Core/Groups: Use iterators instead of raw LinkedListElement to interact with group members

31 files changed, 251 insertions, 321 deletions

diff --git a/src/server/game/AI/CoreAI/PetAI.cpp b/src/server/game/AI/CoreAI/PetAI.cpp
index fb2d3848946..249f9a64afb 100644
--- a/src/server/game/AI/CoreAI/PetAI.cpp
+++ b/src/server/game/AI/CoreAI/PetAI.cpp
@@ -613,10 +613,10 @@ void PetAI::UpdateAllies()
     _allySet.insert(me->GetGUID());
     if (group) // add group
     {
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* Target = itr->GetSource();
-            if (!Target || !Target->IsInMap(owner) || !group->SameSubGroup(owner->ToPlayer(), Target))
+            Player* Target = itr.GetSource();
+            if (!Target->IsInMap(owner) || !group->SameSubGroup(owner->ToPlayer(), Target))
                 continue;
 
             if (Target->GetGUID() == owner->GetGUID())
diff --git a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
index 572861113e5..a6343124e51 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedEscortAI.cpp
@@ -60,10 +60,9 @@ void EscortAI::JustDied(Unit* /*killer*/)
     {
         if (Group* group = player->GetGroup())
         {
-            for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
-                if (Player* member = groupRef->GetSource())
-                    if (member->IsInMap(player))
-                        member->FailQuest(_escortQuest->GetQuestId());
+            for (GroupReference const& groupRef : group->GetMembers())
+                if (groupRef.GetSource()->IsInMap(player))
+                    groupRef.GetSource()->FailQuest(_escortQuest->GetQuestId());
         }
         else
             player->FailQuest(_escortQuest->GetQuestId());
@@ -417,10 +416,9 @@ bool EscortAI::IsPlayerOrGroupInRange()
     {
         if (Group* group = player->GetGroup())
         {
-            for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
-                if (Player* member = groupRef->GetSource())
-                    if (me->IsWithinDistInMap(member, GetMaxPlayerDistance()))
-                        return true;
+            for (GroupReference const& groupRef : group->GetMembers())
+                if (me->IsWithinDistInMap(groupRef.GetSource(), GetMaxPlayerDistance()))
+                    return true;
         }
         else if (me->IsWithinDistInMap(player, GetMaxPlayerDistance()))
             return true;
diff --git a/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp b/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
index 5c048d36f07..f91ff6f1207 100644
--- a/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
+++ b/src/server/game/AI/ScriptedAI/ScriptedFollowerAI.cpp
@@ -51,10 +51,9 @@ void FollowerAI::JustDied(Unit* /*killer*/)
     {
         if (Group* group = player->GetGroup())
         {
-            for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
-                if (Player* member = groupRef->GetSource())
-                    if (member->IsInMap(player))
-                        member->FailQuest(_questForFollow);
+            for (GroupReference const& groupRef : group->GetMembers())
+                if (groupRef.GetSource()->IsInMap(player))
+                    groupRef.GetSource()->FailQuest(_questForFollow);
         }
         else
             player->FailQuest(_questForFollow);
@@ -101,11 +100,9 @@ void FollowerAI::UpdateAI(uint32 uiDiff)
             {
                 if (Group* group = player->GetGroup())
                 {
-                    for (GroupReference* groupRef = group->GetFirstMember(); groupRef && (maxRangeExceeded || questAbandoned); groupRef = groupRef->next())
+                    for (GroupReference const& groupRef : group->GetMembers())
                     {
-                        Player* member = groupRef->GetSource();
-                        if (!member)
-                            continue;
+                        Player* member = groupRef.GetSource();
                         if (maxRangeExceeded && me->IsWithinDistInMap(member, MAX_PLAYER_DISTANCE))
                             maxRangeExceeded = false;
                         if (questAbandoned)
@@ -238,10 +235,10 @@ Player* FollowerAI::GetLeaderForFollower()
         {
             if (Group* group = player->GetGroup())
             {
-                for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
+                for (GroupReference const& groupRef : group->GetMembers())
                 {
-                    Player* member = groupRef->GetSource();
-                    if (member && me->IsWithinDistInMap(member, MAX_PLAYER_DISTANCE) && member->IsAlive())
+                    Player* member = groupRef.GetSource();
+                    if (me->IsWithinDistInMap(member, MAX_PLAYER_DISTANCE) && member->IsAlive())
                     {
                         TC_LOG_DEBUG("scripts.ai.followerai", "FollowerAI::GetLeaderForFollower: GetLeader changed and returned new leader. ({})", me->GetGUID().ToString());
                         _leaderGUID = member->GetGUID();
diff --git a/src/server/game/AI/SmartScripts/SmartAI.cpp b/src/server/game/AI/SmartScripts/SmartAI.cpp
index 11f645bc6da..de5fbddfb5a 100644
--- a/src/server/game/AI/SmartScripts/SmartAI.cpp
+++ b/src/server/game/AI/SmartScripts/SmartAI.cpp
@@ -202,9 +202,9 @@ void SmartAI::EndPath(bool fail)
 
             if (Group* group = player->GetGroup())
             {
-                for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
+                for (GroupReference const& groupRef : group->GetMembers())
                 {
-                    Player* groupGuy = groupRef->GetSource();
+                    Player* groupGuy = groupRef.GetSource();
                     if (!groupGuy->IsInMap(player))
                         continue;
 
@@ -306,9 +306,9 @@ bool SmartAI::IsEscortInvokerInRange()
 
             if (Group* group = player->GetGroup())
             {
-                for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
+                for (GroupReference const& groupRef : group->GetMembers())
                 {
-                    Player* groupGuy = groupRef->GetSource();
+                    Player* groupGuy = groupRef.GetSource();
                     if (groupGuy->IsInMap(player) && me->GetDistance(groupGuy) <= checkDist)
                         return true;
                 }
diff --git a/src/server/game/AI/SmartScripts/SmartScript.cpp b/src/server/game/AI/SmartScripts/SmartScript.cpp
index 3a6054fe3d5..d089abc9ca7 100644
--- a/src/server/game/AI/SmartScripts/SmartScript.cpp
+++ b/src/server/game/AI/SmartScripts/SmartScript.cpp
@@ -2795,10 +2795,9 @@ void SmartScript::GetTargets(ObjectVector& targets, SmartScriptHolder const& e,
                 {
                     if (Group* group = player->GetGroup())
                     {
-                        for (GroupReference* groupRef = group->GetFirstMember(); groupRef != nullptr; groupRef = groupRef->next())
-                            if (Player* member = groupRef->GetSource())
-                                if (member->IsInMap(player))
-                                    targets.push_back(member);
+                        for (GroupReference const& groupRef : group->GetMembers())
+                            if (groupRef.GetSource()->IsInMap(player))
+                                targets.push_back(groupRef.GetSource());
                     }
                     // We still add the player to the list if there is no group. If we do
                     // this even if there is a group (thus the else-check), it will add the
diff --git a/src/server/game/Achievements/AchievementMgr.cpp b/src/server/game/Achievements/AchievementMgr.cpp
index 246cafea6a7..3323e9c7212 100644
--- a/src/server/game/Achievements/AchievementMgr.cpp
+++ b/src/server/game/Achievements/AchievementMgr.cpp
@@ -958,10 +958,9 @@ void GuildAchievementMgr::CompletedAchievement(AchievementEntry const* achieveme
             ca.CompletingPlayers.insert(referencePlayer->GetGUID());
 
