Core/Spells: Implement spell queue (#29409)

(cherry picked from commit 27019a62a4294f8dd48d975f85b1907c5adee0e3)

10 files changed, 388 insertions, 161 deletions

diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index 531a103cc30..7bac3c5a9e2 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -110,6 +110,7 @@
 #include "Spell.h"
 #include "SpellAuraEffects.h"
 #include "SpellAuras.h"
+#include "SpellCastRequest.h"
 #include "SpellHistory.h"
 #include "SpellMgr.h"
 #include "SpellPackets.h"
@@ -938,6 +939,10 @@ void Player::Update(uint32 p_time)
     Unit::Update(p_time);
     SetCanDelayTeleport(false);
 
+    // Unit::Update updates the spell history and spell states. We can now check if we can launch another pending cast.
+    if (CanExecutePendingSpellCastRequest())
+        ExecutePendingSpellCastRequest();
+
     time_t now = GameTime::GetGameTime();
 
     UpdatePvPFlag(now);
@@ -1238,6 +1243,9 @@ void Player::setDeathState(DeathState s)
             return;
         }
 
+        // clear all pending spell cast requests when dying
+        CancelPendingCastRequest();
+
         // drunken state is cleared on death
         SetDrunkValue(0);
         SetPower(POWER_COMBO_POINTS, 0);
@@ -28921,3 +28929,262 @@ uint32 TraitMgr::PlayerDataAccessor::GetPrimarySpecialization() const
 {
     return AsUnderlyingType(_player->GetPrimarySpecialization());
 }
+
+void Player::RequestSpellCast(std::unique_ptr<SpellCastRequest> castRequest)
+{
+    // We are overriding an already existing spell cast request so inform the client that the old cast is being replaced
+    if (_pendingSpellCastRequest)
+        CancelPendingCastRequest();
+
+    _pendingSpellCastRequest = std::move(castRequest);
+
+    // If we can process the cast request right now, do it.
+    if (CanExecutePendingSpellCastRequest())
+        ExecutePendingSpellCastRequest();
+}
+
+void Player::CancelPendingCastRequest()
+{
+    if (!_pendingSpellCastRequest)
+        return;
+
+    // We have to inform the client that the cast has been canceled. Otherwise the cast button will remain highlightened
+    WorldPackets::Spells::CastFailed castFailed;
+    castFailed.CastID = _pendingSpellCastRequest->CastRequest.CastID;
+    castFailed.SpellID = _pendingSpellCastRequest->CastRequest.SpellID;
+    castFailed.Reason = SPELL_FAILED_DONT_REPORT;
+    SendDirectMessage(castFailed.Write());
+
+    _pendingSpellCastRequest = nullptr;
+}
+
+// A spell can be queued up within 400 milliseconds before global cooldown expires or the cast finishes
+static constexpr Milliseconds SPELL_QUEUE_TIME_WINDOW = 400ms;
+
+bool Player::CanRequestSpellCast(SpellInfo const* spellInfo, Unit const* castingUnit) const
+{
+    if (castingUnit->GetSpellHistory()->GetRemainingGlobalCooldown(spellInfo) > SPELL_QUEUE_TIME_WINDOW)
+        return false;
+
+    for (CurrentSpellTypes spellSlot : { CURRENT_MELEE_SPELL, CURRENT_GENERIC_SPELL })
+        if (Spell const* spell = GetCurrentSpell(spellSlot))
+            if (Milliseconds(spell->GetRemainingCastTime()) > SPELL_QUEUE_TIME_WINDOW)
+                return false;
+
+    return true;
+}
+
+void Player::ExecutePendingSpellCastRequest()
+{
+    if (!_pendingSpellCastRequest)
+        return;
+
+    TriggerCastFlags triggerFlag = TRIGGERED_NONE;
+
+    Unit* castingUnit = _pendingSpellCastRequest->CastingUnitGUID == GetGUID() ? this : ObjectAccessor::GetUnit(*this, _pendingSpellCastRequest->CastingUnitGUID);
+
+    // client provided targets
+    SpellCastTargets targets(castingUnit, _pendingSpellCastRequest->CastRequest);
+
+    // The spell cast has been requested by using an item. Handle the cast accordingly.
+    if (_pendingSpellCastRequest->ItemData.has_value())
+    {
+        if (ProcessItemCast(*_pendingSpellCastRequest, targets))
+            _pendingSpellCastRequest = nullptr;
+        else
+            CancelPendingCastRequest();
+        return;
+    }
+
