Refactor SeeingRainbows to new status effect system (#38620)

Content.Shared/StatusEffectNew/StatusEffectSystem.API.cs

@@ -269,7 +269,7 @@ public abstract partial class SharedStatusEffectsSystem
 
         foreach (var effect in container.ActiveStatusEffects)
         {
-            if (!TryComp<StatusEffectComponent>(effect, out var statusComp))
+            if (!_effectQuery.TryComp(effect, out var statusComp))
                 continue;
 
             if (TryComp<T>(effect, out var comp))
@@ -279,6 +279,39 @@ public abstract partial class SharedStatusEffectsSystem
             }
         }
 
-        return effects != null;
+        return effects is not null;
+    }
+
+    /// <summary>
+    /// Helper function for calculating how long it takes for all effects with a particular component to disappear. Useful for overlays.
+    /// </summary>
+    /// <param name="target">An entity from which status effects are checked.</param>
+    /// <param name="endTime">The farthest end time of effects with this component is returned. Can be null if one of the effects is infinite.</param>
+    /// <returns>True if effects with the specified component were found, or False if there are no such effects.</returns>
+    public bool TryGetEffectsEndTimeWithComp<T>(EntityUid? target, out TimeSpan? endTime) where T : IComponent
+    {
+        endTime = _timing.CurTime;
+        if (!_containerQuery.TryComp(target, out var container))
+            return false;
+
+        foreach (var effect in container.ActiveStatusEffects)
+        {
+            if (!HasComp<T>(effect))
+                continue;
+
+            if (!_effectQuery.TryComp(effect, out var statusComp))
+                continue;
+
+            if (statusComp.EndEffectTime is null)
+            {
+                endTime = null;
+                return true; //This effect never ends, so we return null at endTime, but return true that there is time.
+            }
+
+            if (statusComp.EndEffectTime > endTime)
+                endTime = statusComp.EndEffectTime;
+        }
+
+        return endTime is not null;
     }
 }