         if (Group const* group = referencePlayer->GetGroup())
-            for (GroupReference const* ref = group->GetFirstMember(); ref != nullptr; ref = ref->next())
-                if (Player const* groupMember = ref->GetSource())
-                    if (groupMember->GetGuildId() == _owner->GetId())
-                        ca.CompletingPlayers.insert(groupMember->GetGUID());
+            for (GroupReference const& ref : group->GetMembers())
+                if (ref.GetSource()->GetGuildId() == _owner->GetId())
+                    ca.CompletingPlayers.insert(ref.GetSource()->GetGUID());
     }
 
     if (achievement->Flags & (ACHIEVEMENT_FLAG_REALM_FIRST_REACH | ACHIEVEMENT_FLAG_REALM_FIRST_KILL))
diff --git a/src/server/game/Achievements/CriteriaHandler.cpp b/src/server/game/Achievements/CriteriaHandler.cpp
index 708afe85b69..5e1ed43ab1e 100644
--- a/src/server/game/Achievements/CriteriaHandler.cpp
+++ b/src/server/game/Achievements/CriteriaHandler.cpp
@@ -2149,8 +2149,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
         {
             uint32 guildMemberCount = 0;
             if (Group const* group = referencePlayer->GetGroup())
-                for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (itr->GetSource()->GetGuildId() == referencePlayer->GetGuildId())
+                for (GroupReference const& itr : group->GetMembers())
+                    if (itr.GetSource()->GetGuildId() == referencePlayer->GetGuildId())
                         ++guildMemberCount;
 
             if (guildMemberCount < reqValue)
@@ -3088,8 +3088,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
         {
             uint32 memberCount = 0;
             if (Group const* group = referencePlayer->GetGroup())
-                for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (itr->GetSource() != referencePlayer && *referencePlayer->m_playerData->VirtualPlayerRealm == *itr->GetSource()->m_playerData->VirtualPlayerRealm)
+                for (GroupReference const& itr : group->GetMembers())
+                    if (itr.GetSource() != referencePlayer && *referencePlayer->m_playerData->VirtualPlayerRealm == *itr.GetSource()->m_playerData->VirtualPlayerRealm)
                         ++memberCount;
             if (memberCount < reqValue)
                 return false;
@@ -3188,8 +3188,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
             if (Group const* group = referencePlayer->GetGroup())
             {
                 uint32 membersWithAchievement = 0;
-                for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (itr->GetSource()->HasAchieved(secondaryAsset))
+                for (GroupReference const& itr : group->GetMembers())
+                    if (itr.GetSource()->HasAchieved(secondaryAsset))
                         ++membersWithAchievement;
 
                 if (membersWithAchievement > reqValue)
@@ -3551,8 +3551,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
             Group const* group = referencePlayer->GetGroup();
             if (!group)
                 return false;
-            for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                if (itr->GetSource()->GetSession()->GetRecruiterId() == referencePlayer->GetSession()->GetAccountId())
+            for (GroupReference const& itr : group->GetMembers())
+                if (itr.GetSource()->GetSession()->GetRecruiterId() == referencePlayer->GetSession()->GetAccountId())
                     return true;
             return false;
         }
@@ -3561,8 +3561,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
             Group const* group = referencePlayer->GetGroup();
             if (!group)
                 return false;
-            for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                if (itr->GetSource()->GetSession()->GetAccountId() == referencePlayer->GetSession()->GetRecruiterId())
+            for (GroupReference const& itr : group->GetMembers())
+                if (itr.GetSource()->GetSession()->GetAccountId() == referencePlayer->GetSession()->GetRecruiterId())
                     return true;
             return false;
         }
@@ -3693,8 +3693,8 @@ bool CriteriaHandler::ModifierSatisfied(ModifierTreeEntry const* modifier, uint6
         {
             if (Group const* group = referencePlayer->GetGroup())
             {
-                for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (!itr->GetSource()->HasAchieved(reqValue))
+                for (GroupReference const& itr : group->GetMembers())
+                    if (!itr.GetSource()->HasAchieved(reqValue))
                         return false;
             }
             else if (!referencePlayer->HasAchieved(reqValue))
diff --git a/src/server/game/Battlegrounds/BattlegroundQueue.cpp b/src/server/game/Battlegrounds/BattlegroundQueue.cpp
index 29de0d03291..429b1d91b5e 100644
--- a/src/server/game/Battlegrounds/BattlegroundQueue.cpp
+++ b/src/server/game/Battlegrounds/BattlegroundQueue.cpp
@@ -169,11 +169,9 @@ GroupQueueInfo* BattlegroundQueue::AddGroup(Player const* leader, Group const* g
     //add players from group to ginfo
     if (group)
     {
-        for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* member = itr->GetSource();
-            if (!member)
-                continue;   // this should never happen
+            Player* member = itr.GetSource();
             PlayerQueueInfo& pl_info = m_QueuedPlayers[member->GetGUID()];
             pl_info.LastOnlineTime   = lastOnlineTime;
             pl_info.GroupInfo        = ginfo;
diff --git a/src/server/game/DungeonFinding/LFGMgr.cpp b/src/server/game/DungeonFinding/LFGMgr.cpp
index 5dc01536bf6..86d0b5f5148 100644
--- a/src/server/game/DungeonFinding/LFGMgr.cpp
+++ b/src/server/game/DungeonFinding/LFGMgr.cpp
@@ -452,26 +452,27 @@ void LFGMgr::JoinLfg(Player* player, uint8 roles, LfgDungeonSet& dungeons)
         else
         {
             uint8 memberCount = 0;
-            for (GroupReference* itr = grp->GetFirstMember(); itr != nullptr && joinData.result == LFG_JOIN_OK; itr = itr->next())
+            for (GroupReference const& itr : grp->GetMembers())
             {
-                if (Player* plrg = itr->GetSource())
+                Player* plrg = itr.GetSource();
+                if (!plrg->GetSession()->HasPermission(rbac::RBAC_PERM_JOIN_DUNGEON_FINDER))
+                    joinData.result = LFG_JOIN_NO_LFG_OBJECT;
+                if (plrg->HasAura(LFG_SPELL_DUNGEON_DESERTER))
+                    joinData.result = LFG_JOIN_DESERTER_PARTY;
+                else if (!isContinue && plrg->HasAura(LFG_SPELL_DUNGEON_COOLDOWN))
+                    joinData.result = LFG_JOIN_RANDOM_COOLDOWN_PARTY;
+                else if (plrg->InBattleground() || plrg->InArena() || plrg->InBattlegroundQueue())
+                    joinData.result = LFG_JOIN_CANT_USE_DUNGEONS;
+                else if (plrg->HasAura(9454)) // check Freeze debuff
                 {
-                    if (!plrg->GetSession()->HasPermission(rbac::RBAC_PERM_JOIN_DUNGEON_FINDER))
-                        joinData.result = LFG_JOIN_NO_LFG_OBJECT;
-                    if (plrg->HasAura(LFG_SPELL_DUNGEON_DESERTER))
-                        joinData.result = LFG_JOIN_DESERTER_PARTY;
-                    else if (!isContinue && plrg->HasAura(LFG_SPELL_DUNGEON_COOLDOWN))
-                        joinData.result = LFG_JOIN_RANDOM_COOLDOWN_PARTY;
-                    else if (plrg->InBattleground() || plrg->InArena() || plrg->InBattlegroundQueue())
-                        joinData.result = LFG_JOIN_CANT_USE_DUNGEONS;
-                    else if (plrg->HasAura(9454)) // check Freeze debuff
-                    {
-                        joinData.result = LFG_JOIN_NO_SLOTS;
-                        joinData.playersMissingRequirement.push_back(plrg->GetName());
-                    }
-                    ++memberCount;
-                    players.insert(plrg->GetGUID());
+                    joinData.result = LFG_JOIN_NO_SLOTS;
+                    joinData.playersMissingRequirement.push_back(plrg->GetName());
                 }
+                ++memberCount;
+                players.insert(plrg->GetGUID());
+
+                if (joinData.result != LFG_JOIN_OK)
+                    break;
             }
 
