Objectives ecs rework (#19967)

Co-authored-by: deltanedas <@deltanedas:kde.org>

Content.Server/Objectives/Systems/MultipleTraitorsRequirementSystem.cs

@@ -0,0 +1,29 @@
+using Content.Server.GameTicking.Rules;
+using Content.Server.Objectives.Components;
+using Content.Shared.Objectives.Components;
+
+namespace Content.Server.Objectives.Systems;
+
+/// <summary>
+/// Handles requiring multiple traitors being alive for the objective to be given.
+/// </summary>
+public sealed class MultipleTraitorsRequirementSystem : EntitySystem
+{
+    [Dependency] private readonly TraitorRuleSystem _traitorRule = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<MultipleTraitorsRequirementComponent, RequirementCheckEvent>(OnCheck);
+    }
+
+    private void OnCheck(EntityUid uid, MultipleTraitorsRequirementComponent comp, ref RequirementCheckEvent args)
+    {
+        if (args.Cancelled)
+            return;
+
+        if (_traitorRule.GetOtherTraitorMindsAliveAndConnected(args.Mind).Count < comp.Traitors)
+            args.Cancelled = true;
+    }
+}