Core/AI: Clean up charm AI handling, we now have two unique_ptr instead of a crapton of booleans

37 files changed, 249 insertions, 308 deletions

diff --git a/src/server/game/AI/CoreAI/CombatAI.cpp b/src/server/game/AI/CoreAI/CombatAI.cpp
index 680b5ebb7c3..60ed90b8507 100644
--- a/src/server/game/AI/CoreAI/CombatAI.cpp
+++ b/src/server/game/AI/CoreAI/CombatAI.cpp
@@ -288,13 +288,14 @@ void VehicleAI::UpdateAI(uint32 diff)
     }
 }
 
-void VehicleAI::OnCharmed(bool apply)
+void VehicleAI::OnCharmed(bool /*isNew*/)
 {
-    if (!me->GetVehicleKit()->IsVehicleInUse() && !apply && m_HasConditions) // was used and has conditions
+    bool const charmed = me->IsCharmed();
+    if (!me->GetVehicleKit()->IsVehicleInUse() && !charmed && m_HasConditions) // was used and has conditions
     {
         m_DoDismiss = true; // needs reset
     }
-    else if (apply)
+    else if (charmed)
         m_DoDismiss = false; // in use again
 
     m_DismissTimer = VEHICLE_DISMISS_TIME; // reset timer
diff --git a/src/server/game/AI/CoreAI/CombatAI.h b/src/server/game/AI/CoreAI/CombatAI.h
index a27c8fc64ef..7c4525d1b0d 100644
--- a/src/server/game/AI/CoreAI/CombatAI.h
+++ b/src/server/game/AI/CoreAI/CombatAI.h
@@ -103,7 +103,7 @@ struct TC_GAME_API VehicleAI : public CreatureAI
         void UpdateAI(uint32 diff) override;
         void MoveInLineOfSight(Unit*) override { }
         void AttackStart(Unit*) override { }
-        void OnCharmed(bool apply) override;
+        void OnCharmed(bool isNew) override;
 
         static int32 Permissible(Creature const* creature);
 
diff --git a/src/server/game/AI/CoreAI/PassiveAI.cpp b/src/server/game/AI/CoreAI/PassiveAI.cpp
index f0c8958a14c..52b04cc90a0 100644
--- a/src/server/game/AI/CoreAI/PassiveAI.cpp
+++ b/src/server/game/AI/CoreAI/PassiveAI.cpp
@@ -69,12 +69,6 @@ void PossessedAI::KilledUnit(Unit* victim)
         victim->RemoveFlag(UNIT_DYNAMIC_FLAGS, UNIT_DYNFLAG_LOOTABLE);
 }
 
-void PossessedAI::OnCharmed(bool /*apply*/)
-{
-    me->NeedChangeAI = true;
-    me->IsAIEnabled = false;
-}
-
 void CritterAI::DamageTaken(Unit* /*done_by*/, uint32&)
 {
     if (!me->HasUnitState(UNIT_STATE_FLEEING))
diff --git a/src/server/game/AI/CoreAI/PassiveAI.h b/src/server/game/AI/CoreAI/PassiveAI.h
index 93b2577e9f3..ce4efe52372 100644
--- a/src/server/game/AI/CoreAI/PassiveAI.h
+++ b/src/server/game/AI/CoreAI/PassiveAI.h
@@ -46,8 +46,6 @@ class TC_GAME_API PossessedAI : public CreatureAI
         void JustDied(Unit*) override;
         void KilledUnit(Unit* victim) override;
 
-        void OnCharmed(bool /*apply*/) override;
-
         static int32 Permissible(Creature const* /*creature*/) { return PERMIT_BASE_NO; }
 };
 
@@ -60,7 +58,7 @@ class TC_GAME_API NullCreatureAI : public CreatureAI
         void AttackStart(Unit*) override { }
         void UpdateAI(uint32) override { }
         void EnterEvadeMode(EvadeReason /*why*/) override { }
-        void OnCharmed(bool /*apply*/) override { }
+        void OnCharmed(bool /*isNew*/) override { }
 
         static int32 Permissible(Creature const* creature);
 };
diff --git a/src/server/game/AI/CoreAI/PetAI.cpp b/src/server/game/AI/CoreAI/PetAI.cpp
index a16ffc6721d..20a93451c93 100644
--- a/src/server/game/AI/CoreAI/PetAI.cpp
+++ b/src/server/game/AI/CoreAI/PetAI.cpp
@@ -610,12 +610,6 @@ void PetAI::ReceiveEmote(Player* player, uint32 emote)
         }
 }
 
-void PetAI::OnCharmed(bool /*apply*/)
-{
-    me->NeedChangeAI = true;
-    me->IsAIEnabled = false;
-}
-
 void PetAI::ClearCharmInfoFlags()
 {
     // Quick access to set all flags to FALSE
diff --git a/src/server/game/AI/CoreAI/PetAI.h b/src/server/game/AI/CoreAI/PetAI.h
index d8b4002293a..d41a1080f6d 100644
--- a/src/server/game/AI/CoreAI/PetAI.h
+++ b/src/server/game/AI/CoreAI/PetAI.h
@@ -52,8 +52,6 @@ class TC_GAME_API PetAI : public CreatureAI
         void MoveInLineOfSight_Safe(Unit* /*who*/) { } // CreatureAI interferes with returning pets
         void EnterEvadeMode(EvadeReason /*why*/) override { } // For fleeing, pets don't use this type of Evade mechanic
 
-        void OnCharmed(bool /*apply*/) override;
-
     private:
         bool _needToStop(void);
         void _stopAttack(void);
diff --git a/src/server/game/AI/CoreAI/UnitAI.cpp b/src/server/game/AI/CoreAI/UnitAI.cpp
index 0d8700fb091..01c7dd6997f 100644
--- a/src/server/game/AI/CoreAI/UnitAI.cpp
+++ b/src/server/game/AI/CoreAI/UnitAI.cpp
@@ -47,6 +47,12 @@ void UnitAI::InitializeAI()
         Reset();
 }
 
+void UnitAI::OnCharmed(bool isNew)
+{
+    if (!isNew)
+        me->ScheduleAIChange();
+}
+
 void UnitAI::AttackStartCaster(Unit* victim, float dist)
 {
     if (victim && me->Attack(victim, false))
diff --git a/src/server/game/AI/CoreAI/UnitAI.h b/src/server/game/AI/CoreAI/UnitAI.h
index 5b2071b9d8d..a15a15fe199 100644
--- a/src/server/game/AI/CoreAI/UnitAI.h
+++ b/src/server/game/AI/CoreAI/UnitAI.h
@@ -143,8 +143,11 @@ class TC_GAME_API UnitAI
 
         virtual void Reset() { }
 
-        // Called when unit is charmed
-        virtual void OnCharmed(bool apply) = 0;
+        // 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
+        virtual void OnCharmed(bool isNew);
 
         // Pass parameters between AI
         virtual void DoAction(int32 /*param*/) { }
diff --git a/src/server/game/AI/CreatureAI.cpp b/src/server/game/AI/CreatureAI.cpp
index 7b6615f36f1..d322a7d9597 100644
--- a/src/server/game/AI/CreatureAI.cpp
+++ b/src/server/game/AI/CreatureAI.cpp
@@ -33,12 +33,14 @@
 #include "World.h"
 
 //Disable CreatureAI when charmed
-void CreatureAI::OnCharmed(bool apply)
+void CreatureAI::OnCharmed(bool isNew)
 {
-    if (apply)
+    if (isNew && !me->IsCharmed() && me->LastCharmerGUID)
     {
-        me->NeedChangeAI = true;
-        me->IsAIEnabled = false;
+        if (!me->HasReactState(REACT_PASSIVE))
+            if (Unit* lastCharmer = ObjectAccessor::GetUnit(*me, me->LastCharmerGUID))
+                me->EngageWithTarget(lastCharmer);
+            me->LastCharmerGUID.Clear();
     }
 }
 
diff --git a/src/server/game/AI/CreatureAI.h b/src/server/game/AI/CreatureAI.h
index f189462bd8b..c4b67765a63 100644
--- a/src/server/game/AI/CreatureAI.h
+++ b/src/server/game/AI/CreatureAI.h
@@ -139,7 +139,7 @@ class TC_GAME_API CreatureAI : public UnitAI
         // Called at waypoint reached or point movement finished
         virtual void MovementInform(uint32 /*type*/, uint32 /*id*/) { }
 
-        void OnCharmed(bool apply) override;
+        void OnCharmed(bool isNew) override;
 
