local tunnelLength = 50 -- <<< EDIT THIS for tunnel length!

function fuelLevel()
 if turtle.getFuelLevel() < 1000 then
  turtle.select(1)
  turtle.refuel(8)
  print("Refueled")
 end
end

function mine()
 while turtle.detect() do
  turtle.dig()
  sleep(0.5)
 end
 turtle.forward()

 for h = 1, height - 1 do
  if turtle.detectUp() then
   turtle.digUp()
   sleep(0.5)
  end
  turtle.up()
 end

 turtle.digDown()

 for h = 1, height - 1 do
  turtle.down()
 end
end

print("Place fuel in slot 1!")
print("How wide will the tunnel be?")
local x = tonumber(read())
print("How high will the tunnel be?")
height = tonumber(read())

while true do
 for i = 1, tunnelLength do
  fuelLevel()
  mine()
  turtle.turnLeft()
  for j = 1, math.floor(x / 2) do
   mine()
  end
  turtle.turnLeft()
  turtle.turnLeft()
  for j = 1, x - 1 do
   mine()
  end
  turtle.turnLeft()
  turtle.turnLeft()
  for j = 1, math.floor(x / 2) do
   turtle.forward()
  end
  turtle.turnRight()
 end

 -- Return to start
 turtle.turnLeft()
 turtle.turnLeft()
 for i = 1, tunnelLength do
  turtle.forward()
 end
 turtle.turnLeft()
 turtle.turnLeft()
end