Core/AI: Clean up charm AI handling.

Port From (https://github.com/TrinityCore/TrinityCore/commit/e4e8c1c59c8b37216814526b4d2551f23934f465)

Source/Game/AI/CoreAI/CombatAI.cs

@@ -322,11 +322,12 @@ namespace Game.AI
 
         public override void AttackStart(Unit victim) { }
 
-        public override void OnCharmed(bool apply)
+        public override void OnCharmed(bool isNew)
         {
-            if (!me.GetVehicleKit().IsVehicleInUse() && !apply && _hasConditions)//was used and has conditions
+            bool charmed = me.IsCharmed();
+            if (!me.GetVehicleKit().IsVehicleInUse() && !charmed && _hasConditions)//was used and has conditions
                 _doDismiss = true;//needs reset
-            else if (apply)
+            else if (charmed)
                 _doDismiss = false;//in use again
 
             _dismissTimer = VEHICLE_DISMISS_TIME;//reset timer

Source/Game/AI/CoreAI/CreatureAI.cs

@@ -44,13 +44,20 @@ namespace Game.AI
             _moveInLineOfSightLocked = false;
         }
 
-        public override void OnCharmed(bool apply)
+        public override void OnCharmed(bool isNew)
         {
-            if (apply)
+            if (isNew && !me.IsCharmed() && !me.LastCharmerGUID.IsEmpty())
             {
-                me.NeedChangeAI = true;
-                me.IsAIEnabled = false;
+                if (!me.HasReactState(ReactStates.Passive))
+                {
+                    Unit lastCharmer = Global.ObjAccessor.GetUnit(me, me.LastCharmerGUID);
+                    if (lastCharmer != null)
+                        me.EngageWithTarget(lastCharmer);
+                }
+                me.LastCharmerGUID.Clear();
             }
+
+            base.OnCharmed(isNew);
         }
 
         public void Talk(uint id, WorldObject whisperTarget = null)

Source/Game/AI/CoreAI/PassiveAI.cs

@@ -76,12 +76,6 @@ namespace Game.AI
                 me.RemoveDynamicFlag(UnitDynFlags.Lootable);
         }
 
-        public override void OnCharmed(bool apply)
-        {
-            me.NeedChangeAI = true;
-            me.IsAIEnabled = false;
-        }
-
         public override void MoveInLineOfSight(Unit who) { }
 
         public override void EnterEvadeMode(EvadeReason why) { }
@@ -98,7 +92,7 @@ namespace Game.AI
         public override void AttackStart(Unit unit) { }
         public override void UpdateAI(uint diff) { }
         public override void EnterEvadeMode(EvadeReason why) { }
-        public override void OnCharmed(bool apply) { }
+        public override void OnCharmed(bool isNew) { }
     }
 
     public class CritterAI : PassiveAI

Source/Game/AI/CoreAI/PetAI.cs

@@ -601,12 +601,6 @@ namespace Game.AI
                 }
         }
 
-        public override void OnCharmed(bool apply)
-        {
-            me.NeedChangeAI = true;
-            me.IsAIEnabled = false;
-        }
-
         void ClearCharmInfoFlags()
         {
             // Quick access to set all flags to FALSE

Source/Game/AI/CoreAI/UnitAI.cs

@@ -463,7 +463,18 @@ namespace Game.AI
 
         public virtual void Reset() { }
 
-        public virtual void OnCharmed(bool apply) { }
+        /// <summary>
+        // Called when unit's charm state changes with isNew = false
+        // Implementation should call me->ScheduleAIChange() if AI replacement is desired
+        // If this call is made, AI will be replaced on the next tick
+        // When replacement is made, OnCharmed is called with isNew = true
+        /// </summary>
+        /// <param name="apply"></param>
+        public virtual void OnCharmed(bool isNew)
+        {
+            if (!isNew)
+                me.ScheduleAIChange();
+        }
 
