Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When this card is activated: You can add 1 "Drytron" Spell/Trap from your Deck to your hand, except "Drytron Fafnir". The activation and the activated effects of Ritual Spell Cards cannot be negated. Once per turn, if a monster is Normal or Special Summoned face-up while you control a "Drytron" monster (except during the Damage Step): You can reduce that monster's Level by 1 per 1000 of its current ATK (min. Level 1) for the rest of this turn. You can only activate 1 "Drytron Fafnir" per turn.
--竜輝巧－ファフニール
--Drytron Fafnir
--Scripted by Naim
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_TOHAND+CATEGORY_SEARCH)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetCountLimit(1,id,EFFECT_COUNT_CODE_OATH)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
	--Prevent effect and activation from being negated
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_CANNOT_INACTIVATE)
	e2:SetRange(LOCATION_FZONE)
	e2:SetValue(s.effectfilter)
	c:RegisterEffect(e2)
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_FIELD)
	e3:SetCode(EFFECT_CANNOT_DISEFFECT)
	e3:SetRange(LOCATION_FZONE)
	e3:SetValue(s.effectfilter)
	c:RegisterEffect(e3)
	--Decrease Levels
	local e4=Effect.CreateEffect(c)
	e4:SetDescription(aux.Stringid(id,1))
	e4:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e4:SetCode(EVENT_SPSUMMON_SUCCESS)
	e4:SetProperty(EFFECT_FLAG_DELAY)
	e4:SetRange(LOCATION_FZONE)
	e4:SetCountLimit(1,0,EFFECT_COUNT_CODE_SINGLE)
	e4:SetCondition(s.lvcond)
	e4:SetTarget(s.lvtg)
	e4:SetOperation(s.lvop)
	c:RegisterEffect(e4)
	local e5=e4:Clone()
	e5:SetCode(EVENT_SUMMON_SUCCESS)
	c:RegisterEffect(e5)
end
s.listed_names={id}
s.listed_series={SET_DRYTRON}
function s.thfilter(c)
	return c:IsSpellTrap() and c:IsSetCard(SET_DRYTRON) and c:IsAbleToHand() and not c:IsCode(id)
end
function s.activate(e,tp,eg,ep,ev,re,r,rp)
	if not e:GetHandler():IsRelateToEffect(e) then return end
	local g=Duel.GetMatchingGroup(s.thfilter,tp,LOCATION_DECK,0,nil)
	if #g>0 and Duel.SelectYesNo(tp,aux.Stringid(id,0)) then
		Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_ATOHAND)
		local sg=g:Select(tp,1,1,nil)
		Duel.SendtoHand(sg,nil,REASON_EFFECT)
		Duel.ConfirmCards(1-tp,sg)
	end
end
function s.effectfilter(e,ct)
	local te=Duel.GetChainInfo(ct,CHAININFO_TRIGGERING_EFFECT)
	return te:GetHandler():IsRitualSpell()
end
function s.lvcond(e,tp,eg,ep,ev,re,r,rp)
	return Duel.IsExistingMatchingCard(aux.FaceupFilter(Card.IsSetCard,SET_DRYTRON),tp,LOCATION_MZONE,0,1,nil) 
end
function s.lvfilter(c)
	return c:IsFaceup() and c:HasLevel() and c:IsLevelAbove(2) and c:IsAttackAbove(1000)
end
function s.lvtg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return eg and eg:IsExists(s.lvfilter,1,nil) end
end
function s.lvop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if not c:IsRelateToEffect(e) or not eg then return end
	local g=eg:Filter(s.lvfilter,nil)
	if #g>0 then
		for tc in aux.Next(g) do
			local lv=tc:GetAttack()//1000
			local e1=Effect.CreateEffect(c)
			e1:SetType(EFFECT_TYPE_SINGLE)
			e1:SetCode(EFFECT_UPDATE_LEVEL)
			e1:SetValue(-lv)
			e1:SetReset(RESETS_STANDARD_PHASE_END)
			tc:RegisterEffect(e1)
		end
	end
end