Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
When this card destroys an opponent's monster by battle and sends it to the Graveyard: You can discard 1 WATER monster to the Graveyard; Special Summon 1 "Mermail" monster from your Deck in face-up Defense Position. You can only use the effect of "Mermail Abyssnose" once per turn.
--水精鱗－アビスノーズ
--Mermail Abyssnose
local s,id=GetID()
function s.initial_effect(c)
	--special summon
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_SPECIAL_SUMMON)
	e1:SetCode(EVENT_BATTLE_DESTROYING)
	e1:SetType(EFFECT_TYPE_SINGLE+EFFECT_TYPE_TRIGGER_O)
	e1:SetCountLimit(1,id)
	e1:SetCondition(aux.bdogcon)
	e1:SetCost(s.spcost)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
end
s.listed_series={SET_MERMAIL}
function s.cfilter(c)
	return c:IsAttribute(ATTRIBUTE_WATER) and c:IsDiscardable() and c:IsAbleToGraveAsCost()
end
function s.spcost(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.IsExistingMatchingCard(s.cfilter,tp,LOCATION_HAND,0,1,nil) end
	Duel.DiscardHand(tp,s.cfilter,1,1,REASON_COST|REASON_DISCARD)
end
function s.filter(c,e,tp)
	return c:IsSetCard(SET_MERMAIL) and c:IsCanBeSpecialSummoned(e,0,tp,false,false,POS_FACEUP_DEFENSE)
end
function s.sptg(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return Duel.GetLocationCount(tp,LOCATION_MZONE)>0 
		and Duel.IsExistingMatchingCard(s.filter,tp,LOCATION_DECK,0,1,nil,e,tp) end
	Duel.SetOperationInfo(0,CATEGORY_SPECIAL_SUMMON,nil,1,tp,LOCATION_DECK)
end
function s.spop(e,tp,eg,ep,ev,re,r,rp)
	if Duel.GetLocationCount(tp,LOCATION_MZONE)<=0 then return end
	Duel.Hint(HINT_SELECTMSG,tp,HINTMSG_SPSUMMON)
	local g=Duel.SelectMatchingCard(tp,s.filter,tp,LOCATION_DECK,0,1,1,nil,e,tp)
	if #g>0 then
		Duel.SpecialSummon(g,0,tp,tp,false,false,POS_FACEUP_DEFENSE)
	end
end