Core/Creatures: Improved movement interruption while casting spells

src/server/game/Entities/Creature/Creature.cpp

@@ -3236,21 +3236,10 @@ void Creature::ReacquireSpellFocusTarget()
 
 bool Creature::IsMovementPreventedByCasting() const
 {
-    // Creature is not casting. This state check is needed for scripted casting states which are usually considered hacks but for now we keep it.
-    if (!HasUnitState(UNIT_STATE_CASTING))
+    if (!Unit::IsMovementPreventedByCasting() && !HasSpellFocus())
         return false;
 
-    Spell* spellToCheck = nullptr;
-
-   if (Spell* spell = m_currentSpells[CURRENT_CHANNELED_SPELL]) // Check for active channeled spells
-       spellToCheck = spell;
-   else if (Spell* spell = m_currentSpells[CURRENT_GENERIC_SPELL]) // Check for ongoing spell casts
-       spellToCheck = spell;
-
-    if (!spellToCheck)
-        return false;
-
-    return (spellToCheck->CheckMovement() != SPELL_CAST_OK);
+    return true;
 }
 
 void Creature::StartPickPocketRefillTimer()

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

@@ -2892,7 +2892,8 @@ bool Unit::IsMovementPreventedByCasting() const
         return false;
 
     if (Spell* spell = m_currentSpells[CURRENT_GENERIC_SPELL])
-        if (HasAuraTypeWithAffectMask(SPELL_AURA_CAST_WHILE_WALKING, spell->GetSpellInfo()))
+        if (HasAuraTypeWithAffectMask(SPELL_AURA_CAST_WHILE_WALKING, spell->GetSpellInfo()) || spell->getState() == SPELL_STATE_FINISHED ||
+            !spell->m_spellInfo->InterruptFlags.HasFlag(SpellInterruptFlags::Movement))
             return false;
 
     // channeled spells during channel stage (after the initial cast timer) allow movement with a specific spell attribute

src/server/game/Spells/Spell.cpp

@@ -3377,7 +3377,7 @@ SpellCastResult Spell::prepare(SpellCastTargets const& targets, AuraEffect const
     else
         m_casttime = m_spellInfo->CalcCastTime(m_caster->IsUnit() ? m_caster->ToUnit()->getLevel() : 0, this);
 
-    if (m_caster->IsPlayer() && m_caster->ToUnit()->isMoving())
+    if (m_caster->IsUnit() && m_caster->ToUnit()->isMoving())
     {
         result = CheckMovement();
         if (result != SPELL_CAST_OK)
@@ -4076,7 +4076,7 @@ void Spell::update(uint32 difftime)
 
     // check if the player caster has moved before the spell finished
     // with the exception of spells affected with SPELL_AURA_CAST_WHILE_WALKING effect
-    if (m_timer != 0 && m_caster->IsPlayer() && m_caster->ToUnit()->isMoving() && CheckMovement() != SPELL_CAST_OK)
+    if (m_timer != 0 && m_caster->IsUnit() && m_caster->ToUnit()->isMoving() && CheckMovement() != SPELL_CAST_OK)
     {
         // if charmed by creature, trust the AI not to cheat and allow the cast to proceed
         // @todo this is a hack, "creature" movesplines don't differentiate turning/moving right now
@@ -6805,6 +6805,12 @@ SpellCastResult Spell::CheckMovement() const
     if (IsTriggered())
         return SPELL_CAST_OK;
 
+    // Creatures (not controlled) give priority to spell casting over movement.
+    // We assume that the casting is always valid and the current movement
+    // is stopped by Unit:IsmovementPreventedByCasting to prevent casting interruption.
+    if (m_caster->IsCreature() && !m_caster->ToCreature()->IsControlledByPlayer())
+        return SPELL_CAST_OK;
+
     if (Unit* unitCaster = m_caster->ToUnit())
     {
         if (!unitCaster->HasAuraTypeWithAffectMask(SPELL_AURA_CAST_WHILE_WALKING, m_spellInfo))