tunnel

x = 0
invenSlot = 2
size = 0
completed = 0

function tunnel()
  turtle.turnLeft()
  turtle.dig()
  turtle.forward()
  turtle.digUp()
  turtle.up()
  turtle.digUp()
  turtle.turnRight()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  turtle.digUp()
  turtle.dig()
  turtle.forward()
  turtle.digUp()
  turtle.digDown()
  turtle.down()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  x=x+1
end

function back()
  i = 0
  while i <= x do
    turtle.back()
    i = i +1
end
end
function forward()
  i = 0
  while i <= x do
    turtle.forward()
    i = i +1
end
end

function checkFuel()
  if turtle.getFuelLevel() < 100 then
    turtle.select(1)
    turtle.refuel(1)
  end
end

function deposit()
  back()
  inventSlot = 2
  turtle.turnLeft()
  turtle.turnLeft()
  while invenSlot <= 16 do
    turtle.select(invenSlot)
    turtle.drop()
    invenSlot = invenSlot + 1
  end
      invenSlot = 2
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.select(2)
  if completed == 0 then
    forward()
  end
end

function checkFill()
  if turtle.getItemCount(16) > 0 then
  deposit()
  end
end

function program()
  size = 50
  while size > x do
    checkFuel()
    checkFill()
    tunnel()
  end
  completed = 1
  deposit()
end

program()