+    // check known spell or raid marker spell (which not requires player to know it)
+    SpellInfo const* spellInfo = sSpellMgr->AssertSpellInfo(_pendingSpellCastRequest->CastRequest.SpellID, GetMap()->GetDifficultyID());
+    Player* plrCaster = castingUnit->ToPlayer();
+    if (plrCaster && !plrCaster->HasActiveSpell(spellInfo->Id) && !spellInfo->HasAttribute(SPELL_ATTR8_SKIP_IS_KNOWN_CHECK))
+    {
+        bool allow = false;
+
+        // allow casting of unknown spells for special lock cases
+        if (GameObject* go = targets.GetGOTarget())
+            if (go->GetSpellForLock(plrCaster) == spellInfo)
+                allow = true;
+
+        // allow casting of spells triggered by clientside periodic trigger auras
+        if (castingUnit->HasAuraTypeWithTriggerSpell(SPELL_AURA_PERIODIC_TRIGGER_SPELL_FROM_CLIENT, spellInfo->Id))
+        {
+            allow = true;
+            triggerFlag = TRIGGERED_FULL_MASK;
+        }
+
+        if (!allow)
+        {
+            CancelPendingCastRequest();
+            return;
+        }
+    }
+
+    // Check possible spell cast overrides
+    spellInfo = castingUnit->GetCastSpellInfo(spellInfo, triggerFlag);
+    if (spellInfo->IsPassive())
+    {
+        CancelPendingCastRequest();
+        return;
+    }
+
+    // can't use our own spells when we're in possession of another unit
+    if (isPossessing())
+    {
+        CancelPendingCastRequest();
+        return;
+    }
+
+    // Client is resending autoshot cast opcode when other spell is cast during shoot rotation
+    // Skip it to prevent "interrupt" message
+    // Also check targets! target may have changed and we need to interrupt current spell
+    if (spellInfo->IsAutoRepeatRangedSpell())
+    {
+        if (Spell* spell = castingUnit->GetCurrentSpell(CURRENT_AUTOREPEAT_SPELL))
+        {
+            if (spell->m_spellInfo == spellInfo && spell->m_targets.GetUnitTargetGUID() == targets.GetUnitTargetGUID())
+            {
+                CancelPendingCastRequest();
+                return;
+            }
+        }
+    }
+
+    // auto-selection buff level base at target level (in spellInfo)
+    if (targets.GetUnitTarget())
+    {
+        SpellInfo const* actualSpellInfo = spellInfo->GetAuraRankForLevel(targets.GetUnitTarget()->GetLevelForTarget(this));
+
+        // if rank not found then function return NULL but in explicit cast case original spell can be cast and later failed with appropriate error message
+        if (actualSpellInfo)
+            spellInfo = actualSpellInfo;
+    }
+
+    Spell* spell = new Spell(castingUnit, spellInfo, triggerFlag);
+
+    WorldPackets::Spells::SpellPrepare spellPrepare;
+    spellPrepare.ClientCastID = _pendingSpellCastRequest->CastRequest.CastID;
+    spellPrepare.ServerCastID = spell->m_castId;
+    SendDirectMessage(spellPrepare.Write());
+
+    spell->m_fromClient = true;
+    spell->m_misc.Raw.Data[0] = _pendingSpellCastRequest->CastRequest.Misc[0];
+    spell->m_misc.Raw.Data[1] = _pendingSpellCastRequest->CastRequest.Misc[1];
+    spell->prepare(targets);
+
+    _pendingSpellCastRequest = nullptr;
+}
+
+bool Player::ProcessItemCast(SpellCastRequest& castRequest, SpellCastTargets const& targets)
+{
+    Item* item = GetUseableItemByPos(castRequest.ItemData->PackSlot, castRequest.ItemData->Slot);
+    if (!item)
+    {
+        SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, nullptr, nullptr);
+        return false;
+    }
+
+    if (item->GetGUID() != castRequest.ItemData->CastItem)
+    {
+        SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, nullptr, nullptr);
+        return false;
+    }
+
+    ItemTemplate const* proto = item->GetTemplate();
+    if (!proto)
+    {
+        SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, item, nullptr);
+        return false;
+    }
+
+    // some item classes can be used only in equipped state
+    if (proto->GetInventoryType() != INVTYPE_NON_EQUIP && !item->IsEquipped())
+    {
