MobFarmer

function modemStartup()
	--print("Warping modem on " .. modemLocation .. " side")
	modem = peripheral.wrap("bottom")
	modem.open(3)  -- Open channel 3 so that we can listen on it
end

function clearRedstone()
	for key,side in pairs(redstone.getSides()) do
		redstone.setOutput(side, false)
	end
end

function allButSide(side)
	for k,v in pairs(redstone.getSides()) do
		if side == v then
			redstone.setOutput(side, false)
		else
			redstone.setOutput(v, true)
		end
	end
end

------------------------------------------
--Main Program
------------------------------------------
print("Starting spawner control")
modemStartup()

local mobs = {}
mobs["endermen"] = "left"
mobs["ghasts"] = "right"
mobs["pigmen"] = "front"
mobs["creepers"] = "back"
mobs["all"] = "all"
mobs["list"] = "list"

while true do
	local event, modemSide, senderChannel,
	  replyChannel, message, senderDistance = os.pullEvent("modem_message")

	print("Message: "..message)

	local action = mobs[message]
	if action == "all" then
		clearRedstone()
		modem.transmit(replyChannel, 3, "spawning all mobs")
	elseif action == "list" then
		modem.transmit(replyChannel, 3, mobs)
	elseif action then
		allButSide(action)
		modem.transmit(replyChannel, 3, "spawning " .. message)
	else
		allButSide()
		modem.transmit(replyChannel, 3, "spawning no mobs")
	end
end