SAPLING = "minecraft:sapling"--always be slot 2
LOG = "minecraft:log"
FUEL = "minecraft:coal"
--charcoal always slot 1
WIDTH = 2
LENGTH = 11

DELAY = 60 -- seconds

move = 3

function dropLoot()
	local data = turtle.getItemDetail(1)
	if data and data.name ~= FUEL then
		turtle.dropDown(1)
	end
	for i=3,16 do
		turtle.dropDown(i)
	end
end

function refuel()
	local data = turtle.getItemDetail(1)
	if data and data.name == FUEL then
		turtle.select(1)
		turtle.suckDown(64-data.count)
		turtle.refuel()
	else
		turtle.select(1)
		turtle.suckDown(64)
		turtle.refuel()
	end
end

function estimateFuelNeed()
	return WIDTH * LENGTH * 5 * 5
end

function fell()
	refuel()
	if turtle.getFuelLevel() < estimateFuelNeed() then
		return false
	end
	for w=1,WIDTH do
		for i=1,LENGTH do
			for j=1,move do
				while not turtle.forward() do
					turtle.dig()
				end
			end
			local s,d = turtle.inspectDown()
			local saplinginfo = turtle.getItemDetail(2)
			if s then
				if d.name == SAPLING then
					--keep moving, it aint done yet
				elseif d.name == LOG then
					--break all the logs and replant
					turtle.digDown()
					local count = 0
					local s_, d_ = turtle.inspectUp()
					while s_ and d_.name == LOG do
						turtle.digUp()
						turtle.up()
						count = count + 1
						s_, d_ = turtle.inspectUp()
					end
					for j=1,count do
						turtle.down()
					end
					turtle.select(2)
					turtle.placeDown()
				end
			else
				--there should be a sapling or a log here..
				--replanting anyway
				turtle.select(2)
				turtle.placeDown()
			end
			turtle.suck()
			if i ~= LENGTH then
				move = 5
			elseif w == WIDTH then
				for j=1, 3 do
					while not turtle.forward() do
						turtle.dig()
					end
				end
				turtle.turnRight()
				for j=1, 3 do
					while not turtle.forward() do
						turtle.dig()
					end
				end
				dropLoot()
				for j=1, 2 do
					while not turtle.forward() do
						turtle.dig()
					end
				end
				turtle.turnRight()
			else
				move = 5
				turtle.turnRight()
				for j=1, 5 do
					while not turtle.forward() do
						turtle.dig()
					end
				end
				turtle.turnRight()
			end
		end
	end
	return true
end

while true do
	if not fell() then
		print('couldnt start, not enough fuel. need at least ' .. estimateFuelNeed())
	end
	os.sleep(DELAY)
end