Core/Creature: Allow to disable HP regen in Raids even if the target is unreachable

Port From (https://github.com/TrinityCore/TrinityCore/commit/07863a7a6817dbb16fbd740130149bf727a6a136)

Source/Framework/Constants/SharedConst.cs

@@ -1666,6 +1666,7 @@ namespace Framework.Constants
         RateXpBoost,
         RateXpQuest,
         RealmZone,
+        RegenHpCannotReachTargetInRaid,
         ResetDuelCooldowns,
         ResetDuelHealthMana,
         RespawnDynamicEscortNpc,

Source/Game/Entities/Creature/Creature.cs

@@ -590,8 +590,24 @@ namespace Game.Entities
 
                     if (RegenTimer == 0)
                     {
-                        if (!IsInEvadeMode() && (!IsEngaged() || IsPolymorphed() || CanNotReachTarget())) // regenerate health if not in combat or if polymorphed
+                        if (!IsInEvadeMode())
+                        {
+                            // regenerate health if not in combat or if polymorphed)
+                            if (!IsEngaged() || IsPolymorphed())
                                 RegenerateHealth();
+                            else if (CanNotReachTarget())
+                            {
+                                // regenerate health if cannot reach the target and the setting is set to do so.
+                                // this allows to disable the health regen of raid bosses if pathfinding has issues for whatever reason
+                                if (WorldConfig.GetBoolValue(WorldCfg.RegenHpCannotReachTargetInRaid) || !GetMap().IsRaid())
+                                {
+                                    RegenerateHealth();
+                                    Log.outDebug(LogFilter.Unit, $"RegenerateHealth() enabled because Creature cannot reach the target. Detail: {GetDebugInfo()}");
+                                }
+                                else
+                                    Log.outDebug(LogFilter.Unit, $"RegenerateHealth() disabled even if the Creature cannot reach the target. Detail: {GetDebugInfo()}");
+                            }
+                        }
 
                         if (GetPowerType() == PowerType.Energy)
                             Regenerate(PowerType.Energy);
@@ -2800,15 +2816,19 @@ namespace Game.Entities
             return range;
         }
 
-        public void SetCannotReachTarget(bool cannotReach)
+        bool CanNotReachTarget() { return m_cannotReachTarget; }
+
+        void SetCannotReachTarget(bool cannotReach)
         {
             if (cannotReach == m_cannotReachTarget)
                 return;
 
             m_cannotReachTarget = cannotReach;
             m_cannotReachTimer = 0;
+
+            if (cannotReach)
+                Log.outDebug(LogFilter.Unit, $"Creature::SetCannotReachTarget() called with true. Details: {GetDebugInfo()}");
         }
-        bool CanNotReachTarget() { return m_cannotReachTarget; }
 
         public float GetAggroRange(Unit target)
         {

Source/Game/Server/WorldConfig.cs

@@ -312,6 +312,8 @@ namespace Game
             /// @todo Add MonsterSight (with meaning) in worldserver.conf or put them as define
             Values[WorldCfg.SightMonster] = GetDefaultValue("MonsterSight", 50.0f);
 
+            Values[WorldCfg.RegenHpCannotReachTargetInRaid] = GetDefaultValue("Creature.RegenHPCannotReachTargetInRaid", true);
+
             if (reload)
             {
                 int val = GetDefaultValue("GameType", 0);

Source/WorldServer/WorldServer.conf.dist

@@ -1708,6 +1708,14 @@ Creature.MovingStopTimeForPlayer = 180000
 
 MonsterSight = 50.000000
 
+#
+#    Creature.RegenHPCannotReachTargetInRaid
+#        Description: Regenerates HP for Creatures in Raids if they cannot reach the target.
+#        Default:     1 - (Enabled)
+#                     0 - (Disabled)
+
+Creature.RegenHPCannotReachTargetInRaid = 1
+
 #
 ###################################################################################################