local self = turtle
local slots = {
  seeds = 1,
  bonemeal = 2,
  fuel = 3
}
local waitTill
waitTill = function(condition, compare, callback)
  if compare == nil then
    compare = true
  end
  while condition() ~= compare do
    if callback then
      callback()
    end
    os.sleep(0.1)
  end
  return true
end
self.fuel = function(amount)
  if amount == nil then
    amount = 100
  end
  local old = 1
  while self:getFuelLevel() < amount do
    print('Fuel level to low, put fuel in slot 16')
    self:select(slots.fuel)
    self:refuel()
    os.sleep(1)
  end
  return self:select(old)
end
self.forward = function(steps)
  if steps == nil then
    steps = 1
  end
  if steps < 1 then
    return true
  end
  self:fuel()
  waitTill(turtle.forward, true)
  return self:forward(steps - 1)
end
self.up = function(steps)
  if steps == nil then
    steps = 1
  end
  if steps < 1 then
    return true
  end
  self:fuel()
  waitTill(turtle.up, true)
  return up(steps - 1)
end
self.down = function(steps)
  if steps == nil then
    steps = 1
  end
  if steps < 1 then
    return true
  end
  self:fuel()
  waitTill(turtle.down, true)
  return down(steps - 1)
end
self.emptyDown = function(first, last)
  if first == nil then
    first = 1
  end
  if last == nil then
    last = 16
  end
  for slot = first, last do
    self:select(slot)
    self:dropDown()
  end
end
self.fertilize = function()
  local initial = self:getItemCount(slots.bonemeal)
  if initial < 2 then
    return false
  end
  self:select(slots.bonemeal)
  self:placeDown()
  if initial ~= self:getItemCount(slots.bonemeal) then
    self:fertilize()
  end
  return true
end
self.step = function()
  while not self:fertilize() do
    os.sleep(0.5)
  end
  self:select(slots.seeds)
  self:digDown()
  return self:forward()
end
self:forward()
while self:detectDown() do
  self:step()
end