             if (joinData.result == LFG_JOIN_OK && memberCount != grp->GetMembersCount())
@@ -571,21 +572,19 @@ void LFGMgr::JoinLfg(Player* player, uint8 roles, LfgDungeonSet& dungeons)
         SetState(gguid, LFG_STATE_ROLECHECK);
         // Send update to player
         LfgUpdateData updateData = LfgUpdateData(LFG_UPDATETYPE_JOIN_QUEUE, dungeons);
-        for (GroupReference* itr = grp->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : grp->GetMembers())
         {
-            if (Player* plrg = itr->GetSource())
-            {
-                ObjectGuid pguid = plrg->GetGUID();
-                plrg->GetSession()->SendLfgUpdateStatus(updateData, true);
-                SetState(pguid, LFG_STATE_ROLECHECK);
-                SetTicket(pguid, ticket);
-                if (!isContinue)
-                    SetSelectedDungeons(pguid, dungeons);
-                roleCheck.roles[pguid] = 0;
-                if (!debugNames.empty())
-                    debugNames.append(", ");
-                debugNames.append(plrg->GetName());
-            }
+            Player* plrg = itr.GetSource();
+            ObjectGuid pguid = plrg->GetGUID();
+            plrg->GetSession()->SendLfgUpdateStatus(updateData, true);
+            SetState(pguid, LFG_STATE_ROLECHECK);
+            SetTicket(pguid, ticket);
+            if (!isContinue)
+                SetSelectedDungeons(pguid, dungeons);
+            roleCheck.roles[pguid] = 0;
+            if (!debugNames.empty())
+                debugNames.append(", ");
+            debugNames.append(plrg->GetName());
         }
         // Update leader role
         UpdateRoleCheck(gguid, guid, roles);
@@ -1407,10 +1406,10 @@ void LFGMgr::TeleportPlayer(Player* player, bool out, bool fromOpcode /*= false*
         if (!fromOpcode)
         {
             // Select a player inside to be teleported to
-            for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                Player* plrg = itr->GetSource();
-                if (plrg && plrg != player && plrg->GetMapId() == uint32(dungeon->map))
+                Player* plrg = itr.GetSource();
+                if (plrg != player && plrg->GetMapId() == uint32(dungeon->map))
                 {
                     mapid = plrg->GetMapId();
                     x = plrg->GetPositionX();
diff --git a/src/server/game/Entities/Creature/Creature.cpp b/src/server/game/Entities/Creature/Creature.cpp
index 964c6862faf..a44f2c1d420 100644
--- a/src/server/game/Entities/Creature/Creature.cpp
+++ b/src/server/game/Entities/Creature/Creature.cpp
@@ -1391,9 +1391,9 @@ void Creature::SetTappedBy(Unit const* unit, bool withGroup)
     m_tapList.insert(player->GetGUID());
     if (withGroup)
         if (Group const* group = player->GetGroup())
-            for (auto const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                if (GetMap()->IsRaid() || group->SameSubGroup(player, itr->GetSource()))
-                    m_tapList.insert(itr->GetSource()->GetGUID());
+            for (GroupReference const& itr : group->GetMembers())
+                if (GetMap()->IsRaid() || group->SameSubGroup(player, itr.GetSource()))
+                    m_tapList.insert(itr.GetSource()->GetGUID());
 
     if (m_tapList.size() >= CREATURE_TAPPERS_SOFT_CAP)
         SetDynamicFlag(UNIT_DYNFLAG_TAPPED);
@@ -3779,10 +3779,10 @@ void Creature::ForcePartyMembersIntoCombat()
 
     for (Group const* partyToForceIntoCombat : partiesToForceIntoCombat)
     {
-        for (GroupReference const* ref = partyToForceIntoCombat->GetFirstMember(); ref != nullptr; ref = ref->next())
+        for (GroupReference const& ref : partyToForceIntoCombat->GetMembers())
         {
-            Player* player = ref->GetSource();
-            if (!player || !player->IsInWorld() || player->GetMap() != GetMap() || player->IsGameMaster())
+            Player* player = ref.GetSource();
+            if (!player->IsInMap(this) || player->IsGameMaster())
                 continue;
 
             EngageWithTarget(player);
diff --git a/src/server/game/Entities/GameObject/GameObject.cpp b/src/server/game/Entities/GameObject/GameObject.cpp
index 7e15231016a..6bb1f0a6aa1 100644
--- a/src/server/game/Entities/GameObject/GameObject.cpp
+++ b/src/server/game/Entities/GameObject/GameObject.cpp
@@ -2835,10 +2835,9 @@ void GameObject::Use(Unit* user, bool ignoreCastInProgress /*= false*/)
 
                 if (Group* group = player->GetGroup())
                 {
-                    for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                        if (Player* member = itr->GetSource())
-                            if (member->IsAtGroupRewardDistance(this))
-                                member->KillCreditGO(info->entry, GetGUID());
+                    for (GroupReference const& itr : group->GetMembers())
+                        if (itr.GetSource()->IsAtGroupRewardDistance(this))
+                            itr.GetSource()->KillCreditGO(info->entry, GetGUID());
                 }
                 else
                     player->KillCreditGO(info->entry, GetGUID());
diff --git a/src/server/game/Entities/Player/KillRewarder.cpp b/src/server/game/Entities/Player/KillRewarder.cpp
index 99d57edb1a3..742d97761bf 100644
--- a/src/server/game/Entities/Player/KillRewarder.cpp
+++ b/src/server/game/Entities/Player/KillRewarder.cpp
@@ -91,26 +91,24 @@ inline void KillRewarder::_InitGroupData(Player const* killer)
     if (Group const* group = killer->GetGroup())
     {
         // 2. In case when player is in group, initialize variables necessary for group calculations:
-        for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            if (Player* member = itr->GetSource())
+            Player* member = itr.GetSource();
+            if (killer == member || (member->IsAtGroupRewardDistance(_victim) && member->IsAlive()))
             {
-                if (killer == member || (member->IsAtGroupRewardDistance(_victim) && member->IsAlive()))
-                {
-                    const uint8 lvl = member->GetLevel();
-                    // 2.1. _count - number of alive group members within reward distance;
-                    ++_count;
-                    // 2.2. _sumLevel - sum of levels of alive group members within reward distance;
-                    _sumLevel += lvl;
-                    // 2.3. _maxLevel - maximum level of alive group member within reward distance;
-                    if (_maxLevel < lvl)
-                        _maxLevel = lvl;
-                    // 2.4. _maxNotGrayMember - maximum level of alive group member within reward distance,
-                    //      for whom victim is not gray;
-                    uint32 grayLevel = Trinity::XP::GetGrayLevel(lvl);
-                    if (_victim->GetLevelForTarget(member) > grayLevel && (!_maxNotGrayMember || _maxNotGrayMember->GetLevel() < lvl))
-                        _maxNotGrayMember = member;
-                }
+                const uint8 lvl = member->GetLevel();
+                // 2.1. _count - number of alive group members within reward distance;
+                ++_count;
+                // 2.2. _sumLevel - sum of levels of alive group members within reward distance;
+                _sumLevel += lvl;
+                // 2.3. _maxLevel - maximum level of alive group member within reward distance;
+                if (_maxLevel < lvl)
+                    _maxLevel = lvl;
+                // 2.4. _maxNotGrayMember - maximum level of alive group member within reward distance,
+                //      for whom victim is not gray;
+                uint32 grayLevel = Trinity::XP::GetGrayLevel(lvl);
+                if (_victim->GetLevelForTarget(member) > grayLevel && (!_maxNotGrayMember || _maxNotGrayMember->GetLevel() < lvl))
+                    _maxNotGrayMember = member;
             }
         }
         // 2.5. _isFullXP - flag identifying that for all group members victim is not gray,
@@ -241,16 +239,12 @@ void KillRewarder::_RewardGroup(Group const* group, Player const* killer)
             }
 
