Tree Feller

print("Place saplings in slot 1 and bonemeal in slot 2")
print("Place 1 sapling in slot 13 and 1 bonemeal in slot 14")

local i = 1
local p = 1
local v = 1
local fuel = turtle.getFuelLevel()
local tArgs = { ... }

if #tArgs ~= 1 then
    print("Please rate lag 1-20 (20 being the worst)")
    return
end

local function bonemeal()
  turtle.forward()
  turtle.forward()
  turtle.select(1)
  turtle.place()
  sleep(.1)
  turtle.select(2)
  turtle.place()
  turtle.select(1)
end

local function checkdig()
    turtle.dig()
    turtle.forward()
    while true do
      if turtle.detectUp() then
        turtle.digUp()
        turtle.up()
        else turtle.down()
        if turtle.detectDown() then
          turtle.back()
          turtle.back()
          turtle.back()
          break
        end
      end
    end
end

local function checkfuel()
    term.clear()
    term.setCursorPos(1, 1)
    if turtle.getFuelLevel() < 100 then
       print("Please add fuel (At least 100)")
       print("Waiting for fuel, press the E key to refuel")
       print("Press Q to continue.")
       print("Press 1-8 to change slots")
       while true do
       local event, param1 = os.pullEvent("key")
       if param1 > 1 and param1 < 10 then
           local sel = param1 - 1
           turtle.select(sel)
       end
          if param1 == 18 then
              turtle.refuel()
              fuel = turtle.getFuelLevel()
             print(fuel.." Fuel")
          elseif param1 == 16 and fuel > 100 then
              print("Fuel Get!"..fuel.." fuel")
              break
          end
       end
    end
end

local lag = tonumber(tArgs[1])

if lag > 20 then
    print("Error:")
    print("Only numbers 1-20")
end

if lag == nil then
    print("Error")
    print("Numbers Only")
    return
else
    print(lag.."Lag")
end

local lag2 = lag + 20
local lag3 = lag2 * 2

while true do


    if turtle.getItemCount(1) <= 4 then
        print("Not enough saplings. Please refill")
        return
    elseif turtle.getItemCount(2) <= 3 then
        print("Not enough bonemeal. Please refill")
        return
    else
    end
    turtle.select(1)
    if turtle.compareTo(13) == false then
        print("Only spalings in slot 1")
        return
    end
    turtle.select(2)
    if turtle.compareTo(14) == false then
        print("Only bonemeal in slot 2")
        return
    end


  checkfuel()
  bonemeal()
  checkdig()
  for i=1, lag3 do
    turtle.suck()
    sleep(1)
    rs.setOutput("bottom", true)
  end
  rs.setOutput("bottom", false)
  sleep(1)
end