Core/Spell: SpellAura Redux (#22794)

* typo and correction

* spell aura no longer shared between targets

_spellAura isolated

* SPELL_AURA_CONTROL_VEHICLE is not strictly single target spell

Steam Tank Control and Wyrmrest Commander

units can reseat themselves again

* Rename 9999_99_99_99_world.sql to 2019_03_08_00_world.sql

(cherry picked from commit ec3cb05d7fbc5cef60d000af910dc39dd3af92bf)

7 files changed, 50 insertions, 23 deletions

diff --git a/sql/updates/world/master/2021_11_24_26_world_2019_03_08_00_world.sql b/sql/updates/world/master/2021_11_24_26_world_2019_03_08_00_world.sql
new file mode 100644
index 00000000000..1cf16d8a632
--- /dev/null
+++ b/sql/updates/world/master/2021_11_24_26_world_2019_03_08_00_world.sql
@@ -0,0 +1,4 @@
+DELETE FROM `spell_script_names` WHERE `ScriptName` = 'spell_gen_vehicle_control_link' AND `spell_id` IN (49078, 50343);
+INSERT INTO `spell_script_names` (`spell_id`,`ScriptName`) VALUES
+(49078, 'spell_gen_vehicle_control_link'),
+(50343, 'spell_gen_vehicle_control_link');
diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index c101550e500..bedf0e1bddf 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/src/server/game/Entities/Unit/Unit.cpp
@@ -3150,14 +3150,13 @@ void Unit::_AddAura(UnitAura* aura, Unit* caster)
     if (aura->IsRemoved())
         return;
 
-    aura->SetIsSingleTarget(caster && (aura->GetSpellInfo()->IsSingleTarget() || aura->HasEffectType(SPELL_AURA_CONTROL_VEHICLE)));
+    aura->SetIsSingleTarget(caster && aura->GetSpellInfo()->IsSingleTarget());
     if (aura->IsSingleTarget())
     {
-        ASSERT((IsInWorld() && !IsDuringRemoveFromWorld()) || (aura->GetCasterGUID() == GetGUID()) ||
-                (IsLoading() && aura->HasEffectType(SPELL_AURA_CONTROL_VEHICLE)));
+        ASSERT((IsInWorld() && !IsDuringRemoveFromWorld()) || aura->GetCasterGUID() == GetGUID());
                 /* @HACK: Player is not in world during loading auras.
                  *        Single target auras are not saved or loaded from database
-                 *        but may be created as a result of aura links (player mounts with passengers)
+                 *        but may be created as a result of aura links.
                  */
 
         // register single target aura
@@ -11853,6 +11852,11 @@ void Unit::_EnterVehicle(Vehicle* vehicle, int8 seatId, AuraApplication const* a
         }
         else if (seatId >= 0 && seatId == GetTransSeat())
             return;
+        else
+        {
+            //Exit the current vehicle because unit will reenter in a new seat.
+            m_vehicle->GetBase()->RemoveAurasByType(SPELL_AURA_CONTROL_VEHICLE, GetGUID(), aurApp->GetBase());
+        }
     }
 
     if (aurApp->GetRemoveMode())
diff --git a/src/server/game/Spells/Auras/SpellAuras.cpp b/src/server/game/Spells/Auras/SpellAuras.cpp
index 99e24997054..8b37dc1b232 100644
--- a/src/server/game/Spells/Auras/SpellAuras.cpp
+++ b/src/server/game/Spells/Auras/SpellAuras.cpp
@@ -1169,9 +1169,6 @@ bool Aura::IsSingleTargetWith(Aura const* aura) const
             break;
     }
 
-    if (HasEffectType(SPELL_AURA_CONTROL_VEHICLE) && aura->HasEffectType(SPELL_AURA_CONTROL_VEHICLE))
-        return true;
-
     return false;
 }
 
diff --git a/src/server/game/Spells/Spell.cpp b/src/server/game/Spells/Spell.cpp
index 2444044c29c..0c4b991ef23 100644
--- a/src/server/game/Spells/Spell.cpp
+++ b/src/server/game/Spells/Spell.cpp
@@ -2671,7 +2671,9 @@ void Spell::TargetInfo::DoDamageAndTriggers(Spell* spell)
             spell->m_caster->ToPlayer()->UpdatePvP(true);
     }
 
