rail_tunnel.lua

local ms = require("movescript")
local robot = require("robot")
local component = require("component")
local ic = component.inventory_controller

local RECHARGE_THRESHOLD = 0.1
local ENERGY_SLOT = 1
local ENERGY_ITEM = "thermalexpansion:cell"
local CHARGER_SLOT = 2
local CHARGER_ITEM = "opencomputers:charger"
local RS_BLOCK_SLOT = 3
local RS_BLOCK_ITEM = "minecraft:redstone_block"

local args = {...}
local WIDTH = tonumber(args[1])
local LENGTH = tonumber(args[2])

if WIDTH == nil then error("Invalid width") end
if LENGTH == nil then error("Invalid length") end

local energyStack = ic.getStackInInternalSlot(ENERGY_SLOT)
local chargerStack = ic.getStackInInternalSlot(CHARGER_SLOT)
local rsBlockStack = ic.getStackInInternalSlot(RS_BLOCK_SLOT)

if energyStack == nil or energyStack.name ~= ENERGY_ITEM then
  error("Energy cell required in slot "..ENERGY_SLOT)
end
if chargerStack == nil or chargerStack.name ~= CHARGER_ITEM then
  error("Charger required in slot "..CHARGER_SLOT)
end
if rsBlockStack == nil or rsBlockStack.name ~= RS_BLOCK_ITEM then
  error("RS block required in slot "..RS_BLOCK_SLOT)
end

local function safeForward()
  robot.swing()
  while not robot.forward() do
    robot.swing()
  end
end

local function digAllUp()
  robot.swingUp()
  while robot.detectUp() do
    robot.swingUp()
  end
end

local function digRow(startLeft)
  local dir = "L"
  local antiDir = "R"
  if startLeft then dir = "R" antiDir = "L" end
  safeForward()
  if dir == "R" then
    robot.turnRight()
  else
    robot.turnLeft()
  end
  digAllUp()
  robot.swingDown()
  for i=1, WIDTH - 1 do
    safeForward()
    digAllUp()
    robot.swingDown()
  end
  if antiDir == "R" then
    robot.turnRight()
  else
    robot.turnLeft()
  end
end

local function rechargeIfNeeded()
  if ms.getEnergyRatio() < RECHARGE_THRESHOLD then
    robot.select(ENERGY_SLOT)
    ms.exec("d_RRUPD")
    robot.select(CHARGER_SLOT)
    ms.exec("d_PD")
    robot.select(RS_BLOCK_SLOT)
    ms.exec("d_PU")
    ms.waitUntilEnergyRatio(0.95)
    robot.select(ENERGY_SLOT)
    ms.exec("d_USD")
    robot.select(CHARGER_SLOT)
    ms.exec("d_SD")
    robot.select(RS_BLOCK_SLOT)
    ms.exec("d_SURR")
  end
end

-- assume to start on right.
local startLeft = false
for i = 1, LENGTH do
  digRow(startLeft)
  startLeft = not startLeft
  rechargeIfNeeded()
end