Core/Spells: Fix some issues with channeled spells and aura duration mods

Closes #21584

(cherry picked from commit ac976550632f17f5a3ec7eaae354f84faf2656e5)

3 files changed, 54 insertions, 47 deletions

diff --git a/src/server/game/Spells/Auras/SpellAuras.cpp b/src/server/game/Spells/Auras/SpellAuras.cpp
index a6959945d0d..bead326338d 100644
--- a/src/server/game/Spells/Auras/SpellAuras.cpp
+++ b/src/server/game/Spells/Auras/SpellAuras.cpp
@@ -842,23 +842,28 @@ void Aura::Update(uint32 diff, Unit* caster)
 
 int32 Aura::CalcMaxDuration(Unit* caster) const
 {
+    return Aura::CalcMaxDuration(GetSpellInfo(), caster);
+}
+
+/*static*/ int32 Aura::CalcMaxDuration(SpellInfo const* spellInfo, WorldObject* caster)
+{
     Player* modOwner = nullptr;
     int32 maxDuration;
 
     if (caster)
     {
         modOwner = caster->GetSpellModOwner();
-        maxDuration = caster->CalcSpellDuration(m_spellInfo);
+        maxDuration = caster->CalcSpellDuration(spellInfo);
     }
     else
-        maxDuration = m_spellInfo->GetDuration();
+        maxDuration = spellInfo->GetDuration();
 
-    if (IsPassive() && !m_spellInfo->DurationEntry)
+    if (spellInfo->IsPassive() && !spellInfo->DurationEntry)
         maxDuration = -1;
 
     // IsPermanent() checks max duration (which we are supposed to calculate here)
     if (maxDuration != -1 && modOwner)
-        modOwner->ApplySpellMod(GetSpellInfo(), SpellModOp::Duration, maxDuration);
+        modOwner->ApplySpellMod(spellInfo, SpellModOp::Duration, maxDuration);
 
     return maxDuration;
 }
diff --git a/src/server/game/Spells/Auras/SpellAuras.h b/src/server/game/Spells/Auras/SpellAuras.h
index 189b65a7d1d..5a5fdc00544 100644
--- a/src/server/game/Spells/Auras/SpellAuras.h
+++ b/src/server/game/Spells/Auras/SpellAuras.h
@@ -168,6 +168,7 @@ class TC_GAME_API Aura
         void SetMaxDuration(int32 duration) { m_maxDuration = duration; }
         int32 CalcMaxDuration() const { return CalcMaxDuration(GetCaster()); }
         int32 CalcMaxDuration(Unit* caster) const;
+        static int32 CalcMaxDuration(SpellInfo const* spellInfo, WorldObject* caster);
         int32 GetDuration() const { return m_duration; }
         void SetDuration(int32 duration, bool withMods = false);
         void RefreshDuration(bool withMods = false);
diff --git a/src/server/game/Spells/Spell.cpp b/src/server/game/Spells/Spell.cpp
index bc5f090bb38..a24bb14366d 100644
--- a/src/server/game/Spells/Spell.cpp
+++ b/src/server/game/Spells/Spell.cpp
@@ -2814,7 +2814,7 @@ SpellMissInfo Spell::PreprocessSpellHit(Unit* unit, TargetInfo& hitInfo)
             }
         }
 
-        hitInfo.AuraDuration = m_spellInfo->GetMaxDuration();
+        hitInfo.AuraDuration = Aura::CalcMaxDuration(m_spellInfo, origCaster);
 
         // unit is immune to aura if it was diminished to 0 duration
         if (!hitInfo.Positive && !unit->ApplyDiminishingToDuration(m_spellInfo, hitInfo.AuraDuration, origCaster, diminishLevel))
@@ -2852,54 +2852,53 @@ void Spell::DoSpellEffectHit(Unit* unit, SpellEffectInfo const& spellEffectInfo,
                     .IsRefresh = &refresh;
 
                 if (Aura* aura = Aura::TryRefreshStackOrCreate(createInfo))
-                    _spellAura = aura->ToUnitAura();
-            }
-            else
-                _spellAura->AddStaticApplication(unit, aura_effmask);
-
-            if (_spellAura)
-            {
-                // Set aura stack amount to desired value
-                if (m_spellValue->AuraStackAmount > 1)
                 {
-                    if (!refresh)
-                        _spellAura->SetStackAmount(m_spellValue->AuraStackAmount);
-                    else
-                        _spellAura->ModStackAmount(m_spellValue->AuraStackAmount);
-                }
+                    _spellAura = aura->ToUnitAura();
 
