Core/Spells: Corrected aura SPELL_AURA_MOD_CASTING_SPEED_NOT_STACK handling for auras with very high values (#19054)

(cherry picked from commit e30e11d4c7)

src/server/game/Entities/Unit/Unit.cpp

@@ -285,12 +285,12 @@ SpellNonMeleeDamage::SpellNonMeleeDamage(Unit* _attacker, Unit* _target, uint32
 }
 
 Unit::Unit(bool isWorldObject) :
-    WorldObject(isWorldObject), m_playerMovingMe(NULL), m_lastSanctuaryTime(0),
+    WorldObject(isWorldObject), m_playerMovingMe(nullptr), m_lastSanctuaryTime(0),
     IsAIEnabled(false), NeedChangeAI(false), LastCharmerGUID(),
     m_ControlledByPlayer(false), movespline(new Movement::MoveSpline()),
-    i_AI(NULL), i_disabledAI(NULL), m_AutoRepeatFirstCast(false), m_procDeep(0),
+    i_AI(nullptr), i_disabledAI(nullptr), m_AutoRepeatFirstCast(false), m_procDeep(0),
     m_removedAurasCount(0), i_motionMaster(new MotionMaster(this)), m_regenTimer(0), m_ThreatManager(this),
-    m_vehicle(NULL), m_vehicleKit(NULL), m_unitTypeMask(UNIT_MASK_NONE),
+    m_vehicle(nullptr), m_vehicleKit(nullptr), m_unitTypeMask(UNIT_MASK_NONE),
     m_HostileRefManager(this), _aiAnimKitId(0), _movementAnimKitId(0), _meleeAnimKitId(0),
     _spellHistory(new SpellHistory(this))
 {
@@ -389,10 +389,11 @@ Unit::Unit(bool isWorldObject) :
 
     m_serverSideVisibility.SetValue(SERVERSIDE_VISIBILITY_GHOST, GHOST_VISIBILITY_ALIVE);
 
-    _lastLiquid = NULL;
+    _lastLiquid = nullptr;
 
     _oldFactionId = 0;
     _isWalkingBeforeCharm = false;
+    _instantCast = false;
 }
 
 ////////////////////////////////////////////////////////////
@@ -9158,7 +9159,7 @@ void Unit::ModSpellCastTime(SpellInfo const* spellInfo, int32 & castTime, Spell*
 
     if (!(spellInfo->HasAttribute(SPELL_ATTR0_ABILITY) || spellInfo->HasAttribute(SPELL_ATTR0_TRADESPELL) || spellInfo->HasAttribute(SPELL_ATTR3_NO_DONE_BONUS)) &&
         ((GetTypeId() == TYPEID_PLAYER && spellInfo->SpellFamilyName) || GetTypeId() == TYPEID_UNIT))
-        castTime = int32(float(castTime) * m_unitData->ModCastingSpeed);
+        castTime = CanInstantCast() ? 0 : int32(float(castTime) * m_unitData->ModCastingSpeed);
     else if (spellInfo->HasAttribute(SPELL_ATTR0_REQ_AMMO) && !spellInfo->HasAttribute(SPELL_ATTR2_AUTOREPEAT_FLAG))
         castTime = int32(float(castTime) * m_modAttackSpeedPct[RANGED_ATTACK]);
     else if (IsPartOfSkillLine(SKILL_COOKING, spellInfo->Id) && HasAura(67556)) // cooking with Chef Hat.

src/server/game/Entities/Unit/Unit.h

@@ -1999,6 +1999,9 @@ class TC_GAME_API Unit : public WorldObject
         ObjectGuid GetTarget() const { return m_unitData->Target; }
         virtual void SetTarget(ObjectGuid const& /*guid*/) = 0;
 
+        void SetInstantCast(bool set) { _instantCast = set; }
+        bool CanInstantCast() const { return _instantCast; }
+
         // Movement info
         Movement::MoveSpline * movespline;
 
@@ -2151,6 +2154,7 @@ class TC_GAME_API Unit : public WorldObject
 
         bool m_cleanupDone; // lock made to not add stuff after cleanup before delete
         bool m_duringRemoveFromWorld; // lock made to not add stuff after begining removing from world
+        bool _instantCast;
 
         uint32 _oldFactionId;           ///< faction before charm
         bool _isWalkingBeforeCharm;     ///< Are we walking before we were charmed?

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -4072,6 +4072,34 @@ void AuraEffect::HandleModCastingSpeed(AuraApplication const* aurApp, uint8 mode
 
     Unit* target = aurApp->GetTarget();
 
+    // Do not apply such auras in normal way
+    if (GetAmount() >= 1000)
+    {
+        if (apply)
+            target->SetInstantCast(true);
+        else
+        {
+            // only SPELL_AURA_MOD_CASTING_SPEED_NOT_STACK can have this high amount
+            // it's some rare case that you have 2 auras like that, but just in case ;)
+
+            bool remove = true;
+            Unit::AuraEffectList const& castingSpeedNotStack = target->GetAuraEffectsByType(SPELL_AURA_MOD_CASTING_SPEED_NOT_STACK);
+            for (AuraEffect const* aurEff : castingSpeedNotStack)
+            {
+                if (aurEff != this && aurEff->GetAmount() >= 1000)
+                {
+                    remove = false;
+                    break;
+                }
+            }
+
+            if (remove)
+                target->SetInstantCast(false);
+        }
+
+        return;
+    }
+
     target->ApplyCastTimePercentMod((float)GetAmount(), apply);
 }