Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
During the Battle Phase, if your opponent controls more monsters than you do: Special Summon 1 "War Rock" monster from your Deck, and if you activated this card during your opponent's turn, for the rest of this turn while you control the face-up Special Summoned monster, your opponent's monsters cannot attack, except to attack that monster. You can only activate 1 "War Rock Generations" per turn.
--ウォークライ・ジェネレート
--War Rock Generations
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetCountLimit(1,id,EFFECT_COUNT_CODE_OATH)
	e1:SetHintTiming(0,TIMING_BATTLE_START)
	e1:SetCondition(s.condition)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
s.listed_series={SET_WAR_ROCK}
function s.condition(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsBattlePhase() and Duel.GetFieldGroupCount(tp,0,LOCATION_MZONE)>Duel.GetFieldGroupCount(tp,LOCATION_MZONE,0)
end
function s.cfilter(c,e,tp)
	return c:IsSetCard(SET_WAR_ROCK) and c:IsCanBeSpecialSummoned(e,0,tp,false,false)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsExistingMatchingCard(s.cfilter,tp,LOCATION_DECK,0,1,nil,e,tp) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,nil,1,0,LOCATION_DECK)
end
function s.activate(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,s.cfilter,tp,LOCATION_DECK,0,1,1,nil,e,tp)
	local tc=g:GetFirst()
	if tc and Duel.SpecialSummon(tc,0,tp,tp,false,false,POS_FACEUP)>0 then
		if Duel.IsTurnPlayer(1-tp) then
			--Opponent's monsters cannot attack except this monster
			local e1=Effect.CreateEffect(e:GetHandler())
			e1:SetType(EFFECT_TYPE_FIELD)
			e1:SetCode(EFFECT_ONLY_ATTACK_MONSTER)
			e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE)
			e1:SetRange(LOCATION_MZONE)
			e1:SetTargetRange(0,LOCATION_MZONE)
			e1:SetValue(s.atklimit)
			e1:SetLabel(tc:GetRealFieldID())
			e1:SetReset(RESETS_STANDARD_PHASE_END)
			tc:RegisterEffect(e1)
		end
		Duel.SpecialSummonComplete()
	end
end
function s.atklimit(e,c)
	return c:GetRealFieldID()==e:GetLabel()
end