Implemented OnHeartbeat AuraScript hook and refactored an aurascript to use it as example

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

@@ -502,7 +502,7 @@ void Unit::Heartbeat()
     // SMSG_FLIGHT_SPLINE_SYNC for cyclic splines
     SendFlightSplineSyncUpdate();
 
-    // Trigger heartbeat procs and generic aura behavior such as food emotes
+    // Trigger heartbeat procs and generic aura behavior such as food emotes and invoking aura script hooks
     TriggerAuraHeartbeat();
 
     // Update Vignette position and visibility

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

@@ -2066,6 +2066,18 @@ void Aura::CallScriptAfterDispel(DispelInfo* dispelInfo)
     }
 }
 
+void Aura::CallScriptOnHeartbeat()
+{
+    for (AuraScript* script : m_loadedScripts)
+    {
+        script->_PrepareScriptCall(AURA_SCRIPT_HOOK_ON_HEARTBEAT);
+        for (AuraScript::AuraHeartbeatHandler const& onHeartbeat : script->OnHeartbeat)
+            onHeartbeat.Call(script);
+
+        script->_FinishScriptCall();
+    }
+}
+
 bool Aura::CallScriptEffectApplyHandlers(AuraEffect const* aurEff, AuraApplication const* aurApp, AuraEffectHandleModes mode)
 {
     bool preventDefault = false;
@@ -2620,6 +2632,9 @@ void UnitAura::Heartbeat()
 
     // Periodic food and drink emote animation
     HandlePeriodicFoodSpellVisualKit();
+
+    // Invoke the OnHeartbeat AuraScript hook
+    CallScriptOnHeartbeat();
 }
 
 void UnitAura::HandlePeriodicFoodSpellVisualKit()

src/server/game/Spells/Auras/SpellAuras.h

@@ -264,6 +264,7 @@ class TC_GAME_API Aura
         bool CallScriptCheckAreaTargetHandlers(Unit* target);
         void CallScriptDispel(DispelInfo* dispelInfo);
         void CallScriptAfterDispel(DispelInfo* dispelInfo);
+        void CallScriptOnHeartbeat();
         bool CallScriptEffectApplyHandlers(AuraEffect const* aurEff, AuraApplication const* aurApp, AuraEffectHandleModes mode);
         bool CallScriptEffectRemoveHandlers(AuraEffect const* aurEff, AuraApplication const* aurApp, AuraEffectHandleModes mode);
         void CallScriptAfterEffectApplyHandlers(AuraEffect const* aurEff, AuraApplication const* aurApp, AuraEffectHandleModes mode);

src/server/game/Spells/SpellScript.h

@@ -1048,6 +1048,7 @@ enum AuraScriptHookType
     AURA_SCRIPT_HOOK_CHECK_AREA_TARGET,
     AURA_SCRIPT_HOOK_DISPEL,
     AURA_SCRIPT_HOOK_AFTER_DISPEL,
+    AURA_SCRIPT_HOOK_ON_HEARTBEAT,
     AURA_SCRIPT_HOOK_ENTER_LEAVE_COMBAT,
     // Spell Proc Hooks
     AURA_SCRIPT_HOOK_CHECK_PROC,
@@ -1174,6 +1175,58 @@ class TC_GAME_API AuraScript : public SpellScriptBase
         SafeWrapperType _safeWrapper;
     };
 
