Tree chopper

local invalid = true
local width
local height = 0

repeat
  print( "How many blocks wide is the tree?" )
  width = tonumber(io.read())
  if width < 1 then
    print( "Tree width must be at least 1 block!" )
    invalid = true
  end
  if width > 2 then
    print( "Max width for Tree is 2 blocks" )
    invalid = true
  end
  if (width >=1) and (width <=2) then
    print( "Chopping " .. width .. " wide tree")
    invalid = false
  end
until invalid == false

if width == 1 then
  if turtle.detect() then
    turtle.dig()
    turtle.forward()
  end
  while turtle.detectUp() do
    turtle.digUp()
    turtle.up()
    height=height+1
  end
  for i=1,height do
    turtle.down()
  end
end

if width == 2 then
  if turtle.detect() then
    turtle.dig()
    turtle.forward()
  end
  while turtle.detect() do
    turtle.dig()
    turtle.turnRight()
    if turtle.detect() then
      turtle.dig()
    end
    turtle.turnLeft()
    if turtle.detectUp() then
      turtle.digUp()
      turtle.up()
      height=height+1
    end
  end
  turtle.forward()
  turtle.turnRight()
  if turtle.detect() then
    turtle.dig()
  end
  turtle.forward()
  turtle.turnLeft()
  for i=1,height do
    turtle.digDown()
    turtle.down()
  end
end