pamcotton

local function goBack()
    for i = 1, 13 do
        turtle.back(i)
    end
end

local function findSlot()
    for i = 1,15 do
        if turtle.getItemSpace(i) > 0 then
            turtle.select(i)
            return
        end
    end
end

while true do
    local isBlock, data = turtle.inspectDown()
    if isBlock then
        if data.state and data.state.age == 3 then
            turtle.digDown()
            turtle.select(1)
            turtle.placeDown()
        end
        if data.state and data.state.age < 3 then
            turtle.forward()
        end
    else
        goBack()
        findSlot()
        turtle.back()
        turtle.down()
        turtle.select(1)
        turtle.dropDown()
        turtle.up()
        turtle.forward()
        sleep(300)
    end
end