Dig

local args = { ... }

numArgs = table.getn(args)

FUEL_INV_LOC = 1
FUEL_REFUEL_AMMT = 1
FUEL_LOWER_BOUND = 0
TORCH_INV_LOC = 2
TORCH_INTERVAL = 5

function fuel ()
  if turtle.getFuelLevel() == FUEL_LOWER_BOUND then
    turtle.select(FUEL_INV_LOC)
    turtle.refuel(FUEL_REFUEL_AMMT)
  end
end

function plantTunnelTorch ()
  turtle.select(TORCH_INV_LOC)
  turtle.placeDown()
end

function goodDig ()
  while turtle.detect() do
    fuel()
    turtle.dig()
  end
  fuel()
end

function goodDigUp ()
  while turtle.detectUp() do
    fuel()
    turtle.digUp()
    sleep(0.5)
  end
  fuel()
end

function clearUpDown ()
  goodDigUp()
  turtle.digDown()
  fuel()
end

function tunnel (len, toTorch)
  count = 0
  torch = TORCH_INTERVAL
  while count < len do
    clearUpDown()

    if torch == TORCH_INTERVAL and toTorch == true then
      plantTunnelTorch()
      torch = 0
    end
    goodDig()
    turtle.forward()
    clearUpDown()
    fuel()
    count = count+1
    torch = torch+1
  end
end

function leftOrRight (dire)
  if dire == 'l' then
    turtle.turnLeft()
  elseif dire == 'r' then
    turtle.turnRight()
  else
    term.write("Error, bad direction.")
  end
end

function swapDirection (dire)
  if dire == 'l' then
    return 'r'
  elseif dire == 'r' then
    return 'l'
  end
end

--================Main===============--
digNum = tonumber(args[1])

if numArgs == 1.0 then
  tunnel(digNum, true)
elseif numArgs == 4.0 then
  interval = tonumber(args[2])
  direction = args[3]
  if direction ~= 'r' and direction ~= 'l' then
    error("Third argument must be 'r' or 'l'")
  end
  repeatNum = tonumber(args[4])

  if interval > 1 then
    dropTorch = true
  else
    dropTorch = false
  end

  while repeatNum > 0 do
    tunnel(digNum, true)
    repeatNum = repeatNum - 1
    if repeatNum > 0 then
      leftOrRight(direction)
      tunnel(interval, true)
      leftOrRight(direction)
      tunnel(digNum, dropTorch)
      repeatNum = repeatNum - 1
      direction = swapDirection(direction)
      leftOrRight(direction)
      tunnel(interval, true)
      leftOrRight(direction)
      direction = swapDirection(direction)
    end
  end

else
  error("Usage: dig [int:dist] [int:interval] opt[l | r] [int:times]")
end