         // Called at reaching home after evade
         virtual void JustReachedHome() { }
diff --git a/src/server/game/AI/PlayerAI/PlayerAI.cpp b/src/server/game/AI/PlayerAI/PlayerAI.cpp
index 98cfbd287f7..a17e465c131 100644
--- a/src/server/game/AI/PlayerAI/PlayerAI.cpp
+++ b/src/server/game/AI/PlayerAI/PlayerAI.cpp
@@ -806,7 +806,11 @@ bool SimpleCharmedPlayerAI::CanAIAttack(Unit const* who) const
 Unit* SimpleCharmedPlayerAI::SelectAttackTarget() const
 {
     if (Unit* charmer = me->GetCharmer())
-        return charmer->IsAIEnabled ? charmer->GetAI()->SelectTarget(SELECT_TARGET_RANDOM, 0, ValidTargetSelectPredicate(this)) : charmer->GetVictim();
+    {
+        if (UnitAI* charmerAI = charmer->GetAI())
+            return charmerAI->SelectTarget(SELECT_TARGET_RANDOM, 0, ValidTargetSelectPredicate(this));
+        return charmer->GetVictim();
+    }
     return nullptr;
 }
 
@@ -1321,6 +1325,7 @@ PlayerAI::TargetedSpell SimpleCharmedPlayerAI::SelectAppropriateCastForSpec()
 static const float CASTER_CHASE_DISTANCE = 28.0f;
 void SimpleCharmedPlayerAI::UpdateAI(const uint32 diff)
 {
+    printf("SCPAI updateai %u\n", diff);
     Creature* charmer = GetCharmer();
     if (!charmer)
         return;
@@ -1422,9 +1427,10 @@ void SimpleCharmedPlayerAI::UpdateAI(const uint32 diff)
     }
 }
 
-void SimpleCharmedPlayerAI::OnCharmed(bool apply)
+void SimpleCharmedPlayerAI::OnCharmed(bool isNew)
 {
-    if (apply)
+    printf("SCPAI oncharm %u\n", isNew);
+    if (me->IsCharmed())
     {
         me->CastStop();
         me->AttackStop();
@@ -1440,4 +1446,5 @@ void SimpleCharmedPlayerAI::OnCharmed(bool apply)
         me->GetMotionMaster()->Clear();
         me->StopMoving();
     }
+    PlayerAI::OnCharmed(isNew);
 }
diff --git a/src/server/game/AI/PlayerAI/PlayerAI.h b/src/server/game/AI/PlayerAI/PlayerAI.h
index 348e89ba52c..ed77e46c1eb 100644
--- a/src/server/game/AI/PlayerAI/PlayerAI.h
+++ b/src/server/game/AI/PlayerAI/PlayerAI.h
@@ -29,8 +29,6 @@ class TC_GAME_API PlayerAI : public UnitAI
     public:
         explicit PlayerAI(Player* player);
 
-        void OnCharmed(bool /*apply*/) override { } // charm AI application for players is handled by Unit::SetCharmedBy / Unit::RemoveCharmedBy
-
         Creature* GetCharmer() const;
 
         // helper functions to determine player info
@@ -101,7 +99,7 @@ class TC_GAME_API SimpleCharmedPlayerAI : public PlayerAI
     public:
         SimpleCharmedPlayerAI(Player* player) : PlayerAI(player), _castCheckTimer(2500), _chaseCloser(false), _forceFacing(true), _isFollowing(false) { }
         void UpdateAI(uint32 diff) override;
-        void OnCharmed(bool apply) override;
+        void OnCharmed(bool isNew) override;
 
     protected:
         bool CanAIAttack(Unit const* who) const override;
diff --git a/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp b/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
index f58cd12829f..d57dc6c4c24 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
@@ -54,7 +54,7 @@ void SummonList::DoZoneInCombat(uint32 entry)
     {
         Creature* summon = ObjectAccessor::GetCreature(*me, *i);
         ++i;
-        if (summon && summon->IsAIEnabled
+        if (summon && summon->IsAIEnabled()
                 && (!entry || summon->GetEntry() == entry))
         {
             summon->AI()->DoZoneInCombat(nullptr);
@@ -118,7 +118,7 @@ void SummonList::DoActionImpl(int32 action, StorageType const& summons)
     for (auto const& guid : summons)
     {
         Creature* summon = ObjectAccessor::GetCreature(*me, guid);
-        if (summon && summon->IsAIEnabled)
+        if (summon && summon->IsAIEnabled())
             summon->AI()->DoAction(action);
     }
 }
diff --git a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
index c82ad99911a..56675f48218 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
@@ -154,13 +154,6 @@ void EscortAI::MovementInform(uint32 type, uint32 id)
     }
 }
 
-///@todo investigate whether if its necessary to handle anything on charm
-/*
-void EscortAI::OnCharmed(bool apply)
-{
-}
-*/
-
 void EscortAI::UpdateAI(uint32 diff)
 {
     // Waypoint Updating
diff --git a/src/server/game/AI/SmartScripts/SmartAI.cpp b/src/server/game/AI/SmartScripts/SmartAI.cpp
index 56bad41e3a4..058652563c3 100644
--- a/src/server/game/AI/SmartScripts/SmartAI.cpp
+++ b/src/server/game/AI/SmartScripts/SmartAI.cpp
@@ -661,17 +661,18 @@ void SmartAI::PassengerBoarded(Unit* who, int8 seatId, bool apply)
     GetScript()->ProcessEventsFor(apply ? SMART_EVENT_PASSENGER_BOARDED : SMART_EVENT_PASSENGER_REMOVED, who, uint32(seatId), 0, apply);
 }
 
-void SmartAI::OnCharmed(bool apply)
+void SmartAI::OnCharmed(bool /*isNew*/)
 {
-    if (apply) // do this before we change charmed state, as charmed state might prevent these things from processing
+    bool const charmed = me->IsCharmed();
+    if (charmed) // do this before we change charmed state, as charmed state might prevent these things from processing
     {
         if (HasEscortState(SMART_ESCORT_ESCORTING | SMART_ESCORT_PAUSED | SMART_ESCORT_RETURNING))
             EndPath(true);
     }
 
-    mIsCharmed = apply;
+    mIsCharmed = charmed;
 
-    if (!apply && !me->IsInEvadeMode())
+    if (!charmed && !me->IsInEvadeMode())
     {
         if (_repeatWaypointPath)
             StartPath(mRun, GetScript()->GetPathId(), true);
@@ -682,7 +683,7 @@ void SmartAI::OnCharmed(bool apply)
             AttackStart(charmer);
     }
 
-    GetScript()->ProcessEventsFor(SMART_EVENT_CHARMED, nullptr, 0, 0, apply);
+    GetScript()->ProcessEventsFor(SMART_EVENT_CHARMED, nullptr, 0, 0, charmed);
 }
 
 void SmartAI::DoAction(int32 param)
diff --git a/src/server/game/AI/SmartScripts/SmartAI.h b/src/server/game/AI/SmartScripts/SmartAI.h
index 2164509ac52..b96682564fe 100644
--- a/src/server/game/AI/SmartScripts/SmartAI.h
+++ b/src/server/game/AI/SmartScripts/SmartAI.h
@@ -140,7 +140,7 @@ class TC_GAME_API SmartAI : public CreatureAI
         void InitializeAI() override;
 
         // Called when creature gets charmed by another unit
-        void OnCharmed(bool apply) override;
+        void OnCharmed(bool isNew) override;
 
         // Used in scripts to share variables
         void DoAction(int32 param = 0) override;
diff --git a/src/server/game/AI/SmartScripts/SmartScript.cpp b/src/server/game/AI/SmartScripts/SmartScript.cpp
index cc5aeb2dcd5..7d5bbac162c 100644
--- a/src/server/game/AI/SmartScripts/SmartScript.cpp
+++ b/src/server/game/AI/SmartScripts/SmartScript.cpp
@@ -1037,7 +1037,7 @@ void SmartScript::ProcessAction(SmartScriptHolder& e, Unit* unit, uint32 var0, u
         }
         case SMART_ACTION_SET_IN_COMBAT_WITH_ZONE:
         {
-            if (me && me->IsAIEnabled)
+            if (me && me->IsAIEnabled())
             {
                 me->AI()->DoZoneInCombat();
                 TC_LOG_DEBUG("scripts.ai", "SmartScript::ProcessAction: SMART_ACTION_SET_IN_COMBAT_WITH_ZONE: Creature %u", me->GetGUID().GetCounter());
diff --git a/src/server/game/Combat/CombatManager.cpp b/src/server/game/Combat/CombatManager.cpp
index 2e90d37bcb7..0024195bbed 100644
--- a/src/server/game/Combat/CombatManager.cpp
+++ b/src/server/game/Combat/CombatManager.cpp
@@ -71,10 +71,12 @@ void CombatReference::EndCombat()
     bool const needSecondAI = second->GetCombatManager().UpdateOwnerCombatState();
 
