Core/Scripts: Adding script hooks to allow for third party scripts to modify damage dealt.

Originally from the VAS Autobalance script, slightly modified.

Only addresses Spells, Dots, and Melee Damage. I'll have look at the current modules on ways of doing this but, Environmental Damage(fire/lava/drowning), Fall Damage, and Potentially AoE aren't covered by these.

Closes #7867

Signed-off-by: Nay <dnpd.dd@gmail.com>

src/server/game/Entities/Unit/Unit.cpp

@@ -1038,6 +1038,9 @@ void Unit::CalculateSpellDamageTaken(SpellNonMeleeDamage* damageInfo, int32 dama
             break;
     }
 
+    // Script Hook For CalculateSpellDamageTaken -- Allow scripts to change the Damage post class mitigation calculations
+    sScriptMgr->ModifySpellDamageTaken(damageInfo->target, damageInfo->attacker, damage);
+
     // Calculate absorb resist
     if (damage > 0)
     {
@@ -1134,6 +1137,9 @@ void Unit::CalculateMeleeDamage(Unit* victim, uint32 damage, CalcDamageInfo* dam
     damage = MeleeDamageBonusDone(damageInfo->target, damage, damageInfo->attackType);
     damage = damageInfo->target->MeleeDamageBonusTaken(this, damage, damageInfo->attackType);
 
+    // Script Hook For CalculateMeleeDamage -- Allow scripts to change the Damage pre class mitigation calculations
+    sScriptMgr->ModifyMeleeDamage(damageInfo->target, damageInfo->attacker, damage);
+
     // Calculate armor reduction
     if (IsDamageReducedByArmor((SpellSchoolMask)(damageInfo->damageSchoolMask)))
     {

src/server/game/Scripting/ScriptMgr.cpp

@@ -217,6 +217,7 @@ void ScriptMgr::Unload()
     SCR_CLEAR(PlayerScript);
     SCR_CLEAR(GuildScript);
     SCR_CLEAR(GroupScript);
+    SCR_CLEAR(UnitScript);
 
     #undef SCR_CLEAR
 }
@@ -1338,6 +1339,22 @@ void ScriptMgr::OnGroupDisband(Group* group)
     FOREACH_SCRIPT(GroupScript)->OnDisband(group);
 }
 
+// Unit
+void ScriptMgr::ModifyPeriodicDamageAurasTick(Unit* target, Unit* attacker, uint32& damage)
+{
+    FOREACH_SCRIPT(UnitScript)->ModifyPeriodicDamageAurasTick(target, attacker, damage);
+}
+
+void ScriptMgr::ModifyMeleeDamage(Unit* target, Unit* attacker, uint32& damage)
+{
+    FOREACH_SCRIPT(UnitScript)->ModifyMeleeDamage(target, attacker, damage);
+}
+
+void ScriptMgr::ModifySpellDamageTaken(Unit* target, Unit* attacker, int32& damage)
+{
+    FOREACH_SCRIPT(UnitScript)->ModifySpellDamageTaken(target, attacker, damage);
+}
+
 SpellScriptLoader::SpellScriptLoader(const char* name)
     : ScriptObject(name)
 {
@@ -1362,6 +1379,12 @@ FormulaScript::FormulaScript(const char* name)
     ScriptRegistry<FormulaScript>::AddScript(this);
 }
 
+UnitScript::UnitScript(const char* name)
+    : ScriptObject(name)
+{
+    ScriptRegistry<UnitScript>::AddScript(this);
+}
+
 WorldMapScript::WorldMapScript(const char* name, uint32 mapId)
     : ScriptObject(name), MapScript<Map>(mapId)
 {
@@ -1396,7 +1419,7 @@ ItemScript::ItemScript(const char* name)
 }
 
 CreatureScript::CreatureScript(const char* name)
-    : ScriptObject(name)
+    : UnitScript(name)
 {
     ScriptRegistry<CreatureScript>::AddScript(this);
 }
@@ -1450,7 +1473,7 @@ ConditionScript::ConditionScript(const char* name)
 }
 
