Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Once per turn: You can target 1 monster you control that attacked this turn; change that target to Defense Position. If this face-up card is destroyed in a Monster Zone, you can place it face-up in your Spell & Trap Zone as a Continuous Spell, instead of sending it to the GY.
--宝玉獣 エメラルド・タートル
--Crystal Beast Emerald Tortoise
local s,id=GetID()
function s.initial_effect(c)
	--send replace
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetCode(EFFECT_TO_GRAVE_REDIRECT_CB)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE)
	e1:SetCondition(s.repcon)
	e1:SetOperation(s.repop)
	c:RegisterEffect(e1)
	--change pos
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,1))
	e2:SetCategory(CATEGORY_POSITION)
	e2:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e2:SetType(EFFECT_TYPE_IGNITION)
	e2:SetRange(LOCATION_MZONE)
	e2:SetCountLimit(1)
	e2:SetTarget(s.target)
	e2:SetOperation(s.operation)
	c:RegisterEffect(e2)
end
function s.repcon(e)
	local c=e:GetHandler()
	return c:IsFaceup() and c:IsLocation(LOCATION_MZONE) and c:IsReason(REASON_DESTROY)
end
function s.repop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	local e1=Effect.CreateEffect(c)
	e1:SetCode(EFFECT_CHANGE_TYPE)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE)
	e1:SetReset(RESET_EVENT|RESETS_STANDARD&~RESET_TURN_SET)
	e1:SetValue(TYPE_SPELL+TYPE_CONTINUOUS)
	c:RegisterEffect(e1)
	Duel.RaiseEvent(c,EVENT_CUSTOM+CARD_CRYSTAL_TREE,e,0,tp,0,0)
end
function s.filter(c)
	return c:IsAttackPos() and c:GetAttackedCount()>0 and c:IsCanChangePosition()
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsControler(tp) and s.filter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.filter,tp,LOCATION_MZONE,0,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_POSCHANGE)
	local g=Duel.SelectTarget(tp,s.filter,tp,LOCATION_MZONE,0,1,1,nil)
	Duel.SetOperationInfo(0,CATEGORY_POSITION,g,1,0,0)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc and tc:IsRelateToEffect(e) then
		Duel.ChangePosition(tc,POS_FACEUP_DEFENSE,POS_FACEDOWN_DEFENSE,0,0)
	end
end