stripmine

print("Mining program")

print("")
print("Place turtle on the surface facing away")
print("from a chest.  Turtle will move forward")
print("one block and then mine in a X by Y grid.")
print("Be sure to fuel the turtle before mining.")

print("")
print("How many squares forward should it mine?")
local x = tonumber(read())

print("")
print("How many squares right should it mine?")
local y = tonumber(read())

print("")
print("How many squares down should it mine? (0 = to bedrock)")
local z = tonumber(read())

if z == 0 then
    z = 999
end

if x < 1 or y < 1 or z < 1 then
  error("Invalid arguments")
end

print("")

-- function to move the turtle
-- with up to five retries

local function go(movefunc)

  local moved = false
  local retry = 0

  while moved == false and retry < 10 do

    if retry > 0 then
      if movefunc == turtle.forward and turtle.detect() == false then
        turtle.attack()
      end
      os.sleep(0.5)
    end

    if movefunc == turtle.forward and turtle.detect() then
      turtle.dig()
    end

    moved = movefunc()
    retry = retry + 1

  end

  if moved == false then
    error("failed to move turtle")
  end

end

-- docking station is assumed to be 0,1
-- chest is assumed to be -1,1

for loopy=1,y do
  for loopx=1,x do

    -- check fuel level

    if turtle.getFuelLevel() < (loopx + loopy + 128) then
      error("Not enough fuel")
    end

    -- go to the initial square (1,1)

    go(turtle.forward)

    -- find the column we are working on

    col = 1
    turtle.turnRight()

    while col < loopy do
      go(turtle.forward)
      col = col + 1
    end

    -- find the row we are working on

    row = 1
    turtle.turnLeft()

    while row < loopx do
      go(turtle.forward)
      row = row + 1
    end

    -- dig to bedrock

    depth = 0

    while depth < z and (turtle.detectDown() == false or turtle.digDown()) do
      go(turtle.down)
      depth = depth + 1
    end

    for loopz=1,depth do
      go(turtle.up)
    end

    -- return home
    turtle.turnLeft()

    while col > 1 do
      go(turtle.forward)
      col = col - 1
    end

    turtle.turnLeft()

    while row > 0 do
      go(turtle.forward)
      row = row - 1
    end

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

    turtle.turnRight()
    turtle.turnRight()

  end
end