Force tree farm

height = 0
treeNum = 1

function moveUp()
	if turtle.up() then
		height = height + 1
	end
end

function moveDown()
	if turtle.down() then
		height = height - 1
	end
end

function moveTo(h)
	while h < height do
		moveDown()
	end
	while h > height do
		moveUp()
	end
end

function checkGrow()
	turtle.select(1)
	return not turtle.compare()
end

function getSapling()
	print("Checking saplings.")
	if turtle.getItemCount(1) < 10 then
		print("Getting new saplings.")
		turtle.select(1)
		turtle.turnLeft()
		turtle.suck()
		turtle.turnRight()
	end
end

function dropOff()
	print("Dropping off items.")
	turtle.turnRight()
	num = 2
	while turtle.getItemCount(num) > 0 do
		turtle.select(num)
		turtle.drop()
		num = num + 1
	end
	turtle.select(1)
	turtle.turnLeft()
end

function checkFuel()
	print("Checking fuel ("..turtle.getFuelLevel()..").")
	while turtle.getFuelLevel() < 1000 do
		print("Refueling...")
		turtle.select(2)
		turtle.refuel(1)
		if turtle.getItemCount(2) == 0 then
			print("No wood to refuel with.")
			break
		end
	end
	if turtle.getFuelLevel() < 100 then
		print("Fuel at critical level, ended program.")
		return false
	end
	return true
end

function chopTree()
	print("Chopping tree down.")
	while turtle.detect() do
		turtle.dig()
		turtle.digUp()
		moveUp()
	end
	print("Detected no more tree at height "..height..".")
	moveTo(0)
	turtle.select(1)
	print("Placing sapling.")
	while not turtle.place() do
		os.sleep(1)
	end
	if not checkFuel() then
		return false
	end
	getSapling()
	dropOff()
	return true
end

while true do
	if checkGrow() then
		print("Detected tree number "..treeNum)
		if not chopTree() then
			break
		end
		treeNum = treeNum + 1
	else
		os.sleep(10)
	end
end