Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be used as a Synchro Material. Twice per turn: You can target 1 Fish monster on the field, then activate 1 of these effects. ● Increase its Level by 1. ● Reduce its Level by 1. You cannot Special Summon any monsters during the turn you activate this effect, except WATER monsters.
--セイバー・シャーク
--Saber Shark
local s,id=GetID()
function s.initial_effect(c)
	--Cannot be used as Synchro Material
	local e0=Effect.CreateEffect(c)
	e0:SetType(EFFECT_TYPE_SINGLE)
	e0:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e0:SetCode(EFFECT_CANNOT_BE_SYNCHRO_MATERIAL)
	e0:SetValue(1)
	c:RegisterEffect(e0)
	--Increase or reduce the Level of 1 Fish monster on the field by 1
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_LVCHANGE)
	e1:SetType(EFFECT_TYPE_IGNITION)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e1:SetRange(LOCATION_MZONE)
	e1:SetCountLimit(2)
	e1:SetCost(s.lvcost)
	e1:SetTarget(s.lvtg)
	e1:SetOperation(s.lvop)
	c:RegisterEffect(e1)
	Duel.AddCustomActivityCounter(id,ACTIVITY_SPSUMMON,s.counterfilter)
end
function s.counterfilter(c)
	return not c:IsAttributeExcept(ATTRIBUTE_WATER)
end
function s.lvcost(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetCustomActivityCount(id,tp,ACTIVITY_SPSUMMON)==0 end
	--Cannot Special Summon non-WATER monsters
	local e1=Effect.CreateEffect(e:GetHandler())
	e1:SetDescription(aux.Stringid(id,3))
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetProperty(EFFECT_FLAG_PLAYER_TARGET+EFFECT_FLAG_OATH+EFFECT_FLAG_CLIENT_HINT)
	e1:SetCode(EFFECT_CANNOT_SPECIAL_SUMMON)
	e1:SetReset(RESET_PHASE|PHASE_END)
	e1:SetTargetRange(1,0)
	e1:SetTarget(function(_,c) return c:IsAttributeExcept(ATTRIBUTE_WATER) end)
	Duel.RegisterEffect(e1,tp)
end
function s.lvfilter(c)
	return c:IsFaceup() and c:IsRace(RACE_FISH) and c:HasLevel()
end
function s.lvtg(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and s.lvfilter(chkc) end
	if chk==0 then return Duel.IsExistingTarget(s.lvfilter,tp,LOCATION_MZONE,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	local tc=Duel.SelectTarget(tp,s.lvfilter,tp,LOCATION_MZONE,LOCATION_MZONE,1,1,nil):GetFirst()
	local b1=true
	local b2=tc:IsLevelAbove(2)
	local op=Duel.SelectEffect(tp,
		{b1,aux.Stringid(id,1)},
		{b2,aux.Stringid(id,2)})
	e:SetLabel(op)
end
function s.lvop(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsFaceup() and tc:IsRelateToEffect(e) then
		--Increase/reduce Level
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE)
		e1:SetCode(EFFECT_UPDATE_LEVEL)
		local lvl=e:GetLabel()==1 and 1 or -1
		e1:SetValue(lvl)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		tc:RegisterEffect(e1)
	end
end