     // ...and if that happened, also notify the AI of it...
-    if (needFirstAI && first->IsAIEnabled)
-        first->GetAI()->JustExitedCombat();
-    if (needSecondAI && second->IsAIEnabled)
-        second->GetAI()->JustExitedCombat();
+    if (needFirstAI)
+        if (UnitAI* firstAI = first->GetAI())
+            firstAI->JustExitedCombat();
+    if (needSecondAI)
+        if (UnitAI* secondAI = second->GetAI())
+            secondAI->JustExitedCombat();
 
     // ...and finally clean up the reference object
     delete this;
@@ -114,8 +116,8 @@ void PvPCombatReference::SuppressFor(Unit* who)
 {
     Suppress(who);
     if (who->GetCombatManager().UpdateOwnerCombatState())
-        if (who->IsAIEnabled)
-            who->GetAI()->JustExitedCombat();
+        if (UnitAI* ai = who->GetAI())
+            ai->JustExitedCombat();
 }
 
 CombatManager::~CombatManager()
@@ -271,8 +273,8 @@ void CombatManager::SuppressPvPCombat()
     for (auto const& pair : _pvpRefs)
         pair.second->Suppress(_owner);
     if (UpdateOwnerCombatState())
-        if (_owner->IsAIEnabled)
-            _owner->GetAI()->JustExitedCombat();
+        if (UnitAI* ownerAI = _owner->GetAI())
+            ownerAI->JustExitedCombat();
 }
 
 void CombatManager::EndAllPvECombat()
@@ -292,7 +294,7 @@ void CombatManager::EndAllPvPCombat()
 
 /*static*/ void CombatManager::NotifyAICombat(Unit* me, Unit* other)
 {
-    if (!me->IsAIEnabled)
+    if (!me->IsAIEnabled())
         return;
     me->GetAI()->JustEnteredCombat(other);
 
diff --git a/src/server/game/Combat/ThreatManager.cpp b/src/server/game/Combat/ThreatManager.cpp
index 0a28183b3fd..50e195088c1 100644
--- a/src/server/game/Combat/ThreatManager.cpp
+++ b/src/server/game/Combat/ThreatManager.cpp
@@ -96,7 +96,7 @@ ThreatReference::OnlineState ThreatReference::SelectOnlineState()
         return ONLINE_STATE_OFFLINE;
     if (!FlagsAllowFighting(_owner, _victim) || !FlagsAllowFighting(_victim, _owner))
         return ONLINE_STATE_OFFLINE;
-    if (_owner->IsAIEnabled && !_owner->GetAI()->CanAIAttack(_victim))
+    if (_owner->IsAIEnabled() && !_owner->GetAI()->CanAIAttack(_victim))
         return ONLINE_STATE_OFFLINE;
     // next, check suppression (immunity to chosen melee attack school)
     if (_victim->IsImmunedToDamage(_owner->GetMeleeDamageSchoolMask()))
@@ -280,7 +280,7 @@ void ThreatManager::UpdateOnlineStates(bool meThreateningOthers, bool othersThre
 static void SaveCreatureHomePositionIfNeed(Creature* c)
 {
     MovementGeneratorType const movetype = c->GetMotionMaster()->GetCurrentMovementGeneratorType();
-    if (movetype == WAYPOINT_MOTION_TYPE || movetype == POINT_MOTION_TYPE || (c->IsAIEnabled && c->AI()->IsEscorted()))
+    if (movetype == WAYPOINT_MOTION_TYPE || movetype == POINT_MOTION_TYPE || (c->IsAIEnabled() && c->AI()->IsEscorted()))
         c->SetHomePosition(c->GetPosition());
 }
 
@@ -374,8 +374,8 @@ void ThreatManager::AddThreat(Unit* target, float amount, SpellInfo const* spell
         Creature* cOwner = _owner->ToCreature();
         ASSERT(cOwner); // if we got here the owner can have a threat list, and must be a creature!
         SaveCreatureHomePositionIfNeed(cOwner);
-        if (cOwner->IsAIEnabled)
-            cOwner->AI()->JustEngagedWith(target);
+        if (CreatureAI* ownerAI = cOwner->AI())
+            ownerAI->JustEngagedWith(target);
     }
 }
 
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index 0951a75ead1..6df264d909f 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -272,15 +272,6 @@ Creature::Creature(bool isWorldObject): Unit(isWorldObject), MapObject(), m_grou
     m_isTempWorldObject = false;
 }
 
-Creature::~Creature()
-{
-    delete i_AI;
-    i_AI = nullptr;
-
-    //if (m_uint32Values)
-    //    TC_LOG_ERROR("entities.unit", "Deconstruct Creature Entry = %u", GetEntry());
-}
-
 void Creature::AddToWorld()
 {
     ///- Register the creature for guid lookup
@@ -388,8 +379,8 @@ void Creature::RemoveCorpse(bool setSpawnTime, bool destroyForNearbyPlayers)
         RemoveAllAuras();
         loot.clear();
         uint32 respawnDelay = m_respawnDelay;
-        if (IsAIEnabled)
-            AI()->CorpseRemoved(respawnDelay);
+        if (CreatureAI* ai = AI())
+            ai->CorpseRemoved(respawnDelay);
 
         if (destroyForNearbyPlayers)
             DestroyForNearbyPlayers();
@@ -637,7 +628,7 @@ bool Creature::UpdateEntry(uint32 entry, CreatureData const* data /*= nullptr*/,
 
 void Creature::Update(uint32 diff)
 {
-    if (IsAIEnabled && m_triggerJustAppeared && m_deathState != DEAD)
+    if (IsAIEnabled() && m_triggerJustAppeared && m_deathState != DEAD)
     {
         if (m_respawnCompatibilityMode && m_vehicleKit)
             m_vehicleKit->Reset();
@@ -755,21 +746,8 @@ void Creature::Update(uint32 diff)
                 m_shouldReacquireTarget = false;
             }
 
-            // if creature is charmed, switch to charmed AI (and back)
-            if (NeedChangeAI)
-            {
-                UpdateCharmAI();
-                NeedChangeAI = false;
-                IsAIEnabled = true;
-                if (!IsInEvadeMode() && LastCharmerGUID)
-                    if (Unit* charmer = ObjectAccessor::GetUnit(*this, LastCharmerGUID))
-                        EngageWithTarget(charmer);
-
-                LastCharmerGUID.Clear();
-            }
-
             // periodic check to see if the creature has passed an evade boundary
-            if (IsAIEnabled && !IsInEvadeMode() && IsEngaged())
+            if (IsAIEnabled() && !IsInEvadeMode() && IsEngaged())
             {
                 if (diff >= m_boundaryCheckTime)
                 {
@@ -808,14 +786,11 @@ void Creature::Update(uint32 diff)
                 }
             }
 
-            if (!IsInEvadeMode() && IsAIEnabled)
-            {
-                // do not allow the AI to be changed during update
-                m_AI_locked = true;
 
-                i_AI->UpdateAI(diff);
-                m_AI_locked = false;
-            }
+            // do not allow the AI to be changed during update
+            m_AI_locked = true;
+            Unit::AIUpdateTick(diff);
+            m_AI_locked = false;
 
             // creature can be dead after UpdateAI call
             // CORPSE/DEAD state will processed at next tick (in other case death timer will be updated unexpectedly)
@@ -851,8 +826,8 @@ void Creature::Update(uint32 diff)
             {
                 m_cannotReachTimer += diff;
                 if (m_cannotReachTimer >= CREATURE_NOPATH_EVADE_TIME)
-                    if (IsAIEnabled)
-                        AI()->EnterEvadeMode(CreatureAI::EVADE_REASON_NO_PATH);
+                    if (CreatureAI* ai = AI())
+                        ai->EnterEvadeMode(CreatureAI::EVADE_REASON_NO_PATH);
             }
             break;
         }
@@ -988,13 +963,7 @@ bool Creature::AIM_Destroy()
         return false;
     }
 
-    ASSERT(!i_disabledAI,
-           "The disabled AI wasn't cleared!");
-
-    delete i_AI;
-    i_AI = nullptr;
-
-    IsAIEnabled = false;
+    SetAI(nullptr);
     return true;
 }
 
