Core/Spells: Delay combat flagging for spell targets until spell missile lands

Port From (https://github.com/TrinityCore/TrinityCore/commit/ff99952dfb7d2b532de2d1aedc825fb96038f4c2)

Source/Game/Combat/CombatManager.cs

@@ -113,7 +113,7 @@ namespace Game.Combat
             return null;
         }
 
-        public bool SetInCombatWith(Unit who)
+        public bool SetInCombatWith(Unit who, bool suppressPvpSecond = false)
         {
             // Are we already in combat? If yes, refresh pvp combat
             var pvpRefe = _pvpRefs.LookupByKey(who.GetGUID());
@@ -126,13 +126,18 @@ namespace Game.Combat
                 return true;
 
             // Otherwise, check validity...
-            if (!CombatManager.CanBeginCombat(_owner, who))
+            if (!CanBeginCombat(_owner, who))
                 return false;
 
             // ...then create new reference
             CombatReference refe;
             if (_owner.IsControlledByPlayer() && who.IsControlledByPlayer())
-                refe = new PvPCombatReference(_owner, who);
+            {
+                PvPCombatReference refPvp = new PvPCombatReference(_owner, who);
+                if (suppressPvpSecond)
+                    refPvp.SuppressFor(who);
+                refe = refPvp;
+            }
             else
                 refe = new CombatReference(_owner, who);
 

Source/Game/Entities/Unit/Unit.Combat.cs

@@ -95,10 +95,10 @@ namespace Game.Entities
 
         public bool IsPetInCombat() { return HasUnitFlag(UnitFlags.PetInCombat); }
 
-        public void SetInCombatWith(Unit enemy)
+        public void SetInCombatWith(Unit enemy, bool suppressPvpTargetCombat = false)
         {
             if (enemy != null)
-                m_combatManager.SetInCombatWith(enemy);
+                m_combatManager.SetInCombatWith(enemy, suppressPvpTargetCombat);
         }
 
         public void EngageWithTarget(Unit enemy)

Source/Game/Spells/Spell.cs

@@ -1852,8 +1852,13 @@ namespace Game.Spells
 
             // Calculate hit result
             WorldObject caster = m_originalCaster ? m_originalCaster : m_caster;
+            Unit unitCaster = m_caster.ToUnit();
             targetInfo.MissCondition = caster.SpellHitResult(target, m_spellInfo, m_canReflect && !(IsPositive() && m_caster.IsFriendlyTo(target)));
 
+            // This will only cause combat - the target will engage once the projectile hits (in DoAllEffectOnTarget)
+            if (m_originalCaster != null && targetInfo.MissCondition != SpellMissInfo.Evade && !m_originalCaster.IsFriendlyTo(target) && (!m_spellInfo.IsPositive() || m_spellInfo.HasEffect(SpellEffectName.Dispel)) && (m_spellInfo.HasInitialAggro() || target.IsEngaged()))
+                m_originalCaster.SetInCombatWith(target, true);
+
             // Spell have speed - need calculate incoming time
             // Incoming time is zero for self casts. At least I think so.
             if (m_caster != target)
@@ -1886,6 +1891,15 @@ namespace Game.Spells
                 }
 
                 targetInfo.TimeDelay += (ulong)Math.Floor(hitDelay * 1000.0f);
+
+                if (unitCaster != null && targetInfo.MissCondition != SpellMissInfo.Evade)
+                {
+                    bool enterCombat = !caster.IsFriendlyTo(target) && (!m_spellInfo.IsPositive() || m_spellInfo.HasEffect(SpellEffectName.Dispel)) && (m_spellInfo.HasInitialAggro() || target.IsEngaged());
+                    bool enablePVP = targetInfo.IsPVPEnabling();
+
+                    if (enterCombat || enablePVP)
+                        target.m_Events.AddEvent(new ProcImpactDelayed(target, m_originalCasterGUID, enterCombat, enablePVP), target.m_Events.CalculateTime(TimeSpan.FromMilliseconds(targetInfo.TimeDelay)));
+                }
             }
             else
                 targetInfo.TimeDelay = 0L;
@@ -1894,7 +1908,7 @@ namespace Game.Spells
             if (targetInfo.MissCondition == SpellMissInfo.Reflect)
             {
                 // Calculate reflected spell result on caster (shouldn't be able to reflect gameobject spells)
-                Unit unitCaster = m_caster.ToUnit();
+                Cypher.Assert(unitCaster != null);
                 targetInfo.ReflectResult = unitCaster.SpellHitResult(unitCaster, m_spellInfo, false); // can't reflect twice
 
