Create a new version of paste:

-- Chopper
-- ----------------------------------------------------------

-- Efficiency test; can this turtle provide a semi-decent
-- income of wood/charcoal?

-- For those reading, plan is to add a companion turtle that
-- uses the resulting (minor) power generation to produce
-- supplies of various building blocks. Stone bricks,
-- glass, planks, etc.

-- And then a third that'll build a base from those blocks.

-- ----------------------------------------------------------

-- Initialise important values:

-- ----------------------------------------------------------

-- Load locations of interest:
shell.run("node")

local facing = {"north","east","south","west"}
local pos, report = {}
local modem = peripheral.wrap("right")

-- Number of inventory servers (that should be) online:
local invServerCount, invServer = 0, {}

-- ----------------------------------------------------------

-- Functions and stuff:

-- ----------------------------------------------------------

-- Tell the turtle server I'm alive.
local function doTurtleServerReport()
	rednet.send(report,{"Hello TurtleServer",os.getComputerLabel()})
	report = nil
end

-- Poll the inventory servers re a given barrel.
local function getAmountOf(barreltype)
	local myMessage
	for i=1,3 do
		for i=1,invServerCount do rednet.send(invServer[i],barreltype) end
		myMessage = {rednet.receive(3)}
		if myMessage and tonumber(myMessage[2]) then break end
	end
	
	if not tonumber(myMessage[2]) then
		print("Warning: Could not get reading for amount of "..barreltype..".")
		return 0
	else return tonumber(myMessage[2]) end
end

-- Check if the barrels I fill are filled.
local function barrelsFull()
	for i=1,#barrel do if getAmountOf(barrel[i]) < 4096 then return false end end
	return true
end

-- Returns true if the turtle is carrying anything.
local function carrying()
	for i=1,16 do if turtle.getItemCount(i) ~= 0 then return true end end
	return false
end

-- Accepts strings representing compass-facings to turn the turtle.
local function faceDirection(targetdirection)
	local tardir = 1
	for i=1,4 do if targetdirection == facing[i] then tardir = i end end
	
	if tardir < pos.direction then
		if tardir == 1 and pos.direction == 4 then
			while not turtle.turnRight() do end
		else
			for i=1,pos.direction-tardir do while not turtle.turnLeft() do end end
		end
	elseif tardir > pos.direction then
		if tardir == 4 and pos.direction == 1 then
			while not turtle.turnLeft() do end
		else
			for i=1,tardir-pos.direction do while not turtle.turnRight() do end end
		end
	end
	
	pos.direction = tardir
end

-- Move ahead a block, keeping track of the turtle's position.
local function forward()
	while not turtle.forward() do
		turtle.dig()
		turtle.attack()
	end
	
	if pos.direction == 1 then pos.y = pos.y - 1
	elseif pos.direction == 2 then pos.x = pos.x + 1
	elseif pos.direction == 3 then pos.y = pos.y + 1
	else pos.x = pos.x - 1 end
end

local function turn(tardir)
	if tardir == "left" then
		while not turtle.turnLeft() do end
		pos.direction = pos.direction - 1
		if pos.direction < 1 then pos.direction = 4 end
	elseif tardir == "right" then
		while not turtle.turnRight() do end
		pos.direction = pos.direction + 1
		if pos.direction > 4 then pos.direction = 1 end
	end
end

-- Travel to a co-ordinate.
local function goToPos(target,digger)
	while (pos.x ~= node[target][1]) or (pos.y ~= node[target][2]) or (pos.z ~= node[target][3]) do
		if pos.z > node[target][3] then
			if digger then
				while not turtle.down() do
					turtle.digDown()
					turtle.attackDown()
				end
				pos.z = pos.z - 1
			elseif turtle.down() then pos.z = pos.z - 1 end
		elseif pos.z < node[target][3] then
			if digger then
				while not turtle.up() do
					turtle.digUp()
					turtle.attackUp()
				end
				pos.z = pos.z + 1
			elseif turtle.up() then pos.z = pos.z + 1 end
		end
		
