Creature/Scripting: Move CreatureAI::CanRespawn to CreatureScript::CanSpawn. Now also applies to initial spawn. Dynamic spawning prep.

(cherry picked from commit b3d44d6c366c7e4f12a6ce30ee5cf6b9bff68a06)

Game/Scripting: Follow-up to b3d44d6. Fix script selection for creatures on difficulty > 0.
(cherry picked from commit 91c2b3162d350ab1a09053574ad67f45f089175b)

Build fix.
(cherry picked from commit a9f1151f2ca56394e315d0b07741c240ef59c2ff)

Fine, this time I actually built it. Promise.
(cherry picked from commit 0c2c88ed5025d9b51b6cbdf0603ceaf1ea54c80a)

6 files changed, 23 insertions, 15 deletions

diff --git a/src/server/game/AI/CreatureAI.h b/src/server/game/AI/CreatureAI.h
index 007f6ceabc8..72c2e254c47 100644
--- a/src/server/game/AI/CreatureAI.h
+++ b/src/server/game/AI/CreatureAI.h
@@ -106,9 +106,6 @@ class TC_GAME_API CreatureAI : public UnitAI
         // Trigger Creature "Alert" state (creature can see stealthed unit)
         void TriggerAlert(Unit const* who) const;
 
-        // Called in Creature::Update when deathstate = DEAD. Inherited classes may maniuplate the ability to respawn based on scripted events.
-        virtual bool CanRespawn() { return true; }
-
         // Called for reaction at stopping attack at no attackers or targets
         virtual void EnterEvadeMode(EvadeReason why = EVADE_REASON_OTHER);
 
diff --git a/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp b/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
index 6503c703c58..f4dbb0e128a 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedCreature.cpp
@@ -496,14 +496,6 @@ void BossAI::_EnterCombat()
     ScheduleTasks();
 }
 
-bool BossAI::CanRespawn()
-{
-    if (instance && instance->GetBossState(_bossId) == DONE)
-        return false;
-
-    return true;
-}
-
 void BossAI::TeleportCheaters()
 {
     float x, y, z;
diff --git a/src/server/game/AI/ScriptedAI/ScriptedCreature.h b/src/server/game/AI/ScriptedAI/ScriptedCreature.h
index 8eee577b097..7639f45ead8 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedCreature.h
+++ b/src/server/game/AI/ScriptedAI/ScriptedCreature.h
@@ -358,7 +358,6 @@ class TC_GAME_API BossAI : public ScriptedAI
         void JustReachedHome() override { _JustReachedHome(); }
 
         bool CanAIAttack(Unit const* target) const override { return CheckBoundary(target); }
-        bool CanRespawn() override;
 
     protected:
         void _Reset();
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index d19cc9602d4..958d97e785e 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -525,9 +525,9 @@ void Creature::Update(uint32 diff)
             time_t now = time(NULL);
             if (m_respawnTime <= now)
             {
-                bool allowed = IsAIEnabled ? AI()->CanRespawn() : true;     // First check if there are any scripts that object to us respawning
-                if (!allowed)                                               // Will be rechecked on next Update call
-                    break;
+                // First check if there are any scripts that object to us respawning
+                if (!sScriptMgr->CanSpawn(GetSpawnId(), GetEntry(), GetCreatureTemplate(), GetCreatureData(), GetMap()))
+                    break; // Will be rechecked on next Update call
 