             // 3.1.3. Reward each group member (even dead or corpse) within reward distance.
-            for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                if (Player* member = itr->GetSource())
-                {
-                    // Killer may not be at reward distance, check directly
-                    if (killer == member || member->IsAtGroupRewardDistance(_victim))
-                    {
-                        _RewardPlayer(member, isDungeon);
-                    }
-                }
+                Player* member = itr.GetSource();
+                // Killer may not be at reward distance, check directly
+                if (killer == member || member->IsAtGroupRewardDistance(_victim))
+                    _RewardPlayer(member, isDungeon);
             }
         }
     }
diff --git a/src/server/game/Entities/Player/Player.cpp b/src/server/game/Entities/Player/Player.cpp
index be44c7a9898..017c19bb6c7 100644
--- a/src/server/game/Entities/Player/Player.cpp
+++ b/src/server/game/Entities/Player/Player.cpp
@@ -16582,12 +16582,12 @@ void Player::GroupEventHappens(uint32 questId, WorldObject const* pEventObject)
 {
     if (Group* group = GetGroup())
     {
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* player = itr->GetSource();
+            Player* player = itr.GetSource();
 
             // for any leave or dead (with not released body) group member at appropriate distance
-            if (player && player->IsAtGroupRewardDistance(pEventObject) && !player->GetCorpse())
+            if (player->IsAtGroupRewardDistance(pEventObject) && !player->GetCorpse())
                 player->AreaExploredOrEventHappens(questId);
         }
     }
@@ -26209,12 +26209,9 @@ bool Player::GetsRecruitAFriendBonus(bool forXP)
     {
         if (Group* group = GetGroup())
         {
-            for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                Player* player = itr->GetSource();
-                if (!player)
-                    continue;
-
+                Player* player = itr.GetSource();
                 if (!player->IsAtRecruitAFriendDistance(this))
                     continue;                               // member (alive or dead) or his corpse at req. distance
 
@@ -26253,12 +26250,9 @@ void Player::RewardPlayerAndGroupAtEvent(uint32 creature_id, WorldObject* pRewar
     // prepare data for near group iteration
     if (Group* group = GetGroup())
     {
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* player = itr->GetSource();
-            if (!player)
-                continue;
-
+            Player* player = itr.GetSource();
             if (!player->IsAtGroupRewardDistance(pRewardSource))
                 continue;                               // member (alive or dead) or his corpse at req. distance
 
@@ -26501,12 +26495,12 @@ Player* Player::GetNextRandomRaidMember(float radius)
     std::vector<Player*> nearMembers;
     nearMembers.reserve(group->GetMembersCount());
 
-    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : group->GetMembers())
     {
-        Player* Target = itr->GetSource();
+        Player* Target = itr.GetSource();
 
         // IsHostileTo check duel and controlled by enemy
-        if (Target && Target != this && IsWithinDistInMap(Target, radius) &&
+        if (Target != this && IsWithinDistInMap(Target, radius) &&
             !Target->HasInvisibilityAura() && !IsHostileTo(Target))
             nearMembers.push_back(Target);
     }
@@ -26545,8 +26539,8 @@ PartyResult Player::CanUninviteFromGroup(ObjectGuid guidMember, Optional<uint8>
             return ERR_PARTY_LFG_BOOT_LOOT_ROLLS;
 
         /// @todo Should also be sent when anyone has recently left combat, with an aprox ~5 seconds timer.
-        for (GroupReference const* itr = grp->GetFirstMember(); itr != nullptr; itr = itr->next())
-            if (itr->GetSource() && itr->GetSource()->IsInMap(this) && itr->GetSource()->IsInCombat())
+        for (GroupReference const& itr : grp->GetMembers())
+            if (itr.GetSource()->IsInMap(this) && itr.GetSource()->IsInCombat())
                 return ERR_PARTY_LFG_BOOT_IN_COMBAT;
 
         /* Missing support for these types
diff --git a/src/server/game/Entities/Totem/Totem.cpp b/src/server/game/Entities/Totem/Totem.cpp
index 4cf2095bc21..acbd66883f0 100644
--- a/src/server/game/Entities/Totem/Totem.cpp
+++ b/src/server/game/Entities/Totem/Totem.cpp
@@ -130,10 +130,10 @@ void Totem::UnSummon(uint32 msTime)
 
         if (Group* group = owner->GetGroup())
         {
-            for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                Player* target = itr->GetSource();
-                if (target && target->IsInMap(owner) && group->SameSubGroup(owner, target))
+                Player* target = itr.GetSource();
+                if (target->IsInMap(owner) && group->SameSubGroup(owner, target))
                     target->RemoveAurasDueToSpell(GetSpell(), GetGUID());
             }
         }
diff --git a/src/server/game/Entities/Unit/Unit.cpp b/src/server/game/Entities/Unit/Unit.cpp
index 63eeb3b1ea2..91ab4c5168c 100644
--- a/src/server/game/Entities/Unit/Unit.cpp
+++ b/src/server/game/Entities/Unit/Unit.cpp
@@ -6612,18 +6612,18 @@ Unit* Unit::GetNextRandomRaidMemberOrPet(float radius)
     // reserve place for players and pets because resizing vector every unit push is unefficient (vector is reallocated then)
     nearMembers.reserve(group->GetMembersCount() * 2);
 
-    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-        if (Player* Target = itr->GetSource())
-        {
-            // IsHostileTo check duel and controlled by enemy
-            if (Target != this && IsWithinDistInMap(Target, radius) && Target->IsAlive() && !IsHostileTo(Target))
-                nearMembers.push_back(Target);
+    for (GroupReference const& itr : group->GetMembers())
+    {
+        Player* Target = itr.GetSource();
+        // IsHostileTo check duel and controlled by enemy
+        if (Target != this && IsWithinDistInMap(Target, radius) && Target->IsAlive() && !IsHostileTo(Target))
+            nearMembers.push_back(Target);
 
         // Push player's pet to vector
         if (Unit* pet = Target->GetGuardianPet())
             if (pet != this && IsWithinDistInMap(pet, radius) && pet->IsAlive() && !IsHostileTo(pet))
                 nearMembers.push_back(pet);
-        }
+    }
 
     if (nearMembers.empty())
         return nullptr;
@@ -11978,12 +11978,12 @@ void Unit::GetPartyMembers(std::list<Unit*> &TagUnitMap)
     {
         uint8 subgroup = owner->ToPlayer()->GetSubGroup();
 
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* Target = itr->GetSource();
+            Player* Target = itr.GetSource();
 
