25x25x25

-- A program to make turtle computercraft dig a 25x25x25 hole
-- The turtle should start at the top left corner of the hole
-- The turtle should have enough fuel and a chest in slot 1

local length = 25 -- The length of the hole
local width = 25 -- The width of the hole
local depth = 25 -- The depth of the hole

-- A function to check if the turtle has enough fuel
local function checkFuel()
  if turtle.getFuelLevel() < 10 then -- If the fuel level is less than 10
    print("Low fuel. Refueling...") -- Print a message
    turtle.select(16) -- Select the last slot
    if turtle.refuel(1) then -- Try to refuel with one item
      print("Refueled.") -- Print a message
    else -- If refueling failed
      print("No fuel. Please insert fuel in slot 16.") -- Print a message
      while not turtle.refuel(1) do -- Wait until refueling succeeds
        os.sleep(1) -- Sleep for one second
      end
      print("Refueled.") -- Print a message
    end
  end
end

-- A function to dig forward and move forward
local function digForward()
  checkFuel() -- Check the fuel level
  while turtle.detect() do -- While there is a block in front
    turtle.dig() -- Dig the block
  end
  turtle.forward() -- Move forward
end

-- A function to dig down and move down
local function digDown()
  checkFuel() -- Check the fuel level
  while turtle.detectDown() do -- While there is a block below
    turtle.digDown() -- Dig the block
  end
  turtle.down() -- Move down
end

-- A function to dig up and move up
local function digUp()
  checkFuel() -- Check the fuel level
  while turtle.detectUp() do -- While there is a block above
    turtle.digUp() -- Dig the block
  end
  turtle.up() -- Move up
end

-- A function to turn around
local function turnAround()
  turtle.turnLeft() -- Turn left
  turtle.turnLeft() -- Turn left again
end

-- A function to place a chest and empty the inventory
local function emptyInventory()
  print("Inventory full. Emptying...") -- Print a message
  turtle.select(1) -- Select the first slot (chest)
  while not turtle.placeDown() do -- While placing the chest fails
    digDown() -- Dig down and move down
  end
  for i = 2, 16 do -- For each slot except the first one (chest)
    turtle.select(i) -- Select the slot
    turtle.dropDown() -- Drop the item into the chest
  end
  turtle.select(1) -- Select the first slot (chest)
  digUp() -- Dig up and move up (back to original position)
end

-- A function to check if the inventory is full
local function checkInventory()
  if turtle.getItemCount(16) > 0 then -- If the last slot is not empty
    emptyInventory() -- Empty the inventory into a chest below
  end
end

-- Start digging the hole

print("Starting to dig...") -- Print a message

for i = 1, depth do -- For each layer of depth

  for j = 1, width do -- For each row of width

    for k = 1, length - 1 do -- For each column of length except the last one

      digForward() -- Dig forward and move forward

      checkInventory() -- Check if the inventory is full

    end

    if j < width then -- If this is not the last row

      if j % 2 == 0 then -- If this is an even row

        turtle.turnLeft() -- Turn left

        digForward() -- Dig forward and move forward

        checkInventory() -- Check if the inventory is full

        turtle.turnLeft() -- Turn left

      else -- If this is an odd row

        turtle.turnRight() -- Turn right

        digForward() -- Dig forward and move forward

        checkInventory() -- Check if the inventory is full

        turtle.turnRight() -- Turn right

      end

    elseif i < depth then -- If this is the last row but not the last layer

      turnAround() -- Turn around

      for l = 1, length -1 do -- For each column of length except the first one

        digForward() -- Dig forward and move forward

        checkInventory() -- Check if the inventory is full

      end

      digDown() -- Dig down and move down

      checkInventory() -- Check if the inventory is full

    end

  end

end

print("Finished digging.") -- Print a message