Turtle Strip Mining

local args = {...}
local defaultBranchLength = 60
local branchLength = tonumber(args[1]) or defaultBranchLength
local enderChestMode = true

local cobblestone =  1
local torch       = 15
local enderChest  = 16

function dig ()
  turtle.select(1)
  local tries = 0

  turtle.dig()

  while turtle.detect() and tries < 120 do
    tries = tries + 1
    turtle.dig()
    sleep(0.8)
  end

  slotsFilled()
end

function forward (n, digUp)
  local steps = n or 1

  for i = 1, steps do
    dig()

    while not turtle.forward() do
      dig()
      sleep(0.8)
    end

    if digUp then
      local tries = 0
      turtle.digUp()

      while turtle.detectUp and tries < 120 do
        tries = tries + 1
        turtle.digUp()
      end
    end
  end
end

function up ()
  turtle.digUp()

  while not turtle.up() do
    turtle.digUp()
    sleep(0.8)
  end
end

function placeTorch ()
  if turtle.getItemCount(torch) > 1 then
    turtle.select(torch)

    if not turtle.place() and turtle.getItemCount(cobblestone) > 1 then
      forward()
      turtle.select(cobblestone)
      turtle.place()
      turtle.back()
      turtle.select(torch)
      turtle.place()
    end
  end
end

function emptyInventory()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.dig()
  turtle.select(enderChest)

  while turtle.getItemCount(enderChest) == 0 do
    print("No chest found, press Enter to continue")

    repeat
      event, key = os.pullEvent("key")
    until key == keys.enter
  end

  turtle.place()

  for slot = 2, 14 do
    if turtle.getItemCount(slot) > 0 then
      turtle.select(slot)
      turtle.drop()
    end
  end

  turtle.select(enderChest)

  if enderChestMode then
    turtle.dig()
  end

  turtle.turnLeft()
  turtle.turnLeft()
end

function floor ()
  if not turtle.detectDown() and turtle.getItemCount(cobblestone) > 1 then
    turtle.select(cobblestone)
    turtle.placeDown()
  end
end

function ceiling ()
  if not turtle.detectUp() and turtle.getItemCount(cobblestone) > 1 then
    turtle.select(cobblestone)
    turtle.placeUp()
  end
end

function dig1x3 (i)
  turtle.turnLeft()
  dig()
  turtle.turnRight()
  turtle.turnRight()
  dig()

  if i and i % 7 == 1 then
    placeTorch()
  end

  turtle.turnLeft()
end

function dig2x3 (i)
  forward()
  floor()
  up()
  dig1x3(i)
  ceiling()
  turtle.down()
  dig1x3()
end

function slotsFilled ()
  local filled = true

  for slot = 2, 14 do
    if turtle.getItemCount(slot) == 0 then
      filled = false

      break
    end
  end

  if filled then
    emptyInventory()
  end
end

function nextBranch (n)
  local odd = n % 2 == 1
  local turn = nil

  if odd then
    turn = turtle.turnRight
  else
    turn = turtle.turnLeft
  end

  forward(1, true)
  floor()
  turn()

  for i = 1, 5 do
    forward(1, true)
    floor()
  end

  turn()
end

--Main program
print("lzStrip v0.2")
print("(C) LayZee 2013")
print("")
print("Place Cobblestones in slot 1")
print("Place Torches in slot 15")
print("Place an Ender Chest in slot 16")
print("Press Enter to start strip mining")

repeat
  local event, key = os.pullEvent("key")
until key == keys.enter

while true do
  local branch = 1

  while turtle.getFuelLevel() >= branchLength * 2 + 12 + branchLength / 7 do
    for i = 1, branchLength do
      dig2x3(i)
    end

    branch = branch + 1
    nextBranch(branch)
  end

  print("Out of fuel")
  print("")
  print("1. Remove Cobblestones from slot 1")
  print("2. Place fuel source in slot 1")
  print("3. Press any key to refuel")
  os.pullEvent("key")

  while turtle.getFuelLevel() < branchLength * 2 + 12 do
    turtle.select(1)
    turtle.refuel()

    local timerId = os.startTimer(2)
    local event = ""
    local id = 0

    while timerId ~= id do
      event, id = os.pullEvent("timer")
    end
  end

  print("4. Place Cobblestone in slot 1")
  print("5. Press Enter to resume strip mining")

  repeat
    event, key = os.pullEvent("key")
  until key == keys.enter
end

print("ERROR: Broke out of main loop")
print("Report to layzee.dk@gmail.com")