Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If "Gaia The Fierce Knight", "Swift Gaia the Fierce Knight", or "Gaia the Dragon Champion" you control attacks a Defense Position monster, inflict piercing battle damage to your opponent. If "Gaia the Dragon Champion" inflicts battle damage with this effect: Draw 2 cards, then discard 1 card.
--螺旋槍殺
--Spiral Spear Strike
local s,id=GetID()
function s.initial_effect(c)
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_FREE_CHAIN)
	c:RegisterEffect(e1)
	--pierce
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_PIERCE)
	e2:SetRange(LOCATION_SZONE)
	e2:SetTargetRange(LOCATION_MZONE,0)
	e2:SetTarget(s.pietg)
	c:RegisterEffect(e2)
	--shuffle
	local e3=Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id,0))
	e3:SetCategory(CATEGORY_DRAW+CATEGORY_HANDES)
	e3:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_F)
	e3:SetCode(EVENT_BATTLE_DAMAGE)
	e3:SetRange(LOCATION_SZONE)
	e3:SetCondition(s.condition)
	e3:SetTarget(s.target)
	e3:SetOperation(s.operation)
	c:RegisterEffect(e3)
end
s.listed_names={CARD_GAIA_CHAMPION}
function s.pietg(e,c)
	return c:IsCode(6368038,16589042,CARD_GAIA_CHAMPION)
end
function s.condition(e,tp,eg,ep,ev,re,r,rp)
	local tc=eg:GetFirst()
	local bc=tc:GetBattleTarget()
	return tc:IsControler(tp) and bc and bc:IsDefensePos() and tc:IsCode(CARD_GAIA_CHAMPION)
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.SetOperationInfo(0,CATEGORY_DRAW,nil,0,tp,2)
	Duel.SetOperationInfo(0,CATEGORY_HANDES,nil,0,tp,1)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	if not e:GetHandler():IsRelateToEffect(e) or Duel.GetFieldGroupCount(tp,LOCATION_DECK,0)==0 then return end
	if Duel.Draw(tp,2,REASON_EFFECT)==2 then
		Duel.ShuffleHand(tp)
		Duel.BreakEffect()
		Duel.DiscardHand(tp,nil,1,1,REASON_EFFECT|REASON_DISCARD)
	end
end