CC Train System - Controller

-- For use with a pocket computer!

-- Command Structure: "controller direction start_station_name end_station_name"
-- Example Usage: "controller up my_cool_station my_even_cooler_station"

local TRAIN_COMM_PORT = 101

local modem = peripheral.wrap("back")

local args = {...}

local direction = args[1]
local start_station_name = args[2]
local end_station_name = args[3]

if (not direction == "up") and (not direction == "down") then
    print("ERROR: INVALID DIRECTION! (Must be 'up' or 'down')")
    shell.exit()
end

local direction_port = 103
if direction == "up" then
    direction_port = 104
end

modem.transmit(TRAIN_COMM_PORT, 102, start_station_name)

sleep(15)

while true do
    modem.transmit(TRAIN_COMM_PORT, direction_port, end_station_name)
    sleep(1)
end