Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When a Beast-Warrior-Type "Bujin" monster you control is targeted for an attack by an opponent's monster: You can send this card from your hand to the Graveyard; negate the attack, and if you do, inflict damage to your opponent equal to half the attacker's ATK. You can only use the effect of "Bujingi Crow" once per turn.
--武神器－ヤタ
--Bujingi Crow
local s,id=GetID()
function s.initial_effect(c)
	--negate attack
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_DAMAGE)
	e1:SetType(EFFECT_TYPE_QUICK_O)
	e1:SetCode(EVENT_BE_BATTLE_TARGET)
	e1:SetRange(LOCATION_HAND)
	e1:SetCountLimit(1,id)
	e1:SetCondition(s.nacon)
	e1:SetCost(Cost.SelfToGrave)
	e1:SetTarget(s.natg)
	e1:SetOperation(s.naop)
	c:RegisterEffect(e1)
end
s.listed_series={SET_BUJIN}
function s.nacon(e,tp,eg,ep,ev,re,r,rp)
	local at=Duel.GetAttackTarget()
	return at:IsControler(tp) and at:IsFaceup() and at:IsSetCard(SET_BUJIN) and at:IsRace(RACE_BEASTWARRIOR)
end
function s.natg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetAttacker():IsOnField() end
	local dam=Duel.GetAttacker():GetAttack()/2
	Duel.SetOperationInfo(0,CATEGORY_DAMAGE,nil,0,1-tp,dam)
end
function s.naop(e,tp,eg,ep,ev,re,r,rp)
	local a=Duel.GetAttacker()
	if Duel.NegateAttack() then
		Duel.Damage(1-tp,a:GetAttack()/2,REASON_EFFECT)
	end
end