Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If this card is targeted for an attack: Target 1 Level 7 or higher Dragon-Type monster in your Graveyard; Special Summon it, and if you do, change the attack target to it and perform damage calculation.
--デコイドラゴン
--Decoy Dragon
local s,id=GetID()
function s.initial_effect(c)
	--change battle target
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e1:SetCode(EVENT_BE_BATTLE_TARGET)
	e1:SetRange(LOCATION_MZONE)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
end
function s.spfilter(c,e,tp)
	return c:IsLevelAbove(7) and c:IsRace(RACE_DRAGON) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_GRAVE) and chkc:IsControler(tp) and s.spfilter(chkc,e,tp) end
	if chk==0 then return true end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectTarget(tp,s.spfilter,tp,LOCATION_GRAVE,0,1,1,nil,e,tp)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,g,1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) and Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)>0 then
		local a=Duel.GetAttacker()
		if a:CanAttack() and not a:IsImmuneToEffect(e) then
			Duel.CalculateDamage(a,tc)
		end
	end
end