Train Switch Controller MK 3

--this program wakes up the computer, and then communicates with any nearby trains for instructions
StationID = "n"
StationX = 0
StationY = 0
StationFace = "N"
StationConnections = ["n","n"]
DetectedMethod = nil
local ContactedTrain = nil
SwitchSet = 0
local Target = nil

start()

function start()
	rednet.open("bottom")
	TrackManager()
end

function TrackManager()
	if SwitchSet == 0 then
		redstone.setOutput("back", off)
	else if SwitchSet == 1 then
		redstone.setOutput("back", on)
	end
	local id, message
	repeat
		id, message = rednet.receive()
	until message == "["..StationX..","..StationY.."]" or message == StationID
	if message == "["..StationX..","..StationY.."]" then
		DetectedMethod = "Grid"
	else if message == StationID then
		DetectedMethod = "Detail"
	end
	ContactedTrain = id
	TrainComms()
end

function TrainComms()
	rednet.send(ContactedTrain, "["..StationX..","..StationY.."]",2300)
	repeat
		id, message = rednet.receive()
	until id == ContactedTrain
	if message == Ready then
		rednet.send(ContactedTrain,"y",3450)
		repeat
			id, message = rednet.receive()
		until id == ContactedTrain
		Target = message
		SetupTracks()
	end
end

function SetupTracks()
	if DetectedMethod == "Grid" then
		local DesX = Target[1]
		local DesY = Target[2]
		if StationFace == "N"  then
			if StationX > DesX then
				SwitchSet = 0
			else if StationX < DesX then
				SwitchSet = 1
			end
		else if StationFace == "East" then
			if StationY > DesY then
				SwitchSet = 0
			else if StationY < DesY then
				SwitchSet = 1
			end
		else if StationFace == "South" then
			if StationX > DesX then
				SwitchSet = 1
			else if StationX < DesX then
				SwitchSet = 0
			end
		else if StationFace == "West" then
			if StationY > DesY then
				SwitchSet = 0
			else if StationY < DesY then
				SwitchSet = 1
			end
		end
	else

	end
	repeat until redstone.getOutput("front") >= 1
	rednet.send(ContactedTrain,"Passed",3450)
	os.reboot()
end