Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Target 1 Dragon monster you control; its ATK becomes doubled (until the end of this turn), then, if your opponent currently controls a Dragon monster, the activation of the targeted monster's effects cannot be negated for the rest of this turn. During your Main Phase: You can banish this card from your GY; Special Summon 1 of your Dragon Xyz Monsters that is banished or in your GY, in Defense Position. You can only use 1 "Saga of the Dragon Emperor" effect per turn, and only once that turn.
--竜皇神話
--Saga of the Dragon Emperor
--Scripted by Hatter
local s,id=GetID()
function s.initial_effect(c)
	--Double ATK
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetHintTiming(TIMING_DAMAGE_STEP)
	e1:SetCountLimit(1,id)
	e1:SetCondition(aux.StatChangeDamageStepCondition)
	e1:SetTarget(s.atktg)
	e1:SetOperation(s.atkop)
	c:RegisterEffect(e1)
	--Special Summon
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,1))
	e2:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e2:SetType(EFFECT_TYPE_IGNITION)
	e2:SetCode(EVENT_FREE_CHAIN)
	e2:SetRange(LOCATION_GRAVE)
	e2:SetCountLimit(1,id)
	e2:SetCost(Cost.SelfBanish)
	e2:SetTarget(s.sptg)
	e2:SetOperation(s.spop)
	c:RegisterEffect(e2)
end
function s.atktg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsControler(tp) and chkc:IsFaceup() and chkc:IsRace(RACE_DRAGON) end
	if chk==0 then return Duel.IsExistingTarget(aux.FaceupFilter(Card.IsRace,RACE_DRAGON),tp,LOCATION_MZONE,0,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_ATKDEF)
	Duel.SelectTarget(tp,aux.FaceupFilter(Card.IsRace,RACE_DRAGON),tp,LOCATION_MZONE,0,1,1,nil)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if not tc:IsRelateToEffect(e) or tc:IsFacedown() then return end
	local c=e:GetHandler()
	--Double ATK
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_SET_ATTACK_FINAL)
	e1:SetValue(tc:GetAttack()*2)
	e1:SetReset(RESETS_STANDARD_PHASE_END)
	tc:RegisterEffect(e1)
	if Duel.IsExistingMatchingCard(aux.FaceupFilter(Card.IsRace,RACE_DRAGON),tp,0,LOCATION_MZONE,1,nil) then
		--Cannot negate activation of effects
		local e2=Effect.CreateEffect(c)
		e2:SetDescription(aux.Stringid(id,2))
		e2:SetType(EFFECT_TYPE_FIELD)
		e2:SetProperty(EFFECT_FLAG_CLIENT_HINT)
		e2:SetCode(EFFECT_CANNOT_INACTIVATE)
		e2:SetRange(LOCATION_MZONE)
		e2:SetValue(function(e,ct) return e:GetHandler()==Duel.GetChainInfo(ct,CHAININFO_TRIGGERING_EFFECT):GetHandler() end)
		e2:SetReset(RESETS_STANDARD_PHASE_END)
		tc:RegisterEffect(e2)
	end
end
function s.spfilter(c,e,tp)
	return c:IsFaceup() and c:IsRace(RACE_DRAGON) and c:IsType(TYPE_XYZ) and c:IsCanBeSpecialSummoned(e,0,tp,false,false,POS_FACEUP_DEFENSE)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingMatchingCard(s.spfilter,tp,LOCATION_GRAVE|LOCATION_REMOVED,0,1,nil,e,tp) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,nil,1,tp,LOCATION_GRAVE|LOCATION_REMOVED)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	if Duel.GetLocationCount(tp,LOCATION_MZONE)<=0 then return end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectMatchingCard(tp,aux.NecroValleyFilter(s.spfilter),tp,LOCATION_GRAVE|LOCATION_REMOVED,0,1,1,nil,e,tp)
	if #g>0 then
		Duel.SpecialSummon(g,0,tp,tp,false,false,POS_FACEUP_DEFENSE)
	end
end