+    spell->_spellAura = HitAura;
     spell->CallScriptAfterHitHandlers();
+    spell->_spellAura = nullptr;
 }
 
 void Spell::GOTargetInfo::DoTargetSpellHit(Spell* spell, SpellEffectInfo const& spellEffectInfo)
@@ -2841,8 +2843,7 @@ void Spell::DoSpellEffectHit(Unit* unit, SpellEffectInfo const& spellEffectInfo,
         {
             bool refresh = false;
 
-            // delayed spells with multiple targets need to create a new aura object, otherwise we'll access a deleted aura
-            if (!_spellAura || (m_spellInfo->HasHitDelay() && !m_spellInfo->IsChanneled()))
+            if (!hitInfo.HitAura)
             {
                 bool const resetPeriodicTimer = !(_triggeredCastFlags & TRIGGERED_DONT_RESET_PERIODIC_TIMER);
                 uint32 const allAuraEffectMask = Aura::BuildEffectMaskForOwner(m_spellInfo, MAX_EFFECT_MASK, unit);
@@ -2858,22 +2859,22 @@ void Spell::DoSpellEffectHit(Unit* unit, SpellEffectInfo const& spellEffectInfo,
 
                 if (Aura* aura = Aura::TryRefreshStackOrCreate(createInfo))
                 {
-                    _spellAura = aura->ToUnitAura();
+                    hitInfo.HitAura = aura->ToUnitAura();
 
                     // Set aura stack amount to desired value
                     if (m_spellValue->AuraStackAmount > 1)
                     {
                         if (!refresh)
-                            _spellAura->SetStackAmount(m_spellValue->AuraStackAmount);
+                            hitInfo.HitAura->SetStackAmount(m_spellValue->AuraStackAmount);
                         else
-                            _spellAura->ModStackAmount(m_spellValue->AuraStackAmount);
+                            hitInfo.HitAura->ModStackAmount(m_spellValue->AuraStackAmount);
                     }
 
-                    _spellAura->SetDiminishGroup(hitInfo.DRGroup);
+                    hitInfo.HitAura->SetDiminishGroup(hitInfo.DRGroup);
 
                     if (!m_spellValue->Duration)
                     {
-                        hitInfo.AuraDuration = caster->ModSpellDuration(m_spellInfo, unit, hitInfo.AuraDuration, hitInfo.Positive, _spellAura->GetEffectMask());
+                        hitInfo.AuraDuration = caster->ModSpellDuration(m_spellInfo, unit, hitInfo.AuraDuration, hitInfo.Positive, hitInfo.HitAura->GetEffectMask());
 
                         if (hitInfo.AuraDuration > 0)
                         {
@@ -2886,7 +2887,7 @@ void Spell::DoSpellEffectHit(Unit* unit, SpellEffectInfo const& spellEffectInfo,
                             {
                                 int32 origDuration = hitInfo.AuraDuration;
                                 hitInfo.AuraDuration = 0;
-                                for (AuraEffect const* auraEff : _spellAura->GetAuraEffects())
+                                for (AuraEffect const* auraEff : hitInfo.HitAura->GetAuraEffects())
                                     if (auraEff)
                                         if (int32 period = auraEff->GetPeriod())  // period is hastened by UNIT_MOD_CAST_SPEED
                                             hitInfo.AuraDuration = std::max(std::max(origDuration / period, 1) * period, hitInfo.AuraDuration);
@@ -2900,21 +2901,21 @@ void Spell::DoSpellEffectHit(Unit* unit, SpellEffectInfo const& spellEffectInfo,
                     else
                         hitInfo.AuraDuration = m_spellValue->Duration.get();
 
-                    if (hitInfo.AuraDuration != _spellAura->GetMaxDuration())
+                    if (hitInfo.AuraDuration != hitInfo.HitAura->GetMaxDuration())
                     {
-                        _spellAura->SetMaxDuration(hitInfo.AuraDuration);
-                        _spellAura->SetDuration(hitInfo.AuraDuration);
+                        hitInfo.HitAura->SetMaxDuration(hitInfo.AuraDuration);
+                        hitInfo.HitAura->SetDuration(hitInfo.AuraDuration);
                     }
                 }
             }
             else
-                _spellAura->AddStaticApplication(unit, aura_effmask);
-
-            hitInfo.HitAura = _spellAura;
+                hitInfo.HitAura->AddStaticApplication(unit, aura_effmask);
         }
     }
 
