function refuel()
	if turtle.getFuelLevel() < 15 then
		turtle.select(1)
		turtle.refuel(1)
	end
end

function interactTree(right)
	a, b = turtle.inspect()
	if a then
		if b.name == "minecraft:sapling" then
		elseif b.name == "minecraft:log" then
			mineTree(right)
		else
			print("WARNING: Unknown block found: ", b.name)
			turtle.dig()
			plantSaplings(right)
		end
	else
		--plantSaplings()
	end
end

function plantSaplings(right)
	refuel()
	findItem("minecraft:sapling")
	if right then
		turtle.forward()
		turtle.forward()
		turtle.turnLeft()
		turtle.place()
		turtle.turnRight()
		turtle.back()
		turtle.place()
		turtle.turnLeft()
		turtle.place()
		turtle.turnRight()
		turtle.back()
		turtle.place()
	else
		turtle.forward()
		turtle.forward()
		turtle.turnRight()
		turtle.place()
		turtle.turnLeft()
		turtle.back()
		turtle.place()
		turtle.turnRight()
		turtle.place()
		turtle.turnLeft()
		turtle.back()
		turtle.place()
	end
end

function mineTree(right)
	refuel()
	turtle.dig()
	turtle.forward()
	while true do
		refuel()
		turtle.dig()
		turtle.digUp()
		turtle.up()
		a, b = turtle.inspectUp()
		if a then
			if not b.name == "minecraft:log" then
				break
			end
		else
			break
		end
	end
	turtle.digUp()
	turtle.up()
	turtle.dig()
	if right then
		turtle.turnRight()
		turtle.forward()
		turtle.turnLeft()
	else
		turtle.turnLeft()
		turtle.forward()
		turtle.turnRight()
	end
	while true do
		refuel()
		turtle.dig()
		turtle.digDown()
		turtle.down()
		a, b = turtle.inspectDown()
		if a then
			if not b.name == "minecraft:log" then
				break
			end
		else
			break
		end
	end
	if right then
		turtle.turnRight()
		turtle.forward()
		turtle.turnRight()
		turtle.forward()
		turtle.turnRight()
	else
		turtle.turnLeft()
		turtle.forward()
		turtle.turnLeft()
		turtle.forward()
		turtle.turnLeft()
	end
end

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

function harvest()
	-- Go forward one lane
	for i=1, 7 do
		refuel()
		turtle.turnLeft()
		interactTree(false)
		turtle.turnRight()
		turtle.turnRight()
		interactTree(true)
		turtle.turnLeft()
		turtle.forward()
		turtle.forward()
		turtle.forward()
	end

	-- Switch to right next lane

	turtle.turnRight()
	for i=1, 6 do
		refuel()
		turtle.forward()
	end
	turtle.turnRight()

	turtle.forward()
	turtle.forward()

	-- Go forward one lane

	for i=1, 7 do
		refuel()
		turtle.turnLeft()
		interactTree()
		turtle.turnRight()
		turtle.turnRight()
		interactTree()
		turtle.turnLeft()
		turtle.forward()
		turtle.forward()
		turtle.forward()
	end

	-- Switch to left next lane

	turtle.turnLeft()
	for i=1, 6 do
		refuel()
		turtle.forward()
	end
	turtle.turnLeft()

	turtle.forward()
	turtle.forward()

	-- Go forward one lane

	for i=1, 7 do
		refuel()
		turtle.turnLeft()
		interactTree()
		turtle.turnRight()
		turtle.turnRight()
		interactTree()
		turtle.turnLeft()
		turtle.forward()
		turtle.forward()
		turtle.forward()
	end

	-- Switch to right next lane

	turtle.turnRight()
	turtle.forward()
	turtle.forward()
	turtle.forward()
	turtle.turnRight()
	turtle.forward()
	turtle.forward()

	-- Go forward one lane

	for i=1, 7 do
		refuel()
		turtle.turnLeft()
		interactTree()
		turtle.turnRight()
		turtle.forward()
		turtle.forward()
		turtle.forward()
	end
	turtle.turnRight()
	for i=1, 15 do
		refuel()
		turtle.forward()
	end
	turtle.turnLeft()
	turtle.forward()

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

startup()
harvest()