+    class AuraHeartbeatHandler final
+    {
+    public:
+        union AuraHeartbeatFnType
+        {
+            void(AuraScript::* Member)();
+            void(*Static)();
+        };
+
+        using SafeWrapperType = void(*)(AuraScript* auraScript, AuraHeartbeatFnType callImpl);
+
+        template<typename ScriptFunc>
+        explicit AuraHeartbeatHandler(ScriptFunc handler)
+        {
+            using ScriptClass = GetScriptClass_t<ScriptFunc>;
+
+            static_assert(sizeof(AuraHeartbeatFnType) >= sizeof(ScriptFunc));
+            static_assert(alignof(AuraHeartbeatFnType) >= alignof(ScriptFunc));
+
+            if constexpr (!std::is_void_v<ScriptClass>)
+            {
+                static_assert(std::is_invocable_r_v<void, ScriptFunc, ScriptClass>,
+                    "AuraHeartbeat signature must be \"void HandleHeartbeat()\"");
+
+                _callImpl = { .Member = reinterpret_cast<decltype(AuraHeartbeatFnType::Member)>(handler) };
+                _safeWrapper = [](AuraScript* auraScript, AuraHeartbeatFnType callImpl) -> void
+                {
+                    return (static_cast<ScriptClass*>(auraScript)->*reinterpret_cast<ScriptFunc>(callImpl.Member))();
+                };
+            }
+            else
+            {
+                static_assert(std::is_invocable_r_v<void, ScriptFunc>,
+                    "AuraHeartbeatHandler signature must be \"static void HandleHeartbeat()\"");
+
+                _callImpl = { .Static = reinterpret_cast<decltype(AuraHeartbeatFnType::Static)>(handler) };
+                _safeWrapper = [](AuraScript* /*auraScript*/, AuraHeartbeatFnType callImpl) -> void
+                {
+                    return reinterpret_cast<ScriptFunc>(callImpl.Static)();
+                };
+            }
+        }
+
+        void Call(AuraScript* auraScript) const
+        {
+            return _safeWrapper(auraScript, _callImpl);
+        }
+    private:
+        AuraHeartbeatFnType _callImpl;
+        SafeWrapperType _safeWrapper;
+    };
+
     class TC_GAME_API EffectBase : public EffectHook
     {
     public:
@@ -2017,6 +2070,12 @@ class TC_GAME_API AuraScript : public SpellScriptBase
     HookList<AuraDispelHandler> AfterDispel;
     #define AuraDispelFn(F) AuraDispelHandler(&F)
 
+    // executed on every heartbeat of a unit
+    // example: OnHeartbeat += AuraHeartbeatFn(class::function);
+    // where function is: void function ();
+    HookList<AuraHeartbeatHandler> OnHeartbeat;
+    #define AuraHeartbeatFn(F) AuraHeartbeatHandler(&F)
+
     // executed when aura effect is applied with specified mode to target
     // should be used when when effect handler preventing/replacing is needed, do not use this hook for triggering spellcasts/removing auras etc - may be unsafe
     // example: OnEffectApply += AuraEffectApplyFn(class::function, EffectIndexSpecifier, EffectAuraNameSpecifier, AuraEffectHandleModes);

src/server/scripts/Spells/spell_item.cpp

@@ -4326,17 +4326,9 @@ class spell_item_amalgams_seventh_spine : public AuraScript
         });
     }
 
-    void ForcePeriodic(AuraEffect const* /*aurEff*/, bool& isPeriodic, int32& amplitude)
+    void UpdateSpecAura()
     {
-        // simulate heartbeat timer
-        isPeriodic = true;
-        amplitude = 5000;
-    }
-
-    void UpdateSpecAura(AuraEffect const* aurEff)
-    {
-        PreventDefaultAction();
-        Player* target = GetTarget()->ToPlayer();
+        Player* target = GetUnitOwner()->ToPlayer();
         if (!target)
             return;
 
@@ -4345,7 +4337,7 @@ class spell_item_amalgams_seventh_spine : public AuraScript
             if (target->GetPrimarySpecialization() != spec)
                 target->RemoveAurasDueToSpell(aura);
             else if (!target->HasAura(aura))
-                target->CastSpell(target, aura, aurEff);
+                target->CastSpell(target, aura, GetEffect(EFFECT_0));
         };
 
         switch (target->GetClass())
@@ -4373,8 +4365,7 @@ class spell_item_amalgams_seventh_spine : public AuraScript
 
     void Register() override
     {
-        DoEffectCalcPeriodic += AuraEffectCalcPeriodicFn(spell_item_amalgams_seventh_spine::ForcePeriodic, EFFECT_0, SPELL_AURA_DUMMY);
-        OnEffectPeriodic += AuraEffectPeriodicFn(spell_item_amalgams_seventh_spine::UpdateSpecAura, EFFECT_0, SPELL_AURA_DUMMY);
+        OnHeartbeat += AuraHeartbeatFn(spell_item_amalgams_seventh_spine::UpdateSpecAura);
     }
 };