         public virtual bool ShouldSparWith(Unit target) { return false; }
 

Source/Game/AI/PlayerAI/PlayerAI.cs

@@ -655,8 +655,6 @@ namespace Game.AI
             return null;
         }
 
-        public override void OnCharmed(bool apply) { }
-
         // helper functions to determine player info
         public bool IsHealer(Player who = null)
         {
@@ -710,7 +708,14 @@ namespace Game.AI
         {
             Unit charmer = me.GetCharmer();
             if (charmer)
-                return charmer.IsAIEnabled ? charmer.GetAI().SelectTarget(SelectAggroTarget.Random, 0, new ValidTargetSelectPredicate(this)) : charmer.GetVictim();
+            {
+                UnitAI charmerAI = charmer.GetAI();
+                if (charmerAI != null)
+                    return charmerAI.SelectTarget(SelectAggroTarget.Random, 0, new ValidTargetSelectPredicate(this));
+
+                return charmer.GetVictim();
+            }
+
             return null;
         }
 
@@ -1344,9 +1349,9 @@ namespace Game.AI
             }
         }
 
-        public override void OnCharmed(bool apply)
+        public override void OnCharmed(bool isNew)
         {
-            if (apply)
+            if (me.IsCharmed())
             {
                 me.CastStop();
                 me.AttackStop();
@@ -1362,6 +1367,8 @@ namespace Game.AI
                 me.GetMotionMaster().Clear();
                 me.StopMoving();
             }
+
+            base.OnCharmed(isNew);
         }
     }
 

Source/Game/AI/ScriptedAI/ScriptedAI.cs

@@ -673,7 +673,7 @@ namespace Game.AI
             foreach (var id in this)
             {
                 Creature summon = ObjectAccessor.GetCreature(_me, id);
-                if (summon && summon.IsAIEnabled && (entry == 0 || summon.GetEntry() == entry))
+                if (summon && summon.IsAIEnabled() && (entry == 0 || summon.GetEntry() == entry))
                 {
                     summon.GetAI().DoZoneInCombat(null);
                 }
@@ -760,7 +760,7 @@ namespace Game.AI
             foreach (var guid in summons)
             {
                 Creature summon = ObjectAccessor.GetCreature(_me, guid);
-                if (summon && summon.IsAIEnabled)
+                if (summon && summon.IsAIEnabled())
                     summon.GetAI().DoAction(action);
             }
         }

Source/Game/AI/SmartScripts/SmartAI.cs

@@ -714,17 +714,18 @@ namespace Game.AI
             GetScript().ProcessEventsFor(apply ? SmartEvents.PassengerBoarded : SmartEvents.PassengerRemoved, passenger, (uint)seatId, 0, apply);
         }
 
-        public override void OnCharmed(bool apply)
+        public override void OnCharmed(bool isNew)
         {
-            if (apply) // do this before we change charmed state, as charmed state might prevent these things from processing
+            bool charmed = me.IsCharmed();
+            if (charmed) // do this before we change charmed state, as charmed state might prevent these things from processing
             {
                 if (HasEscortState(SmartEscortState.Escorting | SmartEscortState.Paused | SmartEscortState.Returning))
                     EndPath(true);
             }
 
-            _isCharmed = apply;
+            _isCharmed = charmed;
 
-            if (!apply && !me.IsInEvadeMode())
+            if (!charmed && !me.IsInEvadeMode())
             {
                 if (_repeatWaypointPath)
                     StartPath(_run, GetScript().GetPathId(), true);
@@ -736,7 +737,7 @@ namespace Game.AI
                     AttackStart(charmer);
             }
 
-            GetScript().ProcessEventsFor(SmartEvents.Charmed, null, 0, 0, apply);
+            GetScript().ProcessEventsFor(SmartEvents.Charmed, null, 0, 0, charmed);
         }
 
         public override void DoAction(int param)

Source/Game/AI/SmartScripts/SmartScript.cs

@@ -958,7 +958,7 @@ namespace Game.AI
                 }
                 case SmartActions.SetInCombatWithZone:
                 {
-                    if (_me != null && _me.IsAIEnabled)
+                    if (_me != null && _me.IsAIEnabled())
                     {
                         _me.GetAI().DoZoneInCombat();
                         Log.outDebug(LogFilter.ScriptsAi, $"SmartScript.ProcessAction: SMART_ACTION_SET_IN_COMBAT_WITH_ZONE: Creature: {_me.GetGUID()}");