+        SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, item, nullptr);
+        return false;
+    }
+
+    InventoryResult msg = CanUseItem(item);
+    if (msg != EQUIP_ERR_OK)
+    {
+        SendEquipError(msg, item, nullptr);
+        return false;
+    }
+
+    // only allow conjured consumable, bandage, poisons (all should have the 2^21 item flag set in DB)
+    if (proto->GetClass() == ITEM_CLASS_CONSUMABLE && !proto->HasFlag(ITEM_FLAG_IGNORE_DEFAULT_ARENA_RESTRICTIONS) && InArena())
+    {
+        SendEquipError(EQUIP_ERR_NOT_DURING_ARENA_MATCH, item, nullptr);
+        return false;
+    }
+
+    // don't allow items banned in arena
+    if (proto->HasFlag(ITEM_FLAG_NOT_USEABLE_IN_ARENA) && InArena())
+    {
+        SendEquipError(EQUIP_ERR_NOT_DURING_ARENA_MATCH, item, nullptr);
+        return false;
+    }
+
+    if (IsInCombat())
+    {
+        for (ItemEffectEntry const* effect : item->GetEffects())
+        {
+            if (SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(effect->SpellID, GetMap()->GetDifficultyID()))
+            {
+                if (!spellInfo->CanBeUsedInCombat(this))
+                {
+                    SendEquipError(EQUIP_ERR_NOT_IN_COMBAT, item, nullptr);
+                    return false;
+                }
+            }
+        }
+    }
+
+    // check also  BIND_ON_ACQUIRE and BIND_QUEST for .additem or .additemset case by GM (not binded at adding to inventory)
+    if (item->GetBonding() == BIND_ON_USE || item->GetBonding() == BIND_ON_ACQUIRE || item->GetBonding() == BIND_QUEST)
+    {
+        if (!item->IsSoulBound())
+        {
+            item->SetState(ITEM_CHANGED, this);
+            item->SetBinding(true);
+            GetSession()->GetCollectionMgr()->AddItemAppearance(item);
+        }
+    }
+
+    RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::ItemUse);
+
+    // Note: If script stop casting it must send appropriate data to client to prevent stuck item in gray state.
+    if (!sScriptMgr->OnItemUse(this, item, targets, castRequest.CastRequest.CastID))
+    {
+        // no script or script not process request by self
+        CastItemUseSpell(item, targets, castRequest.CastRequest.CastID, castRequest.CastRequest.Misc);
+    }
+
+    return true;
+}
+
+bool Player::CanExecutePendingSpellCastRequest()
+{
+    if (!_pendingSpellCastRequest)
+        return false;
+
+    Unit const* castingUnit = _pendingSpellCastRequest->CastingUnitGUID == GetGUID() ? this : ObjectAccessor::GetUnit(*this, _pendingSpellCastRequest->CastingUnitGUID);
+    if (!castingUnit || !castingUnit->IsInWorld() || (castingUnit != this && GetUnitBeingMoved() != castingUnit))
+    {
+        // If the casting unit is no longer available, just cancel the entire spell cast request and be done with it
+        CancelPendingCastRequest();
+        return false;
+    }
+
+    // Generic and melee spells have to wait, channeled spells can be processed immediately.
+    if (!castingUnit->GetCurrentSpell(CURRENT_CHANNELED_SPELL) && castingUnit->HasUnitState(UNIT_STATE_CASTING))
+        return false;
+
+    // Waiting for the global cooldown to expire before attempting to execute the cast request
+    if (castingUnit->GetSpellHistory()->GetRemainingGlobalCooldown(sSpellMgr->AssertSpellInfo(_pendingSpellCastRequest->CastRequest.SpellID, GetMap()->GetDifficultyID())) > 0ms)
+        return false;
+
+    return true;
+}
diff --git a/src/server/game/Entities/Player/Player.h b/src/server/game/Entities/Player/Player.h
index b4a32eba905..e15f22fdd7a 100644
--- a/src/server/game/Entities/Player/Player.h
+++ b/src/server/game/Entities/Player/Player.h
@@ -57,6 +57,7 @@ struct PvpTalentEntry;
 struct QuestPackageItemEntry;
 struct RewardPackEntry;
 struct SkillRaceClassInfoEntry;
+struct SpellCastRequest;
 struct TalentEntry;
 struct TrainerSpell;
 struct TransferAbortParams;
@@ -3147,6 +3148,19 @@ class TC_GAME_API Player : public Unit, public GridObject<Player>
 
