3x3-m

local robot = require('robot')
local computer = require('component').computer

local tArgs = {...}

if #tArgs ~= 1 then
  print("Usage: tunnel <length>")
  return
end

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

local depth = 0
local collected = 0

local function collect()

  collected = collected + 1
  if math.fmod(collected, 25) == 0 then
    print("Mined "..collected.." items.")
  end
end

local function tryDig()
  while robot.detect() do
    if robot.swing() then
      collect()
      os.sleep(0.5)
    else
      return false
    end
  end
  return true
end

local function tryDigUp()
  while robot.detectUp() do
    if robot.swingUp() then
      collect()
      os.sleep(0.5)
    else
      return false
    end
  end
  return true
end

local function tryDigDown()
  while robot.detectDown() do
    if robot.swingDown() then
      collect()
      os.sleep(0.5)
    else
      return false
    end
  end
  return true
end

local function tryUp()
  while not robot.up() do
    if robot.detectUp() then
      if not tryDigUp() then
        return false
      end
    elseif robot.swingkUp() then
      collect()
    else
      os.sleep(0.5)
    end
  end
  return true
end

local function tryDown()
  while not robot.down() do
    if robot.detectDown() then
      if not tryDigDown() then
        return false
      end
    elseif robot.swingDown() then
      collect()
    else
      os.sleep(0.5)
    end
  end
  return true
end

local function tryForward()
  while not robot.forward() do
    if robot.detect() then
      if not tryDig() then
        return false
      end
    elseif robot.attack() then
      collect()
    else
      os.sleep(0.5)
    end
  end
  return true
end

print("Tunnelling...")

for n=1,length do
  robot.placeDown()
  tryDigUp()
  robot.turnLeft()
  tryDig()
  tryUp()
  tryDig()
  robot.turnRight()
  robot.turnRight()
  tryDig()
  tryDown()
  tryDig()
  robot.turnLeft()

  if n<length then
    tryDig()
    if not tryForward() then
      print("Aborting Tunnel.")
      break
    end
  else
    print("Tunnel complete.")
  end

end

print("Tunnel complete.")
print("Mined "..collected.." items total.")