Core: Combat/threat system rewrite (PR #19930)

- PvE combat is now always mutual. UNIT_FLAG_IN_COMBAT is backed by actual references to the units we're in combat with.
- PvP combat is now also tracked, and almost always mutual; spells like Vanish and Feign Death can break this rule. That means we can easily determine a list of players we're fighting.
- By extension, IsInCombatWith now has sensible behavior when invoked on nonplayers.
- Threat and combat systems are no longer the same.
  - They still have an enforced relationship (threat implies combat - clearing combat clears threat)...
  - ...but we can have combat without threat. A creature (with threat list) isn't considered to be engaged until it has an entry on its threat list...
  - ...which means we can now faithfully replicate retail engage behavior. Combat on projectile launch - engagement start on projectile impact. Yay for progress!
- AI method refactor, as already ported in 6113b9d - `JustEngagedWith`, `JustEnteredCombat` and `JustExitedCombat`.
- Vehicle threat is now properly pooled on the main vehicle body (fixes #16542).
- Various edge case bug fixes for threat redirects (Misdirection "cancelling" Vigilance and similar).
- Target re-selection is now significantly faster.
- Fixed a ton of other smaller edge case bugs, probably.

Closes #7951 and #19998.

(cherry picked from commit 532ab1c7f8653d1a2e48aa1f1f8a9ba1041d4bb7)

1 files changed, 12 insertions, 5 deletions

diff --git a/src/server/scripts/World/npcs_special.cpp b/src/server/scripts/World/npcs_special.cpp
index 3c8dac9d8de..0591f7c4a76 100644
--- a/src/server/scripts/World/npcs_special.cpp
+++ b/src/server/scripts/World/npcs_special.cpp
@@ -1806,21 +1806,28 @@ public:
                 {
                     case EVENT_TD_CHECK_COMBAT:
                     {
-                        time_t now = GameTime::GetGameTime();
-                        for (std::unordered_map<ObjectGuid, time_t>::iterator itr = _damageTimes.begin(); itr != _damageTimes.end();)
+                        time_t const now = GameTime::GetGameTime();
+                        auto const& pveRefs = me->GetCombatManager().GetPvECombatRefs();
+                        for (auto itr = _damageTimes.begin(); itr != _damageTimes.end();)
                         {
                             // If unit has not dealt damage to training dummy for 5 seconds, remove him from combat
                             if (itr->second < now - 5)
                             {
-                                if (Unit* unit = ObjectAccessor::GetUnit(*me, itr->first))
-                                    unit->getHostileRefManager().deleteReference(me);
+                                auto it = pveRefs.find(itr->first);
+                                if (it != pveRefs.end())
+                                    it->second->EndCombat();
 
                                 itr = _damageTimes.erase(itr);
                             }
                             else
                                 ++itr;
                         }
-                        _events.ScheduleEvent(EVENT_TD_CHECK_COMBAT, 1000);
+
+                        for (auto const& pair : pveRefs)
+                            if (_damageTimes.find(pair.first) == _damageTimes.end())
+                                _damageTimes[pair.first] = now;
+
+                        _events.Repeat(1s);
                         break;
                     }
                     case EVENT_TD_DESPAWN: