quarry

function dropOffItems()
  turtle.turnLeft()
  for i=1,16 do
    turtle.select(i)
    turtle.drop()
  end
  turtle.turnRight()
  turtle.select(1)
end

-- refuel chest is behind it
function refuel(minFuelLevel)
  if minFuelLevel ~= nil and turtle.getFuelLevel() >= minFuelLevel then
    return
  end

  turtle.turnRight()
  turtle.turnRight()
  turtle.select(16)
  turtle.suck()
  turtle.refuel()
  turtle.select(1)
  turtle.turnLeft()
  turtle.turnLeft()
end

function bedrockForward_NotFinished()
  local blocksUp = 0

  -- must move forward by exactly 1
  while not turtle.forward() do

    -- clear out block, including sand or gravel
    while turtle.dig() do
      turtle.dig()
    end

    -- block cleared out or unbreakable (bedrock)
    -- try to move forward
    if not turtle.forward() then
      turtle.up()
      blocksUp = blocksUp + 1
    end
  end
end

function bedrockForward()
  local blocksUp = 3
  for i=1,blocksUp do
    turtle.up()
  end
  while turtle.dig() do
    turtle.dig()
  end
  turtle.forward()
  return blocksUp
end

function digDown()
  local blocks = 0
  while 1 do
    if turtle.digDown() then
      turtle.down()
      blocks = blocks + 1
    elseif turtle.down() then
      blocks = blocks + 1
    else
      return blocks
    end
  end
end

function digUp(blocks)
  for i=1,blocks do
    turtle.digUp()
    while not turtle.up() do
      turtle.digUp()
    end
  end
end

function downAndUp()
  bDn = digDown()
  bDn = bDn - bedrockForward()
  digUp(bDn)
  turtle.back()
end


function moveBack(blocks)
  for i=1,blocks do
    turtle.back()
  end
end

function moveForw(blocks)
  for i=1,blocks do
    while not turtle.forward() do
      turtle.dig()
    end
  end
end

function moveRight(blocks)
  turtle.turnRight()
  moveForw(blocks)
  turtle.turnLeft()
end

function moveLeft(blocks)
  turtle.turnLeft()
  moveForw(blocks)
  turtle.turnRight()
end

function checkArgs(args)
  if args[1] == nil or args[2] == nil then
    print( "Usage: quarry <blocks forward> <blocks right>")
    return false
  elseif args[1] % 2 ~= 0 or args[2] % 2 ~= 0 then
    print( "Please use even numbers for blocks")
    return false
  else
    return true
  end
end

args = {...}
if not checkArgs(args) then
  print("Exiting...")
else
  local bForw = args[1]
  local bRight = args[2]
  for r = 0, bRight/2 do
    for f = 0, bForw/2 do
      dropOffItems()
      refuel(1000)

      moveRight( r )
      moveForw( f * 2 )

      downAndUp()

      moveBack( f * 2 )
      moveLeft( r )
    end
  end

  dropOffItems()
end