local function pushValues(buffer, sep, ...)
    local argv = {...}
    local argc = #argv
    for k, v in ipairs(argv) do
        table.insert(buffer, v)
        if k < argc and sep then
            table.insert(buffer, sep)
        end
    end
 end

 function Item.getNameDescription(self)
    local subType = self:getSubType()
    local itemType = self:getType()

    local buffer = {}

    local name = self:getName() or ''
    if(#name ~= 0) then
        if(itemType:isStackable() and subType > 1) then
            pushValues(buffer, ' ', subType, self:getPluralName())
        else
            local article = self:getArticle() or ''
            pushValues(buffer, ' ', select(#article ~= 0 and 1 or 2, article, name))
        end
    else
        pushValues(buffer, ' ', 'an item of type', self:getId())
    end

    return table.concat(buffer)
end

function Container.getContentDescription(self, outputBuffer)
    local firstItem = true
    local buffer = outputBuffer or {}
    for i = 1, self:getSize() do
        local item = self:getItem(i - 1)

        if(firstItem) then
            firstItem = false
        else
            table.insert(buffer, ", ")
        end

        table.insert(buffer, item:getNameDescription())
    end

    if firstItem then
        table.insert(buffer, "nothing")
    end

    if not outputBuffer then
        return table.concat(buffer)
    end
end

local function bind(func, ...)
    local args = {...}
    return function()
        return func(unpack(args))
    end
end

local function filter(list, predicate)
    local ret = {}
    for _, v in ipairs(list) do
        if predicate(v) then
            table.insert(ret, v)
        end
    end
    return ret
end

local function map(list, predicate)
    local ret = {}
    for _, v in ipairs(list) do
        table.insert(ret, predicate(v))
    end
    return ret
end

local config = {
    [40000] = {
        rewards = {
            -- 1x item(2092) with actionId(61000)
            function(player)
                local item = Game.createItem(2092, 1)
                item:setActionId(61000)
                -- If you want a personalized description
                -- item:setAttribute(ITEM_ATTRIBUTE_DESCRIPTION, 'This item was awarded to ' .. player:getName() .. ' because he is badass.')
                return item
            end
        },

        storage = 40000
    },

    [40001] = {
        rewards = {
            -- 1x item(2092)
            bind(Game.createItem, 2092, 1),
            -- 50k
            bind(Game.createItem, 2160, 5)
        },

        storage = 40001
    }
}

function onUse(player, item, fromPosition, target, toPosition, isHotkey)
    local chest = config[item:getUniqueId()]
    if not chest or #chest.rewards == 0 then
        return true
    end

    if player:getStorageValue(chest.storage) > 0 then
        player:sendTextMessage(MESSAGE_INFO_DESCR, 'You have already completed this quest.')
        return true
    end

    local monsters = filter(Game.getSpectators(player:getPosition()), function(creature) return creature:isMonster() end)
    if #monsters > 0 then
        local names = map(monsters, function(monster) return monster:getName() end)
        player:showTextDialog(item:getId(), 'You cannot receive your rewards before killing the following monsters:\n\n' .. table.concat(names, '\n'), false, 999)
        return true
    end

    local bag = Game.createItem(ITEM_BAG)
    for _, func in ipairs(chest.rewards) do
        bag:addItemEx(func(player))
    end

    local ret = player:addItemEx(bag)
    if ret == RETURNVALUE_NOERROR then
        player:setStorageValue(chest.storage, 1)
        player:sendTextMessage(MESSAGE_INFO_DESCR, 'You have received a bag containing ' .. bag:getContentDescription())
    else
        player:sendTextMessage(MESSAGE_INFO_DESCR, Game.getReturnMessage(ret))
    end
    return true
end