Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
Cannot be Normal Summoned/Set. Must be Special Summoned by a Dragon-Type Xyz Monster's effect in your possession, and cannot be Special Summoned by other ways. When Special Summoned, if your Life Points are lower than your opponent's: This card gains ATK equal to your current Life Point deficit, and if it does, your opponent takes no further damage this turn. This card cannot attack your opponent directly.
--魂食神龍ドレイン・ドラゴン
--Soul Drain Dragon
local s,id=GetID()
function s.initial_effect(c)
	c:EnableUnsummonable()
	--spsummon condition
	local e1=Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_SINGLE)
	e1:SetProperty(EFFECT_FLAG_CANNOT_DISABLE+EFFECT_FLAG_UNCOPYABLE)
	e1:SetCode(EFFECT_SPSUMMON_CONDITION)
	e1:SetValue(s.splimit)
	c:RegisterEffect(e1)
	--atkup
	local e2=Effect.CreateEffect(c)
	e2:SetDescription(aux.Stringid(id,0))
	e2:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_F)
	e2:SetCode(EVENT_SPSUMMON_SUCCESS)
	e2:SetCondition(s.atkcon)
	e2:SetOperation(s.atkop)
	c:RegisterEffect(e2)
	--
	local e3=Effect.CreateEffect(c)
	e3:SetType(EFFECT_TYPE_SINGLE)
	e3:SetCode(EFFECT_CANNOT_DIRECT_ATTACK)
	c:RegisterEffect(e3)
end
function s.splimit(e,se,sp,st)
	local sc=se:GetHandler()
	return sc:IsType(TYPE_XYZ) and sc:IsRace(RACE_DRAGON)
end
function s.atkcon(e,tp,eg,ep,ev,re,r,rp)
	return Duel.GetLP(tp)<Duel.GetLP(1-tp)
end
function s.atkop(e,tp,eg,ep,ev,re,r,rp)
	local c=e:GetHandler()
	if c:IsFaceup() and c:IsRelateToEffect(e) and Duel.GetLP(tp)<Duel.GetLP(1-tp) then
		local e1=Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(Duel.GetLP(1-tp)-Duel.GetLP(tp))
		e1:SetReset(RESET_EVENT|RESETS_STANDARD_DISABLE)
		c:RegisterEffect(e1)
	end
	local e2=Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_CHANGE_DAMAGE)
	e2:SetProperty(EFFECT_FLAG_PLAYER_TARGET)
	e2:SetTargetRange(0,1)
	e2:SetValue(0)
	e2:SetReset(RESET_PHASE|PHASE_END)
	Duel.RegisterEffect(e2,tp)
	local e3=e2:Clone()
	e3:SetCode(EFFECT_NO_EFFECT_DAMAGE)
	e3:SetReset(RESET_PHASE|PHASE_END)
	Duel.RegisterEffect(e3,tp)
end