                 ObjectGuid dbtableHighGuid = ObjectGuid::Create<HighGuid::Creature>(GetMapId(), GetEntry(), m_spawnId);
                 time_t linkedRespawntime = GetMap()->GetLinkedRespawnTime(dbtableHighGuid);
@@ -1412,6 +1412,11 @@ bool Creature::LoadCreatureFromDB(ObjectGuid::LowType spawnId, Map* map, bool ad
     m_deathState = ALIVE;
 
     m_respawnTime  = GetMap()->GetCreatureRespawnTime(m_spawnId);
+
+    // Is the creature script objecting to us spawning? If yes, delay by one second (then re-check in ::Update)
+    if (!m_respawnTime && !sScriptMgr->CanSpawn(spawnId, GetEntry(), GetCreatureTemplate(), GetCreatureData(), map))
+        m_respawnTime = time(NULL)+1;
+
     if (m_respawnTime)                          // respawn on Update
     {
         m_deathState = DEAD;
diff --git a/src/server/game/Scripting/ScriptMgr.cpp b/src/server/game/Scripting/ScriptMgr.cpp
index 7c94aa3ed55..8ad749ef53a 100644
--- a/src/server/game/Scripting/ScriptMgr.cpp
+++ b/src/server/game/Scripting/ScriptMgr.cpp
@@ -1706,6 +1706,15 @@ uint32 ScriptMgr::GetDialogStatus(Player* player, Creature* creature)
     return tmpscript->GetDialogStatus(player, creature);
 }
 
+bool ScriptMgr::CanSpawn(ObjectGuid::LowType spawnId, uint32 entry, CreatureTemplate const* actTemplate, CreatureData const* cData, Map const* map)
+{
+    ASSERT(actTemplate);
+
+    CreatureTemplate const* baseTemplate = sObjectMgr->GetCreatureTemplate(entry);
+    GET_SCRIPT_RET(CreatureScript, baseTemplate->ScriptID, tmpscript, true);
+    return tmpscript->CanSpawn(spawnId, entry, baseTemplate, actTemplate, cData, map);
+}
+
 CreatureAI* ScriptMgr::GetCreatureAI(Creature* creature)
 {
     ASSERT(creature);
diff --git a/src/server/game/Scripting/ScriptMgr.h b/src/server/game/Scripting/ScriptMgr.h
index 76a5f663f82..72b71651bd9 100644
--- a/src/server/game/Scripting/ScriptMgr.h
+++ b/src/server/game/Scripting/ScriptMgr.h
@@ -68,6 +68,8 @@ struct AreaTriggerEntry;
 struct AuctionEntry;
 struct ConditionSourceInfo;
 struct Condition;
+struct CreatureTemplate;
+struct CreatureData;
 struct ItemTemplate;
 struct MapEntry;
 struct OutdoorPvPData;
@@ -436,6 +438,9 @@ class TC_GAME_API CreatureScript : public UnitScript, public UpdatableScript<Cre
         // Called when the dialog status between a player and the creature is requested.
         virtual uint32 GetDialogStatus(Player* /*player*/, Creature* /*creature*/) { return DIALOG_STATUS_SCRIPTED_NO_STATUS; }
 
+        // Called when the creature tries to spawn. Return false to block spawn and re-evaluate on next tick.
+        virtual bool CanSpawn(ObjectGuid::LowType /*spawnId*/, uint32 /*entry*/, CreatureTemplate const* /*baseTemplate*/, CreatureTemplate const* /*actTemplate*/, CreatureData const* /*cData*/, Map const* /*map*/) const { return true; }
+
         // Called when a CreatureAI object is needed for the creature.
         virtual CreatureAI* GetAI(Creature* /*creature*/) const { return NULL; }
 };
@@ -1016,6 +1021,7 @@ class TC_GAME_API ScriptMgr
         bool OnQuestSelect(Player* player, Creature* creature, Quest const* quest);
         bool OnQuestReward(Player* player, Creature* creature, Quest const* quest, uint32 opt);
         uint32 GetDialogStatus(Player* player, Creature* creature);
+        bool CanSpawn(ObjectGuid::LowType spawnId, uint32 entry, CreatureTemplate const* actTemplate, CreatureData const* cData, Map const* map);
         CreatureAI* GetCreatureAI(Creature* creature);
         void OnCreatureUpdate(Creature* creature, uint32 diff);