Send email alerts for NJ transit

njtransit_alerts.rb

#!/usr/bin/env ruby
#
# Sends an email about alerts for NJ transit trains.
#
# Usage:
#
#  njtransit email? city?
#
# Examples:
#
#  njtransit
#  njtransit user@domain.com
#  njtransit user@domain.com "Atlantic City"
#

require 'open-uri'
require 'net/smtp'

STATE_NONE = 0
STATE_LOOKING_FOR_CITY = 1
STATE_LOOKING_FOR_ALERT = 2

def note(s)
  STDERR.puts s
  STDERR.flush
end

def sendmail(from,to,subject,message)
  note "Sending to #{to}..."
	msg = <<HERE
From: #{from}
To: #{to}
Subject: #{subject}
	
#{message}
HERE
  Net::SMTP.start('localhost') do |smtp|
    smtp.send_message msg, from, to
  end
end

def main(argv)
  addr = argv.shift || ENV['USER']
  target = argv.shift || 'Morris & Essex'
  real_target = target
  target = target.downcase
  target = target.gsub /&/,'&amp;'
  note "Searching for #{real_target}"
  url = 'http://www.njtransit.com/hp/hp_servlet.srv?hdnPageAction=HomePageTo'
  state = STATE_NONE
  open(url).read.split("\n").each do |line|
    case state
    when STATE_NONE
      if line =~ /<img src="http:\/\/www.njtransit.com\/images\/status_\w+\.jpg"/
        state = STATE_LOOKING_FOR_CITY
      end
    when STATE_LOOKING_FOR_CITY
      line.scan /<td[^>]*>([^<]+)<\/td>/ do |res|
        if res[0].downcase == target#~ /#{target}/
          state = STATE_LOOKING_FOR_ALERT
        else
          state = STATE_NONE
        end
      end
    when STATE_LOOKING_FOR_ALERT
      case line
      when />View Alert<\/a><\/td>/
        note "Found alert for #{real_target}"
        sendmail addr,addr,'NJ Transit',
          "Check out http://njtransit.com for alerts on #{real_target}"
      when /<\/tr>/
        break
      end
    end
  end
end

main ARGV