Move rotting stages and examine to shared (#24183)

Content.Shared/Atmos/Rotting/SharedRottingSystem.cs

@@ -0,0 +1,39 @@
+using Content.Shared.Examine;
+using Content.Shared.IdentityManagement;
+
+namespace Content.Shared.Atmos.Rotting;
+
+public abstract class SharedRottingSystem : EntitySystem
+{
+    public const int MaxStages = 3;
+
+    public override void Initialize()
+    {
+        base.Initialize();
+
+        SubscribeLocalEvent<RottingComponent, ExaminedEvent>(OnExamined);
+    }
+
+    /// <summary>
+    /// Return the rot stage, usually from 0 to 2 inclusive.
+    /// </summary>
+    public int RotStage(EntityUid uid, RottingComponent? comp = null, PerishableComponent? perishable = null)
+    {
+        if (!Resolve(uid, ref comp, ref perishable))
+            return 0;
+
+        return (int) (comp.TotalRotTime.TotalSeconds / perishable.RotAfter.TotalSeconds);
+    }
+
+    private void OnExamined(EntityUid uid, RottingComponent component, ExaminedEvent args)
+    {
+        var stage = RotStage(uid, component);
+        var description = stage switch
+        {
+            >= 2 => "rotting-extremely-bloated",
+            >= 1 => "rotting-bloated",
+            _ => "rotting-rotting"
+        };
+        args.PushMarkup(Loc.GetString(description, ("target", Identity.Entity(uid, EntityManager))));
+    }
+}