Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When this card is activated: You can target 1 Level 4 or lower "Ice Barrier" monster in your GY; Special Summon it. While you control 3 or more "Ice Barrier" monsters, "Ice Barrier" monsters you control are unaffected by the activated effects of your opponent's monsters that were Special Summoned from the Extra Deck. You can only activate 1 "Freezing Chains of the Ice Barrier" per turn.
--氷結界の晶壁
--Freezing Chains of the Ice Barrier
--Scripted by Hel
local s,id=GetID()
function s.initial_effect(c)
	--Activate and Special Summon from GY
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetCountLimit(1,id,EFFECT_COUNT_CODE_OATH)
	e1:SetTarget(s.target)
	c:RegisterEffect(e1)
	--Unaffected by activated effect
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_IMMUNE_EFFECT)
	e2:SetCondition(s.unacon)
	e2:SetTarget(aux.TargetBoolFunction(Card.IsSetCard,SET_ICE_BARRIER))
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(LOCATION_MZONE,0)
	e2:SetValue(s.unaval)
	c:RegisterEffect(e2)
end
s.listed_series={SET_ICE_BARRIER}
function s.filter(c,e,tp)
	return c:IsCanBeSpecialSummoned(e,0,tp,false,false) and c:IsSetCard(SET_ICE_BARRIER) and c:IsLevelBelow(4)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_GRAVE) and s.filter(chkc,e,tp) end
	if chk==0 then return true end
	if Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingTarget(s.filter,tp,LOCATION_GRAVE,0,1,nil,e,tp) 
		and Duel.SelectYesNo(tp,aux.Stringid(id,0)) then
			e:SetCategory(CATEGORY_SPECIAL_SUMMON)
			e:SetProperty(EFFECT_FLAG_CARD_TARGET)
			e:SetOperation(s.activate)
			Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
			local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_GRAVE,0,1,1,nil,e,tp)
			Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,g,1,0,0)
	else
			e:SetCategory(0)
			e:SetProperty(0)
			e:SetOperation(nil)
	end
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) then
		Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)
	end
end
function s.unafilter(c)
	return c:IsFaceup() and c:IsSetCard(SET_ICE_BARRIER)
end
function s.unacon(e)
	return Duel.IsExistingMatchingCard(s.unafilter,e:GetHandlerPlayer(),LOCATION_MZONE,0,3,nil)
end
function s.unaval(e,te)
	local tc=te:GetOwner()
	return tc:IsSpecialSummoned() and tc:IsSummonLocation(LOCATION_EXTRA) and te:GetOwnerPlayer()~=e:GetHandlerPlayer()
		and te:IsMonsterEffect() and te:IsActivated() and te:GetActivateLocation()==LOCATION_MZONE
end