Core/Trainers: Implemented learning battle pets from trainers

Port From (https://github.com/TrinityCore/TrinityCore/commit/b02f382ed78b784d547c68cdbbb681148708d7d0)

Source/Game/Entities/Creature/Trainer.cs

@@ -1,8 +1,9 @@
-using System;
+using Framework.Constants;
-using System.Collections.Generic;
+using Game.BattlePets;
-using Framework.Constants;
 using Game.Networking.Packets;
 using Game.Spells;
+using System;
+using System.Collections.Generic;
 
 namespace Game.Entities
 {
@@ -67,6 +68,19 @@ namespace Game.Entities
                 return;
             }
 
+            bool sendSpellVisual = true;
+            var speciesEntry = Global.SpellMgr.GetBattlePetSpecies(trainerSpell.SpellId);
+            if (speciesEntry != null)
+            {
+                if (player.GetSession().GetBattlePetMgr().HasMaxPetCount(speciesEntry, player.GetGUID()))
+                {
+                    // Don't send any error to client (intended)
+                    return;
+                }
+
+                sendSpellVisual = false;
+            }
+
             float reputationDiscount = player.GetReputationPriceDiscount(npc);
             long moneyCost = (long)(trainerSpell.MoneyCost * reputationDiscount);
             if (!player.HasEnoughMoney(moneyCost))
@@ -77,14 +91,29 @@ namespace Game.Entities
 
             player.ModifyMoney(-moneyCost);
 
-            npc.SendPlaySpellVisualKit(179, 0, 0);     // 53 SpellCastDirected
+            if (sendSpellVisual)
-            player.SendPlaySpellVisualKit(362, 1, 0);  // 113 EmoteSalute
+            {
+                npc.SendPlaySpellVisualKit(179, 0, 0);     // 53 SpellCastDirected
+                player.SendPlaySpellVisualKit(362, 1, 0);  // 113 EmoteSalute
+            }
 
             // learn explicitly or cast explicitly
             if (trainerSpell.IsCastable())
                 player.CastSpell(player, trainerSpell.SpellId, true);
             else
-                player.LearnSpell(trainerSpell.SpellId, false);
+            {
+                bool dependent = false;
+
+                if (speciesEntry != null)
+                {
+                    player.GetSession().GetBattlePetMgr().AddPet(speciesEntry.Id, BattlePetMgr.SelectPetDisplay(speciesEntry), BattlePetMgr.RollPetBreed(speciesEntry.Id), BattlePetMgr.GetDefaultPetQuality(speciesEntry.Id));
+                    // If the spell summons a battle pet, we fake that it has been learned and the battle pet is added
+                    // marking as dependent prevents saving the spell to database (intended)
+                    dependent = true;
+                }
+
+                player.LearnSpell(trainerSpell.SpellId, dependent);
+            }
         }
 
         TrainerSpell GetSpell(uint spellId)