-                _spellAura->SetDiminishGroup(hitInfo.DRGroup);
+                    // Set aura stack amount to desired value
+                    if (m_spellValue->AuraStackAmount > 1)
+                    {
+                        if (!refresh)
+                            _spellAura->SetStackAmount(m_spellValue->AuraStackAmount);
+                        else
+                            _spellAura->ModStackAmount(m_spellValue->AuraStackAmount);
+                    }
 
-                hitInfo.AuraDuration = caster->ModSpellDuration(m_spellInfo, unit, hitInfo.AuraDuration, hitInfo.Positive, _spellAura->GetEffectMask());
+                    _spellAura->SetDiminishGroup(hitInfo.DRGroup);
 
-                if (hitInfo.AuraDuration > 0)
-                {
-                    hitInfo.AuraDuration *= m_spellValue->DurationMul;
+                    hitInfo.AuraDuration = caster->ModSpellDuration(m_spellInfo, unit, hitInfo.AuraDuration, hitInfo.Positive, _spellAura->GetEffectMask());
 
-                    // Haste modifies duration of channeled spells
-                    if (m_spellInfo->IsChanneled())
-                        caster->ModSpellDurationTime(m_spellInfo, hitInfo.AuraDuration, this);
-                    else if (m_spellInfo->HasAttribute(SPELL_ATTR5_HASTE_AFFECT_DURATION))
+                    if (hitInfo.AuraDuration > 0)
                     {
-                        int32 origDuration = hitInfo.AuraDuration;
-                        hitInfo.AuraDuration = 0;
-                        for (AuraEffect const* auraEff : _spellAura->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);
-
-                        // if there is no periodic effect
-                        if (!hitInfo.AuraDuration)
-                            hitInfo.AuraDuration = int32(origDuration * m_originalCaster->m_unitData->ModCastingSpeed);
+                        hitInfo.AuraDuration *= m_spellValue->DurationMul;
+
+                        // Haste modifies duration of channeled spells
+                        if (m_spellInfo->IsChanneled())
+                            caster->ModSpellDurationTime(m_spellInfo, hitInfo.AuraDuration, this);
+                        else if (m_spellInfo->HasAttribute(SPELL_ATTR5_HASTE_AFFECT_DURATION))
+                        {
+                            int32 origDuration = hitInfo.AuraDuration;
+                            hitInfo.AuraDuration = 0;
+                            for (AuraEffect const* auraEff : _spellAura->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);
+
+                            // if there is no periodic effect
+                            if (!hitInfo.AuraDuration)
+                                hitInfo.AuraDuration = int32(origDuration * m_originalCaster->m_unitData->ModCastingSpeed);
+                        }
                     }
-                }
 
-                if (hitInfo.AuraDuration != _spellAura->GetMaxDuration())
-                {
-                    _spellAura->SetMaxDuration(hitInfo.AuraDuration);
-                    _spellAura->SetDuration(hitInfo.AuraDuration);
+                    if (hitInfo.AuraDuration != _spellAura->GetMaxDuration())
+                    {
+                        _spellAura->SetMaxDuration(hitInfo.AuraDuration);
+                        _spellAura->SetDuration(hitInfo.AuraDuration);
+                    }
                 }
             }
+            else
+                _spellAura->AddStaticApplication(unit, aura_effmask);
         }
     }
 
@@ -3582,10 +3581,12 @@ void Spell::handle_immediate()
         else if (duration == -1)
             SendChannelStart(duration);
 
-        m_spellState = SPELL_STATE_CASTING;
-
-        // GameObjects shouldn't cast channeled spells
-        ASSERT_NOTNULL(m_caster->ToUnit())->AddInterruptMask(m_spellInfo->ChannelInterruptFlags, m_spellInfo->ChannelInterruptFlags2);
+        if (duration != 0)
+        {
+            m_spellState = SPELL_STATE_CASTING;
+            // GameObjects shouldn't cast channeled spells
+            ASSERT_NOTNULL(m_caster->ToUnit())->AddInterruptMask(m_spellInfo->ChannelInterruptFlags, m_spellInfo->ChannelInterruptFlags2);
+        }
     }
 
     PrepareTargetProcessing();