Train Tablet Program Mk 3

--this program is for the tablet in control of a train.
NextStation = nil
CStation = nil
NextX = nil
NextY = nil
DestinationX = nil
DestinationY = nil
TrainX = nil
TrainY = nil
TrainID = nil
PathMethod = nil
Wait = 0
ContactedStation_ID = nil
Target =

start()

function start()
	local Settings = fs.open("TrainData","r")
	local TrainCords = readLine(1)
	TrainX = TrainCords[1]
	TrainY = TrainCords[2]
	Settings.close()
	local Travel = fs.open("JourneySettings","r")
	PathMethod = Travel.readLine(7)
	DestinationX = Travel.readLine(5)
	DestinationY = Travel.readLine(6)
	Travel.close()
	TravelManager()
end

function TravelManager()
	while true do
		if PathMethod == "Grid" then
			GridControl()
		else if PathMethod == "Detail" then
			DetailControl()
		end
	end
end

function GridControl()
	if Wait == 15 then
		Wait = 0
		SwitchContact()
	else
		Wait = Wait + 1
	end
end

function DetailControl()
	if Wait == 15 then
		Wait = 0
		SwitchContact()
	else
		Wait = Wait + 1
	end
end

function SwitchContact()
	rednet.open("back")
	if PathMethod == "Grid" then
		rednet.broadcast("["..TrainX..","..TrainY.."]", 3632)
	else if PathMethod == "Detail" then
		rednet.broadcast(NextStation,3632)
	end
	local id, message = rednet.receive(2300,5)
	if message == [TrainX,TrainY] or message == CStation then
		ContactedStation_ID = id
		SwitchController()
	end
end

function SwitchController()
	rednet.open("back")
	rednet.send(ContactedStation_ID, "Ready", 3450)
	local id, message
	repeat
		id, message = rednet.receive()
	until id == ContactedStation_ID
	if message == "n" then

	else if message == "y" then
		if PathMethod == "Grid" then
			Target = [DestinationX,DestinationY]
		else if PathMethod == "Detail" then
			Target = NextStation
		end
		rednet.send(ContactedStation_ID, Target, 3450)
		repeat
			id, message = rednet.receive()
		until id == ContactedStation_ID
		if message == "Ready" then
			repeat
				id, message = rednet.receive()
			until id == ContactedStation_ID
			if message == "Passed" then
				TrainX = NextX
				TrainY = NextY
				ChangeNext()
			end
		end
	end
end

function ChangeNext()
	if PathMethod == "Grid" then
		local h = fs.open("TrainData","a")
		h.setCursorPos(1,1)
		h.clearLine()
		h.writeLine("["..NextX..","..NextY.."]"
		h.close()
		if TrainX > DestinationX then
			NextX = TrainX-1
		else if TrainX < DestinationX then
			NextX = TrainX+1
		else
			NextX = TrainX
		end
		if TrainY > DestinationY then
			NextY = TrainY-1
		else if TrainY < DestinationY then
			NextY = TrainY+1
		else
			NextY = TrainY
		end
		local t = fs.open("JourneySettings","a")
		t.setCursorPos(1,5)
		t.clearLine()
		t.writeLine(NextX)
		t.setCursorPos(1,6)
		t.clearLine()
		t.writeLine(NextY)
		t.close()
	else PathMethod =="Detail" then
		local file = fs.open("PathData","r")
		for i = 1, #file.list() do
			if file.readLine(i) == NextStation then
				NextStation = file.readLine(i+1)
			end
		end
		file.close()
	end
end