fix dragon spawn location and round end summary (#31890)

* spawn dragon rule at station edge

* 2

* stuff

* fix round end summary not showing

* no invalid euid

Content.Server/GameTicking/Rules/DragonRuleSystem.cs

@@ -0,0 +1,52 @@
+using Content.Server.Antag;
+using Content.Server.GameTicking.Rules.Components;
+using Content.Server.Station.Components;
+using Content.Server.Station.Systems;
+using Content.Shared.Localizations;
+using Robust.Server.GameObjects;
+
+namespace Content.Server.GameTicking.Rules;
+
+public sealed class DragonRuleSystem : GameRuleSystem<DragonRuleComponent>
+{
+    [Dependency] private readonly TransformSystem _transform = default!;
+    [Dependency] private readonly AntagSelectionSystem _antag = default!;
+    [Dependency] private readonly StationSystem _station = default!;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<DragonRuleComponent, AfterAntagEntitySelectedEvent>(AfterAntagEntitySelected);
+    }
+
+    private void AfterAntagEntitySelected(Entity<DragonRuleComponent> ent, ref AfterAntagEntitySelectedEvent args)
+    {
+        _antag.SendBriefing(args.EntityUid, MakeBriefing(args.EntityUid), null, null);
+    }
+
+    private string MakeBriefing(EntityUid dragon)
+    {
+        var direction = string.Empty;
+
+        var dragonXform = Transform(dragon);
+
+        var station = _station.GetStationInMap(dragonXform.MapID);
+        EntityUid? stationGrid = null;
+        if (TryComp<StationDataComponent>(station, out var stationData))
+            stationGrid = _station.GetLargestGrid(stationData);
+
+        if (stationGrid is not null)
+        {
+            var stationPosition = _transform.GetWorldPosition((EntityUid)stationGrid);
+            var dragonPosition = _transform.GetWorldPosition(dragon);
+
+            var vectorToStation = stationPosition - dragonPosition;
+            direction = ContentLocalizationManager.FormatDirection(vectorToStation.GetDir());
+        }
+
+        var briefing = Loc.GetString("dragon-role-briefing", ("direction", direction));
+
+        return briefing;
+    }
+}