Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Send 1 "Phantom Knights" Spell/Trap from your Deck to the GY. When an opponent's monster declares a direct attack while you control no cards and this card is in your GY: You can Special Summon this card in Defense Position as an Effect Monster (Warrior/DARK/Level 4/ATK 300/DEF 600), but banish it when it leaves the field. (This card is NOT treated as a Trap.) If Summoned this way, this card gains 300 DEF for each "Phantom Knights" Spell/Trap in your GY. * The above text is unofficial and describes the card's functionality in the OCG.
--幻影騎士団ダーク・ガントレット
--The Phantom Knights of Dark Gauntlets
local s,id=GetID()
function s.initial_effect(c)
	--Send 1 "Phantom Knights" spell/trap from deck to GY
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_TOGRAVE)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	e1:SetHintTiming(0,TIMING_END_PHASE)
	c:RegisterEffect(e1)
	--Special summon itself from GY as a monster
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e2:SetType(EFFECT_TYPE_QUICK_O)
	e2:SetCode(EVENT_ATTACK_ANNOUNCE)
	e2:SetRange(LOCATION_GRAVE)
	e2:SetCondition(s.spcon)
	e2:SetTarget(s.sptg)
	e2:SetOperation(s.spop)
	c:RegisterEffect(e2)
	--Gains 300 DEF for each "Phantom Knights" spell/trap in your GY
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
	e3:SetRange(LOCATION_MZONE)
	e3:SetCode(EFFECT_UPDATE_DEFENSE)
	e3:SetCondition(s.defcon)
	e3:SetValue(s.defval)
	c:RegisterEffect(e3)
end
s.listed_series={SET_PHANTOM_KNIGHTS}
function s.tgfilter(c)
	return c:IsSetCard(SET_PHANTOM_KNIGHTS) and c:IsSpellTrap() and c:IsAbleToGrave()
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(s.tgfilter,tp,LOCATION_DECK,0,1,nil) end
	Duel.SetOperationInfo(0,CATEGORY_TOGRAVE,nil,1,tp,LOCATION_DECK)
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_TOGRAVE)
	local g=Duel.SelectMatchingCard(tp,s.tgfilter,tp,LOCATION_DECK,0,1,1,nil)
	if #g>0 then
		Duel.SendtoGrave(g,REASON_EFFECT)
	end
end
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.GetFieldGroupCount(tp,LOCATION_ONFIELD,0)==0
		and Duel.GetAttacker():IsControler(1-tp) and Duel.GetAttackTarget()==nil
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return not e:GetHandler():IsStatus(STATUS_CHAINING) and Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsPlayerCanSpecialSummonMonster(tp,id,SET_THE_PHANTOM_KNIGHTS,TYPE_MONSTER|TYPE_EFFECT,300,600,4,RACE_WARRIOR,ATTRIBUTE_DARK) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,e:GetHandler(),1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	if Duel.GetLocationCount(tp,LOCATION_MZONE)<=0 then return end
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) and Duel.IsPlayerCanSpecialSummonMonster(tp,id,SET_THE_PHANTOM_KNIGHTS,TYPE_MONSTER|TYPE_EFFECT,300,600,4,RACE_WARRIOR,ATTRIBUTE_DARK) then
		c:AddMonsterAttribute(TYPE_EFFECT)
		c:AssumeProperty(ASSUME_RACE,RACE_WARRIOR)
		Duel.SpecialSummonStep(c,1,tp,tp,true,false,POS_FACEUP_DEFENSE)
		c:AddMonsterAttributeComplete()
		--Banish it if it leaves the field
		local e1=Effect.CreateEffect(c)
		e1:SetDescription(3300)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_LEAVE_FIELD_REDIRECT)
		e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_CLIENT_HINT)
		e1:SetReset(RESET_EVENT|RESETS_REDIRECT)
		e1:SetValue(LOCATION_REMOVED)
		c:RegisterEffect(e1,true)
		Duel.SpecialSummonComplete()
	end
end
function s.defcon(e)
	return e:GetHandler():GetSummonType()==SUMMON_TYPE_SPECIAL+1
end
function s.filter(c)
	return c:IsSetCard(SET_PHANTOM_KNIGHTS) and c:IsSpellTrap()
end
function s.defval(e,c)
	return Duel.GetMatchingGroupCount(s.filter,c:GetControler(),LOCATION_GRAVE,0,nil)*300
end