local function checkFuel()
  if turtle.getFuelLevel() < 20 then
    turtle.select(1)
    turtle.refuel(1)
  end
end

local function column()
  local height = 0
  while turtle.digUp() do
    turtle.dig()
    checkFuel()
    turtle.up()
    height = height + 1
  end
  turtle.dig()

  checkFuel()
  
  return height
end

local function columnDown(height)
  for i=1,height do
    checkFuel()
    turtle.dig()
    turtle.digDown()
    turtle.down()
  end
  turtle.dig()
end

local function digmove()
  checkFuel()
  turtle.dig()
  turtle.forward()
end

local function fell()
  digmove()
  local height = column()
  turtle.turnRight()
  digmove()
  turtle.turnLeft()
  columnDown(height)
end

local function replant()
  turtle.select(15)
  turtle.suck()
  turtle.place()
  turtle.turnLeft()
  turtle.suck()
  turtle.forward()
  turtle.suck()
  turtle.turnRight()
  turtle.suck()
  turtle.place()
  turtle.turnRight()
  turtle.suck()
  turtle.place()
  turtle.turnRight()
  turtle.suck()
  turtle.forward()
  turtle.suck()
  for slot=3,7 do
    turtle.select(slot)
    turtle.drop()
  end
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.select(15)
  turtle.place()
  turtle.select(2)
  while not turtle.compare() do
    turtle.select(16)
    turtle.place()
    turtle.select(2)
  end
end

function needCoal()
  return turtle.getItemCount(1) < 10
end

function needBonemeal()
  return turtle.getItemCount(16) < 10
end

function getCoal()
  turtle.turnRight()
  turtle.forward()
  turtle.forward()
  while turtle.getItemCount(1) < 60 do
    sleep(0.5)
  end
  turtle.turnRight()
  turtle.turnRight()
  turtle.forward()
  turtle.forward()
  turtle.turnRight()
end  

function getBonemeal()
  turtle.turnLeft()
  turtle.forward()
  while turtle.getItemCount(16) < 60 do
    sleep(0.5)
  end
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnLeft()
end

while true do
  fell()
  replant()
  if needCoal() then
    getCoal()
  end
  if needBonemeal() then
    getBonemeal()
  end
end