         bool _usePvpItemLevels;
         ObjectGuid _areaSpiritHealerGUID;
+
+        // Spell cast request handling
+    public:
+        // Queues up a spell cast request that has been received via packet and processes it whenever possible.
+        void RequestSpellCast(std::unique_ptr<SpellCastRequest> castRequest);
+        void CancelPendingCastRequest();
+        bool CanRequestSpellCast(SpellInfo const* spell, Unit const* castingUnit) const;
+
+    private:
+        std::unique_ptr<SpellCastRequest> _pendingSpellCastRequest;
+        void ExecutePendingSpellCastRequest();
+        bool ProcessItemCast(SpellCastRequest& castRequest, SpellCastTargets const& targets);
+        bool CanExecutePendingSpellCastRequest();
 };
 
 TC_GAME_API void AddItemsSetItem(Player* player, Item const* item);
diff --git a/src/server/game/Handlers/SpellHandler.cpp b/src/server/game/Handlers/SpellHandler.cpp
index 48f51f4632c..1204a90755a 100644
--- a/src/server/game/Handlers/SpellHandler.cpp
+++ b/src/server/game/Handlers/SpellHandler.cpp
@@ -36,6 +36,7 @@
 #include "ScriptMgr.h"
 #include "Spell.h"
 #include "SpellAuraEffects.h"
+#include "SpellCastRequest.h"
 #include "SpellMgr.h"
 #include "SpellPackets.h"
 #include "TemporarySummon.h"
@@ -44,96 +45,22 @@
 
 void WorldSession::HandleUseItemOpcode(WorldPackets::Spells::UseItem& packet)
 {
-    Player* user = _player;
-
     // ignore for remote control state
-    if (user->GetUnitBeingMoved() != user)
-        return;
-
-    Item* item = user->GetUseableItemByPos(packet.PackSlot, packet.Slot);
-    if (!item)
-    {
-        user->SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, nullptr, nullptr);
-        return;
-    }
-
-    if (item->GetGUID() != packet.CastItem)
-    {
-        user->SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, nullptr, nullptr);
-        return;
-    }
-
-    ItemTemplate const* proto = item->GetTemplate();
-    if (!proto)
-    {
-        user->SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, item, nullptr);
-        return;
-    }
-
-    // some item classes can be used only in equipped state
-    if (proto->GetInventoryType() != INVTYPE_NON_EQUIP && !item->IsEquipped())
-    {
-        user->SendEquipError(EQUIP_ERR_ITEM_NOT_FOUND, item, nullptr);
-        return;
-    }
-
-    InventoryResult msg = user->CanUseItem(item);
-    if (msg != EQUIP_ERR_OK)
-    {
-        user->SendEquipError(msg, item, nullptr);
+    if (_player->GetUnitBeingMoved() != _player)
         return;
-    }
 
-    // only allow conjured consumable, bandage, poisons (all should have the 2^21 item flag set in DB)
-    if (proto->GetClass() == ITEM_CLASS_CONSUMABLE && !proto->HasFlag(ITEM_FLAG_IGNORE_DEFAULT_ARENA_RESTRICTIONS) && user->InArena())
-    {
-        user->SendEquipError(EQUIP_ERR_NOT_DURING_ARENA_MATCH, item, nullptr);
-        return;
-    }
-
-    // don't allow items banned in arena
-    if (proto->HasFlag(ITEM_FLAG_NOT_USEABLE_IN_ARENA) && user->InArena())
+    // Skip casting invalid spells right away
+    SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(packet.Cast.SpellID, _player->GetMap()->GetDifficultyID());
+    if (!spellInfo)
     {
-        user->SendEquipError(EQUIP_ERR_NOT_DURING_ARENA_MATCH, item, nullptr);
+        TC_LOG_ERROR("network", "WorldSession::HandleUseItemOpcode: attempted to cast a non-existing spell (Id: {})", packet.Cast.SpellID);
         return;
     }
 
