
        {
            if(ev.PlayerInfo == null) return;

            if (PlayerInfos == null) PlayerInfos = new();

            PlayerInfos[ev.PlayerInfo.SessionId] = ev.PlayerInfo;
            PlayerListChanged?.Invoke(PlayerInfos.Values.ToList());
        }

        private void OnPlayerListChanged(FullPlayerListEvent msg)
        {
            PlayerInfos = msg.PlayersInfo.ToDictionary(x => x.SessionId, x => x);
            PlayerListChanged?.Invoke(msg.PlayersInfo);
        }
    }
}