fmi_bistro.rb

require 'rubygems'
require 'rss/maker'
require 'nokogiri'
require 'open-uri'

URL = 'http://wwwrbg.in.tum.de/kontakt/FMI_Bistro/aktuell.html'
DAY_PATTERN = /\d?\d\.\d?\d.\d{4}/
MEAL_PATTERN = /(\d+)\.((?:.|\n)+?\d\.\d\d)$/

DATES = {
  Date.today.strftime("%-1d.%-1m.%Y") => "Heute",
  (Date.today + 1).strftime("%d.%-1m.%Y") => "Morgen",
}

feed = RSS::Maker.make('2.0') do |rss|
  doc = Nokogiri::HTML(open(URL))

  rss.channel.title = (doc/'title').text
  rss.channel.description = rss.channel.title
  rss.channel.link = URL
  rss.channel.lastBuildDate = Time.now
  rss.encoding = 'iso-8859-1'

  text = (doc/'.maincontent').text
  text.scan(/(#{DAY_PATTERN})$((\s*#{MEAL_PATTERN})+)/) do |day, meals|
    dayname = DATES[day] or next
    meals.scan(MEAL_PATTERN).map do |meal|
      meal[1] = meal[1].
        gsub(/\b[VKRS+]+\s/, '').
        gsub(/(\b| )\d(?=,| )(,\d)*/, '').
        gsub(/\*{1,3}/, '').
        gsub(/\s+/, ' ')
      rss.items.new_item do |item|
        item.title = "#{dayname} - #{meal[0]}. #{meal[1]}"
        item.link = URL
        item.guid.content = URL + "#" + day + "-" + meal[0]
      end
    end
  end
end

puts feed