-    if (user->IsInCombat())
-    {
-        for (ItemEffectEntry const* effect : item->GetEffects())
-        {
-            if (SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(effect->SpellID, user->GetMap()->GetDifficultyID()))
-            {
-                if (!spellInfo->CanBeUsedInCombat(user))
-                {
-                    user->SendEquipError(EQUIP_ERR_NOT_IN_COMBAT, item, nullptr);
-                    return;
-                }
-            }
-        }
-    }
-
-    // check also  BIND_ON_ACQUIRE and BIND_QUEST for .additem or .additemset case by GM (not binded at adding to inventory)
-    if (item->GetBonding() == BIND_ON_USE || item->GetBonding() == BIND_ON_ACQUIRE || item->GetBonding() == BIND_QUEST)
-    {
-        if (!item->IsSoulBound())
-        {
-            item->SetState(ITEM_CHANGED, user);
-            item->SetBinding(true);
-            GetCollectionMgr()->AddItemAppearance(item);
-        }
-    }
-
-    user->RemoveAurasWithInterruptFlags(SpellAuraInterruptFlags::ItemUse);
-
-    SpellCastTargets targets(user, packet.Cast);
-
-    // Note: If script stop casting it must send appropriate data to client to prevent stuck item in gray state.
-    if (!sScriptMgr->OnItemUse(user, item, targets, packet.Cast.CastID))
-    {
-        // no script or script not process request by self
-        user->CastItemUseSpell(item, targets, packet.Cast.CastID, packet.Cast.Misc);
-    }
+    if (_player->CanRequestSpellCast(spellInfo, _player))
+        _player->RequestSpellCast(std::make_unique<SpellCastRequest>(std::move(packet.Cast), _player->GetGUID(), SpellCastRequestItemData(packet.PackSlot, packet.Slot, packet.CastItem)));
+    else
+        Spell::SendCastResult(_player, spellInfo, {}, packet.Cast.CastID, SPELL_FAILED_SPELL_IN_PROGRESS);
 }
 
 void WorldSession::HandleOpenItemOpcode(WorldPackets::Spells::OpenItem& packet)
@@ -299,103 +226,46 @@ void WorldSession::HandleGameobjectReportUse(WorldPackets::GameObject::GameObjRe
 
 void WorldSession::HandleCastSpellOpcode(WorldPackets::Spells::CastSpell& cast)
 {
-    // ignore for remote control state (for player case)
-    Unit* mover = _player->GetUnitBeingMoved();
-    if (mover != _player && mover->GetTypeId() == TYPEID_PLAYER)
-        return;
-
-    SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(cast.Cast.SpellID, mover->GetMap()->GetDifficultyID());
+    // Skip casting invalid spells right away
+    SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(cast.Cast.SpellID, _player->GetMap()->GetDifficultyID());
     if (!spellInfo)
     {
-        TC_LOG_ERROR("network", "WORLD: unknown spell id {}", cast.Cast.SpellID);
+        TC_LOG_ERROR("network", "WorldSession::HandleCastSpellOpcode: attempted to cast a non-existing spell (Id: {})", cast.Cast.SpellID);
         return;
     }
 
-    Unit* caster = mover;
-    if (caster->GetTypeId() == TYPEID_UNIT && !caster->ToCreature()->HasSpell(spellInfo->Id))
+    // ignore for remote control state (for player case)
+    Unit* mover = _player->GetUnitBeingMoved();
+    if (mover != _player && mover->GetTypeId() == TYPEID_PLAYER)
+        return;
+
+    Unit* castingUnit = mover;
+    if (castingUnit->IsCreature() && !castingUnit->ToCreature()->HasSpell(spellInfo->Id))
     {
         // If the vehicle creature does not have the spell but it allows the passenger to cast own spells
         // change caster to player and let him cast
-        if (!_player->IsOnVehicle(caster) || spellInfo->CheckVehicle(_player) != SPELL_CAST_OK)
+        if (!_player->IsOnVehicle(castingUnit) || spellInfo->CheckVehicle(_player) != SPELL_CAST_OK)
             return;
 
