Fix/Feat: Stop bots in party from PVP when master isn't, and PVP probablity system (#1914)

There are two related PVP components in this PR. First is the simple yet
fundamental change to bot behaviour when they are in party. Right now
bots with a master will go into PVP when there's a nearby PVP target,
even if master is not in PVP. This absolutely should not happen. Bots
should not consider PVP at all if master is not in PVP. The fix is only
3 lines in EnemyPlayerValue

The second component is introducing PVP probabilities, to make decisions
more realistic. Right now even a level 1 bot will 100% go into PVP if it
sees a level 80 PVP target. They can't help themselves. So the change
here addresses that insanity. Several thresholds (subject to community
review) are introduced:

1. Bots will not fight a target 5 or more levels higher than them
2. Bots have a 25% chance starting a fight with a target +/- 4 levels
from them.
3. Bots have a 50% chance starting a fight with a target +/- 3 levels
from them.
4. Bots have a 75% chance starting a fight with a target +/- 2 levels
from them.
5. Bots have a 100% chance starting a fight with a target +/- 1 level
from them.
6. Bots have a 25% chance starting a fight with a target 5 or more
levels below them (ganking. thought it would be funny, and technically
realistic of player behaviour)

Exception of course exist for BG/Arena/Duel, and in capitals where bots
will always PVP. Also bots will always defend themselves if attacked.

Few notes: 
1. The if/ else if logic can be further simplified, but only if we use
thresholds that are different by one. So current logic allows for
flexibility of using values like 10/7/5/3 instead of 5/4/3/2.
2. The caching system is per-bot basis. So for some target X, if some
bot decides to attack it, another bot will make its own decision. At
first I used a simplified global system (thinking there might be
performance concerns) where if one bot decides to attack a target then
they all do, but when I switched to the more realistic per-bot basis, I
didn't see an effect on performance.
3. Variables are obviously not configurable right now. I'm starting to
see Bash's POV that maybe we have too many configs 😬 Still,
they can be easily exposed in the future, and if someone is reading this
then, remember to change constexpr to const.

src/strategy/values/EnemyPlayerValue.cpp

@@ -11,6 +11,10 @@
 
 bool NearestEnemyPlayersValue::AcceptUnit(Unit* unit)
 {
+    // Apply parent's filtering first (includes level difference checks)
+    if (!PossibleTargetsValue::AcceptUnit(unit))
+        return false;
+
     bool inCannon = botAI->IsInVehicle(false, true);
     Player* enemy = dynamic_cast<Player*>(unit);
     if (enemy && botAI->IsOpposing(enemy) && enemy->IsPvP() &&
@@ -19,7 +23,14 @@ bool NearestEnemyPlayersValue::AcceptUnit(Unit* unit)
         ((inCannon || !enemy->HasFlag(UNIT_FIELD_FLAGS, UNIT_FLAG_NOT_SELECTABLE))) &&
         /*!enemy->HasStealthAura() && !enemy->HasInvisibilityAura()*/ enemy->CanSeeOrDetect(bot) &&
         !(enemy->HasSpiritOfRedemptionAura()))
+    {
+        // If with master, only attack if master is PvP flagged
+        Player* master = botAI->GetMaster();
+        if (master && !master->IsPvP() && !master->IsFFAPvP())
+            return false;
+
         return true;
+    }
 
     return false;
 }

src/strategy/values/PossibleTargetsValue.cpp

@@ -16,6 +16,32 @@
 #include "SpellAuraEffects.h"
 #include "SpellMgr.h"
 #include "Unit.h"
+#include "AreaDefines.h"
+#include <unordered_map>
+
+// Level difference thresholds for attack probability
+constexpr int32 EXTREME_LEVEL_DIFF = 5;  // Don't attack if enemy is this much higher
+constexpr int32 HIGH_LEVEL_DIFF = 4;     // 25% chance at +/- this difference
+constexpr int32 MID_LEVEL_DIFF = 3;      // 50% chance at +/- this difference
+constexpr int32 LOW_LEVEL_DIFF = 2;      // 75% chance at +/- this difference
+
+// Cache duration before reconsidering attack decision, and old cache cleanup interval
+constexpr uint32 ATTACK_DECISION_CACHE_DURATION = 2 * MINUTE;
+constexpr uint32 ATTACK_DECISION_CACHE_CLEANUP_INTERVAL = 10 * MINUTE;
+
+// Custom hash function for (botGUID, targetGUID) pairs
+struct PairGuidHash
+{
+    std::size_t operator()(const std::pair<ObjectGuid, ObjectGuid>& pair) const
+    {
+        return std::hash<uint64>()(pair.first.GetRawValue()) ^
+               (std::hash<uint64>()(pair.second.GetRawValue()) << 1);
+    }
+};
+
+// Cache for probability-based attack decisions (Per-bot: non-global)
+// Map: (botGUID, targetGUID) -> (should attack decision, timestamp)
+static std::unordered_map<std::pair<ObjectGuid, ObjectGuid>, std::pair<bool, time_t>, PairGuidHash> attackDecisionCache;
 
 void PossibleTargetsValue::FindUnits(std::list<Unit*>& targets)
 {
@@ -24,7 +50,117 @@ void PossibleTargetsValue::FindUnits(std::list<Unit*>& targets)
     Cell::VisitObjects(bot, searcher, range);
 }
 
