Jackman 1.0

-- Jackman 1.0
-- by MCKerrnel
--
-- A ComputerCraft program to
-- operate a smalltree farm.
-- Turtle will chop down trees
-- and replant in the same cycle.

-- Size of farm grid that turtle
-- will traverse.
local width = 5
local length = 13

-- Fuel needed to start a cycle.
local fuelCycle = 250

-- Replants a sapling.
function plantTree()
	-- We are already one block
	-- above ground, so let's
	-- just place a sapling
	-- underneath us.
	turtle.select(1)
	turtle.placeDown()
end

-- Chops a tree down starting at
-- the base and going to top.
-- Does not work for anything
-- bigger than 1x1.
function chopTree()
	turtle.dig()
	turtle.forward()
	turtle.digDown()

	local vertical = 0
	while turtle.detectUp() do
		turtle.digUp()
		turtle.up()
		vertical = vertical + 1
	end

	while vertical > 0 do
		turtle.down()
		vertical = vertical - 1
	end

	-- Replant a new sapling.
	plantTree()
end

function chopCycle()
	local pass = 1
	local colPos = 1
	local rowPos = 1

	while pass <= 2 do
		for rowPos = 1, length, 1 do
			if turtle.detect() then
				chopTree()
			else
				turtle.forward()
			end
		end

		turtle.turnLeft()

		if pass == 1 then
			for colPos = 1, width, 1 do
				if turtle.detect() then
					chopTree()
				else
					turtle.forward()
				end
			end
			turtle.turnLeft()
		end
		pass = pass + 1
	end
end

-- Unloads the wood from the turtle
-- into the chest for wood.
function emptyWood()
	turtle.turnRight()
	for slot = 2, 16, 1 do
		turtle.select(slot)
		turtle.drop()
	end
	turtle.turnLeft()
end

-- A quick function to convert a decimal
-- value into an integer.  Dunno why
-- LUA has to be so difficult with this.
-- Should be a built-in function!
function toInt(decimalNum)
        local D2I = string.format("%i", decimalNum)
        return D2I
end

function refuel(fuelCycles)
        -- Refuel.  This is a regular turtle
        -- so can only hold 20,000 units.
        if fuelCycles < 1 then
		turtle.turnRight()
                turtle.select(2)

                -- Try to fill up, but if not enough to
                -- fill up, that's ok.
                while fuelCycles < 1 or turtle.getFuelLevel() < 20000 do
                        -- If there's nothing to grab, error out.
                        if turtle.suck() == false then
                                break
                        end
                        turtle.refuel()
                        fuelCycles = turtle.getFuelLevel() / fuelCycle
                end

                -- If we still need fuel
                -- then alert console.
                if fuelCycles < 1 then
                        print "NO FUEL: Reload the FUEL chest."
                end
		turtle.turnLeft()
        end
        return fuelCycles
end


-- MAINLINE
local fuelCycles = turtle.getFuelLevel() / fuelCycle
print("Enough fuel to chop ", toInt(fuelCycles), " cycles.")

-- This is where it all happens.
while true do
	-- Fuel Up
	fuelCycles = turtle.getFuelLevel() / fuelCycle
	if fuelCycles < 1 then
		fuelCycles = refuel(fuelCycles)
	end

	--Restock Saplings
	if turtle.getItemCount(1) < 7 then
		turtle.select(1)
		turtle.suckDown()
		if turtle.getItemCount(1) < 7 then
			print("NO SAPLINGS: Restock sapling chest!")
		end
	end

	if fuelCycles >= 1 and turtle.getItemCount(1) > 6 then
		-- Send turtle out to chop!
		turtle.up()
		chopCycle()

		-- Return to start
		for count = 1, 5, 1 do
			turtle.forward()
		end
		turtle.down()

		-- Empty inventory
		emptyWood()
		turtle.turnLeft()
	end

	sleep(300)
end