 VehicleScript::VehicleScript(const char* name)
-    : ScriptObject(name)
+    : UnitScript(name)
 {
     ScriptRegistry<VehicleScript>::AddScript(this);
 }
@@ -1474,7 +1497,7 @@ AchievementCriteriaScript::AchievementCriteriaScript(const char* name)
 }
 
 PlayerScript::PlayerScript(const char* name)
-    : ScriptObject(name)
+    : UnitScript(name)
 {
     ScriptRegistry<PlayerScript>::AddScript(this);
 }
@@ -1520,6 +1543,7 @@ template class ScriptRegistry<AchievementCriteriaScript>;
 template class ScriptRegistry<PlayerScript>;
 template class ScriptRegistry<GuildScript>;
 template class ScriptRegistry<GroupScript>;
+template class ScriptRegistry<UnitScript>;
 
 // Undefine utility macros.
 #undef GET_SCRIPT_RET

src/server/game/Scripting/ScriptMgr.h

@@ -392,7 +392,24 @@ class ItemScript : public ScriptObject
         virtual bool OnExpire(Player* /*player*/, ItemTemplate const* /*proto*/) { return false; }
 };
 
-class CreatureScript : public ScriptObject, public UpdatableScript<Creature>
+class UnitScript : public ScriptObject
+{
+    protected:
+
+        UnitScript(const char* name);
+
+    public:
+        // Called when DoT's Tick Damage is being Dealt
+        virtual void ModifyPeriodicDamageAurasTick(Unit* /*target*/, Unit* /*attacker*/, uint32& /*damage*/) { }
+
+        // Called when Melee Damage is being Dealt
+        virtual void ModifyMeleeDamage(Unit* /*target*/, Unit* /*attacker*/, uint32& /*damage*/) { }
+
+        // Called when Spell Damage is being Dealt
+        virtual void ModifySpellDamageTaken(Unit* /*target*/, Unit* /*attacker*/, int32& /*damage*/) { }
+};
+
+class CreatureScript : public UnitScript, public UpdatableScript<Creature>
 {
     protected:
 
@@ -583,7 +600,7 @@ class ConditionScript : public ScriptObject
         virtual bool OnConditionCheck(Condition* /*condition*/, ConditionSourceInfo& /*sourceInfo*/) { return true; }
 };
 
-class VehicleScript : public ScriptObject
+class VehicleScript : public UnitScript
 {
     protected:
 
@@ -654,7 +671,7 @@ class AchievementCriteriaScript : public ScriptObject
         virtual bool OnCheck(Player* source, Unit* target) = 0;
 };
 
-class PlayerScript : public ScriptObject
+class PlayerScript : public UnitScript
 {
     protected:
 
@@ -1031,6 +1048,12 @@ class ScriptMgr
         void OnGroupChangeLeader(Group* group, uint64 newLeaderGuid, uint64 oldLeaderGuid);
         void OnGroupDisband(Group* group);
 
+    public: /* UnitScript */
+
+        void ModifyPeriodicDamageAurasTick(Unit* target, Unit* attacker, uint32& damage);
+        void ModifyMeleeDamage(Unit* target, Unit* attacker, uint32& damage);
+        void ModifySpellDamageTaken(Unit* target, Unit* attacker, int32& damage);
+
     public: /* Scheduled scripts */
 
         uint32 IncreaseScheduledScriptsCount() { return ++_scheduledScripts; }

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -6169,6 +6169,9 @@ void AuraEffect::HandlePeriodicDamageAurasTick(Unit* target, Unit* caster) const
     // ignore non positive values (can be result apply spellmods to aura damage
     uint32 damage = std::max(GetAmount(), 0);
 
+    // Script Hook For HandlePeriodicDamageAurasTick -- Allow scripts to change the Damage pre class mitigation calculations
+    sScriptMgr->ModifyPeriodicDamageAurasTick(target, caster, damage);
+
     if (GetAuraType() == SPELL_AURA_PERIODIC_DAMAGE)
     {
         damage = caster->SpellDamageBonusDone(target, GetSpellInfo(), damage, DOT, GetBase()->GetStackAmount());