Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Equip only to a Normal Summoned/Set monster you control. It is unaffected by your opponent's activated effects of Special Summoned monsters. During damage calculation, if the equipped monster battles an opponent's Special Summoned monster: That opponent's monster loses ATK/DEF equal to the equipped monster's original ATK, during that damage calculation only.
--モルトシュラーク
--Mordschlag
--scripted by Naim
local s,id=GetID()
function s.initial_effect(c)
	aux.AddEquipProcedure(c,0,aux.FilterBoolFunction(Card.IsSummonType,SUMMON_TYPE_NORMAL))
	--immune
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_EQUIP)
	e1:SetCode(EFFECT_IMMUNE_EFFECT)
	e1:SetValue(s.immval)
	c:RegisterEffect(e1)
	--atk/def
	local e2=Effect.CreateEffect(c)
	e2:SetCategory(CATEGORY_ATKCHANGE+CATEGORY_DEFCHANGE)
	e2:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_PRE_DAMAGE_CALCULATE)
	e2:SetRange(LOCATION_SZONE)
	e2:SetCondition(s.adcon)
	e2:SetOperation(s.adop)
	c:RegisterEffect(e2)
end
function s.immval(e,te)
	return te:GetOwnerPlayer()~=e:GetHandlerPlayer() and te:IsMonsterEffect() and te:IsActivated() and te:GetHandler():IsSpecialSummoned()
end
function s.adcon(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler():GetEquipTarget()
	local bc=c:GetBattleTarget()
	return bc and bc:IsFaceup() and (bc:GetSummonType()&SUMMON_TYPE_SPECIAL)==SUMMON_TYPE_SPECIAL
end
function s.adop(e,tp,eg,ep,ev,re,r,rp)
	if not e:GetHandler():IsRelateToEffect(e) then return end
	local ec=e:GetHandler():GetEquipTarget()
	local bc=ec:GetBattleTarget()
	if bc:IsRelateToBattle() then
		local value=ec:GetBaseAttack()
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(-value)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD|RESET_PHASE|PHASE_DAMAGE_CAL)
		bc:RegisterEffect(e1)
		local e2=e1:Clone()
		e2:SetCode(EFFECT_UPDATE_DEFENSE)
		bc:RegisterEffect(e2)
	end
end