Core/Creatures: added helper to check if a class trainer can train a player and use it in various places to get rid of multiple checks

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

@@ -1119,9 +1119,12 @@ bool Creature::isCanInteractWithBattleMaster(Player* player, bool msg) const
 
 bool Creature::isCanTrainingAndResetTalentsOf(Player* player) const
 {
-    return player->getLevel() >= 10
-        && GetCreatureTemplate()->trainer_type == TRAINER_TYPE_CLASS
-        && player->getClass() == GetCreatureTemplate()->trainer_class;
+    return player->getLevel() >= 10 && IsClassTrainerOf(player);
+}
+
+bool Creature::IsClassTrainerOf(Player const* player) const
+{
+    return GetCreatureTemplate()->trainer_type == TRAINER_TYPE_CLASS && player->getClass() == GetCreatureTemplate()->trainer_class;
 }
 
 Player* Creature::GetLootRecipient() const

src/server/game/Entities/Creature/Creature.h

@@ -109,6 +109,7 @@ class TC_GAME_API Creature : public Unit, public GridObject<Creature>, public Ma
         /// @todo Rename these properly
         bool isCanInteractWithBattleMaster(Player* player, bool msg) const;
         bool isCanTrainingAndResetTalentsOf(Player* player) const;
+        bool IsClassTrainerOf(Player const* player) const;
         bool CanCreatureAttack(Unit const* victim, bool force = true) const;
         void LoadTemplateImmunities();
         bool IsImmunedToSpell(SpellInfo const* spellInfo, Unit* caster) const override;

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

@@ -14381,7 +14381,7 @@ void Player::PrepareGossipMenu(WorldObject* source, uint32 menuId /*= 0*/, bool
                     canTalk = false;
                     break;
                 case GOSSIP_OPTION_TRAINER:
-                    if (getClass() != creature->GetCreatureTemplate()->trainer_class && creature->GetCreatureTemplate()->trainer_type == TRAINER_TYPE_CLASS)
+                    if (!creature->IsClassTrainerOf(this))
                     {
                         TC_LOG_ERROR("sql.sql", "GOSSIP_OPTION_TRAINER:: Player %s (GUID: %u) requested wrong gossip menu: %u with wrong class: %u at Creature: %s (Entry: %u, Trainer Class: %u)",
                             GetName().c_str(), GetGUID().GetCounter(), menu->GetGossipMenu().GetMenuId(), getClass(), creature->GetName().c_str(), creature->GetEntry(), creature->GetCreatureTemplate()->trainer_class);

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

@@ -14504,7 +14504,7 @@ void Unit::BuildValuesUpdate(uint8 updateType, ByteBuffer* data, Player* target)
                     if (!target->CanSeeSpellClickOn(creature))
                         appendValue &= ~UNIT_NPC_FLAG_SPELLCLICK;
 
-                    if (target->IsPlayer() && !creature->isCanTrainingAndResetTalentsOf(target->ToPlayer()))
+                    if (target->IsPlayer() && !creature->IsClassTrainerOf(target->ToPlayer()))
                         appendValue &= ~UNIT_NPC_FLAG_TRAINER_CLASS;
                 }