Turtle Program: Three High Mirrored

local t = { ... }

local direction = 0
if #t < 2 then
  local programName = shell.getRunningProgram()
  print("Usage: "..fs.getName(programName).." <length> <width>")
  return
end

length = tonumber(t[1])
depth = tonumber(t[2])
hits = 0

length = length - 1

print("Digging...")

local function refuel()
  if turtle.getFuelLevel() < 50 then
    turtle.select(1)
    turtle.refuel(1)
  end
end

local function unload()
  for n = 1,14 do
    turtle.select(n)
    turtle.drop()
  end
end

local function tunnel()
  refuel()
  attacks = 0
  for a = 1,length do
    while not turtle.forward() do
      if turtle.detect() then
        turtle.dig()
      else
        turtle.attack()
        attacks = attacks + 1
      end
    end
    while turtle.detectUp() or turtle.detectDown() do
      if turtle.detectUp() then
        turtle.digUp()
      else
        turtle.digDown()
      end
    end
  end
  return attacks
end

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

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

turtle.digUp()
turtle.digDown()
hits = tunnel() + hits
for d = 1,(depth-1) do
  if direction == 0 then
    turnTowards()
    direction = 1
  else
    turnAway()
    direction = 0
  end
  hits = tunnel() + hits
end
if direction == 0 then
  turtle.turnLeft()
  turtle.turnLeft()
  for q = 1,length do
    turtle.forward()
  end
end
turtle.turnLeft()
for j = 1,(depth-1) do
  turtle.forward()
end
turtle.turnRight()
unload()
turtle.turnLeft()
turtle.turnLeft()
print("Done digging")

if hits > 0 then
  print("I attacked "..hits.." times.")
end