		if pos.x > node[target][1] then
			if pos.direction ~= 4 then faceDirection("west") end
			if digger then forward() elseif turtle.forward() then pos.x = pos.x - 1 end
		elseif pos.x < node[target][1] then
			if pos.direction ~= 2 then faceDirection("east") end
			if digger then forward() elseif turtle.forward() then pos.x = pos.x + 1 end
		end
		
		if pos.y > node[target][2] then
			if pos.direction ~= 1 then faceDirection("north") end
			if digger then forward() elseif turtle.forward() then pos.y = pos.y - 1 end
		elseif pos.y < node[target][2] then
			if pos.direction ~= 3 then faceDirection("south") end
			if digger then forward() elseif turtle.forward() then pos.y = pos.y + 1 end
		end
	end
	
	faceDirection(node[target][4])
end

-- Refuel the turtle itself.
local function goGetFuel()
	print("I'm hungry. Off to eat some EU...")
	goToPos(3)
	print("OMNOMNOM")
	turtle.select(10)
	while turtle.getFuelLevel() < 5000 do
		turtle.suckUp()
		turtle.refuel() 
		sleep(1)
	end
	print("Ah, that hit the spot!")
	print("")
end

-- Dumps the turtle's inventory into the dropoff chest.
local function dropOff()
	print("Dropping off loot...")
	
	local safe = false
	if (node[1][4] == "north" and pos.y < node[8][2]) or
	   (node[1][4] == "east"  and pos.x > node[8][1]) or
	   (node[1][4] == "south" and pos.y > node[8][2]) or
	   (node[1][4] == "west"  and pos.x < node[8][1]) then safe = true end
	
	goToPos(8,safe)
	while not turtle.down() do turtle.attackDown() end
	pos.z = pos.z - 1
	for i=1,16 do if turtle.getItemCount(i) ~= 0 then
		turtle.select(i)
		turtle.dropDown()
	end end
	turtle.select(1)
	print("")
end

-- Roam the plot collecting and planting.
local function harvest()
	print("I'm a lumberjack and I'm OK!")
	print("")
	
	if node[10][1] then
		goToPos(10,true)
		node[10] = {}
	else
		forward()
		pos.lastX, pos.lastY = 1, 1
	end
	
	for xx = pos.lastX,16 do
		for yy = pos.lastY,16 do
			-- Check if a return to base is required.
			if turtle.getFuelLevel() < 1000 or turtle.getItemCount(15) == 0 or turtle.getItemCount(14) > 0 then
				node[10][1] = pos.x
				node[10][2] = pos.y
				node[10][3] = pos.z
				node[10][4] = facing[pos.direction]
				pos.lastX = xx
				pos.lastY = yy
				return
			end
			
			-- Combine sapling piles.
			if turtle.getItemCount(15) < 5 then
				for i=1,14 do if turtle.getItemCount(i) ~= 0 then
					turtle.select(i)
					if turtle.compareTo(15) then turtle.transferTo(15) end
					if turtle.getItemCount(15) == 64 then break end
				end end
			end
			
			if turtle.detectDown() then
				-- Dig out the current column if need be.
				turtle.select(1)
				while turtle.detectUp() do
					while not turtle.up() do turtle.digUp() end
					pos.z = pos.z + 1
					for i=1,4 do
						while turtle.detect() do turtle.dig() end
						while not turtle.turnRight() do end
					end
				end
				while pos.z > node[1][3] do
					while not turtle.down() do turtle.digDown() end
					pos.z = pos.z - 1
				end
			end
			
			-- Re-plant.
			turtle.select(16)
			if turtle.compareDown() or not turtle.detectDown() then
				while turtle.compareDown() do turtle.digDown() end
				turtle.select(15)
				turtle.placeDown()
			end
			
			while turtle.suckDown() do end
			
			-- Move ahead.
			if yy < 16 then
				forward()
			elseif xx < 16 then
				if facing[pos.direction] == node[1][4] then
					turn("right")
					forward()
					turn("right")
				else
					turn("left")
					forward()
					turn("left")
				end
			end
			
			if report then doTurtleServerReport() end
		end
	end
end

-- ----------------------------------------------------------

-- Primary functions:

