Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be destroyed by battle. After damage calculation, if this card was attacked, and was face-down at the start of the Damage Step: The attacking player takes 1000 damage.
--マシュマロン
--Marshmallon
local s,id=GetID()
function s.initial_effect(c)
	--damage
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_DAMAGE)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e1:SetCode(EVENT_BATTLED)
	e1:SetCondition(s.condition)
	e1:SetTarget(s.target)
	e1:SetOperation(s.operation)
	c:RegisterEffect(e1)
	--battle indestructable
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_SINGLE)
	e2:SetCode(EFFECT_INDESTRUCTABLE_BATTLE)
	e2:SetValue(1)
	c:RegisterEffect(e2)
end
function s.condition(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	local pos=c:GetBattlePosition()
	return c==Duel.GetAttackTarget() and (pos==POS_FACEDOWN_DEFENSE or pos==POS_FACEDOWN_ATTACK) and c:IsLocation(LOCATION_MZONE)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.SetTargetPlayer(Duel.GetAttacker():GetControler())
	Duel.SetTargetParam(1000)
	Duel.SetOperationInfo(0,CATEGORY_DAMAGE,0,0,1-tp,1000)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local p,d=Duel.GetChainInfo(0,CHAININFO_TARGET_PLAYER,CHAININFO_TARGET_PARAM)
	Duel.Damage(p,d,REASON_EFFECT)
end