Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
If your LP is 4000 or less, when an attack is declared involving a monster you control and an opponent's monster: Pay half your LP, then target 1 face-up monster you control; it gains ATK equal to the deficit between your current LP and 4000 until the end of your opponent's turn. You can only activate 1 "Soul Strike" per turn.
--魂の一撃
--Soul Strike
local s,id=GetID()
function s.initial_effect(c)
	--Activate
	local e1=Effect.CreateEffect(c)
	e1:SetCategory(CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_ACTIVATE)
	e1:SetCode(EVENT_ATTACK_ANNOUNCE)
	e1:SetProperty(EFFECT_FLAG_CARD_TARGET)
	e1:SetCountLimit(1,id,EFFECT_COUNT_CODE_OATH)
	e1:SetCondition(s.condition)
	e1:SetCost(s.cost)
	e1:SetTarget(s.target)
	e1:SetOperation(s.activate)
	c:RegisterEffect(e1)
end
function s.condition(e,tp,eg,ep,ev,re,r,rp)
	return Duel.GetLP(tp)<=4000 and Duel.GetAttackTarget()~=nil
end
function s.cost(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return true end
	Duel.PayLPCost(tp,math.floor(Duel.GetLP(tp)/2))
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk,chkc)
	if chkc then return chkc:IsLocation(LOCATION_MZONE) and chkc:IsControler(tp) and chkc:IsFaceup() end
	if chk==0 then return Duel.IsExistingTarget(Card.IsFaceup,tp,LOCATION_MZONE,0,1,nil) end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_FACEUP)
	Duel.SelectTarget(tp,Card.IsFaceup,tp,LOCATION_MZONE,0,1,1,nil)
end
function s.activate(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(4000-Duel.GetLP(tp))
		e1:SetReset(RESETS_STANDARD_PHASE_END|RESET_OPPO_TURN)
		tc:RegisterEffect(e1)
	end
end