Remove IMoveSpeedModifier in favor of events (#5212)

* Remove IMoveSpeedModifier

* fucking magboots

* yope

* rabiews

Content.Shared/Movement/EntitySystems/MovementSpeedModifierSystem.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using Content.Shared.Movement.Components;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameStates;
@@ -8,6 +10,18 @@ namespace Content.Shared.Movement.EntitySystems
 {
     public sealed class MovementSpeedModifierSystem : EntitySystem
     {
+        private readonly HashSet<EntityUid> _needsRefresh = new();
+
+        public override void Update(float frameTime)
+        {
+            foreach (var uid in _needsRefresh)
+            {
+                RecalculateMovementSpeedModifiers(uid);
+            }
+
+            _needsRefresh.Clear();
+        }
+
         public override void Initialize()
         {
             base.Initialize();
@@ -31,6 +45,25 @@ namespace Content.Shared.Movement.EntitySystems
             component.BaseSprintSpeed = state.BaseSprintSpeed;
         }
 
+        public void RefreshMovementSpeedModifiers(EntityUid uid)
+        {
+            _needsRefresh.Add(uid);
+        }
+
+        private void RecalculateMovementSpeedModifiers(EntityUid uid, MovementSpeedModifierComponent? move = null)
+        {
+            if (!Resolve(uid, ref move, false))
+                return;
+
+            var ev = new RefreshMovementSpeedModifiersEvent();
+            RaiseLocalEvent(uid, ev, false);
+
+            move.WalkSpeedModifier = ev.WalkSpeedModifier;
+            move.SprintSpeedModifier = ev.SprintSpeedModifier;
+
+            move.Dirty();
+        }
+
         [Serializable, NetSerializable]
         private sealed class MovementSpeedModifierComponentState : ComponentState
         {
@@ -38,4 +71,21 @@ namespace Content.Shared.Movement.EntitySystems
             public float BaseSprintSpeed;
         }
     }
+
+    /// <summary>
+    ///     Raised on an entity to determine its new movement speed. Any system that wishes to change movement speed
+    ///     should hook into this event and set it then. If you want this event to be raised,
+    ///     call <see cref="MovementSpeedModifierSystem.RefreshMovementSpeedModifiers"/>.
+    /// </summary>
+    public class RefreshMovementSpeedModifiersEvent : EntityEventArgs
+    {
+        public float WalkSpeedModifier { get; private set; } = 1.0f;
+        public float SprintSpeedModifier { get; private set; } = 1.0f;
+
+        public void ModifySpeed(float walk, float sprint)
+        {
+            WalkSpeedModifier *= walk;
+            SprintSpeedModifier *= sprint;
+        }
+    }
 }