@@ -1007,29 +976,24 @@ bool Creature::AIM_Create(CreatureAI* ai /*= nullptr*/)
         return false;
     }
 
-    AIM_Destroy();
+    if (!ai)
+        ai = FactorySelector::SelectAI(this);
+
+    SetAI(ai);
 
     Motion_Initialize();
 
-    i_AI = ai ? ai : FactorySelector::SelectAI(this);
     return true;
 }
 
-void Creature::AI_InitializeAndEnable()
-{
-    IsAIEnabled = true;
-    i_AI->InitializeAI();
-    // Initialize vehicle
-    if (GetVehicleKit())
-        GetVehicleKit()->Reset();
-}
-
 bool Creature::AIM_Initialize(CreatureAI* ai)
 {
     if (!AIM_Create(ai))
         return false;
 
-    AI_InitializeAndEnable();
+    AI()->InitializeAI();
+    if (GetVehicleKit())
+        GetVehicleKit()->Reset();
     return true;
 }
 
@@ -1831,7 +1795,7 @@ bool Creature::IsInvisibleDueToDespawn() const
 
 bool Creature::CanAlwaysSee(WorldObject const* obj) const
 {
-    if (IsAIEnabled && AI()->CanSeeAlways(obj))
+    if (IsAIEnabled() && AI()->CanSeeAlways(obj))
         return true;
 
     return false;
@@ -2079,8 +2043,8 @@ void Creature::Respawn(bool force)
             // Re-initialize reactstate that could be altered by movementgenerators
             InitializeReactState();
 
-            if (IsAIEnabled) // reset the AI to be sure no dirty or uninitialized values will be used till next tick
-                AI()->Reset();
+            if (UnitAI* ai = AI()) // reset the AI to be sure no dirty or uninitialized values will be used till next tick
+                ai->Reset();
 
             m_triggerJustAppeared = true;
 
@@ -2445,7 +2409,7 @@ bool Creature::CanCreatureAttack(Unit const* victim, bool /*force*/) const
     if (!victim->isInAccessiblePlaceFor(this))
         return false;
 
-    if (IsAIEnabled && !AI()->CanAIAttack(victim))
+    if (IsAIEnabled() && !AI()->CanAIAttack(victim))
         return false;
 
     // we cannot attack in evade mode
@@ -3275,8 +3239,7 @@ void Creature::AtExitCombat()
 
 bool Creature::IsEscortNPC(bool onlyIfActive)
 {
-    if (!IsAIEnabled)
-        return false;
-
-    return AI()->IsEscortNPC(onlyIfActive);
+    if (CreatureAI* ai = AI())
+        return ai->IsEscortNPC(onlyIfActive);
+    return false;
 }
diff --git a/src/server/game/Entities/Creature/Creature.h b/src/server/game/Entities/Creature/Creature.h
index 23e567f7332..f6424e2ec11 100644
--- a/src/server/game/Entities/Creature/Creature.h
+++ b/src/server/game/Entities/Creature/Creature.h
@@ -62,7 +62,6 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
 {
     public:
         explicit Creature(bool isWorldObject = false);
-        virtual ~Creature();
 
         void AddToWorld() override;
         void RemoveFromWorld() override;
@@ -134,11 +133,10 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
 
         bool AIM_Destroy();
         bool AIM_Create(CreatureAI* ai = nullptr);
-        void AI_InitializeAndEnable();
         bool AIM_Initialize(CreatureAI* ai = nullptr);
         void Motion_Initialize();
 
-        CreatureAI* AI() const { return reinterpret_cast<CreatureAI*>(i_AI); }
+        CreatureAI* AI() const { return reinterpret_cast<CreatureAI*>(GetAI()); }
 
         bool SetWalk(bool enable) override;
         bool SetDisableGravity(bool disable, bool packetOnly = false) override;
diff --git a/src/server/game/Entities/Creature/TemporarySummon.cpp b/src/server/game/Entities/Creature/TemporarySummon.cpp
index 6bb6d864006..0f92d0e29aa 100644
--- a/src/server/game/Entities/Creature/TemporarySummon.cpp
+++ b/src/server/game/Entities/Creature/TemporarySummon.cpp
@@ -206,9 +206,9 @@ void TempSummon::InitSummon()
     Unit* owner = GetSummoner();
     if (owner)
     {
-        if (owner->GetTypeId() == TYPEID_UNIT && owner->ToCreature()->IsAIEnabled)
+        if (owner->GetTypeId() == TYPEID_UNIT && owner->ToCreature()->IsAIEnabled())
             owner->ToCreature()->AI()->JustSummoned(this);
-        if (IsAIEnabled)
+        if (IsAIEnabled())
             AI()->IsSummonedBy(owner);
     }
 }
@@ -242,7 +242,7 @@ void TempSummon::UnSummon(uint32 msTime)
     }
 
     Unit* owner = GetSummoner();
-    if (owner && owner->GetTypeId() == TYPEID_UNIT && owner->ToCreature()->IsAIEnabled)
+    if (owner && owner->GetTypeId() == TYPEID_UNIT && owner->ToCreature()->IsAIEnabled())
         owner->ToCreature()->AI()->SummonedCreatureDespawn(this);
 
     AddObjectToRemoveList();
diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index 8902b8575ea..14492cb203b 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -1058,14 +1058,7 @@ void Player::Update(uint32 p_time)
 
     UpdateAfkReport(now);
 
-    if (IsAIEnabled && GetAI())
-        GetAI()->UpdateAI(p_time);
-    else if (NeedChangeAI)
-    {
-        UpdateCharmAI();
-        NeedChangeAI = false;
-        IsAIEnabled = (GetAI() != nullptr);
-    }
+    AIUpdateTick(p_time);
 
     // Update items that have just a limited lifetime
     if (now > m_Last_tick)
diff --git a/src/server/game/Entities/Player/Player.h b/src/server/game/Entities/Player/Player.h
index 0bb4b515ac0..c6b8511c7ee 100644
--- a/src/server/game/Entities/Player/Player.h
+++ b/src/server/game/Entities/Player/Player.h
@@ -886,7 +886,7 @@ class TC_GAME_API Player : public Unit, public GridObject<Player>
         explicit Player(WorldSession* session);
         ~Player();
 
-        PlayerAI* AI() const { return reinterpret_cast<PlayerAI*>(i_AI); }
+        PlayerAI* AI() const { return reinterpret_cast<PlayerAI*>(GetAI()); }
 
         void CleanupsBeforeDelete(bool finalCleanup = true) override;
 
diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index 09f5ef01a5e..dc948fa498d 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/src/server/game/Entities/Unit/Unit.cpp
@@ -289,12 +289,11 @@ bool DispelableAura::RollDispel() const
 
 Unit::Unit(bool isWorldObject) :
     WorldObject(isWorldObject), m_playerMovingMe(nullptr), m_lastSanctuaryTime(0),
-    IsAIEnabled(false), NeedChangeAI(false), LastCharmerGUID(), m_ControlledByPlayer(false),
-    movespline(new Movement::MoveSpline()), i_AI(nullptr), i_disabledAI(nullptr),
-    m_AutoRepeatFirstCast(false), m_procDeep(0), m_removedAurasCount(0),
-    i_motionMaster(new MotionMaster(this)), m_regenTimer(0), m_vehicle(nullptr),
-    m_vehicleKit(nullptr), m_unitTypeMask(UNIT_MASK_NONE), m_Diminishing(), m_combatManager(this),
-    m_threatManager(this), m_comboTarget(nullptr), m_comboPoints(0), m_spellHistory(new SpellHistory(this))
+    LastCharmerGUID(), m_ControlledByPlayer(false),
+    movespline(new Movement::MoveSpline()), m_AutoRepeatFirstCast(false), m_procDeep(0), m_removedAurasCount(0),
+    i_motionMaster(new MotionMaster(this)), m_regenTimer(0), m_vehicle(nullptr), m_vehicleKit(nullptr),
+    m_unitTypeMask(UNIT_MASK_NONE), m_Diminishing(), m_combatManager(this), m_threatManager(this),
+    m_comboTarget(nullptr), m_comboPoints(0), m_spellHistory(new SpellHistory(this))
 {
     m_objectType |= TYPEMASK_UNIT;
     m_objectTypeId = TYPEID_UNIT;
@@ -453,6 +452,9 @@ void Unit::Update(uint32 p_time)
 
