Core/Scripts: fix Nightfall proc chance and reduce it for victims with level above 60. (#3304)

* Core/Scripts: fix Nightfall proc chance and reduce it for victims with level above 60

Adding a TrinityCore commit eac9c1f0b9

* Update rev_1597581112860069800.sql

* Update rev_1597581112860069800.sql

Co-authored-by: Francesco Borzì <borzifrancesco@gmail.com>
Co-authored-by: Stefano Borzì <stefanoborzi32@gmail.com>

data/sql/updates/pending_db_world/rev_1597581112860069800.sql

@@ -0,0 +1,5 @@
+INSERT INTO `version_db_world` (`sql_rev`) VALUES ('1597581112860069800');
+
+-- Nightfall
+UPDATE `item_template` SET `spellppmRate_1`=2.5, `ScriptName`='item_generic_limit_chance_above_60' WHERE `entry`=19169;
+

src/server/game/Entities/Player/Player.cpp

@@ -8564,7 +8564,7 @@ void Player::CastItemCombatSpell(Unit* target, WeaponAttackType attType, uint32
                 chance = GetWeaponProcChance();
             }
 
-            if (roll_chance_f(chance))
+            if (roll_chance_f(chance) && sScriptMgr->OnCastItemCombatSpell(this, target, spellInfo, item))
                 CastSpell(target, spellInfo->Id, TriggerCastFlags(TRIGGERED_FULL_MASK&~TRIGGERED_IGNORE_SPELL_AND_CATEGORY_CD), item);
         }
     }

src/server/game/Scripting/ScriptMgr.cpp

@@ -722,6 +722,17 @@ bool ScriptMgr::OnItemRemove(Player * player, Item * item)
 
 }
 
+bool ScriptMgr::OnCastItemCombatSpell(Player* player, Unit* victim, SpellInfo const* spellInfo, Item* item)
+{
+    ASSERT(player);
+    ASSERT(victim);
+    ASSERT(spellInfo);
+    ASSERT(item);
+
+    GET_SCRIPT_RET(ItemScript, item->GetScriptId(), tmpscript, true);
+    return tmpscript->OnCastItemCombatSpell(player, victim, spellInfo, item);
+}
+
 void ScriptMgr::OnGossipSelect(Player* player, Item* item, uint32 sender, uint32 action)
 {
     ASSERT(player);

src/server/game/Scripting/ScriptMgr.h

@@ -47,6 +47,7 @@ class Quest;
 class ScriptMgr;
 class Spell;
 class SpellScript;
+class SpellInfo;
 class SpellCastTargets;
 class Transport;
 class StaticTransport;
@@ -425,6 +426,9 @@ class ItemScript : public ScriptObject
         // Called when the item is destroyed.
         virtual bool OnRemove(Player* /*player*/, Item* /*item*/) { return false; }
 
+        // Called before casting a combat spell from this item (chance on hit spells of item template, can be used to prevent cast if returning false)
+        virtual bool OnCastItemCombatSpell(Player* /*player*/, Unit* /*victim*/, SpellInfo const* /*spellInfo*/, Item* /*item*/) { return true; }
+
         // Called when the item expires (is destroyed).
         virtual bool OnExpire(Player* /*player*/, ItemTemplate const* /*proto*/) { return false; }
 
@@ -1304,6 +1308,7 @@ class ScriptMgr
         bool OnItemUse(Player* player, Item* item, SpellCastTargets const& targets);
         bool OnItemExpire(Player* player, ItemTemplate const* proto);
         bool OnItemRemove(Player* player, Item* item);
+        bool OnCastItemCombatSpell(Player* player, Unit* victim, SpellInfo const* spellInfo, Item* item);
         void OnGossipSelect(Player* player, Item* item, uint32 sender, uint32 action);
         void OnGossipSelectCode(Player* player, Item* item, uint32 sender, uint32 action, const char* code);
 

src/server/scripts/World/item_scripts.cpp

@@ -234,6 +234,30 @@ public:
     }
 };
 
+// Only used currently for
+// 19169: Nightfall
+class item_generic_limit_chance_above_60 : public ItemScript
+{
+public:
+    item_generic_limit_chance_above_60() : ItemScript("item_generic_limit_chance_above_60") { }
+
+    bool OnCastItemCombatSpell(Player* /*player*/, Unit* victim, SpellInfo const* /*spellInfo*/, Item* /*item*/) override
+    {
+        // spell proc chance gets severely reduced on victims > 60 (formula unknown)
+        if (victim->getLevel() > 60)
+        {
+            // gives ~0.1% proc chance at lvl 70
+            float const lvlPenaltyFactor = 9.93f;
+            float const failureChance = (victim->getLevel() - 60) * lvlPenaltyFactor;
+
+            // base ppm chance was already rolled, only roll success chance
+            return !roll_chance_f(failureChance);
+        }
+
+        return true;
+    }
+};
+
 void AddSC_item_scripts()
 {
     new item_only_for_flight();
@@ -244,4 +268,5 @@ void AddSC_item_scripts()
     new item_disgusting_jar();
     new item_petrov_cluster_bombs();
     new item_captured_frog();
+    new item_generic_limit_chance_above_60();
 }