-bool PossibleTargetsValue::AcceptUnit(Unit* unit) { return AttackersValue::IsPossibleTarget(unit, bot, range); }
+static void CleanupAttackDecisionCache()
+{
+    time_t currentTime = time(nullptr);
+    for (auto it = attackDecisionCache.begin(); it != attackDecisionCache.end();)
+    {
+        if (currentTime - it->second.second >= ATTACK_DECISION_CACHE_DURATION)
+            it = attackDecisionCache.erase(it);
+        else
+            ++it;
+    }
+}
+
+bool PossibleTargetsValue::AcceptUnit(Unit* unit)
+{
+    // attackDecisionCache cleanup
+    static time_t lastCleanup = 0;
+    time_t currentTime = time(nullptr);
+    if (currentTime - lastCleanup > ATTACK_DECISION_CACHE_CLEANUP_INTERVAL)
+    {
+        CleanupAttackDecisionCache();
+        lastCleanup = currentTime;
+    }
+
+    if (!AttackersValue::IsPossibleTarget(unit, bot, range))
+        return false;
+
+    // Level-based PvP restrictions
+    if (unit->IsPlayer())
+    {
+        // Self-defense - always allow fighting back
+        if (bot->IsInCombat() && bot->GetVictim() == unit)
+            return true;  // Already fighting
+
+        Unit* botAttacker = bot->getAttackerForHelper();
+        if (botAttacker)
+        {
+            if (botAttacker == unit)
+                return true;  // Enemy attacking
+
+            if (botAttacker->IsPet())
+            {
+                Unit* petOwner = botAttacker->GetOwner();
+                if (petOwner && petOwner == unit)
+                    return true;  // Enemy's pet attacking
+            }
+        }
+
+        // Skip restrictions in BG/Arena
+        if (bot->InBattleground() || bot->InArena())
+            return true;
+
+        // Skip restrictions if in duel with this player
+        if (bot->duel && bot->duel->Opponent == unit)
+            return true;
+
+        // Capital cities - no restrictions
+        uint32 zoneId = bot->GetZoneId();
+        bool inCapitalCity = (zoneId == AREA_STORMWIND_CITY ||
+                            zoneId == AREA_IRONFORGE        ||
+                            zoneId == AREA_DARNASSUS        ||
+                            zoneId == AREA_THE_EXODAR       ||
+                            zoneId == AREA_ORGRIMMAR        ||
+                            zoneId == AREA_THUNDER_BLUFF    ||
+                            zoneId == AREA_UNDERCITY        ||
+                            zoneId == AREA_SILVERMOON_CITY);
+
+        if (inCapitalCity)
+            return true;
+
+        // Level difference check
+        int32 levelDifference = unit->GetLevel() - bot->GetLevel();
+        int32 absLevelDifference = std::abs(levelDifference);
+
+        // Extreme difference - do not attack
+        if (levelDifference >= EXTREME_LEVEL_DIFF)
+            return false;
+
+        // Calculate attack chance based on level difference
+        uint32 attackChance = 100; // Default 100%: Bot and target's levels are very close
+
+        // There's a chance a bot might gank on an extremly low target
+        if ((absLevelDifference < EXTREME_LEVEL_DIFF && absLevelDifference >= HIGH_LEVEL_DIFF) ||
+            levelDifference <= -EXTREME_LEVEL_DIFF)
+            attackChance = 25;
+
+        else if (absLevelDifference < HIGH_LEVEL_DIFF && absLevelDifference >= MID_LEVEL_DIFF)
+            attackChance = 50;
+
+        else if (absLevelDifference < MID_LEVEL_DIFF && absLevelDifference >= LOW_LEVEL_DIFF)
+            attackChance = 75;
+
+        // If probability check needed, use cache
+        if (attackChance < 100)
+        {
+            std::pair<ObjectGuid, ObjectGuid> cacheKey = std::make_pair(bot->GetGUID(), unit->GetGUID());
+
+            auto it = attackDecisionCache.find(cacheKey);
+            if (it != attackDecisionCache.end())
+            {
+                if (currentTime - it->second.second < ATTACK_DECISION_CACHE_DURATION)
+                    return it->second.first;
+            }
+
+            bool shouldAttack = (urand(1, 100) <= attackChance);
+            attackDecisionCache[cacheKey] = std::make_pair(shouldAttack, currentTime);
+            return shouldAttack;
+        }
+    }
+
+    return true;
+}
 
 void PossibleTriggersValue::FindUnits(std::list<Unit*>& targets)
 {
@@ -36,9 +172,8 @@ void PossibleTriggersValue::FindUnits(std::list<Unit*>& targets)
 bool PossibleTriggersValue::AcceptUnit(Unit* unit)
 {
     if (!unit->HasUnitFlag(UNIT_FLAG_NOT_SELECTABLE))
-    {
         return false;
-    }
+
     Unit::AuraEffectList const& aurasPeriodicTriggerSpell =
         unit->GetAuraEffectsByType(SPELL_AURA_PERIODIC_TRIGGER_SPELL);
     Unit::AuraEffectList const& aurasPeriodicTriggerWithValueSpell =
@@ -58,11 +193,9 @@ bool PossibleTriggersValue::AcceptUnit(Unit* unit)
             for (int j = 0; j < MAX_SPELL_EFFECTS; j++)
             {
                 if (triggerSpellInfo->Effects[j].Effect == SPELL_EFFECT_SCHOOL_DAMAGE)
-                {
                     return true;
             }
         }
     }
-    }
     return false;
 }