Minecraft Turtle Lumberjack v1

tArgs = {...}

local fuelSlot, chestSlot = 16, 15
local height = 0

function goUp(distance)
  if distance == nil then distance = 1 end
  shell.run("go", "up", distance)
end

function goDown(distance)
  if distance == nil then distance = 1 end
  shell.run("go", "up", distance)
end

function goForward(distance)
  if distance == nil then distance = 1 end
  shell.run("go", "forward", distance)
end

function goBack(distance)
  if distance == nil then distance = 1 end
  shell.run("go", "back", distance)
end

function digUp(distance)
  if distance == nil then distance = 1 end
  for i = 1, distance do
    while turtle.detectUp() == true do
      turtle.digUp()
      sleep(0.5)
    end
    if distance > 1 then
      goUp()
    end
  end
end

function dig(distance)
  if distance == nil then distance = 1 end
  for i = 1, distance do
    while turtle.detect() == true do
      turtle.dig()
      sleep(0.5)
    end
  end
end

function digDown(distance)
  if distance == nil then distance = 1 end
  for i = 1, distance do
    turtle.digDown()
    sleep(0.5)
    if distance > 1 then
      goDown()
    end
  end
end

function getFuel()
  return turtle.getFuelLevel()
end

function returnToStart()
  goDown(height)
  height = 0
end

function dropLoad()
  shell.run("turn", "around")
  for i = 1, 14 do
    turtle.select(i)
    turtle.drop()
  end
  turtle.select(1)
end

if tArgs[1] == "-h" then
  print("Usage: lumberjack <redwood>")
elseif tArgs[1] == nil then
  if turtle.getItemCount(chestSlot) == 0 or turtle.getItemCount(fuelSlot) == 0 then
    print("Please insert a chest into slot "..chestSlot.." and fuel into slot "..fuelSlot..", then run lumberjack again")
  else
    shell.run("turn", "around")
    turtle.select(chestSlot)
    turtle.place()
    turtle.select(1)
    shell.run("turn", "around")
    dig()
    goForward()
    while turtle.detectUp() == true do
      digUp()
      goUp()
      height = height + 1
      if getFuel() == 0 then
        turtle.select(fuelSlot)
        turtle.refuel(5)
        turtle.select(1)
      end
    end
    returnToStart()
    dropLoad()
  end
elseif tArgs[1] == "redwood" then
  if turtle.getItemCount(chestSlot) == 0 or turtle.getItemCount(fuelSlot) == 0 then
    print("Please insert a chest into slot "..chestSlot.." and fuel into slot "..fuelSlot..", then run lumberjack again")
  else
    shell.run("turn", "around")
    turtle.select(chestSlot)
    turtle.place()
    turtle.select(1)
    shell.run("turn", "around")
    dig()
    goForward()
    while turtle.detectUp() == true do
      shell.run("turn", "right")
      dig()
      shell.run("turn", "left")
      dig()
      goForward()
      shell.run("turn", "right")
      dig()
      shell.run("turn", "left")
      goBack()
      digUp()
      goUp()
      height = height + 1
      if getFuel() == 0 then
        turtle.select(fuelSlot)
        turtle.refuel(5)
        turtle.select(1)
      end
    end
    if turtle.detect() == true then
      dig()
      shell.run("turn", "right")
      dig()
      shell.run("turn", "left")
      goForward()
      shell.run("turn", "right")
      dig()
      shell.run("turn", "left")
      goBack()
    end
    returnToStart()
    dropLoad()
  end
else
  print("Usage: lumberjack <redwood>")
end