                 // Proc spell reflect aura when missile hits the original target
@@ -7212,10 +7226,6 @@ namespace Game.Spells
             if (unit == null)
                 return;
 
-            // This will only cause combat - the target will engage once the projectile hits (in DoAllEffectOnTarget)
-            if (m_originalCaster != null && targetInfo.MissCondition != SpellMissInfo.Evade && !m_originalCaster.IsFriendlyTo(unit) && (!m_spellInfo.IsPositive() || m_spellInfo.HasEffect(SpellEffectName.Dispel)) && (m_spellInfo.HasInitialAggro() || unit.IsEngaged()))
-                m_originalCaster.SetInCombatWith(unit);
-
             m_damage = 0;
             m_healing = 0;
 
@@ -8552,7 +8562,7 @@ namespace Game.Spells
                         }
                     }
 
-                if (!spell.m_spellInfo.HasAttribute(SpellAttr3.DoNotTriggerTargetStand) && !unit.IsStandState())
+                    if (!spell.m_spellInfo.HasAttribute(SpellAttr3.DoNotTriggerTargetStand) && !unit.IsStandState())
                         unit.SetStandState(UnitStandStateType.Stand);
                 }
 
@@ -8596,7 +8606,7 @@ namespace Game.Spells
                 // Needs to be called after dealing damage/healing to not remove breaking on damage auras
                 spell.DoTriggersOnSpellHit(_spellHitTarget);
             }
-            
+
             if (_enablePVP)
                 spell.GetCaster().ToPlayer().UpdatePvP(true);
 
@@ -8604,6 +8614,8 @@ namespace Game.Spells
             spell.CallScriptAfterHitHandlers();
             spell.spellAura = null;
         }
+
+        public bool IsPVPEnabling() { return _enablePVP; }
     }
 
     public class GOTargetInfo : TargetInfoBase
@@ -9101,6 +9113,41 @@ namespace Game.Spells
         Spell m_Spell;
     }
 
+    class ProcImpactDelayed : BasicEvent
+    {
+        Unit _owner;
+        ObjectGuid _casterGUID;
+        bool _enterCombat;
+        bool _enablePVP;
+
+        public ProcImpactDelayed(Unit owner, ObjectGuid casterGUID, bool enterCombat, bool enablePVP)
+        {
+            _owner = owner;
+            _casterGUID = casterGUID;
+            _enterCombat = enterCombat;
+            _enablePVP = enablePVP;
+        }
+
+        public override bool Execute(ulong e_time, uint p_time)
+        {
+            if (_owner == null)
+                return true;
+
+            Unit caster = Global.ObjAccessor.GetUnit(_owner, _casterGUID);
+            if (caster == null)
+                return true;
+
+            // This will only cause combat - the target will engage once the projectile hits (in DoAllEffectOnTarget)
+            if (_enterCombat)
+                _owner.SetInCombatWith(caster);
+
+            if (_enablePVP && caster.ToPlayer())
+                caster.ToPlayer().UpdatePvP(true);
+
+            return true;
+        }
+    }
+    
     class ProcReflectDelayed : BasicEvent
     {
         public ProcReflectDelayed(Unit owner, ObjectGuid casterGuid)