-        caster = _player;
+        castingUnit = _player;
     }
 
-    TriggerCastFlags triggerFlag = TRIGGERED_NONE;
-
-    // client provided targets
-    SpellCastTargets targets(caster, cast.Cast);
-
-    // check known spell or raid marker spell (which not requires player to know it)
-    if (caster->GetTypeId() == TYPEID_PLAYER && !caster->ToPlayer()->HasActiveSpell(spellInfo->Id) && !spellInfo->HasAttribute(SPELL_ATTR8_SKIP_IS_KNOWN_CHECK))
-    {
-        bool allow = false;
-
-        // allow casting of unknown spells for special lock cases
-        if (GameObject* go = targets.GetGOTarget())
-            if (go->GetSpellForLock(caster->ToPlayer()) == spellInfo)
-                allow = true;
-
-        // allow casting of spells triggered by clientside periodic trigger auras
-        if (caster->HasAuraTypeWithTriggerSpell(SPELL_AURA_PERIODIC_TRIGGER_SPELL_FROM_CLIENT, spellInfo->Id))
-        {
-            allow = true;
-            triggerFlag = TRIGGERED_FULL_MASK;
-        }
-
-        if (!allow)
-            return;
-    }
-
-    // Check possible spell cast overrides
-    spellInfo = caster->GetCastSpellInfo(spellInfo, triggerFlag);
-
-    if (spellInfo->IsPassive())
-        return;
-
-    // can't use our own spells when we're in possession of another unit,
-    if (_player->isPossessing())
-        return;
-
-    // Client is resending autoshot cast opcode when other spell is cast during shoot rotation
-    // Skip it to prevent "interrupt" message
-    // Also check targets! target may have changed and we need to interrupt current spell
-    if (spellInfo->IsAutoRepeatRangedSpell())
-        if (Spell* spell = caster->GetCurrentSpell(CURRENT_AUTOREPEAT_SPELL))
-            if (spell->m_spellInfo == spellInfo && spell->m_targets.GetUnitTargetGUID() == targets.GetUnitTargetGUID())
-                return;
-
-    // auto-selection buff level base at target level (in spellInfo)
-    if (targets.GetUnitTarget())
-    {
-        SpellInfo const* actualSpellInfo = spellInfo->GetAuraRankForLevel(targets.GetUnitTarget()->GetLevelForTarget(caster));
-
-        // if rank not found then function return NULL but in explicit cast case original spell can be cast and later failed with appropriate error message
-        if (actualSpellInfo)
-            spellInfo = actualSpellInfo;
-    }
-
-    if (cast.Cast.MoveUpdate)
+    if (cast.Cast.MoveUpdate.has_value())
         HandleMovementOpcode(CMSG_MOVE_STOP, *cast.Cast.MoveUpdate);
 
-    Spell* spell = new Spell(caster, spellInfo, triggerFlag);
-
-    WorldPackets::Spells::SpellPrepare spellPrepare;
-    spellPrepare.ClientCastID = cast.Cast.CastID;
-    spellPrepare.ServerCastID = spell->m_castId;
-    SendPacket(spellPrepare.Write());
-
-    spell->m_fromClient = true;
-    spell->m_misc.Raw.Data[0] = cast.Cast.Misc[0];
-    spell->m_misc.Raw.Data[1] = cast.Cast.Misc[1];
-    spell->prepare(targets);
+    if (_player->CanRequestSpellCast(spellInfo, castingUnit))
+        _player->RequestSpellCast(std::make_unique<SpellCastRequest>(std::move(cast.Cast), castingUnit->GetGUID()));
+    else
+        Spell::SendCastResult(_player, spellInfo, {}, cast.Cast.CastID, SPELL_FAILED_SPELL_IN_PROGRESS);
 }
 
 void WorldSession::HandleCancelCastOpcode(WorldPackets::Spells::CancelCast& packet)
 {
     if (_player->IsNonMeleeSpellCast(false))
+    {
         _player->InterruptNonMeleeSpells(false, packet.SpellID, false);
+        _player->CancelPendingCastRequest(); // canceling casts also cancels pending spell cast requests
+    }
 }
 
 void WorldSession::HandleCancelAuraOpcode(WorldPackets::Spells::CancelAura& cancelAura)
@@ -495,6 +365,11 @@ void WorldSession::HandleCancelAutoRepeatSpellOpcode(WorldPackets::Spells::Cance
     _player->InterruptSpell(CURRENT_AUTOREPEAT_SPELL);
 }
 
