fix(Scripts/Vehicles): The next player entering Salvaged Siege Engine… (#10987)

… should control turret if it's not occupied.

data/sql/updates/pending_db_world/rev_1647104625347732100.sql

@@ -0,0 +1,3 @@
+INSERT INTO `version_db_world` (`sql_rev`) VALUES ('1647104625347732100');
+
+UPDATE `creature_template` SET `ScriptName`='npc_salvaged_siege_engine' WHERE `entry`=33060;

src/server/game/AI/CreatureAI.h

@@ -177,6 +177,8 @@ public:
     /// == Fields =======================================
     virtual void PassengerBoarded(Unit* /*passenger*/, int8 /*seatId*/, bool /*apply*/) {}
 
+    virtual bool BeforeSpellClick(Unit* /*clicker*/) { return true; }
+
     virtual void OnSpellClick(Unit* /*clicker*/, bool& /*result*/) { }
 
     virtual bool CanSeeAlways(WorldObject const* /*obj*/) { return false; }

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

@@ -18899,6 +18899,15 @@ void Unit::JumpTo(WorldObject* obj, float speedZ)
 
 bool Unit::HandleSpellClick(Unit* clicker, int8 seatId)
 {
+    Creature* creature = ToCreature();
+    if (creature && creature->IsAIEnabled)
+    {
+        if (!creature->AI()->BeforeSpellClick(clicker))
+        {
+            return false;
+        }
+    }
+
     bool result = false;
     uint32 spellClickEntry = GetVehicleKit() ? GetVehicleKit()->GetCreatureEntry() : GetEntry();
     SpellClickInfoMapBounds clickPair = sObjectMgr->GetSpellClickInfoMapBounds(spellClickEntry);
@@ -18967,7 +18976,6 @@ bool Unit::HandleSpellClick(Unit* clicker, int8 seatId)
         result = true;
     }
 
-    Creature* creature = ToCreature();
     if (creature && creature->IsAIEnabled)
         creature->AI()->OnSpellClick(clicker, result);
 

src/server/scripts/Northrend/Ulduar/Ulduar/ulduar.cpp

@@ -16,12 +16,14 @@
  */
 
 #include "ulduar.h"
+#include "CombatAI.h"
 #include "Player.h"
 #include "ScriptMgr.h"
 #include "ScriptedCreature.h"
 #include "ScriptedGossip.h"
 #include "SpellAuraEffects.h"
 #include "SpellScript.h"
+#include "Vehicle.h"
 
 class npc_ulduar_keeper : public CreatureScript
 {
@@ -423,6 +425,31 @@ public:
     }
 };
 
+struct npc_salvaged_siege_engine : public VehicleAI
+{
+    npc_salvaged_siege_engine(Creature* creature) : VehicleAI(creature) { }
+
+    bool BeforeSpellClick(Unit* clicker) override
+    {
+        if (Vehicle* vehicle = me->GetVehicleKit())
+        {
+            if (vehicle->IsVehicleInUse())
+            {
+                if (Unit* turret = vehicle->GetPassenger(7))
+                {
+                    if (!turret->GetVehicleKit()->IsVehicleInUse())
+                    {
+                        turret->HandleSpellClick(clicker);
+                        return false;
+                    }
+                }
+            }
+        }
+
+        return true;
+    }
+};
+
 void AddSC_ulduar()
 {
     new npc_ulduar_keeper();
@@ -435,4 +462,6 @@ void AddSC_ulduar()
 
     new AreaTrigger_at_celestial_planetarium_enterance();
     new go_call_tram();
+
+    RegisterCreatureAI(npc_salvaged_siege_engine);
 }