local levelHeight = 3
local currLevel = 0
local maxLevel = 5

function refuel()
	if turtle.getFuelLevel() < 5 then
		turtle.select(1)
		turtle.refuel(1)
	end
end

function startup()
	refuel()
	turtle.up()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
end

function harvest(level)
	goToLevel(level)
	turtle.turnLeft()
	turtle.turnLeft()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.turnRight()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.turnRight()

	for j=1, 4 do
		for i=1, 8 do
			refuel()
			harvestCrop()
			turtle.forward()
		end
		turtle.turnRight()
		turtle.forward()
		harvestCrop()
		turtle.turnRight()
		for i=1, 8 do
			refuel()
			harvestCrop()
			turtle.forward()
		end
		turtle.turnLeft()
		harvestCrop()
		turtle.forward()
		turtle.turnLeft()
	end
	for i=1, 8 do
		refuel()
		harvestCrop()
		turtle.forward()
	end
	harvestCrop()
	turtle.turnLeft()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.turnLeft()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.turnLeft()
	turtle.turnLeft()
end

function harvestCrop()
	a, b = turtle.inspectDown()
	if a then
		if b.state.age == 3 then
			turtle.select(2)
			turtle.digDown()
			turtle.placeDown()
		end
	end
end

function goToLevel(level)
	if level == currLevel then
		return
	end
	refuel()
	turtle.forward()

	local blocksDown = 0

	while not turtle.detectDown() do
		refuel()
		if turtle.down() then
			blocksDown = blocksDown + 1
		end
	end

	for i=2, 16 do
		turtle.select(i)
		turtle.dropDown()
	end

	for i=1, blocksDown do
		refuel()
		while not turtle.up() do
			os.sleep(0.1)
		end
	end

	if currLevel < level then
		for i=1, level - currLevel do
			for i=1, levelHeight do
				refuel()
				turtle.up()
			end
		end
	end

	if currLevel > level then
		for i=1, currLevel - level do
			for i=1, levelHeight do
				refuel()
				turtle.down()
			end
		end
	end

	turtle.back()
	currLevel = level
end

function checkHarvest()
	for level=0, maxLevel do
		harvest(level)
	end
end

startup()
while true do
	checkHarvest(currLevel)
	goToLevel(0)
	os.sleep(60 * 5)
end