     UpdateSplineMovement(p_time);
     i_motionMaster->Update(p_time);
+
+    if (!i_AI && (GetTypeId() != TYPEID_PLAYER || IsCharmed()))
+        UpdateCharmAI();
 }
 
 bool Unit::haveOffhandWeapon() const
@@ -640,11 +642,11 @@ bool Unit::HasBreakableByDamageCrowdControlAura(Unit* excludeCasterChannel) cons
 {
     uint32 rage_damage = damage + (cleanDamage ? cleanDamage->absorbed_damage : 0);
 
-    if (victim->IsAIEnabled)
-        victim->GetAI()->DamageTaken(attacker, damage);
+    if (UnitAI* victimAI = victim->GetAI())
+        victimAI->DamageTaken(attacker, damage);
 
-    if (attacker && attacker->IsAIEnabled)
-        attacker->GetAI()->DamageDealt(victim, damage, damagetype);
+    if (UnitAI* attackerAI = attacker ? attacker->GetAI() : nullptr)
+        attackerAI->DamageDealt(victim, damage, damagetype);
 
     // Hook for OnDamage Event
     sScriptMgr->OnDamage(attacker, victim, damage);
@@ -656,8 +658,8 @@ bool Unit::HasBreakableByDamageCrowdControlAura(Unit* excludeCasterChannel) cons
         {
             for (Unit* controlled : victim->m_Controlled)
                 if (Creature* cControlled = controlled->ToCreature())
-                    if (cControlled->IsAIEnabled)
-                        cControlled->AI()->OwnerAttackedBy(attacker);
+                    if (CreatureAI* controlledAI = cControlled->AI())
+                        controlledAI->OwnerAttackedBy(attacker);
         }
 
         if (victim->ToPlayer()->GetCommandStatus(CHEAT_GOD))
@@ -5544,8 +5546,8 @@ bool Unit::Attack(Unit* victim, bool meleeAttack)
     {
         for (Unit* controlled : m_Controlled)
             if (Creature* cControlled = controlled->ToCreature())
-                if (cControlled->IsAIEnabled)
-                    cControlled->AI()->OwnerAttacked(victim);
+                if (CreatureAI* controlledAI = cControlled->AI())
+                    controlledAI->OwnerAttacked(victim);
     }
 
     return true;
@@ -6093,14 +6095,11 @@ void Unit::SetCharm(Unit* charm, bool apply)
     Unit* victim = healInfo.GetTarget();
     uint32 addhealth = healInfo.GetHeal();
 
-    if (healer)
-    {
-        if (victim->IsAIEnabled)
-            victim->GetAI()->HealReceived(healer, addhealth);
+    if (UnitAI* victimAI = victim->GetAI())
+        victimAI->HealReceived(healer, addhealth);
 
-        if (healer->IsAIEnabled)
-            healer->GetAI()->HealDone(victim, addhealth);
-    }
+    if (UnitAI* healerAI = healer ? healer->GetAI() : nullptr)
+        healerAI->HealDone(victim, addhealth);
 
     if (addhealth)
         gain = victim->ModifyHealth(int32(addhealth));
@@ -9408,12 +9407,49 @@ uint32 Unit::GetCreatePowers(Powers power) const
     return 0;
 }
 
+void Unit::AIUpdateTick(uint32 diff, bool /*force*/)
+{
+    if (!diff) // some places call with diff = 0, which does nothing (for now), see PR #22296
+        return;
+    if (UnitAI* ai = GetAI())
+        ai->UpdateAI(diff);
+}
+
+void Unit::SetAI(UnitAI* newAI)
+{
+    if (i_AI)
+        AIUpdateTick(0, true); // old AI gets a final tick if enabled
+    i_AI.reset(newAI);
+    AIUpdateTick(0, true); // new AI gets its initial tick
+}
+
+void Unit::ScheduleAIChange()
+{
+    printf("ScheduleAIChange %s\n", GetName().c_str());
+    bool const charmed = IsCharmed();
+    // if charm is applied, we can't have disabled AI already, and vice versa
+    if (charmed)
+        ASSERT(!i_disabledAI, "Attempt to schedule charm AI change on unit that already has disabled AI");
+    else if (GetTypeId() != TYPEID_PLAYER)
+        ASSERT(i_disabledAI, "Attempt to schedule charm ID change on unit that doesn't have disabled AI");
+
+    if (charmed)
+        i_disabledAI = std::move(i_AI);
+    else
+        i_AI.reset();
+}
+
+void Unit::RestoreDisabledAI()
+{
+    ASSERT((GetTypeId() == TYPEID_PLAYER) || i_disabledAI, "Attempt to restore disabled AI on creature without disabled AI");
+    i_AI = std::move(i_disabledAI);
+    AIUpdateTick(0, true);
+}
+
 void Unit::AddToWorld()
 {
     if (!IsInWorld())
-    {
         WorldObject::AddToWorld();
-    }
 }
 
 void Unit::RemoveFromWorld()
@@ -9424,8 +9460,8 @@ void Unit::RemoveFromWorld()
     if (IsInWorld())
     {
         m_duringRemoveFromWorld = true;
-        if (IsAIEnabled)
-            GetAI()->LeavingWorld();
+        if (UnitAI* ai = GetAI())
+            ai->LeavingWorld();
 
         if (IsVehicle())
             RemoveVehicleKit();
@@ -9501,80 +9537,44 @@ void Unit::CleanupsBeforeDelete(bool finalCleanup)
 
 void Unit::UpdateCharmAI()
 {
-    switch (GetTypeId())
+    if (IsCharmed())
     {
-        case TYPEID_UNIT:
-            if (i_disabledAI) // disabled AI must be primary AI
-            {
-                if (!IsCharmed())
-                {
-                    delete i_AI;
-                    i_AI = i_disabledAI;
-                    i_disabledAI = nullptr;
-
-                    if (GetTypeId() == TYPEID_UNIT)
-                        ToCreature()->AI()->OnCharmed(false);
-                }
-            }
-            else
-            {
-                if (IsCharmed())
-                {
-                    i_disabledAI = i_AI;
-                    if (isPossessed() || IsVehicle())
-                        i_AI = new PossessedAI(ToCreature());
-                    else
-                        i_AI = new PetAI(ToCreature());
-                }
-            }
-            break;
-        case TYPEID_PLAYER:
+        UnitAI* newAI = nullptr;
+        if (GetTypeId() == TYPEID_PLAYER)
         {
-            if (IsCharmed()) // if we are currently being charmed, then we should apply charm AI
+            if (Unit* charmer = GetCharmer())
             {
-                i_disabledAI = i_AI;
-
-                UnitAI* newAI = nullptr;
                 // first, we check if the creature's own AI specifies an override playerai for its owned players
-                if (Unit* charmer = GetCharmer())
-                {
-                    if (Creature* creatureCharmer = charmer->ToCreature())
-                    {
-                        if (PlayerAI* charmAI = creatureCharmer->IsAIEnabled ? creatureCharmer->AI()->GetAIForCharmedPlayer(ToPlayer()) : nullptr)
-                            newAI = charmAI;
-                    }
-                    else
-                    {
-                        TC_LOG_ERROR("misc", "Attempt to assign charm AI to player %s who is charmed by non-creature %s.", GetGUID().ToString().c_str(), GetCharmerGUID().ToString().c_str());
-                    }
-                }
-                if (!newAI) // otherwise, we default to the generic one
-                    newAI = new SimpleCharmedPlayerAI(ToPlayer());
-                i_AI = newAI;
-                newAI->OnCharmed(true);
-            }
-            else
-            {
-                if (i_AI)
+                if (Creature* creatureCharmer = charmer->ToCreature())
                 {
-                    // we allow the charmed PlayerAI to clean up
-                    i_AI->OnCharmed(false);
-                    // then delete it
-                    delete i_AI;
+                    if (CreatureAI* charmerAI = creatureCharmer->AI())
+                        newAI = charmerAI->GetAIForCharmedPlayer(ToPlayer());
                 }
                 else
-                {
-                    TC_LOG_ERROR("misc", "Attempt to remove charm AI from player %s who doesn't currently have charm AI.", GetGUID().ToString().c_str());
-                }
-                // and restore our previous PlayerAI (if we had one)
-                i_AI = i_disabledAI;
-                i_disabledAI = nullptr;
-                // IsAIEnabled gets handled in the caller
+                    TC_LOG_ERROR("misc", "Attempt to assign charm AI to player %s who is charmed by non-creature %s.", GetGUID().ToString().c_str(), GetCharmerGUID().ToString().c_str());
             }
-            break;
+            if (!newAI) // otherwise, we default to the generic one
+                newAI = new SimpleCharmedPlayerAI(ToPlayer());
         }
-        default:
-            TC_LOG_ERROR("misc", "Attempt to update charm AI for unit %s, which is neither player nor creature.", GetGUID().ToString().c_str());
+        else
+        {
+            ASSERT(GetTypeId() == TYPEID_UNIT);
+            if (isPossessed() || IsVehicle())
+                newAI = new PossessedAI(ToCreature());
+            else
+                newAI = new PetAI(ToCreature());
+        }
+
+        ASSERT(newAI);
+        i_AI.reset(newAI);
+        newAI->OnCharmed(true);
+        AIUpdateTick(0, true);
+    }
+    else
+    {
+        RestoreDisabledAI();
+        if (i_AI)
+            i_AI->OnCharmed(true);
     }
 }
 
