Core/Group: implement automatic party/raid leader change when the leader has been offline for two minutes

Port From (https://github.com/TrinityCore/TrinityCore/commit/cc141e9bad5dc06a56179f820670bd6944651804)

Source/Game/Groups/Group.cs

@@ -44,6 +44,63 @@ namespace Game.Groups
             m_lootThreshold = ItemQuality.Uncommon;
         }
 
+        public void Update(uint diff)
+        {
+            if (_isLeaderOffline)
+            {
+                _leaderOfflineTimer.Update((int)diff);
+                if (_leaderOfflineTimer.Passed())
+                {
+                    SelectNewPartyOrRaidLeader();
+                    _isLeaderOffline = false;
+                }
+            }
+
+            UpdateReadyCheck(diff);
+        }
+
+        void SelectNewPartyOrRaidLeader()
+        {
+            Player newLeader = null;
+
+            // Attempt to give leadership to main assistant first
+            if (IsRaidGroup())
+            {
+                foreach (var memberSlot in m_memberSlots)
+                {
+                    if (memberSlot.flags.HasFlag(GroupMemberFlags.Assistant))
+                    {
+                        Player player = Global.ObjAccessor.FindPlayer(memberSlot.guid);
+                        if (player != null)
+                        {
+                            newLeader = player;
+                            break;
+                        }
+                    }
+                }
+            }
+
+            // If there aren't assistants in raid, or if the group is not a raid, pick the first available member
+            if (!newLeader)
+            {
+                foreach (var memberSlot in m_memberSlots)
+                {
+                    Player player = Global.ObjAccessor.FindPlayer(memberSlot.guid);
+                    if (player != null)
+                    {
+                        newLeader = player;
+                        break;
+                    }
+                }
+            }
+
+            if (newLeader)
+            {
+                ChangeLeader(newLeader.GetGUID());
+                SendUpdate();
+            }
+        }
+
         public bool Create(Player leader)
         {
             ObjectGuid leaderGuid = leader.GetGUID();
@@ -2150,11 +2207,6 @@ namespace Game.Groups
             return slot.roles;
         }
 
-        public void Update(uint diff)
-        {
-            UpdateReadyCheck(diff);
-        }
-
         void UpdateReadyCheck(uint diff)
         {
             if (!m_readyCheckStarted)
@@ -2567,6 +2619,17 @@ namespace Game.Groups
                 slot.flags &= ~flag;
         }
 
+        public void StartLeaderOfflineTimer()
+        {
+            _isLeaderOffline = true;
+            _leaderOfflineTimer.Reset(2 * Time.Minute * Time.InMilliseconds);
+        }
+
+        public void StopLeaderOfflineTimer()
+        {
+            _isLeaderOffline = false;
+        }
+
         public void SetEveryoneIsAssistant(bool apply)
         {
             if (apply)
@@ -2620,6 +2683,8 @@ namespace Game.Groups
         ObjectGuid m_guid;
         uint m_maxEnchantingLevel;
         uint m_dbStoreId;
+        bool _isLeaderOffline;
+        TimeTrackerSmall _leaderOfflineTimer = new();
 
         // Ready Check
         bool m_readyCheckStarted;

Source/Game/Groups/GroupManager.cs

@@ -89,6 +89,12 @@ namespace Game.Groups
             return GroupStore.LookupByKey(groupId.GetCounter());
         }
 
+        public void Update(uint diff)
+        {
+            foreach (var group in GroupStore.Values)
+                    group.Update(diff);
+        }
+
         public void AddGroup(Group group)
         {
             GroupStore[group.GetGUID().GetCounter()] = group;
@@ -222,15 +228,6 @@ namespace Game.Groups
             }
         }
 
-        public void Update(uint diff)
-        {
-            foreach (var group in GroupStore.Values)
-            {
-                if (group)
-                    group.Update(diff);
-            }
-        }
-
         Dictionary<ulong, Group> GroupStore = new();
         Dictionary<uint, Group> GroupDbStore = new();
         ulong NextGroupId;

Source/Game/Handlers/CharacterHandler.cs

@@ -861,6 +861,8 @@ namespace Game
             {
                 group.SendUpdate();
                 group.ResetMaxEnchantingLevel();
+                if (group.GetLeaderGUID() == pCurrChar.GetGUID())
+                    group.StopLeaderOfflineTimer();
             }
 
             // friend status

Source/Game/Server/WorldSession.cs

@@ -188,16 +188,14 @@ namespace Game
                 // If the player is in a group (or invited), remove him. If the group if then only 1 person, disband the group.
                 _player.UninviteFromGroup();
 
-                // remove player from the group if he is:
-                // a) in group; b) not in raid group; c) logging out normally (not being kicked or disconnected)
-                if (_player.GetGroup() && !_player.GetGroup().IsRaidGroup() && m_Socket[(int)ConnectionType.Realm] != null)
-                    _player.RemoveFromGroup();
-
                 //! Send update to group and reset stored max enchanting level
-                if (_player.GetGroup())
+                var group = _player.GetGroup();
+                if (group != null)
                 {
-                    _player.GetGroup().SendUpdate();
-                    _player.GetGroup().ResetMaxEnchantingLevel();
+                    group.SendUpdate();
+                    group.ResetMaxEnchantingLevel();
+                    if (group.GetLeaderGUID() == _player.GetGUID())
+                        group.StartLeaderOfflineTimer();
                 }
 
                 //! Broadcast a logout message to the player's friends