Core/AI: Make critters flee as soon as engaged in combat and make them evade after they stop running in fear

Port From (https://github.com/TrinityCore/TrinityCore/commit/934c320d4b0da40691be7449f860447fe79b4083)

Source/Game/AI/CoreAI/PassiveAI.cs

@@ -119,12 +119,18 @@ namespace Game.AI
             me.SetReactState(ReactStates.Passive);
         }
 
-        public override void DamageTaken(Unit done_by, ref uint damage)
+        public override void JustEngagedWith(Unit who)
         {
             if (!me.HasUnitState(UnitState.Fleeing))
                 me.SetControlled(true, UnitState.Fleeing);
         }
 
+        public override void OnMovementGeneratorFinalized(MovementGeneratorType type)
+        {
+            if (type == MovementGeneratorType.TimedFleeing)
+                EnterEvadeMode(EvadeReason.Other);
+        }
+
         public override void EnterEvadeMode(EvadeReason why)
         {
             if (me.HasUnitState(UnitState.Fleeing))

Source/Game/AI/CoreAI/UnitAI.cs

@@ -502,6 +502,8 @@ namespace Game.AI
         /// </summary>
         public virtual void OnGameEvent(bool start, ushort eventId) { }
 
+        public virtual void OnMovementGeneratorFinalized(MovementGeneratorType type) { }
+
         public virtual string GetDebugInfo()
         {
             return $"Me: {(me != null ? me.GetDebugInfo() : "NULL")}";

Source/Game/Movement/Generators/MovementGenerators.cs

@@ -16,6 +16,7 @@
  */
 
 using Framework.Constants;
+using Game.AI;
 using Game.Entities;
 using System;
 
@@ -60,6 +61,12 @@ namespace Game.Movement
             return false;
         }
 
+        public void NotifyAIOnFinalize(Unit obj)
+        {
+            UnitAI ai = obj.GetAI();
+            ai?.OnMovementGeneratorFinalized(GetMovementGeneratorType());
+        }
+
         public void AddFlag(MovementGeneratorFlags flag) { Flags |= flag; }
         public bool HasFlag(MovementGeneratorFlags flag) { return (Flags & flag) != 0; }
         public void RemoveFlag(MovementGeneratorFlags flag) { Flags &= ~flag; }

Source/Game/Movement/MotionMaster.cs

@@ -16,6 +16,7 @@
  */
 
 using Framework.Constants;
+using Framework.Dynamic;
 using Game.AI;
 using Game.DataStorage;
 using Game.Entities;
@@ -23,7 +24,6 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Numerics;
-using Framework.Dynamic;
 
 namespace Game.Movement
 {
@@ -1113,7 +1113,10 @@ namespace Game.Movement
             {
                 case MovementSlot.Default:
                     if (_defaultGenerator != null)
+                    {
                         _defaultGenerator.Finalize(_owner, _generators.Empty(), false);
+                        _defaultGenerator.NotifyAIOnFinalize(_owner);
+                    }
 
                     _defaultGenerator = movement;
                     if (IsStatic(movement))
@@ -1151,12 +1154,14 @@ namespace Game.Movement
         void Delete(MovementGenerator movement, bool active, bool movementInform)
         {
             movement.Finalize(_owner, active, movementInform);
+            movement.NotifyAIOnFinalize(_owner);
             ClearBaseUnitState(movement);
         }
 
         void DeleteDefault(bool active, bool movementInform)
         {
             _defaultGenerator.Finalize(_owner, active, movementInform);
+            _defaultGenerator.NotifyAIOnFinalize(_owner);
             _defaultGenerator = GetIdleMovementGenerator();
             AddFlag(MotionMasterFlags.StaticInitializationPending);
         }