@@ -10946,7 +10946,7 @@ bool Unit::InitTamedPet(Pet* pet, uint8 level, uint32 spell_id)
             plrVictim->SendDirectMessage(&data);
         }
         // Call KilledUnit for creatures
-        if (attacker && attacker->GetTypeId() == TYPEID_UNIT && attacker->IsAIEnabled)
+        if (attacker && attacker->GetTypeId() == TYPEID_UNIT && attacker->IsAIEnabled())
             attacker->ToCreature()->AI()->KilledUnit(victim);
 
         // last damage from non duel opponent or opponent controlled creature
@@ -10973,16 +10973,16 @@ bool Unit::InitTamedPet(Pet* pet, uint8 level, uint32 spell_id)
         }
 
         // Call KilledUnit for creatures, this needs to be called after the lootable flag is set
-        if (attacker && attacker->GetTypeId() == TYPEID_UNIT && attacker->IsAIEnabled)
+        if (attacker && attacker->GetTypeId() == TYPEID_UNIT && attacker->IsAIEnabled())
             attacker->ToCreature()->AI()->KilledUnit(victim);
 
         // Call creature just died function
-        if (creature->IsAIEnabled)
-            creature->AI()->JustDied(attacker);
+        if (CreatureAI* ai = creature->AI())
+            ai->JustDied(attacker);
 
         if (TempSummon* summon = creature->ToTempSummon())
             if (Unit* summoner = summon->GetSummoner())
-                if (summoner->ToCreature() && summoner->IsAIEnabled)
+                if (summoner->ToCreature() && summoner->IsAIEnabled())
                     summoner->ToCreature()->AI()->SummonedCreatureDies(creature, attacker);
 
         // Dungeon specific stuff, only applies to players killing creatures
@@ -11400,7 +11400,11 @@ bool Unit::SetCharmedBy(Unit* charmer, CharmType type, AuraApplication const* au
 
         StopMoving();
 
-        ToCreature()->AI()->OnCharmed(true);
+        // AI will schedule its own change if appropriate
+        if (UnitAI* ai = GetAI())
+            ai->OnCharmed(false);
+        else
+            ScheduleAIChange();
     }
     else if (Player* player = ToPlayer())
     {
@@ -11410,12 +11414,10 @@ bool Unit::SetCharmedBy(Unit* charmer, CharmType type, AuraApplication const* au
         if (charmer->GetTypeId() == TYPEID_UNIT) // we are charmed by a creature
         {
             // change AI to charmed AI on next Update tick
-            NeedChangeAI = true;
-            if (IsAIEnabled)
-            {
-                IsAIEnabled = false;
-                player->AI()->OnCharmed(true);
-            }
+            if (UnitAI* ai = GetAI())
+                ai->OnCharmed(false);
+            else
+                player->ScheduleAIChange();
         }
         player->SetClientControl(this, false);
     }
@@ -11517,16 +11519,9 @@ void Unit::RemoveCharmedBy(Unit* charmer)
     ///@todo Handle SLOT_IDLE motion resume
     GetMotionMaster()->InitializeDefault();
 
-    if (Creature* creature = ToCreature())
-    {
-        // Creature will restore its old AI on next update
-        if (creature->AI())
-            creature->AI()->OnCharmed(false);
-
-        // Vehicle should not attack its passenger after he exists the seat
-        if (type != CHARM_TYPE_VEHICLE)
-            LastCharmerGUID = ASSERT_NOTNULL(charmer)->GetGUID();
-    }
+    // Vehicle should not attack its passenger after he exists the seat
+    if (type != CHARM_TYPE_VEHICLE)
+        LastCharmerGUID = ASSERT_NOTNULL(charmer)->GetGUID();
 
     // If charmer still exists
     if (!charmer)
@@ -11573,16 +11568,11 @@ void Unit::RemoveCharmedBy(Unit* charmer)
         }
     }
 
-    if (Player* player = ToPlayer())
-    {
-        if (charmer->GetTypeId() == TYPEID_UNIT) // charmed by a creature, this means we had PlayerAI
-        {
-            NeedChangeAI = true;
-            IsAIEnabled = false;
-        }
+    if (GetTypeId() != TYPEID_PLAYER || charmer->GetTypeId() == TYPEID_UNIT)
+        GetAI()->OnCharmed(false); // AI will potentially schedule a charm ai update
 
+    if (Player* player = ToPlayer())
         player->SetClientControl(this, true);
-    }
 
     // a guardian should always have charminfo
     if (playerCharmer && this != charmer->GetFirstControlled())
@@ -12466,7 +12456,7 @@ void Unit::HandleSpellClick(Unit* clicker, int8 seatId /*= -1*/)
     }
 
     Creature* creature = ToCreature();
-    if (creature && creature->IsAIEnabled)
+    if (creature && creature->IsAIEnabled())
         creature->AI()->OnSpellClick(clicker, spellClickHandled);
 }
 
diff --git a/src/server/game/Entities/Unit/Unit.h b/src/server/game/Entities/Unit/Unit.h
index dfd1c1e020c..774ba7d5c46 100644
--- a/src/server/game/Entities/Unit/Unit.h
+++ b/src/server/game/Entities/Unit/Unit.h
@@ -28,6 +28,7 @@
 #include "UnitDefines.h"
 #include "Util.h"
 #include <map>
+#include <memory>
 
 #define VISUAL_WAYPOINT 1 // Creature Entry ID used for waypoints show, visible only for GMs
 #define WORLD_TRIGGER 12999
@@ -763,8 +764,11 @@ class TC_GAME_API Unit : public WorldObject
 
         virtual ~Unit();
 
-        UnitAI* GetAI() { return i_AI; }
-        void SetAI(UnitAI* newAI) { i_AI = newAI; }
+        bool IsAIEnabled() const { return (i_AI != nullptr); }
+        void AIUpdateTick(uint32 diff, bool force = false);
+        UnitAI* GetAI() const { return i_AI.get(); }
+        void SetAI(UnitAI* newAI);
+        void ScheduleAIChange();
 
         void AddToWorld() override;
         void RemoveFromWorld() override;
@@ -1180,7 +1184,6 @@ class TC_GAME_API Unit : public WorldObject
         CharmInfo* GetCharmInfo() { return m_charmInfo; }
         CharmInfo* InitCharmInfo();
         void DeleteCharmInfo();
-        void UpdateCharmAI();
         // returns the unit that this player IS CONTROLLING
         Unit* GetUnitBeingMoved() const;
         // returns the player that this player IS CONTROLLING
@@ -1595,7 +1598,6 @@ class TC_GAME_API Unit : public WorldObject
         uint32 GetModelForTotem(PlayerTotemType totemType);
 
         friend class VehicleJoinEvent;
-        bool IsAIEnabled, NeedChangeAI;
         ObjectGuid LastCharmerGUID;
         bool CreateVehicleKit(uint32 id, uint32 creatureEntry);
         void RemoveVehicleKit();
@@ -1681,8 +1683,6 @@ class TC_GAME_API Unit : public WorldObject
 
         void BuildValuesUpdate(uint8 updatetype, ByteBuffer* data, Player* target) const override;
 
-        UnitAI* i_AI, *i_disabledAI;
-
         void _UpdateSpells(uint32 time);
         void _DeleteRemovedAuras();
 
@@ -1785,6 +1785,10 @@ class TC_GAME_API Unit : public WorldObject
         friend class ThreatManager;
         ThreatManager m_threatManager;
 
+        void UpdateCharmAI();
+        void RestoreDisabledAI();
+        std::unique_ptr<UnitAI> i_AI, i_disabledAI;
+
         std::unordered_set<AbstractFollower*> m_followingMe;
 
