Computercraft Simple Tunnel

-- Simple Tunnel
-- pastebin get ZBceps6U simpleTunnel
-- simpleTunnel 75

-- DESCRIPTION
--  Like the default tunnel program, but instead of mining a 3x2 tunnel, this program will mine a 1x2 tunnel.


local argv = {...}
local mine_dist = tonumber(argv[1])

local CONST_TORCH_INTERVAL = 8

local curr_dist = 0

local function check_fuel()
    if turtle.getFuelLevel() < 80 then
        turtle.select(1)
        turtle.refuel(1)
    end
end

local function select_cobble()
    for s=2, 16 do
        local item_data = turtle.getItemDetail(s)
        if item_data then
            if item_data.name == "minecraft:cobblestone" then
                turtle.select(s)
                return true
            end
        end
    end
    return false
end

local function select_torch()
    for s=2, 16 do
        local item_data = turtle.getItemDetail(s)
        if item_data then
            if item_data.name == "minecraft:torch" then
                turtle.select(s)
                return true
            end
        end
    end
    return false
end

local function tick()
    check_fuel()
    while not turtle.forward() do
        turtle.dig()
    end
    if turtle.detectUp() then
        turtle.digUp()
    end
    if (not turtle.detectDown()) and select_cobble() then
        turtle.placeDown()
    end
    if (curr_dist > 0 and curr_dist % CONST_TORCH_INTERVAL == 0) and select_torch() then
        if (not turtle.placeUp()) and select_cobble() then
            turtle.up()
            turtle.turnLeft()
            turtle.place()
            turtle.turnRight()
            turtle.down()
            select_torch()
            turtle.placeUp()
        end
    end
    curr_dist = curr_dist + 1
end

print("Beginning tunnel of length " .. tostring(mine_dist))
while curr_dist < mine_dist do
    tick()
end
print("Success!")