Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When an opponent's monster declares a direct attack: You can Special Summon this card from your hand. Once per turn, during either player's turn: You can have this card gain 300 DEF until the end of this turn.
--ジャンク・ディフェンダー
--Junk Defender
local s,id=GetID()
function s.initial_effect(c)
	--spsummon
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e1:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e1:SetCode(EVENT_ATTACK_ANNOUNCE)
	e1:SetRange(LOCATION_HAND)
	e1:SetCondition(s.spcon)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
	--spsummon
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,1))
	e2:SetCategory(CATEGORY_DEFCHANGE)
	e2:SetType(EFFECT_TYPE_QUICK_O)
	e2:SetCode(EVENT_FREE_CHAIN)
	e2:SetRange(LOCATION_MZONE)
	e2:SetProperty(EFFECT_FLAG_DAMAGE_STEP)
	e2:SetHintTiming(TIMING_DAMAGE_STEP)
	e2:SetCountLimit(1)
	e2:SetCondition(aux.StatChangeDamageStepCondition)
	e2:SetOperation(s.defup)
	c:RegisterEffect(e2)
end
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	local at=Duel.GetAttacker()
	return at:GetControler()~=tp and Duel.GetAttackTarget()==nil
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	local c=e:GetHandler()
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and c:IsCanBeSpecialSummoned(e,0,tp,false,false) end
	Duel.ConfirmCards(1-tp,c)
	Duel.ShuffleHand(tp)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,c,1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if not c:IsRelateToEffect(e) then return end
	Duel.SpecialSummon(c,0,tp,tp,false,false,POS_FACEUP)
end
function s.defup(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_UPDATE_DEFENSE)
	e1:SetValue(300)
	e1:SetReset(RESETS_STANDARD_PHASE_END)
	c:RegisterEffect(e1)
end