Add indicator showing amount of ghost roles available (#5150)

* Add indicator showing amount of ghost roles available

* Make the indicator turn red if ghost roles are available

Content.Server/Ghost/Roles/GhostRoleSystem.cs

@@ -6,6 +6,7 @@ using Content.Server.Ghost.Roles.Components;
 using Content.Server.Ghost.Roles.UI;
 using Content.Shared.GameTicking;
 using Content.Shared.Ghost.Roles;
+using Content.Shared.Ghost;
 using JetBrains.Annotations;
 using Robust.Server.GameObjects;
 using Robust.Server.Player;
@@ -13,6 +14,7 @@ using Robust.Shared.Console;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.ViewVariables;
+using Robust.Shared.Enums;
 
 namespace Content.Server.Ghost.Roles
 {
@@ -20,8 +22,10 @@ namespace Content.Server.Ghost.Roles
     public class GhostRoleSystem : EntitySystem
     {
         [Dependency] private readonly EuiManager _euiManager = default!;
+        [Dependency] private IPlayerManager _playerManager = default!;
 
         private uint _nextRoleIdentifier = 0;
+        private bool _needsUpdateGhostRoleCount = true;
         private readonly Dictionary<uint, GhostRoleComponent> _ghostRoles = new();
         private readonly Dictionary<IPlayerSession, GhostRolesEui> _openUis = new();
         private readonly Dictionary<IPlayerSession, MakeGhostRoleEui> _openMakeGhostRoleUis = new();
@@ -35,6 +39,15 @@ namespace Content.Server.Ghost.Roles
 
             SubscribeLocalEvent<RoundRestartCleanupEvent>(Reset);
             SubscribeLocalEvent<PlayerAttachedEvent>(OnPlayerAttached);
+
+            _playerManager.PlayerStatusChanged += PlayerStatusChanged;
+        }
+
+        public override void Shutdown()
+        {
+            base.Shutdown();
+
+            _playerManager.PlayerStatusChanged -= PlayerStatusChanged;
         }
 
         private uint GetNextRoleIdentifier()
@@ -91,6 +104,31 @@ namespace Content.Server.Ghost.Roles
             {
                 eui.StateDirty();
             }
+            // Note that this, like the EUIs, is deferred.
+            // This is for roughly the same reasons, too:
+            // Someone might spawn a ton of ghost roles at once.
+            _needsUpdateGhostRoleCount = true;
+        }
+
+        public override void Update(float frameTime)
+        {
+            base.Update(frameTime);
+            if (_needsUpdateGhostRoleCount)
+            {
+                _needsUpdateGhostRoleCount = false;
+                var response = new GhostUpdateGhostRoleCountEvent(_ghostRoles.Count);
+                foreach (var player in _playerManager.GetAllPlayers())
+                    RaiseNetworkEvent(response, player.ConnectedClient);
+            }
+        }
+
+        private void PlayerStatusChanged(object? blah, SessionStatusEventArgs args)
+        {
+            if (args.NewStatus == SessionStatus.InGame)
+            {
+                var response = new GhostUpdateGhostRoleCountEvent(_ghostRoles.Count);
+                RaiseNetworkEvent(response, args.Session.ConnectedClient);
+            }
         }
 
         public void RegisterGhostRole(GhostRoleComponent role)