             // IsHostileTo check duel and controlled by enemy
-            if (Target && Target->IsInMap(owner) && Target->GetSubGroup() == subgroup && !IsHostileTo(Target))
+            if (Target->IsInMap(owner) && Target->GetSubGroup() == subgroup && !IsHostileTo(Target))
             {
                 if (Target->IsAlive())
                     TagUnitMap.push_back(Target);
diff --git a/src/server/game/Groups/Group.cpp b/src/server/game/Groups/Group.cpp
index b1d15f2da29..763b6b001a2 100644
--- a/src/server/game/Groups/Group.cpp
+++ b/src/server/game/Groups/Group.cpp
@@ -531,26 +531,24 @@ bool Group::AddMember(Player* player)
         WorldPacket groupDataPacket;
 
         // Broadcast group members' fields to player
-        for (GroupReference* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : GetMembers())
         {
-            if (itr->GetSource() == player)
+            Player* existingMember = itr.GetSource();
+            if (existingMember == player)
                 continue;
 
-            if (Player* existingMember = itr->GetSource())
-            {
-                if (player->HaveAtClient(existingMember))
-                    existingMember->BuildValuesUpdateBlockForPlayerWithFlag(&groupData, UF::UpdateFieldFlag::PartyMember, player);
+            if (player->HaveAtClient(existingMember))
+                existingMember->BuildValuesUpdateBlockForPlayerWithFlag(&groupData, UF::UpdateFieldFlag::PartyMember, player);
 
-                if (existingMember->HaveAtClient(player))
+            if (existingMember->HaveAtClient(player))
+            {
+                UpdateData newData(player->GetMapId());
+                WorldPacket newDataPacket;
+                player->BuildValuesUpdateBlockForPlayerWithFlag(&newData, UF::UpdateFieldFlag::PartyMember, existingMember);
+                if (newData.HasData())
                 {
-                    UpdateData newData(player->GetMapId());
-                    WorldPacket newDataPacket;
-                    player->BuildValuesUpdateBlockForPlayerWithFlag(&newData, UF::UpdateFieldFlag::PartyMember, existingMember);
-                    if (newData.HasData())
-                    {
-                        newData.BuildPacket(&newDataPacket);
-                        existingMember->SendDirectMessage(&newDataPacket);
-                    }
+                    newData.BuildPacket(&newDataPacket);
+                    existingMember->SendDirectMessage(&newDataPacket);
                 }
             }
         }
@@ -574,16 +572,14 @@ bool Group::RemoveMember(ObjectGuid guid, RemoveMethod method /*= GROUP_REMOVEME
     Player* player = ObjectAccessor::FindConnectedPlayer(guid);
     if (player)
     {
-        for (GroupReference* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : GetMembers())
         {
-            if (Player* groupMember = itr->GetSource())
-            {
-                if (groupMember->GetGUID() == guid)
-                    continue;
+            Player* groupMember = itr.GetSource();
+            if (groupMember->GetGUID() == guid)
+                continue;
 
-                groupMember->RemoveAllGroupBuffsFromCaster(guid);
-                player->RemoveAllGroupBuffsFromCaster(groupMember->GetGUID());
-            }
+            groupMember->RemoveAllGroupBuffsFromCaster(guid);
+            player->RemoveAllGroupBuffsFromCaster(groupMember->GetGUID());
         }
     }
 
@@ -953,36 +949,36 @@ void Group::UpdatePlayerOutOfRange(Player const* player) const
     packet.Initialize(player);
     packet.Write();
 
-    for (GroupReference const* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player const* member = itr->GetSource();
-        if (member && member != player && (!member->IsInMap(player) || !member->IsWithinDist(player, member->GetSightRange(), false)))
+        Player const* member = itr.GetSource();
+        if (member != player && (!member->IsInMap(player) || !member->IsWithinDist(player, member->GetSightRange(), false)))
             member->SendDirectMessage(packet.GetRawPacket());
     }
 }
 
 void Group::BroadcastAddonMessagePacket(WorldPacket const* packet, const std::string& prefix, bool ignorePlayersInBGRaid, int group /*= -1*/, ObjectGuid ignore /*= ObjectGuid::Empty*/) const
 {
-    for (GroupReference const* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player* player = itr->GetSource();
-        if (!player || (!ignore.IsEmpty() && player->GetGUID() == ignore) || (ignorePlayersInBGRaid && player->GetGroup() != this))
+        Player* player = itr.GetSource();
+        if ((!ignore.IsEmpty() && player->GetGUID() == ignore) || (ignorePlayersInBGRaid && player->GetGroup() != this))
             continue;
 
-        if (player->GetSession()->IsAddonRegistered(prefix) && (group == -1 || itr->getSubGroup() == group))
+        if (player->GetSession()->IsAddonRegistered(prefix) && (group == -1 || itr.getSubGroup() == group))
             player->SendDirectMessage(packet);
     }
 }
 
 void Group::BroadcastPacket(WorldPacket const* packet, bool ignorePlayersInBGRaid, int group, ObjectGuid ignoredPlayer) const
 {
-    for (GroupReference const* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player const* player = itr->GetSource();
-        if (!player || (!ignoredPlayer.IsEmpty() && player->GetGUID() == ignoredPlayer) || (ignorePlayersInBGRaid && player->GetGroup() != this))
+        Player const* player = itr.GetSource();
+        if ((!ignoredPlayer.IsEmpty() && player->GetGUID() == ignoredPlayer) || (ignorePlayersInBGRaid && player->GetGroup() != this))
             continue;
 
-        if (group == -1 || itr->getSubGroup() == group)
+        if (group == -1 || itr.getSubGroup() == group)
             player->SendDirectMessage(packet);
     }
 }
@@ -1211,11 +1207,13 @@ GroupJoinBattlegroundResult Group::CanJoinBattlegroundQueue(BattlegroundTemplate
         return ERR_BATTLEGROUND_NONE;                        // ERR_GROUP_JOIN_BATTLEGROUND_TOO_MANY handled on client side
 
     // get a player as reference, to compare other players' stats to (arena team id, queue id based on level, etc.)
-    Player* reference = ASSERT_NOTNULL(GetFirstMember())->GetSource();
+    auto membersIterator = GetMembers().begin();
+    auto membersEnd = GetMembers().end();
     // no reference found, can't join this way
-    if (!reference)
+    if (membersIterator == membersEnd)
         return ERR_BATTLEGROUND_JOIN_FAILED;
 
+    Player* reference = membersIterator->GetSource();
     PVPDifficultyEntry const* bracketEntry = DB2Manager::GetBattlegroundBracketByLevel(bgOrTemplate->MapIDs.front(), reference->GetLevel());
     if (!bracketEntry)
         return ERR_BATTLEGROUND_JOIN_FAILED;
@@ -1226,9 +1224,9 @@ GroupJoinBattlegroundResult Group::CanJoinBattlegroundQueue(BattlegroundTemplate
 
     // check every member of the group to be able to join
     memberscount = 0;
-    for (GroupReference const* itr = GetFirstMember(); itr != nullptr; itr = itr->next(), ++memberscount)
+    for (; membersIterator != membersEnd; ++membersIterator)
     {
-        Player* member = itr->GetSource();
+        Player* member = membersIterator->GetSource();
         // offline member? don't let join
         if (!member)
             return ERR_BATTLEGROUND_JOIN_FAILED;
@@ -1295,12 +1293,9 @@ void Group::SetDungeonDifficultyID(Difficulty difficulty)
         CharacterDatabase.Execute(stmt);
     }
 
