Computercraft - snake pattern mining

-- snake

os.loadAPI("path")
os.loadAPI("dig")

local foundBlockToMine = 0

function digIt()
  path.forward()

  -- Algorithm continuation: while nothing detected 'up', simply move on. First time we find something, start being throrough again.
  if turtle.detectUp() and foundBlockToMine == 0 then
    foundBlockToMine = 1
    print("* Found first block to mine, being thorough now")
  end
  if foundBlockToMine == 0 then return end

  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.up()
  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.up()
  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.up()
  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.up()
  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.up()
  dig.leftWithoutMoving()
  dig.rightWithoutMoving()

  dig.down()
  dig.down()
  dig.down()
  dig.down()
  dig.down()
end

function placeTorch()
  turtle.turnLeft()
  if turtle.getItemCount(16) > 0 then
    turtle.select(16)
    turtle.place()
    turtle.select(1)
  else
    print("* No torches in inventory to place")
  end
  turtle.turnRight()
end

function fuelCheck()
  if path.length() + 50 > turtle.getFuelLevel() then
    print("* I'm about to go out of fuel, going back")
    path.navigateBack()
    print("* I'm back. Emptying and shutting down.")
    emptyInventory()
    quit()
  end
end

function fullCheck()
  if turtle.getItemCount(15) > 0 then
    print("* My 15th slot is used. Heading back to empty.")
    path.navigateBack()
    print("* I'm back, emptying!")
    emptyInventory()
    if (path.length() * 2) + 50 > turtle.getFuelLevel() then
      print("* Fuel is kind of low, not heading out!")
      quit()
    else
      print("* Heading out again!")
      path.navigateForward()
    end
  end
end

function emptyInventory()
  print("* Finding something to drop items in!")
  if turtle.detect() then
    emptyInventoryFront()
  end
  turtle.turnLeft()
  if turtle.detect() then
    emptyInventoryFront()
  end
  turtle.turnLeft()
  if turtle.detect() then
    emptyInventoryFront()
  end
  turtle.turnLeft()
  if turtle.detect() then
    emptyInventoryFront()
  end
  turtle.turnLeft()
end

function emptyInventoryFront()
  print("* Found something, dropping items!")
  for l = 1, 15 do
    turtle.select(l)
    turtle.drop()
  end
  turtle.select(1)
end

-- Q: Length of the lane?
local lanelength = 0
term.write("Length of the lane (#)? ")
lanelength = tonumber(read())

-- Q: Do we go LEFT or RIGHT at end of lane?
local leftright = ""
term.write("Left or Right at end (L/R)? ")
leftright = read()
local leftrightmod = 1
if leftright == "l" or leftright == "L" then
  leftrightmod = 0
end

-- Q: How many lanes?
local lanecount = 0
term.write("How many lanes (#)? ")
lanecount = tonumber(read())

-- Q: Start at lane?
local offset = 0
term.write("Lane offset (#)? ")
offset = tonumber(read()) * 5

-- Simple fuel check before we start
if turtle.getFuelLevel() < 100 then
  print("* Fuel me first, mister!")
  quit()
end

-- Offsets?
if offset > 0 and leftrightmod == 1 then
  path.right()
  for i = 1, offset do
    path.forward()
  end
  path.left()
end
if offset > 0 and leftrightmod == 0 then
  path.left()
  for i = 1, offset do
    path.forward()
  end
  path.right()
end

-- Go through lanes
for i = 1, lanecount do
  print("* Proceeding with lane "..i)

  -- Go through the current lane
  for j = 1, lanelength do
    fuelCheck()
    fullCheck()
    digIt()
    if j % 7 == 0 then placeTorch() end
  end

  -- If this was the last lane, break out
  if i < lanecount then
    -- When we finished a lane and there's more to do, move a bit for the next lane
    print("* Going around the corner!")
    digIt()
    path.back()
    if i % 2 == leftrightmod then
      -- Turn right
      path.right()
      digIt()
      digIt()
      digIt()
      digIt()
      digIt()
      digIt()
      path.back()
      path.right()
    else
      -- Turn left
      path.left()
      digIt()
      digIt()
      digIt()
      digIt()
      digIt()
      digIt()
      path.back()
      path.left()
    end
  end
end

-- All done
print("* All done! Heading back.")
path.navigateBack()
emptyInventory()
print("* Shutting down!")