+    _spellAura = hitInfo.HitAura;
     HandleEffects(unit, nullptr, nullptr, spellEffectInfo, SPELL_EFFECT_HANDLE_HIT_TARGET);
+    _spellAura = nullptr;
 }
 
 void Spell::DoTriggersOnSpellHit(Unit* unit, uint32 effMask)
diff --git a/src/server/game/Spells/SpellScript.h b/src/server/game/Spells/SpellScript.h
index 599518e9214..00397833b18 100644
--- a/src/server/game/Spells/SpellScript.h
+++ b/src/server/game/Spells/SpellScript.h
@@ -801,7 +801,7 @@ class TC_GAME_API AuraScript : public _SpellScript
         #define AuraEffectApplyFn(F, I, N, M) EffectApplyHandlerFunction(&F, I, N, M)
 
         // executed after aura effect is removed with specified mode from target
-        // should be used when when effect handler preventing/replacing is needed, do not use this hook for triggering spellcasts/removing auras etc - may be unsafe
+        // should be used when effect handler preventing/replacing is needed, do not use this hook for triggering spellcasts/removing auras etc - may be unsafe
         // example: OnEffectRemove += AuraEffectRemoveFn(class::function, EffectIndexSpecifier, EffectAuraNameSpecifier, AuraEffectHandleModes);
         // where function is: void function (AuraEffect const* aurEff, AuraEffectHandleModes mode);
         HookList<EffectApplyHandler> OnEffectRemove;
diff --git a/src/server/scripts/Spells/spell_generic.cpp b/src/server/scripts/Spells/spell_generic.cpp
index 24edf343028..e8a8756a109 100644
--- a/src/server/scripts/Spells/spell_generic.cpp
+++ b/src/server/scripts/Spells/spell_generic.cpp
@@ -4060,6 +4060,26 @@ class spell_corrupting_plague_aura : public AuraScript
     }
 };
 
+enum SiegeTankControl
+{
+    SPELL_SIEGE_TANK_CONTROL = 47963
+};
+
+class spell_gen_vehicle_control_link : public AuraScript
+{
+    PrepareAuraScript(spell_gen_vehicle_control_link);
+
+    void OnRemove(AuraEffect const* /*aurEff*/, AuraEffectHandleModes /*mode*/)
+    {
+        GetTarget()->RemoveAurasDueToSpell(SPELL_SIEGE_TANK_CONTROL); //aurEff->GetAmount()
+    }
+
+    void Register() override
+    {
+        AfterEffectRemove += AuraEffectRemoveFn(spell_gen_vehicle_control_link::OnRemove, EFFECT_1, SPELL_AURA_DUMMY, AURA_EFFECT_HANDLE_REAL);
+    }
+};
+
 // 34779 - Freezing Circle
 enum FreezingCircleMisc
 {
@@ -4471,6 +4491,7 @@ void AddSC_generic_spell_scripts()
     RegisterSpellScript(spell_gen_clear_debuffs);
     RegisterAuraScript(spell_gen_pony_mount_check);
     RegisterAuraScript(spell_corrupting_plague_aura);
+    RegisterAuraScript(spell_gen_vehicle_control_link);
     RegisterSpellScript(spell_freezing_circle);
     RegisterSpellScript(spell_gen_decimatus_transformation_sickness);
     RegisterSpellScript(spell_gen_anetheron_summon_towering_infernal);
diff --git a/src/server/scripts/Spells/spell_warlock.cpp b/src/server/scripts/Spells/spell_warlock.cpp
index 035262d0b4c..acd01840b92 100644
--- a/src/server/scripts/Spells/spell_warlock.cpp
+++ b/src/server/scripts/Spells/spell_warlock.cpp
@@ -318,7 +318,7 @@ class spell_warl_haunt : public SpellScriptLoader
             {
                 if (Aura* aura = GetHitAura())
                     if (AuraEffect* aurEff = aura->GetEffect(EFFECT_1))
-                        aurEff->SetAmount(CalculatePct(aurEff->GetAmount(), GetHitDamage()));
+                        aurEff->SetAmount(CalculatePct(GetHitDamage(), aurEff->GetAmount()));
             }
 
             void Register() override