         Unit* m_comboTarget;
diff --git a/src/server/game/Entities/Vehicle/Vehicle.cpp b/src/server/game/Entities/Vehicle/Vehicle.cpp
index 528b521f59d..b6a1e2f437c 100755
--- a/src/server/game/Entities/Vehicle/Vehicle.cpp
+++ b/src/server/game/Entities/Vehicle/Vehicle.cpp
@@ -514,7 +514,7 @@ Vehicle* Vehicle::RemovePassenger(Unit* unit)
     if (unit->IsFlying())
         _me->CastSpell(unit, VEHICLE_SPELL_PARACHUTE, true);
 
-    if (_me->GetTypeId() == TYPEID_UNIT && _me->ToCreature()->IsAIEnabled)
+    if (_me->GetTypeId() == TYPEID_UNIT && _me->ToCreature()->IsAIEnabled())
         _me->ToCreature()->AI()->PassengerBoarded(unit, seat->first, false);
 
     if (GetBase()->GetTypeId() == TYPEID_UNIT)
@@ -854,8 +854,8 @@ bool VehicleJoinEvent::Execute(uint64, uint32)
 
     if (Creature* creature = Target->GetBase()->ToCreature())
     {
-        if (creature->IsAIEnabled)
-            creature->AI()->PassengerBoarded(Passenger, Seat->first, true);
+        if (CreatureAI* ai = creature->AI())
+            ai->PassengerBoarded(Passenger, Seat->first, true);
 
         sScriptMgr->OnAddPassenger(Target, Passenger, Seat->first);
 
diff --git a/src/server/game/Events/GameEventMgr.cpp b/src/server/game/Events/GameEventMgr.cpp
index e2930f42552..89c9d27efe7 100644
--- a/src/server/game/Events/GameEventMgr.cpp
+++ b/src/server/game/Events/GameEventMgr.cpp
@@ -1687,7 +1687,7 @@ public:
     void Visit(std::unordered_map<ObjectGuid, Creature*>& creatureMap)
     {
         for (auto const& p : creatureMap)
-            if (p.second->IsInWorld() && p.second->IsAIEnabled)
+            if (p.second->IsInWorld() && p.second->IsAIEnabled())
                 p.second->AI()->OnGameEvent(_activate, _eventId);
     }
 
diff --git a/src/server/game/Grids/Notifiers/GridNotifiers.cpp b/src/server/game/Grids/Notifiers/GridNotifiers.cpp
index 7fb56b3e686..b60f2ef0af4 100644
--- a/src/server/game/Grids/Notifiers/GridNotifiers.cpp
+++ b/src/server/game/Grids/Notifiers/GridNotifiers.cpp
@@ -133,10 +133,10 @@ inline void CreatureUnitRelocationWorker(Creature* c, Unit* u)
 
     if (!c->HasUnitState(UNIT_STATE_SIGHTLESS))
     {
-        if (c->IsAIEnabled && c->CanSeeOrDetect(u, false, true))
+        if (c->IsAIEnabled() && c->CanSeeOrDetect(u, false, true))
             c->AI()->MoveInLineOfSight_Safe(u);
         else
-            if (u->GetTypeId() == TYPEID_PLAYER && u->HasStealthAura() && c->IsAIEnabled && c->CanSeeOrDetect(u, false, true, true))
+            if (u->GetTypeId() == TYPEID_PLAYER && u->HasStealthAura() && c->IsAIEnabled() && c->CanSeeOrDetect(u, false, true, true))
                 c->AI()->TriggerAlert(u);
     }
 }
diff --git a/src/server/game/Grids/Notifiers/GridNotifiers.h b/src/server/game/Grids/Notifiers/GridNotifiers.h
index d4687d1b1ee..f55acdca8d7 100644
--- a/src/server/game/Grids/Notifiers/GridNotifiers.h
+++ b/src/server/game/Grids/Notifiers/GridNotifiers.h
@@ -1102,8 +1102,7 @@ namespace Trinity
                 if (!u->IsWithinLOSInMap(i_enemy))
                     return;
 
-                if (u->GetAI() && u->IsAIEnabled)
-                    u->GetAI()->AttackStart(i_enemy);
+                u->EngageWithTarget(i_enemy);
             }
         private:
             Unit* const i_funit;
diff --git a/src/server/game/Handlers/PetHandler.cpp b/src/server/game/Handlers/PetHandler.cpp
index d266fef5a42..3ef03ffc80b 100644
--- a/src/server/game/Handlers/PetHandler.cpp
+++ b/src/server/game/Handlers/PetHandler.cpp
@@ -209,7 +209,7 @@ void WorldSession::HandlePetActionHelper(Unit* pet, ObjectGuid guid1, uint32 spe
                         if (pet->GetVictim())
                             pet->AttackStop();
 
-                        if (pet->GetTypeId() != TYPEID_PLAYER && pet->ToCreature()->IsAIEnabled)
+                        if (pet->GetTypeId() != TYPEID_PLAYER && pet->ToCreature()->IsAIEnabled())
                         {
                             charmInfo->SetIsCommandAttack(true);
                             charmInfo->SetIsAtStay(false);
@@ -368,9 +368,8 @@ void WorldSession::HandlePetActionHelper(Unit* pet, ObjectGuid guid1, uint32 spe
                     if (pet->GetVictim() != unit_target)
                     {
                         pet->GetMotionMaster()->Clear();
-                        if (pet->ToCreature()->IsAIEnabled)
+                        if (CreatureAI* AI = pet->ToCreature()->AI())
                         {
-                            CreatureAI* AI = pet->ToCreature()->AI();
                             if (PetAI* petAI = dynamic_cast<PetAI*>(AI))
                                 petAI->_AttackStart(unit_target); // force victim switch
                             else
diff --git a/src/server/game/Movement/MovementGenerators/ChaseMovementGenerator.cpp b/src/server/game/Movement/MovementGenerators/ChaseMovementGenerator.cpp
index 973921aafe1..2bf8c3f48f9 100644
--- a/src/server/game/Movement/MovementGenerators/ChaseMovementGenerator.cpp
+++ b/src/server/game/Movement/MovementGenerators/ChaseMovementGenerator.cpp
@@ -52,9 +52,8 @@ static void DoMovementInform(Unit* owner, Unit* target)
     if (owner->GetTypeId() != TYPEID_UNIT)
         return;
 
-    Creature* creatureOwner = owner->ToCreature();
-    if (creatureOwner->IsAIEnabled && creatureOwner->AI())
-        creatureOwner->AI()->MovementInform(CHASE_MOTION_TYPE, target->GetGUID().GetCounter());
+    if (CreatureAI* AI = owner->ToCreature()->AI())
+        AI->MovementInform(CHASE_MOTION_TYPE, target->GetGUID().GetCounter());
 }
 
 ChaseMovementGenerator::ChaseMovementGenerator(Unit* target, Optional<ChaseRange> range, Optional<ChaseAngle> angle) : AbstractFollower(ASSERT_NOTNULL(target)), _range(range), _angle(angle)
diff --git a/src/server/game/Movement/MovementGenerators/FollowMovementGenerator.cpp b/src/server/game/Movement/MovementGenerators/FollowMovementGenerator.cpp
index e4b7fc78832..adcc35b1c86 100644
--- a/src/server/game/Movement/MovementGenerators/FollowMovementGenerator.cpp
+++ b/src/server/game/Movement/MovementGenerators/FollowMovementGenerator.cpp
@@ -31,9 +31,8 @@ static void DoMovementInform(Unit* owner, Unit* target)
     if (owner->GetTypeId() != TYPEID_UNIT)
         return;
 
-    Creature* creatureOwner = owner->ToCreature();
-    if (creatureOwner->IsAIEnabled && creatureOwner->AI())
-        creatureOwner->AI()->MovementInform(FOLLOW_MOTION_TYPE, target->GetGUID().GetCounter());
+    if (CreatureAI* AI = owner->ToCreature()->AI())
+        AI->MovementInform(FOLLOW_MOTION_TYPE, target->GetGUID().GetCounter());
 }
 
