miner.lua

local max_depth = 64
local max_width = 64

local fuel_estimate = max_depth * 2 + 2 * max_width

function forward(dig)
  while not turtle.forward() do
    if dig then
      block, data = turtle.inspect()
      if block and data.name ~= "computercraft:turtle_normal" then
        turtle.dig()
      end
    else
      print("Waiting in queue......")
    end
  end
end

function up(dig)
  while not turtle.up() do
    if dig then
      turtle.digUp()
    else
      print("Waiting in queue......")
    end
  end
end

function down(dig)
  while not turtle.down() do
    if dig then
      turtle.digDown()
    else
      print("Waiting in queue......")
    end
  end
end

print("Waiting for fuel...")

while true do
  turtle.suckDown(1)
  turtle.refuel(1)

  if turtle.getFuelLevel() >= fuel_estimate then
    print("We have enough fuel to go mining!")
    break
  end
end

local width = 0

for i=1, max_width / 2 do
  forward(true)

  width = width + 1
  print("Looking for free mining spot at width=" .. width)

  if turtle.detectDown() then
    print("Free spot at width=" .. width .. "!")
    break
  end
end

turtle.digDown()
up()

local highspot = width % 2 == 1

if highspot then
  print("Going up to high mining spot")

  for i=1, 3 do
    up(true)
  end
end

turtle.turnLeft()

for depth=1, max_depth do
  forward(true)

  turtle.digUp()
  turtle.digDown()

  print("Mining out, depth=" .. depth)
end

print("Gone far enough out, mining back")

if highspot then
  turtle.turnLeft()

  forward(true)
  width = width - 1

  turtle.turnLeft()
else
  turtle.turnRight()

  forward(true)
  width = width + 1

  turtle.turnRight()
end

for i=1, max_depth do
  turtle.digUp()
  turtle.digDown()

  forward(true)

  print("Mining back, depth=" .. (max_depth - i))
end

turtle.digUp()
turtle.digDown()

print("Mining done, returning to station")
turtle.turnRight()

if highspot then
  print("Going down from high mining spot")

  for i=1, 3 do
    down()
  end
end

for i=1, width do
  forward()
end

for i=1, 16 do
  turtle.select(i)
  turtle.dropUp()
end

turtle.select(1)

turtle.turnRight()
turtle.turnRight()

down()

os.reboot()