strip

tunnels = 10

local tArgs = { ...}
if #tArgs ~=1 then
    print( "Usage: strip <length>" )
    return
end

local length = tonumber( tArgs[1] )
if length < 1 then
    print(  "Strip length must be positive" )
    return
end

local function refuel()
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel > 0 then
        return
    end

    local function tryRefuel()
        for n=1,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    turtle.select(1)
                    return true
                end
            end
        end
        turtle.select(1)
        return false
    end

    if not tryRefuel() then
        print( "Add more fuel to continue." )
        while not tryRefuel() do
            sleep(1)
        end
        print( "Resuming Tunnel." )
    end
end

local function detectup()
    if turtle.detectUp() then
        turtle.digUp()
        sleep(0.4)
    end
end

local function strip()
    refuel()
    while not turtle.forward() do
        while not turtle.dig() do
            turtle.attack()
        end
    sleep(0.4)
    detectup()
    end
end

local function otun()
    strip()
    strip()
    detectup()
    turtle.back()
    turtle.back()
end

local function turnaround()
    turtle.turnRight()
    strip()
    strip()
    strip()
    otun()
    turtle.turnRight()
end

for n = 1, tunnels do
    refuel()
    for x = 1, length do
        strip()
    end
    refuel()
    turnaround()
    x = 0
    refuel()
    for x = 1, length do
        strip()
    end
    turtle.back()
    detectup()
    turtle.forward()
    turtle.turnLeft()
    turtle.forward()
    turtle.forward()
    turtle.forward()
    turtle.turnLeft()
end