Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Target 1 face-up monster on the field; it gains 500 ATK/DEF until the end of this turn. Once per Chain, when a Trap Card is activated while this card is in your GY: You can Special Summon this card as a Normal Monster (Aqua/WATER/Level 2/ATK 1200/DEF 0). (This card is NOT treated as a Trap.) If Summoned this way, this card is unaffected by monster effects, also banish it when it leaves the field.
--バージェストマ・エルドニア
--Paleozoic Eldonia
local s,id=GetID()
function s.initial_effect(c)
	--Targeted monster gains 500 ATK/DEF
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_ATKCHANGE+CATEGORY_DEFCHANGE)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET+EFFECT_FLAG_DAMAGE_STEP)
	e1:SetCondition(aux.StatChangeDamageStepCondition)
	e1:SetTarget(s.target)
	e1:SetOperation(s.operation)
	e1:SetHintTiming(0,TIMING_BATTLE_PHASE|TIMING_DAMAGE_STEP)
	c:RegisterEffect(e1)
	--Special summon itself from GY as a monster
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e2:SetType(EFFECT_TYPE_QUICK_O)
	e2:SetCode(EVENT_CHAINING)
	e2:SetRange(LOCATION_GRAVE)
	e2:SetCondition(s.spcon)
	e2:SetTarget(s.sptg)
	e2:SetOperation(s.spop)
	c:RegisterEffect(e2)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsFaceup() end
	if chk==0 then return Duel.IsExistingTarget(Card.IsFaceup,tp,LOCATION_MZONE,LOCATION_MZONE,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	Duel.SelectTarget(tp,Card.IsFaceup,tp,LOCATION_MZONE,LOCATION_MZONE,1,1,nil)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local tc=Duel.GetFirstTarget()
	if tc:IsRelateToEffect(e) and tc:IsFaceup() then
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(500)
		e1:SetReset(RESETS_STANDARD_PHASE_END)
		tc:RegisterEffect(e1)
		local e2=e1:Clone()
		e2:SetCode(EFFECT_UPDATE_DEFENSE)
		tc:RegisterEffect(e2)
	end
end
function s.spcon(e,tp,eg,ep,ev,re,r,rp)
	return re:IsTrapEffect() and re:IsHasType(EFFECT_TYPE_ACTIVATE)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	local c=e:GetHandler()
	if chk==0 then return c:GetFlagEffect(id)==0 and Duel.GetLocationCount(tp,LOCATION_MZONE)>0
		and Duel.IsPlayerCanSpecialSummonMonster(tp,id,SET_PALEOZOIC,TYPE_MONSTER|TYPE_NORMAL,1200,0,2,RACE_AQUA,ATTRIBUTE_WATER) end
	c:RegisterFlagEffect(id,RESET_CHAIN,0,1)
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,c,1,0,0)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	if Duel.GetLocationCount(tp,LOCATION_MZONE)<=0 then return end
	local c=e:GetHandler()
	if c:IsRelateToEffect(e) and Duel.IsPlayerCanSpecialSummonMonster(tp,id,SET_PALEOZOIC,TYPE_MONSTER|TYPE_NORMAL,1200,0,2,RACE_AQUA,ATTRIBUTE_WATER) then
		c:AddMonsterAttribute(TYPE_NORMAL)
		c:AssumeProperty(ASSUME_RACE,RACE_AQUA)
		Duel.SpecialSummonStep(c,0,tp,tp,true,false,POS_FACEUP)
		c:AddMonsterAttributeComplete()
		--Unaffected by monster effects
		local e1=Effect.CreateEffect(c)
		e1:SetDescription(3101)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_IMMUNE_EFFECT)
		e1:SetProperty(EFFECT_FLAG_SINGLE_RANGE+EFFECT_FLAG_CLIENT_HINT)
		e1:SetRange(LOCATION_MZONE)
		e1:SetValue(s.efilter)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		c:RegisterEffect(e1)
		--Banish it if it leaves the field
		local e2=Effect.CreateEffect(c)
		e2:SetDescription(3300)
		e2:SetType(EFFECT_TYPE_SINGLE)
		e2:SetCode(EFFECT_LEAVE_FIELD_REDIRECT)
		e2:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_CLIENT_HINT)
		e2:SetReset(RESET_EVENT|RESETS_REDIRECT)
		e2:SetValue(LOCATION_REMOVED)
		c:RegisterEffect(e2,true)
		Duel.SpecialSummonComplete()
	end
	Duel.SpecialSummonComplete()
end
function s.efilter(e,re)
	return re:IsMonsterEffect()
end