Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be Special Summoned. When this card is Normal Summoned: Change this card to Defense Position. If you control a face-up Xyz Monster that has Xyz Material: You can banish this card from your Graveyard, then target 1 monster your opponent controls; it loses 500 ATK for each Xyz Material attached to a monster you control.
--オーバーレイ・スナイパー
--Overlay Sentinel
local s,id=GetID()
function s.initial_effect(c)
	--cannot special summon
	local e1=Effect.CreateEffect(c)
	e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	c:RegisterEffect(e1)
	--to defense
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_POSITION)
	e2:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_SUMMON_SUCCESS)
	e2:SetTarget(s.potg)
	e2:SetOperation(s.poop)
	c:RegisterEffect(e2)
	--atkdown
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,1))
	e3:SetType(EFFECT_TYPE_IGNITION)
	e3:SetRange(LOCATION_GRAVE)
	e3:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e3:SetCondition(s.atkcon)
	e3:SetCost(Cost.SelfBanish)
	e3:SetTarget(s.atktg)
	e3:SetOperation(s.atkop)
	c:RegisterEffect(e3)
end
function s.potg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return e:GetHandler():IsAttackPos() end
	Duel.SetOperationInfo(0,CATEGORY_POSITION,e:GetHandler(),1,0,0)
end
function s.poop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsPosition(POS_FACEUP_ATTACK) and c:IsRelateToEffect(e) then
		Duel.ChangePosition(c,POS_FACEUP_DEFENSE)
	end
end
function s.filter(c)
	return c:IsFaceup() and c:IsType(TYPE_XYZ) and c:GetOverlayCount()>0
end
function s.atkcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsExistingMatchingCard(s.filter,tp,LOCATION_MZONE,0,1,nil)
end
function s.atktg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsControler(1-tp) and chkc:IsLocation(LOCATION_MZONE) and chkc:IsFaceup() end
	if chk==0 then return Duel.IsExistingTarget(Card.IsFaceup,tp,0,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	Duel.SelectTarget(tp,Card.IsFaceup,tp,0,LOCATION_MZONE,1,1,nil)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsFaceup() and tc:IsRelateToEffect(e) then
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(Duel.GetOverlayCount(tp,1,0)*-500)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		tc:RegisterEffect(e1)
	end
end