local config = {
    health = {points = xxx, amount = xxx},           --{points = quantidade_de_pontos, amount = quantidade_de_HP_ganha},
    mana = {points = xxx, amount = xxx}              --{points = quantidade_de_pontos, amount = quantidade_de_mana_ganha}
}
 
local keywordHandler = KeywordHandler:new()
local npcHandler = NpcHandler:new(keywordHandler)
NpcSystem.parseParameters(npcHandler)
local talkState = {}
function onCreatureAppear(cid) npcHandler:onCreatureAppear(cid) end
function onCreatureDisappear(cid) npcHandler:onCreatureDisappear(cid) end
function onCreatureSay(cid, type, msg) npcHandler:onCreatureSay(cid, type, msg) end
function onThink() npcHandler:onThink() end
function creatureSayCallback(cid, type, msg)
    msg = msg:lower()
    
    if not npcHandler:isFocused(cid) then
        return false
    end
 
    local talkUser, player_points = NPCHANDLER_CONVBEHAVIOR == CONVERSATION_DEFAULT and 0 or cid, getPlayerStorageValue(cid, 3920)
    
    if msgcontains(msg, "points") or msgcontains(msg, "trade") then
        selfSay("I can give you a little more HP and mana in exchange for some points. What do you think? Do you accept my offer?", cid)
        talkState[talkUser] = 1
    elseif msgcontains(msg, "yes") and talkState[talkUser] == 1 then
        selfSay("Well, I can give you {"..config.health.amount.." extra HP} for {"..config.health.points.." points}, and {"..config.mana.amount.." extra mana} for {"..config.mana.points.." points}.", cid)
        selfSay("Would you like more {hp} or more {mana}?", cid)
        talkState[talkUser] = 2
    elseif msgcontains(msg, "no") and talkState[talkUser] == 1 then
        selfSay("No problem, sir.", cid)
        talkState[talkUser] = 0
    elseif talkState[talkUser] == 2 then
        local info_table = {
            ["hp"] = {setCreatureMaxHealth, getCreatureMaxHealth, doCreatureAddHealth, config.health.points, config.health.amount},
            ["mana"] = {setCreatureMaxMana, getCreatureMaxMana, doCreatureAddMana, config.mana.points, config.mana.amount}
        }
        
        local func = info_table[msg]   
        
        if not func then
            selfSay("I told you to tell me if you'd like more {hp} or more {mana}.", cid)
        elseif player_points < func[4] then
            selfSay("You do not have enough points to exchange.", cid)
        else
            if player_points >= func[4] * 2 then
                local multiplier = math.floor(player_points / func[4])
                
                func[4] = func[4] * multiplier
                func[5] = func[5] * multiplier
            end
            
            selfSay("Here you are: "..func[5].." more "..msg.." for "..func[4].." points.", cid)
            setPlayerStorageValue(cid, 3920, player_points - func[4])
            func[1](cid, func[2](cid) + func[5])
            func[3](cid, func[2](cid))
            talkState[talkUser] = 0
        end
    end
    return true
end
 
npcHandler:setCallback(CALLBACK_MESSAGE_DEFAULT, creatureSayCallback)
npcHandler:addModule(FocusModule:new())