feat(Core/Player): implement Spell Queue (#20797)

src/server/game/Entities/Player/Player.cpp

@@ -1026,6 +1026,9 @@ void Player::setDeathState(DeathState s, bool /*despawn = false*/)
             return;
         }
 
+        // clear all pending spell cast requests when dying
+        SpellQueue.clear();
+
         // drunken state is cleared on death
         SetDrunkValue(0);
         // lost combo points at any target (targeted combo points clear in Unit::setDeathState)

src/server/game/Entities/Player/Player.h

@@ -1060,6 +1060,18 @@ struct EntryPointData
     [[nodiscard]] bool HasTaxiPath() const { return taxiPath[0] && taxiPath[1]; }
 };
 
+struct PendingSpellCastRequest
+{
+    uint32 spellId;
+    uint32 category;
+    WorldPacket requestPacket;
+    bool isItem = false;
+    bool cancelInProgress = false;
+
+    PendingSpellCastRequest(uint32 spellId, uint32 category, WorldPacket&& packet, bool item = false, bool cancel = false)
+        : spellId(spellId), category(category), requestPacket(std::move(packet)), isItem(item) , cancelInProgress(cancel) {}
+};
+
 class Player : public Unit, public GridObject<Player>
 {
     friend class WorldSession;
@@ -2615,7 +2627,21 @@ public:
 
     std::string GetDebugInfo() const override;
 
- protected:
+    /*********************************************************/
+    /***               SPELL QUEUE SYSTEM                  ***/
+    /*********************************************************/
+protected:
+    uint32 GetSpellQueueWindow() const;
+    void ProcessSpellQueue();
+
+public:
+    std::deque<PendingSpellCastRequest> SpellQueue;
+    const PendingSpellCastRequest* GetCastRequest(uint32 category) const;
+    bool CanExecutePendingSpellCastRequest(SpellInfo const* spellInfo);
+    void ExecuteOrCancelSpellCastRequest(PendingSpellCastRequest* castRequest, bool isCancel = false);
+    bool CanRequestSpellCast(SpellInfo const* spellInfo);
+
+protected:
     // Gamemaster whisper whitelist
     WhisperListContainer WhisperList;
 

src/server/game/Entities/Player/PlayerUpdates.cpp

@@ -79,6 +79,7 @@ void Player::Update(uint32 p_time)
 
     // used to implement delayed far teleports
     SetMustDelayTeleport(true);
+    ProcessSpellQueue();
     Unit::Update(p_time);
     SetMustDelayTeleport(false);
 
@@ -2255,3 +2256,89 @@ void Player::ProcessTerrainStatusUpdate()
     else
         m_MirrorTimerFlags &= ~(UNDERWATER_INWATER | UNDERWATER_INLAVA | UNDERWATER_INSLIME | UNDERWATER_INDARKWATER);
 }
+
+uint32 Player::GetSpellQueueWindow() const
+{
+    return sWorld->getIntConfig(CONFIG_SPELL_QUEUE_WINDOW);
+}
+
+bool Player::CanExecutePendingSpellCastRequest(SpellInfo const* spellInfo)
+{
+    if (GetGlobalCooldownMgr().HasGlobalCooldown(spellInfo))
+        return false;
+
+    if (GetSpellCooldownDelay(spellInfo->Id) > GetSpellQueueWindow())
+        return false;
+
+    for (CurrentSpellTypes spellSlot : {CURRENT_MELEE_SPELL, CURRENT_GENERIC_SPELL})
+        if (Spell* spell = GetCurrentSpell(spellSlot))
+        {
+            bool autoshot = spell->m_spellInfo->IsAutoRepeatRangedSpell();
+            if (IsNonMeleeSpellCast(false, true, true, autoshot))
+                return false;
+        }
+    return true;
+}
+
+const PendingSpellCastRequest* Player::GetCastRequest(uint32 category) const
+{
+    for (const PendingSpellCastRequest& request : SpellQueue)
+        if (request.category == category)
+            return &request;
+    return nullptr;
+}
+
+bool Player::CanRequestSpellCast(SpellInfo const* spellInfo)
+{
+    if (!sWorld->getBoolConfig(CONFIG_SPELL_QUEUE_ENABLED))
+        return false;
+
+    // Check for existing cast request with the same category
+    if (GetCastRequest(spellInfo->StartRecoveryCategory))
+        return false;
+
+    if (GetGlobalCooldownMgr().GetGlobalCooldown(spellInfo) > GetSpellQueueWindow())
+        return false;
+
+    if (GetSpellCooldownDelay(spellInfo->Id) > GetSpellQueueWindow())
+        return false;
+
+    // If there is an existing cast that will last longer than the allowable
+    // spell queue window, then we can't request a new spell cast
+    for (CurrentSpellTypes spellSlot : { CURRENT_MELEE_SPELL, CURRENT_GENERIC_SPELL })
+        if (Spell* spell = GetCurrentSpell(spellSlot))
+            if (spell->GetCastTimeRemaining() > static_cast<int32>(GetSpellQueueWindow()))
+                return false;
+
+    return true;
+}
+
+void Player::ExecuteOrCancelSpellCastRequest(PendingSpellCastRequest* request, bool isCancel /* = false*/)
+{
+    if (isCancel)
+        request->cancelInProgress = true;
+
+    if (WorldSession* session = GetSession())
+    {
+        if (request->isItem)
+            session->HandleUseItemOpcode(request->requestPacket);
+        else
+            session->HandleCastSpellOpcode(request->requestPacket);
+    }
+}
+
+void Player::ProcessSpellQueue()
+{
+    while (!SpellQueue.empty())
+    {
+        PendingSpellCastRequest& request = SpellQueue.front(); // Peek at the first spell
+        SpellInfo const* spellInfo = sSpellMgr->GetSpellInfo(request.spellId);
+        if (CanExecutePendingSpellCastRequest(spellInfo))
+        {
+            ExecuteOrCancelSpellCastRequest(&request);
+            SpellQueue.pop_front(); // Remove from the queue
+        }
+        else // If the first spell can't execute, stop processing
+            break;
+    }
+}