tunnel

--[[

    This program tells a turtle to tunnel forward by a specified amount.
    The tunnel will be 3 blocks tall, 1 block above and 1 block below the turtle.
    The turtle returns to the starting position.

]]

--[[ Functions ]]

local function fwd()
    while not turtle.forward() do
        turtle.dig()
    end
    turtle.digUp()
    turtle.digDown()
end

local function enoughFuel(x)
    if turtle.getFuelLevel() < 2 * x then
        return false
    else
        return true
    end
end

--[[ Main ]]

-- Query user
print("How much in front of me would you like me to dig?")
local x = read()

-- Check for fuel
if not enoughFuel(x) then
    print("Please refuel. I need at least " .. x * 2 .. " units for that job")
    return
end

-- Dig
for i = 1, x do
    fwd()
end

-- Come back
for i = 1, x do
    turtle.back()
end