function getSaplings()
  repeat
    turtle.suckDown()
    if not turtlelib.isEqual(turtle.getItemDetail(), 'minecraft:sapling') then
      turtle.drop()
    end
  until turtle.getItemCount() > 0
end

function fellTree()
    repeat
      os.sleep(1)
    until turtlelib.isInFront("minecraft:log")
    turtle.select(2)
    turtle.dig()
    turtle.forward()
    local height = 0
    while turtlelib.isAbove('minecraft:log') do
      turtle.digUp()
      turtle.up()
      height = height + 1
    end
    for i=height,0,-1 do
      turtle.down()
    end
    turtle.back()
end  
 
os.loadAPI('turtlelib')
while true do
  fellTree()
  turtle.turnLeft()
  turtle.forward()
  turtle.forward()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
  turtle.select(2)
  if turtle.getFuelLevel() < 200 then
    turtle.select(16)
    turtle.digUp()
    turtle.up()
    turtle.digUp()
    turtle.up()
    turtle.dropDown()
    turtle.select(2)
    turtle.forward()
    turtle.dropDown(turtle.getItemCount() / 2)
    turtle.back()
    turtle.down()
    turtle.drop()
    turtle.down()
    turtle.forward()
    os.sleep(60)
    turtle.suckUp()
    turtle.refuel()
    turtle.back()
  end
  turtle.select(2)
  turtle.down()
  turtle.drop()
  turtle.select(1)
  if turtle.getItemCount() == 0 then
    turtle.turnLeft()
    turtle.forward()
    getSaplings()
    turtle.back()
    turtle.turnRight()
  end
  turtle.up()
  turtle.turnRight()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.forward()
  turtle.turnLeft()
  turtle.place()
end