+void WorldSession::HandleCancelQueuedSpellOpcode(WorldPackets::Spells::CancelQueuedSpell& /*cancelQueuedSpell*/)
+{
+    _player->CancelPendingCastRequest();
+}
+
 void WorldSession::HandleCancelChanneling(WorldPackets::Spells::CancelChannelling& cancelChanneling)
 {
     // ignore for remote control state (for player case)
diff --git a/src/server/game/Server/Packets/SpellPackets.h b/src/server/game/Server/Packets/SpellPackets.h
index 84d00a08f36..dcffa9458a7 100644
--- a/src/server/game/Server/Packets/SpellPackets.h
+++ b/src/server/game/Server/Packets/SpellPackets.h
@@ -1052,6 +1052,14 @@ namespace WorldPackets
             uint16 OverrideID = 0;
         };
 
+        class CancelQueuedSpell final : public ClientPacket
+        {
+        public:
+            CancelQueuedSpell(WorldPacket&& packet) : ClientPacket(CMSG_CANCEL_QUEUED_SPELL, std::move(packet)) { }
+
+            void Read() override { }
+        };
+
         ByteBuffer& operator>>(ByteBuffer& buffer, SpellCastRequest& request);
     }
 }
diff --git a/src/server/game/Server/Protocol/Opcodes.cpp b/src/server/game/Server/Protocol/Opcodes.cpp
index 9575891718f..6ee3b9b353f 100644
--- a/src/server/game/Server/Protocol/Opcodes.cpp
+++ b/src/server/game/Server/Protocol/Opcodes.cpp
@@ -278,7 +278,7 @@ void OpcodeTable::Initialize()
     DEFINE_HANDLER(CMSG_CANCEL_MASTER_LOOT_ROLL,                            STATUS_UNHANDLED, PROCESS_INPLACE,      &WorldSession::Handle_NULL);
     DEFINE_HANDLER(CMSG_CANCEL_MOD_SPEED_NO_CONTROL_AURAS,                  STATUS_LOGGEDIN,  PROCESS_INPLACE,      &WorldSession::HandleCancelModSpeedNoControlAuras);
     DEFINE_HANDLER(CMSG_CANCEL_MOUNT_AURA,                                  STATUS_LOGGEDIN,  PROCESS_INPLACE,      &WorldSession::HandleCancelMountAuraOpcode);
-    DEFINE_HANDLER(CMSG_CANCEL_QUEUED_SPELL,                                STATUS_UNHANDLED, PROCESS_INPLACE,      &WorldSession::Handle_NULL);
+    DEFINE_HANDLER(CMSG_CANCEL_QUEUED_SPELL,                                STATUS_LOGGEDIN,  PROCESS_INPLACE,      &WorldSession::HandleCancelQueuedSpellOpcode);
     DEFINE_HANDLER(CMSG_CANCEL_TEMP_ENCHANTMENT,                            STATUS_LOGGEDIN,  PROCESS_INPLACE,      &WorldSession::HandleCancelTempEnchantmentOpcode);
     DEFINE_HANDLER(CMSG_CANCEL_TRADE,                                       STATUS_LOGGEDIN_OR_RECENTLY_LOGGOUT, PROCESS_THREADUNSAFE, &WorldSession::HandleCancelTradeOpcode);
     DEFINE_HANDLER(CMSG_CAN_DUEL,                                           STATUS_LOGGEDIN,  PROCESS_THREADUNSAFE, &WorldSession::HandleCanDuel);
diff --git a/src/server/game/Server/WorldSession.h b/src/server/game/Server/WorldSession.h
index 296eda86e61..bf297c185d4 100644
--- a/src/server/game/Server/WorldSession.h
+++ b/src/server/game/Server/WorldSession.h
@@ -699,6 +699,7 @@ namespace WorldPackets
         class CancelGrowthAura;
         class CancelMountAura;
         class CancelModSpeedNoControlAuras;
+        class CancelQueuedSpell;
         class PetCancelAura;
         class CancelCast;
         class CastSpell;
@@ -1500,6 +1501,7 @@ class TC_GAME_API WorldSession
         void HandleCancelMountAuraOpcode(WorldPackets::Spells::CancelMountAura& cancelMountAura);
         void HandleCancelModSpeedNoControlAuras(WorldPackets::Spells::CancelModSpeedNoControlAuras& cancelModSpeedNoControlAuras);
         void HandleCancelAutoRepeatSpellOpcode(WorldPackets::Spells::CancelAutoRepeatSpell& cancelAutoRepeatSpell);
+        void HandleCancelQueuedSpellOpcode(WorldPackets::Spells::CancelQueuedSpell& cancelQueuedSpell);
         void HandleMissileTrajectoryCollision(WorldPackets::Spells::MissileTrajectoryCollision& packet);
         void HandleUpdateMissileTrajectory(WorldPackets::Spells::UpdateMissileTrajectory& packet);
 
