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

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

def fetch_doc url
  STDERR.puts "GET #{url}"
  Nokogiri::HTML URI.open(url)
end

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

class Event
  attr_accessor :title, :start, :end, :location, :url, :image
end

events = []

url = "https://www.medienkulturzentrum.de/angebote/"
while url
  list_doc = fetch_doc url
  list_doc.css("a[text()='weiterlesen']").each do |a|
    ev = Event::new
    ev.url = URI.join url, a.attr('href')
    doc = fetch_doc ev.url

    date = doc.css('section.page-document header strong')[0]
    date = date ? date.parent.text : next
    if date =~ /(\d+)\.(\d+)\.(\d+),\s*(\d+):(\d+)\s*-\s*(\d+)\.(\d+)\.(\d+),\s*(\d+):(\d+)/
      ev.start = Time::local $3.to_i, $2.to_i, $1.to_i, $4.to_i, $5.to_i, 0
      ev.end = Time::local $8.to_i, $7.to_i, $6.to_i, $9.to_i, $10.to_i, 0
    elsif date =~ /(\d+)\.(\d+)\.(\d+),\s*(\d+):(\d+)\s*-\s*(\d+):(\d+)/
      ev.start = Time::local $3.to_i, $2.to_i, $1.to_i, $4.to_i, $5.to_i, 0
      ev.end = Time::local $3.to_i, $2.to_i, $1.to_i, $6.to_i, $7.to_i, 0
    elsif date =~ /(\d+)\.(\d+)\.(\d+)\s*-\s*(\d+)\.(\d+)\.(\d+)/
      ev.start = Time::local $3.to_i, $2.to_i, $1.to_i, 0, 0, 0
      ev.end = Time::local $6.to_i, $5.to_i, $4.to_i, 23, 59, 59
    else
      puts "Unrecognized date: #{date}"
      next
    end
    ev.title = doc.css('section.page-document header h1').text
    ev.location = doc.css('section.page-document address').text
                    .lines
                    .collect { |s| s.strip }
                    .filter { |s| not s.empty? }
                    .join(", ")
    ev.image = doc.css('section.page-document article img[1]').attr('src')

    events << ev
  end

  next_page = list_doc.css(".wp-pagenavi .current + .page")[0]
  url = if next_page
          URI.join url, next_page.attr('href')
        else
          nil
        end
end

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.url %>
  DTSTART:<%= fmt_time(ev.start) %>
  DTEND:<%= fmt_time(ev.end) %>
  SUMMARY:<%= ev.title %>
  LOCATION:<%= ev.location %>
  URL:<%= ev.url %>
  ATTACH;FMTTYPE=image/jpeg:<%= ev.image %>
  END:VEVENT
  <% end %>
  END:VCALENDAR
EOF

puts ical.result