#!/usr/bin/env ruby
# coding: utf-8

require 'open-uri'
require 'nokogiri'
require 'erb'

def fmt_time t
  t.strftime "%Y%m%dT%H%M%S"
end

class Event
  attr_accessor :name, :location, :link, :image
  attr_reader :dtstart, :dtend

  def date=(s)
    if s =~ /(\d{1,2})\.\s*(\d{1,2})\.\s*(\d{4}),\s*(\d+):(\d+)\s*-\s*(\d+):(\d+) Uhr/
      year = $3.to_i
      month = $2.to_i
      day = $1.to_i
      start_hour = $4.to_i
      start_minute = $5.to_i
      end_hour = $6.to_i
      end_minute = $7.to_i
      @dtstart = Time::local year, month, day, start_hour, start_minute, 0
      @dtend = Time::local year, month, day, end_hour, end_minute, 0
    else
      raise "Invalid date: #{s.inspect}"
    end
  end
end

events = []

urls = (1..10).collect { |i| "https://riesa-efau.de/kalender/#{i}/" }
while urls.size > 0
  url = urls.shift
  doc = Nokogiri::HTML URI.open(url)
  doc.css(".vevent").each do |vevent|
    ev = Event::new
    next if vevent.css("h3").children.size == 0
    ev.name = vevent.css("h3").children[0].text.strip
    ev.location = vevent.css(".location").text.strip.gsub(/[\r\n\t]+/, ", ") + ", Riesa Efau"
    ev.date = vevent.css(".datum").text
    ev.link = URI.join url, vevent.css("a[1]").attr('href')
    ev.image = URI.join url, vevent.css(".images img").attr('src')
    events << ev
  end
end

events.sort_by! { |ev| ev.dtstart }

ical = ERB::new <<~EOF
  BEGIN:VCALENDAR
  VERSION:2.0
  METHOD:PUBLISH
  X-WR-TIMEZONE;VALUE=TEXT:Europe/Berlin
  <% events.each do |ev| %>
  BEGIN:VEVENT
  METHOD:PUBLISH
  CLASS:PUBLIC
  UID:<%= ev.link %>
  DTSTART:<%= fmt_time(ev.dtstart) %>
  DTEND:<%= fmt_time(ev.dtend) %>
  SUMMARY:<%= ev.name %>
  LOCATION:<%= ev.location %>
  URL:<%= ev.link %>
  ATTACH;FMTTYPE=image/jpeg:<%= ev.image %>
  END:VEVENT
  <% end %>
  END:VCALENDAR
EOF

puts ical.result