Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
While you control a Level 7 or higher Machine monster, your opponent's monsters cannot target Level 6 or lower Machine monsters you control for attacks, also your opponent cannot target them with card effects. If a face-up Machine monster(s) you control is destroyed by battle or card effect: You can target 1 Machine monster in your GY; add it to your hand. You can only use this effect of "Machina Defense Perimeter" once per turn.
--機甲部隊の防衛圏
--Machina Defense Perimeter
--Scripted by Hel
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	c:RegisterEffect(e1)
	--cannot target level <=6
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_CANNOT_BE_EFFECT_TARGET)
	e2:SetRange(LOCATION_SZONE)
	e2:SetProperty(EFFECT_FLAG_IGNORE_IMMUNE)
	e2:SetTargetRange(LOCATION_MZONE,0)
	e2:SetTarget(s.cannottgeff)
	e2:SetCondition(s.cannottgcon)
	e2:SetValue(aux.tgoval)
	c:RegisterEffect(e2)
	--cannot attack level <=6
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_FIELD)
	e3:SetRange(LOCATION_SZONE)
	e3:SetTargetRange(0,LOCATION_MZONE)
	e3:SetCode(EFFECT_CANNOT_SELECT_BATTLE_TARGET)
	e3:SetCondition(s.cannottgcon)
	e3:SetValue(s.cannotatk)
	c:RegisterEffect(e3)
	--Add to Hand
	local e4=Effect.CreateEffect(c)
	e4:SetCategory(CATEGORY_TOHAND)
	e4:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e4:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP+EFFECT_FLAG_DELAY)
	e4:SetCode(EVENT_DESTROYED)
	e4:SetRange(LOCATION_SZONE)
	e4:SetCountLimit(1,id)
	e4:SetCondition(s.tohandcon)
	e4:SetTarget(s.tohandtg)
	e4:SetOperation(s.tohandop)
	c:RegisterEffect(e4)
end
function s.cfilter(c)
	return c:IsFaceup() and c:IsRace(RACE_MACHINE) and c:IsLevelAbove(7)
end
function s.cannottgcon(e)
	return Duel.IsExistingMatchingCard(s.cfilter,e:GetHandlerPlayer(),LOCATION_MZONE,0,1,e:GetHandler())
end
function s.cannottgeff(e,c)
	return c:IsLevelBelow(6) and c:IsRace(RACE_MACHINE)
end
function s.cannotatk(e,c)
	return c:IsFaceup() and c:IsLevelBelow(6) and c:IsRace(RACE_MACHINE)
end
function s.tohandconfilter(c,tp)
	return c:GetPreviousControler()==tp and c:IsPreviousLocation(LOCATION_MZONE) and c:IsReason(REASON_DESTROY)
		and (c:IsReason(REASON_BATTLE) or c:IsReason(REASON_EFFECT))
		and c:IsRace(RACE_MACHINE) and c:IsPreviousPosition(POS_FACEUP)
end
function s.tohandcon(e,tp,eg,ep,ev,re,r,rp)
	return eg:IsExists(s.tohandconfilter,1,nil,tp)
end
function s.tohandfilter(c)
	return c:IsAbleToHand() and c:IsRace(RACE_MACHINE)
end
function s.tohandtg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_GRAVE) and chkc:IsControler(tp) and s.tohandfilter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.filter,tp,LOCATION_GRAVE,0,1,e:GetHandler()) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_ATOHAND)
	local g=Duel.SelectTarget(tp,s.tohandfilter,tp,LOCATION_GRAVE,0,1,1,e:GetHandler())
	Duel.SetOperationInfo(0,CATEGORY_TOHAND,g,#g,0,0)
end
function s.tohandop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) then
		Duel.SendtoHand(tc,nil,REASON_EFFECT)
	end
end