Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be Special Summoned from the Deck. If you control no monsters, you can Normal Summon this card without Tributing. Cannot be destroyed by battle or card effects. You take no battle damage from attacks involving this Attack Position card. At the end of the Battle Phase, if this card battled: Return as many monsters on the field as possible to the hand (other than this card), and if you do, inflict 300 damage to your opponent for each card returned. Once per turn, during your Standby Phase: Shuffle this card into the Deck.
--時械神メタイオン
--Metaion, the Timelord
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+EFFECT_FLAG_SINGLE_RANGE)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetRange(LOCATION_DECK)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	c:RegisterEffect(e1)
	--summon
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e2:SetType(EFFECT_TYPE_SINGLE)
	e2:SetCode(EFFECT_SUMMON_PROC)
	e2:SetCondition(s.ntcon)
	c:RegisterEffect(e2)
	--indes
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e3:SetRange(LOCATION_MZONE)
	e3:SetCode(EFFECT_INDESTRUCTABLE_BATTLE)
	e3:SetValue(1)
	c:RegisterEffect(e3)
	local e4=e3:Clone()
	e4:SetCode(EFFECT_INDESTRUCTABLE_EFFECT)
	c:RegisterEffect(e4)
	local e5=e3:Clone()
	e5:SetCondition(s.damcon)
	e5:SetCode(EFFECT_AVOID_BATTLE_DAMAGE)
	c:RegisterEffect(e5)
	--to hand
	local e6=Effect.CreateEffect(c)
	e6:SetDescription(aux.Stringid(id,1))
	e6:SetCategory(CATEGORY_TOHAND+CATEGORY_DAMAGE)
	e6:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e6:SetCode(EVENT_PHASE|PHASE_BATTLE)
	e6:SetCountLimit(1)
	e6:SetRange(LOCATION_MZONE)
	e6:SetCondition(s.thcon)
	e6:SetTarget(s.thtg)
	e6:SetOperation(s.thop)
	c:RegisterEffect(e6)
	--to deck
	local e7=Effect.CreateEffect(c)
	e7:SetDescription(aux.Stringid(id,2))
	e7:SetCategory(CATEGORY_TODECK)
	e7:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e7:SetCode(EVENT_PHASE|PHASE_STANDBY)
	e7:SetCountLimit(1)
	e7:SetRange(LOCATION_MZONE)
	e7:SetCondition(s.tdcon)
	e7:SetTarget(s.tdtg)
	e7:SetOperation(s.tdop)
	c:RegisterEffect(e7)
end
function s.ntcon(e,c,minc)
	if c==nil then return true end
	return minc==0 and c:GetLevel()>4
		and Duel.GetFieldGroupCount(c:GetControler(),LOCATION_MZONE,0)==0
		and Duel.GetLocationCount(c:GetControler(),LOCATION_MZONE)>0
end
function s.damcon(e)
	return e:GetHandler():IsAttackPos()
end
function s.thcon(e,tp,eg,ep,ev,re,r,rp)
	return e:GetHandler():GetBattledGroupCount()>0
end
function s.thtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	local g=Duel.GetMatchingGroup(Card.IsAbleToHand,tp,LOCATION_MZONE,LOCATION_MZONE,e:GetHandler())
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,#g,0,0)
	Duel.SetOperationInfo(0,CATEGORY_DAMAGE,nil,0,1-tp,#g*300)
end
function s.thop(e,tp,eg,ep,ev,re,r,rp)
	local g=Duel.GetMatchingGroup(Card.IsAbleToHand,tp,LOCATION_MZONE,LOCATION_MZONE,e:GetHandler())
	if #g==0 then return end
	Duel.SendtoHand(g,nil,REASON_EFFECT)
	local og=Duel.GetOperatedGroup()
	local ct=og:FilterCount(Card.IsLocation,nil,LOCATION_HAND|LOCATION_EXTRA)
	Duel.Damage(1-tp,ct*300,REASON_EFFECT)
end
function s.tdcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsTurnPlayer(tp)
end
function s.tdtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.SetOperationInfo(0,CATEGORY_TODECK,e:GetHandler(),1,0,0)
end
function s.tdop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) then
		Duel.SendtoDeck(c,nil,SEQ_DECKSHUFFLE,REASON_EFFECT)
	end
end