-- ----------------------------------------------------------

-- Deal with rednet.
local function turtleServer()
	local turtleServerTimeOut, myEvent = os.startTimer(0)
	while true do
		myEvent = {os.pullEvent()}
		if myEvent[1] == "timer" and myEvent[2] == turtleServerTimeOut then
			report = 65535
			turtleServerTimeOut = os.startTimer(600)
		elseif myEvent[1] == "rednet_message" and myEvent[3] == "Hey, you still there?" then
			report = myEvent[2]
			turtleServerTimeOut = os.startTimer(600)
		end
	end
end

-- Primary work loop.
local function main()
	while true do
		print("Base maintenance...")
		print("")

		if carrying() then dropOff() end      -- Ensure I'm not carrying spare stuff.

		if turtle.getFuelLevel() < 1000 then goGetFuel() end

		goToPos(4)                            -- Goto log barrel, get logs.
		turtle.select(1)
		turtle.suckUp()
		goToPos(6)                            -- Goto furnace, drop logs.
		turtle.drop()
		goToPos(9)                            -- Collect charcoal from furnace.
		turtle.select(2)
		turtle.suckDown()
		goToPos(7)                            -- Goto generator, drop charcoal.
		turtle.drop()
		if carrying() then dropOff() end

		goToPos(2)                            -- Goto sapling barrel, get saplings.
		turtle.select(15)
		turtle.suckUp()

		while turtle.getItemCount(15) == 0 do
			print("Oy! No saplings! Waiting a minute...")
			sleep(60)
			turtle.suckUp()
		end

		if turtle.getItemCount(16) == 0 then
			goToPos(4)                    -- Goto log barrel, get log(s) for comparisons.
			turtle.select(16)
			turtle.suckUp()
		end

		goToPos(8)
		goToPos(1,true)                       -- Prepare to harvest.
		
		--if barrelsFull() then
		--	print("I've filled my barrels, guess I'll take a breather...")
		--	print("")
		--	while barrelsFull() do
		--		sleep(60)
		--		if report then doTurtleServerReport() end
		--	end
		--end
		
		harvest()
	end
end

-- ----------------------------------------------------------

-- I've just booted up. Where am I? Who am I? etc...

-- ----------------------------------------------------------

-- Ping the GPS servers until I get a valid reading:
do
	local counter, tempx, tempy, tempz = 0
	while tempx == nil or tempy == nil or tempz == nil do
		tempx, tempz, tempy = gps.locate(5)
		sleep(5)
	end
	
	while not turtle.forward() do
		while not turtle.turnLeft() do end
		counter = counter + 1
		if counter == 20 then -- I really don't wanna do this
			counter = 0
			turtle.dig()
		end
	end
	
	pos.x,pos.z,pos.y = gps.locate(5)

	if pos.x < tempx then pos.direction = 4
	elseif pos.x > tempx then pos.direction = 2
	elseif pos.y < tempy then pos.direction = 1
	else pos.direction = 3 end
end

-- Broadcast until all inventory servers are identified.
rednet.open("right")
while #invServer < invServerCount do
	rednet.broadcast("Hello InvServer")
	local myTimer = os.startTimer(5)
	while true do
		local myEvent = {os.pullEvent()}
		if myEvent[1] == "timer" and myEvent[2] == myTimer then
			break
		elseif myEvent[1] == "rednet_message" and myEvent[3] == "Hello, InvServerClient!" then
			invServer[#invServer+1] = myEvent[2]
			for i=1,#invServer-1 do if invServer[i] == invServer[#invServer] then invServer[#invServer] = nil end end
			if #invServer == invServerCount then break end
		end
	end
end

print("I'm at "..pos.x..","..pos.y..","..pos.z..", I have "..turtle.getFuelLevel().." fuel and I'm facing "..facing[pos.direction]..".")
print("")

parallel.waitForAny(main, turtleServer)