-    for (GroupReference* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player* player = itr->GetSource();
-        if (!player->GetSession())
-            continue;
-
+        Player* player = itr.GetSource();
         player->SetDungeonDifficultyID(difficulty);
         player->SendDungeonDifficulty();
     }
@@ -1319,12 +1314,9 @@ void Group::SetRaidDifficultyID(Difficulty difficulty)
         CharacterDatabase.Execute(stmt);
     }
 
-    for (GroupReference* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player* player = itr->GetSource();
-        if (!player->GetSession())
-            continue;
-
+        Player* player = itr.GetSource();
         player->SetRaidDifficultyID(difficulty);
         player->SendRaidDifficulty(false);
     }
@@ -1343,12 +1335,9 @@ void Group::SetLegacyRaidDifficultyID(Difficulty difficulty)
         CharacterDatabase.Execute(stmt);
     }
 
-    for (GroupReference* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : GetMembers())
     {
-        Player* player = itr->GetSource();
-        if (!player->GetSession())
-            continue;
-
+        Player* player = itr.GetSource();
         player->SetLegacyRaidDifficultyID(difficulty);
         player->SendRaidDifficulty(true);
     }
@@ -1805,17 +1794,9 @@ void Group::LinkMember(GroupReference* pRef)
 
 void Group::DelinkMember(ObjectGuid guid)
 {
-    GroupReference* ref = m_memberMgr.getFirst();
-    while (ref)
-    {
-        GroupReference* nextRef = ref->next();
-        if (ref->GetSource()->GetGUID() == guid)
-        {
-            ref->unlink();
-            break;
-        }
-        ref = nextRef;
-    }
+    auto itr = std::ranges::find(m_memberMgr, guid, [](GroupReference const& ref) { return ref.GetSource()->GetGUID(); });
+    if (itr != m_memberMgr.end())
+        itr->unlink();
 }
 
 void Group::_initRaidSubGroupsCounter()
diff --git a/src/server/game/Groups/Group.h b/src/server/game/Groups/Group.h
index 0f780f127dc..e3d2930b8a1 100644
--- a/src/server/game/Groups/Group.h
+++ b/src/server/game/Groups/Group.h
@@ -329,9 +329,9 @@ class TC_GAME_API Group
         bool SameSubGroup(Player const* member1, Player const* member2) const;
         bool HasFreeSlotSubGroup(uint8 subgroup) const;
 
+        GroupRefManager& GetMembers() { return m_memberMgr; }
+        GroupRefManager const& GetMembers() const { return m_memberMgr; }
         MemberSlotList const& GetMemberSlots() const { return m_memberSlots; }
-        GroupReference* GetFirstMember() { return m_memberMgr.getFirst(); }
-        GroupReference const* GetFirstMember() const { return m_memberMgr.getFirst(); }
         uint32 GetMembersCount() const { return uint32(m_memberSlots.size()); }
         uint32 GetInviteeCount() const { return m_invitees.size(); }
         GroupFlags GetGroupFlags() const { return m_groupFlags; }
@@ -371,8 +371,8 @@ class TC_GAME_API Group
         template<class Worker>
         void BroadcastWorker(Worker const& worker) const
         {
-            for (GroupReference const* itr = GetFirstMember(); itr != nullptr; itr = itr->next())
-                worker(itr->GetSource());
+            for (GroupReference const& itr : GetMembers())
+                worker(itr.GetSource());
         }
 
         void BroadcastPacket(WorldPacket const* packet, bool ignorePlayersInBGRaid, int group = -1, ObjectGuid ignoredPlayer = ObjectGuid::Empty) const;
diff --git a/src/server/game/Handlers/BattleGroundHandler.cpp b/src/server/game/Handlers/BattleGroundHandler.cpp
index a04564c5a41..cad7634d64a 100644
--- a/src/server/game/Handlers/BattleGroundHandler.cpp
+++ b/src/server/game/Handlers/BattleGroundHandler.cpp
@@ -224,12 +224,9 @@ void WorldSession::HandleBattlemasterJoinOpcode(WorldPackets::Battleground::Batt
             avgTime = bgQueue.GetAverageQueueWaitTime(ginfo, bracketEntry->GetBracketId());
         }
 
-        for (GroupReference const* itr = grp->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : grp->GetMembers())
         {
-            Player* member = itr->GetSource();
-            if (!member)
-                continue;   // this should never happen
-
+            Player* member = itr.GetSource();
             if (err)
             {
                 WorldPackets::Battleground::BattlefieldStatusFailed battlefieldStatus;
@@ -578,12 +575,9 @@ void WorldSession::HandleBattlemasterJoinArena(WorldPackets::Battleground::Battl
         avgTime = bgQueue.GetAverageQueueWaitTime(ginfo, bracketEntry->GetBracketId());
     }
 
-    for (GroupReference* itr = grp->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : grp->GetMembers())
     {
-        Player* member = itr->GetSource();
-        if (!member)
-            continue;
-
+        Player* member = itr.GetSource();
         if (err)
         {
             WorldPackets::Battleground::BattlefieldStatusFailed battlefieldStatus;
diff --git a/src/server/game/Handlers/GroupHandler.cpp b/src/server/game/Handlers/GroupHandler.cpp
index daa0e086981..617850957a9 100644
--- a/src/server/game/Handlers/GroupHandler.cpp
+++ b/src/server/game/Handlers/GroupHandler.cpp
@@ -720,9 +720,9 @@ void WorldSession::HandleSendPingUnit(WorldPackets::Party::SendPingUnit const& p
     broadcastPingUnit.SpellOverrideNameID = pingUnit.SpellOverrideNameID;
     broadcastPingUnit.Write();
 
-    for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : group->GetMembers())
     {
-        Player const* member = itr->GetSource();
+        Player const* member = itr.GetSource();
         if (_player == member || !_player->IsInMap(member))
             continue;
 
@@ -749,9 +749,9 @@ void WorldSession::HandleSendPingWorldPoint(WorldPackets::Party::SendPingWorldPo
     broadcastPingWorldPoint.PingDuration = pingWorldPoint.PingDuration;
     broadcastPingWorldPoint.Write();
 
-    for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : group->GetMembers())
     {
-        Player const* member = itr->GetSource();
+        Player const* member = itr.GetSource();
         if (_player == member || !_player->IsInMap(member))
             continue;
 
diff --git a/src/server/game/Handlers/LFGHandler.cpp b/src/server/game/Handlers/LFGHandler.cpp
index 5abec45cbf8..3e4030a5691 100644
--- a/src/server/game/Handlers/LFGHandler.cpp
+++ b/src/server/game/Handlers/LFGHandler.cpp
@@ -209,12 +209,9 @@ void WorldSession::SendLfgPartyLockInfo()
     WorldPackets::LFG::LfgPartyInfo lfgPartyInfo;
 