diff --git a/src/server/game/Spells/Spell.h b/src/server/game/Spells/Spell.h
index ad87c90f21b..ccdb50c57fe 100644
--- a/src/server/game/Spells/Spell.h
+++ b/src/server/game/Spells/Spell.h
@@ -598,6 +598,7 @@ class TC_GAME_API Spell
         UsedSpellMods m_appliedMods;
 
         int32 GetCastTime() const { return m_casttime; }
+        int32 GetRemainingCastTime() const { return m_timer; }
         bool IsAutoRepeat() const { return m_autoRepeat; }
         void SetAutoRepeat(bool rep) { m_autoRepeat = rep; }
         void ReSetTimer() { m_timer = m_casttime > 0 ? m_casttime : 0; }
diff --git a/src/server/game/Spells/SpellCastRequest.h b/src/server/game/Spells/SpellCastRequest.h
new file mode 100644
index 00000000000..f78be8314db
--- /dev/null
+++ b/src/server/game/Spells/SpellCastRequest.h
@@ -0,0 +1,43 @@
+/*
+ * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef SpellCastRequest_h__
+#define SpellCastRequest_h__
+
+#include "SpellPackets.h"
+
+struct SpellCastRequestItemData
+{
+    SpellCastRequestItemData(uint8 packSlot, uint8 slot, ObjectGuid castItem) :
+        PackSlot(packSlot), Slot(slot), CastItem(castItem) { }
+
+    uint8 PackSlot = 0;
+    uint8 Slot = 0;
+    ObjectGuid CastItem;
+};
+
+struct SpellCastRequest
+{
+    SpellCastRequest(WorldPackets::Spells::SpellCastRequest&& castRequest, ObjectGuid castingUnitGUID, Optional<SpellCastRequestItemData> itemData = {}) :
+        CastRequest(castRequest), CastingUnitGUID(castingUnitGUID), ItemData(itemData) { }
+
+    WorldPackets::Spells::SpellCastRequest CastRequest;
+    ObjectGuid CastingUnitGUID;
+    Optional<SpellCastRequestItemData> ItemData;
+};
+
+#endif // SpellCastRequest_h__
diff --git a/src/server/game/Spells/SpellHistory.cpp b/src/server/game/Spells/SpellHistory.cpp
index 934345b137d..7e090101530 100644
--- a/src/server/game/Spells/SpellHistory.cpp
+++ b/src/server/game/Spells/SpellHistory.cpp
@@ -950,6 +950,22 @@ void SpellHistory::CancelGlobalCooldown(SpellInfo const* spellInfo)
     _globalCooldowns[spellInfo->StartRecoveryCategory] = Clock::time_point(Clock::duration(0));
 }
 
+SpellHistory::Duration SpellHistory::GetRemainingGlobalCooldown(SpellInfo const* spellInfo) const
+{
+    Clock::time_point end;
+    auto cdItr = _globalCooldowns.find(spellInfo->StartRecoveryCategory);
+    if (cdItr == _globalCooldowns.end())
+        return Duration::zero();
+
+    end = cdItr->second;
+    Clock::time_point now = GameTime::GetTime<Clock>();
+    if (end < now)
+        return Duration::zero();
+
+    Clock::duration remaining = end - now;
+    return std::chrono::duration_cast<std::chrono::milliseconds>(remaining);
+}
+
 Player* SpellHistory::GetPlayerOwner() const
 {
     return _owner->GetCharmerOrOwnerPlayerOrPlayerItself();
diff --git a/src/server/game/Spells/SpellHistory.h b/src/server/game/Spells/SpellHistory.h
index f15a51c95c5..0e86193ef02 100644
--- a/src/server/game/Spells/SpellHistory.h
+++ b/src/server/game/Spells/SpellHistory.h
@@ -171,6 +171,7 @@ public:
     bool HasGlobalCooldown(SpellInfo const* spellInfo) const;
     void AddGlobalCooldown(SpellInfo const* spellInfo, Duration duration);
     void CancelGlobalCooldown(SpellInfo const* spellInfo);
+    Duration GetRemainingGlobalCooldown(SpellInfo const* spellInfo) const;
 
     void SaveCooldownStateBeforeDuel();
     void RestoreCooldownStateAfterDuel();