Update puddle stickiness (#16597)

Content.Server/Fluids/EntitySystems/PuddleSystem.cs

@@ -25,6 +25,8 @@ using Solution = Content.Shared.Chemistry.Components.Solution;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Random;
 using Robust.Shared.Timing;
+using Content.Shared.Movement.Components;
+using Content.Shared.Movement.Systems;
 
 namespace Content.Server.Fluids.EntitySystems;
 
@@ -47,6 +49,7 @@ public sealed partial class PuddleSystem : SharedPuddleSystem
     [Dependency] private readonly StepTriggerSystem _stepTrigger = default!;
     [Dependency] private readonly SolutionContainerSystem _solutionContainerSystem = default!;
     [Dependency] private readonly TileFrictionController _tile = default!;
+    [Dependency] private readonly SlowContactsSystem _slowContacts = default!;
 
     public static float PuddleVolume = 1000;
 
@@ -242,6 +245,7 @@ public sealed partial class PuddleSystem : SharedPuddleSystem
 
         _deletionQueue.Remove(uid);
         UpdateSlip(uid, component, args.Solution);
+        UpdateSlow(uid, args.Solution);
         UpdateEvaporation(uid, args.Solution);
         UpdateAppearance(uid, component);
     }
@@ -319,6 +323,26 @@ public sealed partial class PuddleSystem : SharedPuddleSystem
         }
     }
 
+    private void UpdateSlow(EntityUid uid, Solution solution)
+    {
+        var maxViscosity = 0f;
+        foreach (var reagent in solution.Contents)
+        {
+            var reagentProto = _prototypeManager.Index<ReagentPrototype>(reagent.ReagentId);
+            maxViscosity = Math.Max(maxViscosity, reagentProto.Viscosity);
+        }
+        if (maxViscosity > 0)
+        {
+            var comp = EnsureComp<SlowContactsComponent>(uid);
+            var speed = 1 - maxViscosity;
+            _slowContacts.ChangeModifiers(uid, speed, comp);
+        }
+        else
+        {
+            RemComp<SlowContactsComponent>(uid);
+        }
+    }
+
     private void HandlePuddleExamined(EntityUid uid, PuddleComponent component, ExaminedEvent args)
     {
         if (TryComp<StepTriggerComponent>(uid, out var slippery) && slippery.Active)