     // Get the locked dungeons of the other party members
-    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : group->GetMembers())
     {
-        Player* plrg = itr->GetSource();
-        if (!plrg)
-            continue;
-
+        Player* plrg = itr.GetSource();
         ObjectGuid pguid = plrg->GetGUID();
         if (pguid == guid)
             continue;
diff --git a/src/server/game/Handlers/LootHandler.cpp b/src/server/game/Handlers/LootHandler.cpp
index e73fe2a5203..695caeb7282 100644
--- a/src/server/game/Handlers/LootHandler.cpp
+++ b/src/server/game/Handlers/LootHandler.cpp
@@ -155,12 +155,9 @@ void WorldSession::HandleLootMoneyOpcode(WorldPackets::Loot::LootMoney& /*packet
             Group* group = player->GetGroup();
 
             std::vector<Player*> playersNear;
-            for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                Player* member = itr->GetSource();
-                if (!member)
-                    continue;
-
+                Player* member = itr.GetSource();
                 if (!loot->HasAllowedLooter(member->GetGUID()))
                     continue;
 
diff --git a/src/server/game/Handlers/QuestHandler.cpp b/src/server/game/Handlers/QuestHandler.cpp
index d86bbf17cb1..085ec2e1ff9 100644
--- a/src/server/game/Handlers/QuestHandler.cpp
+++ b/src/server/game/Handlers/QuestHandler.cpp
@@ -152,11 +152,11 @@ void WorldSession::HandleQuestgiverAcceptQuestOpcode(WorldPackets::Quest::QuestG
     {
         if (Group* group = _player->GetGroup())
         {
-            for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+            for (GroupReference const& itr : group->GetMembers())
             {
-                Player* player = itr->GetSource();
+                Player* player = itr.GetSource();
 
-                if (!player || player == _player || !player->IsInMap(_player))     // not self and in same map
+                if (player == _player || !player->IsInMap(_player))     // not self and in same map
                     continue;
 
                 if (player->CanTakeQuest(quest, true))
@@ -595,11 +595,11 @@ void WorldSession::HandlePushQuestToParty(WorldPackets::Quest::PushQuestToParty&
         return;
     }
 
-    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+    for (GroupReference const& itr : group->GetMembers())
     {
-        Player* receiver = itr->GetSource();
+        Player* receiver = itr.GetSource();
 
-        if (!receiver || receiver == sender)
+        if (receiver == sender)
             continue;
 
         if (!receiver->GetPlayerSharingQuest().IsEmpty())
diff --git a/src/server/game/Loot/Loot.cpp b/src/server/game/Loot/Loot.cpp
index f8990384b26..d2c22a93373 100644
--- a/src/server/game/Loot/Loot.cpp
+++ b/src/server/game/Loot/Loot.cpp
@@ -884,10 +884,12 @@ bool Loot::FillLoot(uint32 lootId, LootStore const& store, Player* lootOwner, bo
         if (loot_type == LOOT_CORPSE)
             roundRobinPlayer = lootOwner->GetGUID();
 
-        for (GroupReference const* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-            if (Player* player = itr->GetSource())    // should actually be looted object instead of lootOwner but looter has to be really close so doesnt really matter
-                if (player->IsAtGroupRewardDistance(lootOwner))
-                    FillNotNormalLootFor(player);
+        for (GroupReference const& itr : group->GetMembers())
+        {
+            Player* member = itr.GetSource(); // should actually be looted object instead of lootOwner but looter has to be really close so doesnt really matter
+            if (member->IsAtGroupRewardDistance(lootOwner))
+                FillNotNormalLootFor(member);
+        }
 
         for (LootItem& item : items)
         {
diff --git a/src/server/game/Maps/Map.cpp b/src/server/game/Maps/Map.cpp
index 2382850e9f8..290bd2f73f9 100644
--- a/src/server/game/Maps/Map.cpp
+++ b/src/server/game/Maps/Map.cpp
@@ -135,7 +135,7 @@ void Map::DeleteStateMachine()
 Map::Map(uint32 id, time_t expiry, uint32 InstanceId, Difficulty SpawnMode) :
 _creatureToMoveLock(false), _gameObjectsToMoveLock(false), _dynamicObjectsToMoveLock(false), _areaTriggersToMoveLock(false),
 i_mapEntry(sMapStore.LookupEntry(id)), i_spawnMode(SpawnMode), i_InstanceId(InstanceId),
-m_unloadTimer(0), m_VisibleDistance(DEFAULT_VISIBILITY_DISTANCE),
+m_unloadTimer(0), m_VisibleDistance(DEFAULT_VISIBILITY_DISTANCE), m_mapRefIter(m_mapRefManager.end()),
 m_VisibilityNotifyPeriod(DEFAULT_VISIBILITY_NOTIFY_PERIOD),
 m_activeNonPlayersIter(m_activeNonPlayers.end()), _transportsUpdateIter(_transports.end()),
 i_gridExpiry(expiry), m_terrain(sTerrainMgr.LoadTerrain(id)), m_forceEnabledNavMeshFilterFlags(0), m_forceDisabledNavMeshFilterFlags(0),
diff --git a/src/server/game/OutdoorPvP/OutdoorPvP.cpp b/src/server/game/OutdoorPvP/OutdoorPvP.cpp
index 0379f8b15e5..b6db2c304b3 100644
--- a/src/server/game/OutdoorPvP/OutdoorPvP.cpp
+++ b/src/server/game/OutdoorPvP/OutdoorPvP.cpp
@@ -97,12 +97,9 @@ void OutdoorPvP::HandleKill(Player* killer, Unit* killed)
 {
     if (Group* group = killer->GetGroup())
     {
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* groupGuy = itr->GetSource();
-
-            if (!groupGuy)
-                continue;
+            Player* groupGuy = itr.GetSource();
 
             // skip if too far away
             if (!groupGuy->IsAtGroupRewardDistance(killed))
diff --git a/src/server/scripts/Commands/cs_group.cpp b/src/server/scripts/Commands/cs_group.cpp
index 24e412e0c93..83471c9716a 100644
--- a/src/server/scripts/Commands/cs_group.cpp
+++ b/src/server/scripts/Commands/cs_group.cpp
@@ -92,27 +92,24 @@ public:
         if (!groupTarget)
             return false;
 
-        for (GroupReference* it = groupTarget->GetFirstMember(); it != nullptr; it = it->next())
+        for (GroupReference const& it : groupTarget->GetMembers())
         {
-            target = it->GetSource();
-            if (target)
-            {
-                uint8 oldlevel = static_cast<uint8>(target->GetLevel());
+            target = it.GetSource();
+            uint8 oldlevel = static_cast<uint8>(target->GetLevel());
 
-                if (level != oldlevel)
-                {
-                    target->SetLevel(static_cast<uint8>(level));
-                    target->InitTalentForLevel();
-                    target->SetXP(0);
-                }
+            if (level != oldlevel)
+            {
+                target->SetLevel(static_cast<uint8>(level));
+                target->InitTalentForLevel();
+                target->SetXP(0);
+            }
 
-                if (handler->needReportToTarget(target))
-                {
-                    if (oldlevel < static_cast<uint8>(level))
-                        ChatHandler(target->GetSession()).PSendSysMessage(LANG_YOURS_LEVEL_UP, handler->GetNameLink().c_str(), level);
-                    else                                                // if (oldlevel > newlevel)
-                        ChatHandler(target->GetSession()).PSendSysMessage(LANG_YOURS_LEVEL_DOWN, handler->GetNameLink().c_str(), level);
-                }
+            if (handler->needReportToTarget(target))
+            {
+                if (oldlevel < static_cast<uint8>(level))
+                    ChatHandler(target->GetSession()).PSendSysMessage(LANG_YOURS_LEVEL_UP, handler->GetNameLink().c_str(), level);
+                else                                                // if (oldlevel > newlevel)
+                    ChatHandler(target->GetSession()).PSendSysMessage(LANG_YOURS_LEVEL_DOWN, handler->GetNameLink().c_str(), level);
             }
         }
         return true;
@@ -128,15 +125,12 @@ public:
         if (!groupTarget)
             return false;
 
