Scan TAMU course catalog for open seats and notify user when one opens up

course_sniper.rb

#!/usr/bin/env ruby

require 'uri'
require 'open-uri'

BASE_URI = "https://compass-ssb.tamu.edu/pls/PROD/bwykschd.p_disp_detail_sched?term_in=201431&crn_in="

# each course is represented by a CRN number
crns = %w[21179 12263 12265 12266 12267 12268 12271 21180]

def notify(url)
  puts "HOLY SHIT! #{url}"
end

loop do
  crns.each do |crn|
    uri = URI(BASE_URI + crn)

    # request the course data
    response = uri.read

    # their markup sucks horrifically...it's actually easier to use a regex :(
    matches = response.scan(/<TD CLASS="dddefault">([0-9]+)<\/TD>/)
    capacity = matches[0].first.to_i
    actual   = matches[1].first.to_i

    open_seats = capacity - actual

    puts "#{crn} -- #{open_seats}"

    notify(uri.to_s) if open_seats > 0

    # wait a sec before procressing more...
    sleep 5
  end

  # Howdy is dumb as shit but let's try not to flood them anyways...
  sleep 60
end