--TurtleGrinder0.9
--by Shadow_8472
--This program intended for use on melee turtle, but most diamond tools will work.
--The basic operation:
--1 mob presses stone pressure plate directly to the front
--2 turtle attacks
--3 if no mobs or inventory full, then empty inventory
--4 stackables and non-stackables are output to chests (above and below recommended)
--5 a manual kill switch may be installed on one side of a row of attack turtles
--6 operations stop if there are problems with inventory, error signal can be hooked up to turn spawner off

--observed bug: Empty passed to itemOut(), likely just before a pulled event. A flick of the pressure plate should self fix it, but no such event is guaranteed 

--configuration variables
local aDownstream = "bottom"--side where non-stackable items go
local rDownstream = "top"--side where stackable items go
local rsUpstream = "left"--side to listen to for the manual kill
local rsDownstream = "right"--side to pass manual kill signal on to
local upstream = "back"--only side left, itemOut() requires it

--ItemOut, (int, string)
--outputs: bool: success/failure of appropriate turtle.drop() variant
local function itemOut(slot, out1) --(int,string)
	--This function outputs item to either accept or reject paths.
	--Though not used now, this function facilitates dynamic item
	--accept/reject paths. I suppose, if more outputs were needed,
	--they could be added via the first if else statement.
	if out1 == "accept" then--sort between accept and reject mode.
		out = aDownstream
	elseif out1 == "reject" then
		out = rDownstream
	else
		print("Invalid term: "..out1)
		return false--this function designed for only "accept" or "reject"
	end
	
	local mx = 10--number of times to try to output before declaring a failure
	local rt = false--variable rt is the return value saved for console report
	turtle.select(slot)
	for n = 1, mx do--try a few times 
		if rs.getAnalogueInput(out) > 0 then
			--do nothing
		elseif out == "top" then--sort between each of the six faces of a turtle, rotate if need be
			rt = turtle.dropUp()
		elseif out == "front" then
			rt = turtle.drop()
		elseif out == "bottom" then
			rt = turtle.dropDown()
		elseif out == "left" then--elseif statements past here for forward compatibility
			turtle.turnLeft()
			rt = turtle.drop()
			turtle.turnRight()
		elseif out == "right" then
			turtle.turnRight()
			rt = turtle.drop()
			turtle.turnLeft()
		elseif out == "back" then
			turtle.turnLeft()
			turtle.turnLeft()
			rt = turtle.drop()
			turtle.turnLeft()
			turtle.turnLeft()
		else--else statement more for a debug POV.
			print("error: "..out.." is an invalid destination.")
			return false
		end
		
		--console report
		if rt then
			print("Item in slot "..slot.." "..out1.."ed.")
			break
		else--rt is false
			if n < mx then
				os.sleep(.1)
			else
				print("Item in slot "..slot.." could not be "..out1.."ed.")
				rs.setAnalogueOutput(upstream, 15)--call for help
			end
		end
	end
	return rt
end

local function evalItem(n)
	if turtle.getItemCount(n) == 0 then
		return "empty"
	elseif turtle.getItemDetail(n)["maxStackSize"] > 1 then--stackable
		return "reject"
	else
		return "accept"
	end
end

local function getState()
	--Possible states
		--Inventory Full
			--empty inventory
			--collect floating loot
			--empty inventory
		--Mob present
			--attack
		--Mob absent
			--empty inventory
			--collect floating loot
			--empty inventory
	if turtle.getItemCount(16) > 0 then
		return "unload"
	elseif rs.getAnalogInput("front") > 0 and rs.getAnalogueInput(rsUpstream) == 0 then
		return "attack"
	elseif turtle.getItemCount(1) == 0 then
		return "wait"
	else
		return "unload"
	end
end

--main()
local event = false--boolean to flag an os.pullEvent() operation
local state = "start"
local eval = "empty"--string to deal with a small bug when passing "empty" to ItemOut()
while true do
	state = getState()--generate state
	rs.setAnalogueOutput(rsDownstream, rs.getAnalogueInput(rsUpstream))--propagate manual/auto kill signal
	turtle.select(1)--return selection to a default position.
	print("Program state: "..state..".")--output state to console.
	if state == "attack" then--attack mob on a pressure plate
		turtle.attack()
		event = false
	elseif state == "unload" then--remove items from inventory
		for n = 1, 16 do
			eval = evalItem(n)
			if eval ~= "empty" then--"accept" or "reject"
				event = not itemOut(n, eval)--flag an event if item fails to happen
--			else
--				event = false--wait until a wait state
--				break
			end
			if event then
				break--empty slot means no more items expected
			end
		end
		turtle.select(1)
		while turtle.suck() do end--pickup stray items
	elseif state == "wait" then--no mob and empty inventory
		event = not turtle.suck()--only wait when there's nothing to suck
	else--invalid state
		rs.setAnalogueOutput(upstream, 15)
		print("State: "..state.. " not programmed into main loop.")
		event = true --wait for user
	end
	if event then
		turtle.select(1)
		if rs.getAnalogueInput("front") == 0 or not itemOut(1, evalItem(1)) then--final check before event 
			os.sleep(.05)--this line due to a ComputerCraft glitched null event triggered when some states are triggered.
			os.pullEvent()
		end
		rs.setAnalogueOutput(upstream,0)
	end
end