quarry

arg = {...}

width = nil
length = nil

compareSlots = 3
fuelSlots = 1

if arg[1] ~= nil and arg[2] ~= nil then
  width = arg[1]
  length = arg[2]
else
  term.setTextColor(colors.red)
  print("Usage: quarry <width> <length>")
  return
end

x = 0
z = 0
y = 0
facing = 0

function empty()
  turtle.select(1)
  while turtle.detect() do
    turtle.dig()
  end
  turtle.place()
  c = peripheral.wrap("front")
  for slot = 2+compareSlots,16-fuelSlots do
    emptySpace = false
    while not emptySpace do
      itemsNb = #c.getAllStacks()
      invSize = c.getInventorySize()
      if itemsNb < invSize then
        emptySpace = true
      end
      sleep(1)
    end
    turtle.select(slot)
    turtle.drop()
  end
  c = nil
  turtle.dig()
end

function mineMinerals()
  shouldDigUp = true
  shouldDigDown = true
  for slot = 2, 1+compareSlots do
    turtle.select(slot)
    if turtle.compareUp() and shouldDigUp then
      shouldDigUp = false
    else
    end
    if turtle.compareDown() and shouldDigDown then
      shouldDigDown = false
    end
  end
  if shouldDigDown then digDown() end
  if shouldDigUp then digUp() end
end

function quarry()
  while down() do end
  up()
  mineLayer()
  while nextLayer() do
    mineLayer()
  end
  empty()
end

function printInfo()
  term.setCursorPos(1,1)
  term.clear()
  print("x: "..x.." y: "..y.." z: "..z.." f: "..facing)
end

function nextLayer()
  next = true
  if width % 2 == 0 then
    turnRight()
    while x > 0 do step() end
  else
    turnLeft()
    while x > 0 do step() end
    turnLeft()
    while z > 0 do step() end
  end
  lastLayer = y
  while y < lastLayer + 3 do
    if y < 0 then
      up()
    end
  end
  while facing ~= 0 do
    if width % 2 == 0 then
      turnRight()
    else
      turnLeft()
    end
  end
  if y == 0 then next = false end
  return next
end

function refuel()
  if turtle.getFuelLevel() < 5 then
    for slot = 16-fuelSlots, 16 do
      if turtle.getItemCount(slot) > 1 then
        turtle.select(slot)
        turtle.refuel(1)
        return true
      end
    end
  end
  return false
end

function step()
  printInfo()
  mineMinerals()
  while not turtle.forward() do
    if not refuel() then
      if turtle.detect() then
        dig()
      else
        turtle.attack()
      end
    end
  end
  if facing == 0 then z = z + 1 end
  if facing == 2 then z = z - 1 end
  if facing == 1 then x = x + 1 end
  if facing == 3 then x = x - 1 end
end

function up()
  printInfo()
  while not turtle.up() do
    if not refuel() then
      if turtle.detectUp() then
        digUp()
      else
        turtle.attackUp()
      end
    end
  end
  y = y + 1
end

function down()
  printInfo()
  done = false
  while not done do
    done = turtle.down()
    if done then
      y = y - 1
      return true
    end
    if not refuel() then
      if turtle.detectDown() then
        if digDown() then
          turtle.down()
          y = y - 1
          return true
        else return false end
      else
        turtle.attackDown()
      end
    end
  end
end

function turnLeft()
  printInfo()
  turtle.turnLeft()
  facing = facing - 1
  if facing < 0 then facing = 3 end
end

function turnRight()
  printInfo()
  turtle.turnRight()
  facing = facing + 1
  if facing > 3 then facing = 0 end
end

function turnAround()
  if z == length-1 then
    turn = function() turnRight() end
  elseif z == 0 then
    turn = function() turnLeft() end
  end
  turn()
  step()
  turn()
end

function mineLayer()
  for i = 1,width do
    for j = 1,length-1 do
      step()
    end
    if x ~= width - 1 then
      turnAround()
    end
  end
end

function shouldEmpty()
  if turtle.getItemCount(16 - fuelSlots - 1) > 0 then
    empty()
  end
end

function dig()
  shouldEmpty()
  return turtle.dig()
end

function digDown()
  shouldEmpty()
  return turtle.digDown()
end

function digUp()
  shouldEmpty()
  return turtle.digUp()
end

quarry()