 FollowMovementGenerator::FollowMovementGenerator(Unit* target, float range, ChaseAngle angle) : AbstractFollower(ASSERT_NOTNULL(target)), _range(range), _angle(angle)
diff --git a/src/server/game/Movement/MovementGenerators/SplineChainMovementGenerator.cpp b/src/server/game/Movement/MovementGenerators/SplineChainMovementGenerator.cpp
index a90a8b7af36..5df2ea43fef 100644
--- a/src/server/game/Movement/MovementGenerators/SplineChainMovementGenerator.cpp
+++ b/src/server/game/Movement/MovementGenerators/SplineChainMovementGenerator.cpp
@@ -185,8 +185,8 @@ void SplineChainMovementGenerator::Finalize(Unit* owner, bool active, bool movem
     if (movementInform && HasFlag(MOVEMENTGENERATOR_FLAG_INFORM_ENABLED))
     {
         Creature* ownerCreature = owner->ToCreature();
-        if (ownerCreature && ownerCreature->IsAIEnabled)
-            ownerCreature->AI()->MovementInform(SPLINE_CHAIN_MOTION_TYPE, _id);
+        if (CreatureAI* AI = ownerCreature ? ownerCreature->AI() : nullptr)
+            AI->MovementInform(SPLINE_CHAIN_MOTION_TYPE, _id);
     }
 }
 
diff --git a/src/server/game/Movement/MovementGenerators/WaypointMovementGenerator.cpp b/src/server/game/Movement/MovementGenerators/WaypointMovementGenerator.cpp
index 7c0336e6523..aa81d6d0d92 100755
--- a/src/server/game/Movement/MovementGenerators/WaypointMovementGenerator.cpp
+++ b/src/server/game/Movement/MovementGenerators/WaypointMovementGenerator.cpp
@@ -117,8 +117,8 @@ void WaypointMovementGenerator<Creature>::DoInitialize(Creature* owner)
     _nextMoveTime.Reset(1000);
 
     // inform AI
-    if (owner->IsAIEnabled)
-        owner->AI()->WaypointPathStarted(_path->id);
+    if (CreatureAI* AI = owner->AI())
+        AI->WaypointPathStarted(_path->id);
 }
 
 void WaypointMovementGenerator<Creature>::DoReset(Creature* owner)
@@ -256,10 +256,10 @@ void WaypointMovementGenerator<Creature>::OnArrived(Creature* owner)
     }
 
     // inform AI
-    if (owner->IsAIEnabled)
+    if (CreatureAI* AI = owner->AI())
     {
-        owner->AI()->MovementInform(WAYPOINT_MOTION_TYPE, _currentNode);
-        owner->AI()->WaypointReached(waypoint.id, _path->id);
+        AI->MovementInform(WAYPOINT_MOTION_TYPE, _currentNode);
+        AI->WaypointReached(waypoint.id, _path->id);
     }
 
     owner->UpdateCurrentWaypointInfo(waypoint.id, _path->id);
@@ -286,8 +286,8 @@ void WaypointMovementGenerator<Creature>::StartMove(Creature* owner, bool relaun
             ASSERT(_currentNode < _path->nodes.size(), "WaypointMovementGenerator::StartMove: tried to reference a node id (%u) which is not included in path (%u)", _currentNode, _path->id);
 
             // inform AI
-            if (owner->IsAIEnabled)
-                owner->AI()->WaypointStarted(_path->nodes[_currentNode].id, _path->id);
+            if (CreatureAI* AI = owner->AI())
+                AI->WaypointStarted(_path->nodes[_currentNode].id, _path->id);
         }
         else
         {
@@ -314,8 +314,8 @@ void WaypointMovementGenerator<Creature>::StartMove(Creature* owner, bool relaun
             owner->UpdateCurrentWaypointInfo(0, 0);
 
             // inform AI
-            if (owner->IsAIEnabled)
-                owner->AI()->WaypointPathEnded(waypoint.id, _path->id);
+            if (CreatureAI* AI = owner->AI())
+                AI->WaypointPathEnded(waypoint.id, _path->id);
             return;
         }
     }
@@ -324,8 +324,8 @@ void WaypointMovementGenerator<Creature>::StartMove(Creature* owner, bool relaun
         AddFlag(MOVEMENTGENERATOR_FLAG_INITIALIZED);
 
         // inform AI
-        if (owner->IsAIEnabled)
-            owner->AI()->WaypointStarted(_path->nodes[_currentNode].id, _path->id);
+        if (CreatureAI* AI = owner->AI())
+            AI->WaypointStarted(_path->nodes[_currentNode].id, _path->id);
     }
 
     ASSERT(_currentNode < _path->nodes.size(), "WaypointMovementGenerator::StartMove: tried to reference a node id (%u) which is not included in path (%u)", _currentNode, _path->id);
diff --git a/src/server/game/Scripting/ScriptMgr.cpp b/src/server/game/Scripting/ScriptMgr.cpp
index 16c6bc1a281..d63eca92429 100644
--- a/src/server/game/Scripting/ScriptMgr.cpp
+++ b/src/server/game/Scripting/ScriptMgr.cpp
@@ -432,7 +432,9 @@ class CreatureGameObjectScriptRegistrySwapHooks
         if (!creature->IsAlive())
             return;
 
-        creature->AI_InitializeAndEnable();
+        creature->AI()->InitializeAI();
+        if (creature->GetVehicleKit())
+            creature->GetVehicleKit()->Reset();
         creature->AI()->EnterEvadeMode();
 
         // Cast a dummy visual spell asynchronously here to signal
diff --git a/src/server/game/Spells/Spell.cpp b/src/server/game/Spells/Spell.cpp
index 58c2fa7755a..ec8b1202208 100644
--- a/src/server/game/Spells/Spell.cpp
+++ b/src/server/game/Spells/Spell.cpp
@@ -2541,18 +2541,16 @@ void Spell::TargetInfo::DoDamageAndTriggers(Spell* spell)
     if (_spellHitTarget)
     {
         //AI functions
-        if (_spellHitTarget->GetTypeId() == TYPEID_UNIT)
-        {
-            if (_spellHitTarget->ToCreature()->IsAIEnabled)
+        if (Creature* cHitTarget = _spellHitTarget->ToCreature())
+            if (CreatureAI* hitTargetAI = cHitTarget->AI())
             {
                 if (spell->m_caster->GetTypeId() == TYPEID_GAMEOBJECT)
-                    _spellHitTarget->ToCreature()->AI()->SpellHit(spell->m_caster->ToGameObject(), spell->m_spellInfo);
+                    hitTargetAI->SpellHit(spell->m_caster->ToGameObject(), spell->m_spellInfo);
                 else
-                    _spellHitTarget->ToCreature()->AI()->SpellHit(spell->m_caster->ToUnit(), spell->m_spellInfo);
+                    hitTargetAI->SpellHit(spell->m_caster->ToUnit(), spell->m_spellInfo);
             }
-        }
 
-        if (spell->m_caster->GetTypeId() == TYPEID_UNIT && spell->m_caster->ToCreature()->IsAIEnabled)
+        if (spell->m_caster->GetTypeId() == TYPEID_UNIT && spell->m_caster->ToCreature()->IsAIEnabled())
             spell->m_caster->ToCreature()->AI()->SpellHitTarget(_spellHitTarget, spell->m_spellInfo);
         else if (spell->m_caster->GetTypeId() == TYPEID_GAMEOBJECT && spell->m_caster->ToGameObject()->AI())
             spell->m_caster->ToGameObject()->AI()->SpellHitTarget(_spellHitTarget, spell->m_spellInfo);
@@ -2601,7 +2599,7 @@ void Spell::GOTargetInfo::DoTargetSpellHit(Spell* spell, uint8 effIndex)
             go->AI()->SpellHit(spell->m_caster->ToUnit(), spell->m_spellInfo);
     }
 
-    if (spell->m_caster->GetTypeId() == TYPEID_UNIT && spell->m_caster->ToCreature()->IsAIEnabled)
+    if (spell->m_caster->GetTypeId() == TYPEID_UNIT && spell->m_caster->ToCreature()->IsAIEnabled())
         spell->m_caster->ToCreature()->AI()->SpellHitTarget(go, spell->m_spellInfo);
     else if (spell->m_caster->GetTypeId() == TYPEID_GAMEOBJECT && spell->m_caster->ToGameObject()->AI())
         spell->m_caster->ToGameObject()->AI()->SpellHitTarget(go, spell->m_spellInfo);
@@ -3222,8 +3220,8 @@ void Spell::_cast(bool skipCheck)
             if (Unit* target = m_targets.GetUnitTarget())
                 for (Unit* controlled : playerCaster->m_Controlled)
                     if (Creature* cControlled = controlled->ToCreature())
-                        if (cControlled->IsAIEnabled)
-                            cControlled->AI()->OwnerAttacked(target);
+                        if (CreatureAI* controlledAI = cControlled->AI())
+                                controlledAI->OwnerAttacked(target);
     }
 
     SetExecutedCurrently(true);