local FUEL_SLOT = 14
local EMPTY_SLOT = 13
local SEEDS_SLOT = 4

local function farmSquare()
   if turtle.digDown() then
      -- TODO Check if out of seed
      turtle.select(SEEDS_SLOT)
      if not turtle.placeDown() then turtle.digDown() turtle.placeDown() end
   end
   return true
end

while true do
   if turtle.getFuelLevel() < 200 then
      error("Not enough fuel")
   end
   turn = true
   for i=1,4 do
      while turtle.forward() do
         if not farmSquare() then return end
      end
      turnFunc = turtle.turnRight
      if (turn) then turnFunc = turtle.turnLeft end
      turnFunc()
      turtle.forward()
      farmSquare()
      turnFunc()
      turn = not turn
   end

   sleep(420) -- 7 minutes
end