FellingTurtle

local line = 0
local active = false

local function Info(str, cls)
 if (cls) then
  term.clear()
  term.setCursorPos(1, 1)
 end

 print(str)
end

local function Refuel()
 if (turtle.getFuelLevel() == 0) then
  local sl = 1

  turtle.select(16)

  Info("Exepted refueling...", true)

  while (not turtle.refuel(1)) do sleep(1) end

  Info("Refueling is complete!", false)
  turtle.select(sl)
 end
end

local function Init()
 Info("Need wood block!", true)
 while (turtle.getItemCount(1) == 0) do sleep(1) end

 Refuel()
 turtle.dig()
 turtle.suck()
 turtle.forward()

 active = true
end

Init()

while active do
 Refuel()

 if (turtle.compare()) then
  turtle.dig()
  turtle.suck()

  if (line % 2 == 0) then
   turtle.digUp()
   turtle.suckUp()
   turtle.up()
  else
   turtle.digDown()
   turtle.suckDown()
   turtle.down()
  end
 else
  line = line + 1

  if (line == 1) then
   turtle.dig()
   turtle.suck()
   turtle.forward()
   turtle.turnRight()
   turtle.dig()
   turtle.suck()
   turtle.forward()
   turtle.turnRight()
   turtle.dig()
   turtle.suck()
   turtle.digDown()
   turtle.suckDown()
   turtle.down()
  elseif (line == 2) then
   turtle.up()
   turtle.forward()
   turtle.forward()

   Info("Felling the tree is complete.", true)
   active = false

  end
 end
end