ccStairMiner

local depth

local function setup()
    local function depthfunc()
        print "How many blocks deep should the stairs be?"
        depth = tonumber(read())
        if depth == nil or depth <= 0 then
            print "Invalid depth value."
            print "----------------------------------"
            depthfunc()
        end
    end
    depthfunc()
end

setup()

for i=1, depth do
    if i % 3 == 0 then
        turtle.turnRight()
    end
    if turtle.getFuelLevel() < 2 then
        local refueled = false
        for i = 1, 16 do
            local item = turtle.getItemDetail(i)
            if item.name == "minecraft:coal" or item.name == "minecraft:lava_bucket" or item.name == "minecraft:charcoal" then
                turtle.select(i)
                turtle.refuel(1)
                refueled = true
                break
            end
        end
        if not refueled then
            print "not enough fuel to continue! please insert fuel into the selected slot"
            while turtle.getFuelLevel()<2 do
                turtle.refuel(1)
            end
        end
    end
    turtle.dig()
    while not turtle.forward() do
        turtle.dig()
    end
    while turtle.inspectUp() do
        turtle.digUp()
        sleep(1)
    end
    turtle.digDown()
    while not turtle.down() do
        turtle.digDown()
    end
end