-        for (GroupReference* it = groupTarget->GetFirstMember(); it != nullptr; it = it->next())
+        for (GroupReference const& it : groupTarget->GetMembers())
         {
-            Player* target = it->GetSource();
-            if (target)
-            {
-                target->ResurrectPlayer(target->GetSession()->HasPermission(rbac::RBAC_PERM_RESURRECT_WITH_FULL_HPS) ? 1.0f : 0.5f);
-                target->SpawnCorpseBones();
-                target->SaveToDB();
-            }
+            Player* target = it.GetSource();
+            target->ResurrectPlayer(target->GetSession()->HasPermission(rbac::RBAC_PERM_RESURRECT_WITH_FULL_HPS) ? 1.0f : 0.5f);
+            target->SpawnCorpseBones();
+            target->SaveToDB();
         }
 
         return true;
@@ -153,14 +147,8 @@ public:
         if (!groupTarget)
             return false;
 
-        for (GroupReference* it = groupTarget->GetFirstMember(); it != nullptr; it = it->next())
-        {
-            Player* target = it->GetSource();
-            if (target)
-            {
-                target->DurabilityRepairAll(false, 0, false);
-            }
-        }
+        for (GroupReference const& it : groupTarget->GetMembers())
+            it.GetSource()->DurabilityRepairAll(false, 0, false);
 
         return true;
     }
@@ -204,11 +192,11 @@ public:
             }
         }
 
-        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : group->GetMembers())
         {
-            Player* player = itr->GetSource();
+            Player* player = itr.GetSource();
 
-            if (!player || player == gmPlayer || !player->GetSession())
+            if (player == gmPlayer)
                 continue;
 
             // check online security
diff --git a/src/server/scripts/Commands/cs_tele.cpp b/src/server/scripts/Commands/cs_tele.cpp
index 0e1b2178bac..48866791fcb 100644
--- a/src/server/scripts/Commands/cs_tele.cpp
+++ b/src/server/scripts/Commands/cs_tele.cpp
@@ -249,12 +249,9 @@ public:
             return false;
         }
 
-        for (GroupReference* itr = grp->GetFirstMember(); itr != nullptr; itr = itr->next())
+        for (GroupReference const& itr : grp->GetMembers())
         {
-            Player* player = itr->GetSource();
-
-            if (!player || !player->GetSession())
-                continue;
+            Player* player = itr.GetSource();
 
             // check online security
             if (handler->HasLowerSecurity(player, ObjectGuid::Empty))
diff --git a/src/server/scripts/EasternKingdoms/Stratholme/stratholme.cpp b/src/server/scripts/EasternKingdoms/Stratholme/stratholme.cpp
index 920d2f1d0b2..43bd93489d4 100644
--- a/src/server/scripts/EasternKingdoms/Stratholme/stratholme.cpp
+++ b/src/server/scripts/EasternKingdoms/Stratholme/stratholme.cpp
@@ -67,10 +67,10 @@ class go_gauntlet_gate : public GameObjectScript
 
                 if (Group* group = player->GetGroup())
                 {
-                    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+                    for (GroupReference const& itr : group->GetMembers())
                     {
-                        Player* pGroupie = itr->GetSource();
-                        if (!pGroupie || !pGroupie->IsInMap(player))
+                        Player* pGroupie = itr.GetSource();
+                        if (!pGroupie->IsInMap(player))
                             continue;
 
                         if (pGroupie->GetQuestStatus(QUEST_DEAD_MAN_PLEA) == QUEST_STATUS_INCOMPLETE &&
diff --git a/src/server/scripts/EasternKingdoms/zone_blasted_lands.cpp b/src/server/scripts/EasternKingdoms/zone_blasted_lands.cpp
index 06098172780..e369cef4dac 100644
--- a/src/server/scripts/EasternKingdoms/zone_blasted_lands.cpp
+++ b/src/server/scripts/EasternKingdoms/zone_blasted_lands.cpp
@@ -44,10 +44,12 @@ class spell_razelikh_teleport_group : public SpellScript
         {
             if (Group* group = player->GetGroup())
             {
-                for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (Player* member = itr->GetSource())
-                        if (member->IsWithinDistInMap(player, 20.0f) && !member->isDead())
-                            member->CastSpell(member, SPELL_TELEPORT_SINGLE_IN_GROUP, true);
+                for (GroupReference const& itr : group->GetMembers())
+                {
+                    Player* member = itr.GetSource();
+                    if (member->IsWithinDistInMap(player, 20.0f) && !member->isDead())
+                        member->CastSpell(member, SPELL_TELEPORT_SINGLE_IN_GROUP, true);
+                }
             }
             else
                 player->CastSpell(player, SPELL_TELEPORT_SINGLE, true);
diff --git a/src/server/scripts/Northrend/IcecrownCitadel/boss_lady_deathwhisper.cpp b/src/server/scripts/Northrend/IcecrownCitadel/boss_lady_deathwhisper.cpp
index b28d92a4175..7ac91ae5cf8 100644
--- a/src/server/scripts/Northrend/IcecrownCitadel/boss_lady_deathwhisper.cpp
+++ b/src/server/scripts/Northrend/IcecrownCitadel/boss_lady_deathwhisper.cpp
@@ -379,10 +379,9 @@ struct boss_lady_deathwhisper : public BossAI
                 {
                     if (Group* group = owner->GetGroup())
                     {
-                        for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                            if (Player* member = itr->GetSource())
-                                if (member->IsInMap(owner))
-                                    member->KilledMonsterCredit(NPC_DARNAVAN_CREDIT);
+                        for (GroupReference const& itr : group->GetMembers())
+                            if (itr.GetSource()->IsInMap(owner))
+                                itr.GetSource()->KilledMonsterCredit(NPC_DARNAVAN_CREDIT);
                     }
                     else
                         owner->KilledMonsterCredit(NPC_DARNAVAN_CREDIT);
@@ -854,10 +853,9 @@ struct npc_darnavan : public ScriptedAI
         {
             if (Group* group = owner->GetGroup())
             {
-                for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
-                    if (Player* member = itr->GetSource())
-                        if (member->IsInMap(owner))
-                            member->FailQuest(QUEST_DEPROGRAMMING);
+                for (GroupReference const& itr : group->GetMembers())
+                    if (itr.GetSource()->IsInMap(owner))
+                        itr.GetSource()->FailQuest(QUEST_DEPROGRAMMING);
             }
             else
                 owner->FailQuest(QUEST_DEPROGRAMMING);
diff --git a/src/server/scripts/Outland/zone_terokkar_forest.cpp b/src/server/scripts/Outland/zone_terokkar_forest.cpp
index d17045509d5..6a5224a60de 100644
--- a/src/server/scripts/Outland/zone_terokkar_forest.cpp
+++ b/src/server/scripts/Outland/zone_terokkar_forest.cpp
@@ -91,12 +91,12 @@ public:
 
             if (Player* player = done_by->ToPlayer())
             {
-                if (Group* group = player->GetGroup())
+                if (Group const* group = player->GetGroup())
                 {
-                    for (GroupReference* itr = group->GetFirstMember(); itr != nullptr; itr = itr->next())
+                    for (GroupReference const& itr : group->GetMembers())
                     {
-                        Player* groupie = itr->GetSource();
-                        if (groupie && groupie->IsInMap(player) &&
+                        Player* groupie = itr.GetSource();
+                        if (groupie->IsInMap(player) &&
                             groupie->GetQuestStatus(QUEST_DONTKILLTHEFATONE) == QUEST_STATUS_INCOMPLETE &&
                             groupie->GetReqKillOrCastCurrentCount(QUEST_DONTKILLTHEFATONE, NPC_BOULDERFIST_INVADER) == REQUIRED_KILL_COUNT)
                         {