Core/Creatures: Create a CreatureGroup for every SummonCreatureGroup

Port From (https://github.com/TrinityCore/TrinityCore/commit/9a7a83ef3074faaad037cfb4c098784695f49d30)

Source/Game/Entities/Object/WorldObject.cs

@@ -1685,21 +1685,13 @@ namespace Game.Entities
 
         public void SummonCreatureGroup(byte group, out List<TempSummon> list)
         {
-            Cypher.Assert((IsTypeId(TypeId.GameObject) || IsTypeId(TypeId.Unit)), "Only GOs and creatures can summon npc groups!");
+            list = new();
-            list = new List<TempSummon>();
-            var data = Global.ObjectMgr.GetSummonGroup(GetEntry(), IsTypeId(TypeId.GameObject) ? SummonerType.GameObject : SummonerType.Creature, group);
-            if (data.Empty())
-            {
-                Log.outWarn(LogFilter.Scripts, "{0} ({1}) tried to summon non-existing summon group {2}.", GetName(), GetGUID().ToString(), group);
-                return;
-            }
 
-            foreach (var tempSummonData in data)
+            Cypher.Assert(IsTypeId(TypeId.GameObject) || IsTypeId(TypeId.Unit), "Only GOs and creatures can summon npc groups!");
+            Map.SummonCreatureGroup(GetEntry(), GetTypeId() == TypeId.GameObject ? SummonerType.GameObject : SummonerType.Creature, group, list, tempSummonData =>
             {
-                TempSummon summon = SummonCreature(tempSummonData.entry, tempSummonData.pos, tempSummonData.type, tempSummonData.time);
+                return SummonCreature(tempSummonData.entry, tempSummonData.pos, tempSummonData.type, tempSummonData.time);
-                if (summon != null)
+            });
-                    list.Add(summon);
-            }
         }
 
         public Creature FindNearestCreature(uint entry, float range, bool alive = true)

Source/Game/Maps/Map.cs

@@ -3823,6 +3823,44 @@ namespace Game.Maps
             return summon;
         }
 
+        public static void SummonCreatureGroup(uint summonerId, SummonerType summonerType, byte group, List<TempSummon> summoned, Func<TempSummonData, TempSummon> summonCreature)
+        {
+            var data = Global.ObjectMgr.GetSummonGroup(summonerId, summonerType, group);
+            if (data == null)
+            {
+                Log.outWarn(LogFilter.Scripts, $"Summoner {summonerId} type {summonerType} tried to summon non-existing summon group {group}.");
+                return;
+            }
+
+            List<TempSummon> summons = new();
+
+            foreach (TempSummonData tempSummonData in data)
+            {
+                TempSummon summon = summonCreature(tempSummonData);
+                if (summon != null)
+                    summons.Add(summon);
+            }
+
+            CreatureGroup creatureGroup = new CreatureGroup(0);
+            foreach (TempSummon summon in summons)
+            {
+                if (!summon.IsInWorld)   // evil script might despawn a summon
+                    continue;
+
+                creatureGroup.AddMember(summon);
+                if (summoned != null)
+                    summoned.Add(summon);
+            }
+        }
+
+        public void SummonCreatureGroup(byte group, List<TempSummon> list = null)
+        {
+            SummonCreatureGroup(GetId(), SummonerType.Map, group, list, tempSummonData =>
+            {
+                return SummonCreature(tempSummonData.entry, tempSummonData.pos, null, tempSummonData.time);
+            });
+        }
+
         public ulong GenerateLowGuid(HighGuid high)
         {
             return GetGuidSequenceGenerator(high).Generate();