#!/usr/local/bin/ruby

# parse-schedule.rb
#
# parses the 22c3 schedule's iCal file and creates a HTML-version,
# because the official schedule pages can't be printed properly
#
# gets the schedule at http://events.ccc.de/congress/2005/fahrplan/schedule.ics
#
# execute like this:
#
#   ruby parse-schedule.rb > schedule.html
#
#
# NOTES:
# - I attempted to make the logic as flexible as was conveniently possible: timetables change.
# - sorry for the unmaintainable spaghetti code, this was written to get a job done, 
#   not to be beautiful
# - this might work as a basis to parse other iCal files, but don't count on it.
# - PowerBooks rule
#
# by Martin Dittus (martin@dekstop.de), 2005-12-23
# last change: 2005-12-26

require 'net/http'
require 'date'


# ======================
# = load the iCal data =
# ======================

# either read from a local file
# filename = 'schedule.ics'
# ical_data = File.read(filename)

# or from the 22c3 webserver
host = 'events.ccc.de'
url = '/congress/2005/fahrplan/schedule.ics'
ical_data = Net::HTTP.start(host, 80) { |http| http.get(url).response.body }



# ==========
# = parser =
# ==========

# takes a string: the content of the iCal file
#
# returns an array of hashes, each hash storing the fields of an iCal VEVENT
#
# DTSTART and DTEND fields are stored as DateTime instances,
# ATTENDEE fields are arrays of strings (== names),
# all other fields are stored as strings
def parse_schedule(ical_data)

  events = Array.new   # array of hashes
  cur_event_idx = 0

  in_vevent = false

  # for multiline fields: remember where we are
  cur_field = nil
  
  # multiline structured fields can only be parsed after all lines have been read
  in_structured_field = false
  structured_field_data = nil

  ical_data.each do |line|
    
    line.gsub!(/\r?\n?/, '')
  
    if line.match(/^BEGIN:VEVENT/i)
      in_vevent = true
      events[cur_event_idx] = Hash.new
    elsif line.match(/^END:VEVENT/i)
      in_vevent = false
      cur_event_idx += 1
    else
      if in_vevent
        if data = line.match(/^(\w+):(.*)$/)
          # generic string property
          in_structured_field = false
          cur_field = data[1]
          events[cur_event_idx][cur_field] = data[2]
        elsif data = line.match(/^(\w+);(.*)$/)
          # structured data property
          cur_field = data[1]
          if (cur_field.match(/^DTEND/i) || cur_field.match(/^DTSTART/i))
            # date field
            date_str = data[2].match(/:([\dT]+)$/i)[1]
            # DateTime can't parse this format, so we reformat before parsing it
            date_str.gsub!(/^(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})/,
              '\1-\2-\3 \4:\5:\6')
            date = DateTime::strptime(date_str, "%Y-%m-%d %H:%M:%S")
            events[cur_event_idx][cur_field] = date
          elsif (cur_field.match(/^ATTENDEE/i))
            # person
            in_structured_field = true
            structured_field_data = data[2]
          else
            # treat as generic string property
            events[cur_event_idx][cur_field] = data[2]
          end
        elsif data = line.match(/^ (.+)$/)
          if (in_structured_field)
            structured_field_data << data[1]
          else
            events[cur_event_idx][cur_field] += data[1]
          end
        else
          # unknow pattern
          
          # parse the collected structured field data
          if (in_structured_field)
            if (cur_field.match(/^ATTENDEE/i))
              if events[cur_event_idx][cur_field] == nil
                events[cur_event_idx][cur_field] = Array.new
              end
              name = structured_field_data.match(/CN="(.*)"/i)[1]
              events[cur_event_idx][cur_field].push(name)
            end
            in_structured_field = false
            structured_field_data = nil
          end
          
          # close current field
          cur_field = nil
        end
      end
    end
  end
  
  events
end

# ================
# = html helpers =
# ================

# format an event's property hash
# returns an HTML-formatted string
def format_event(event)
  "
    <h3 class=\"summary\">#{event['SUMMARY']}</h3>
    <p class=\"attendee\">By #{event['ATTENDEE'].join(', ')}</p>
    <p class=\"description\">#{event['DESCRIPTION']}</p>
    <p class=\"url\">URL: <a href=\"#{event['URL']}\">#{event['URL'].match(/\/([^\/]+)$/)[1]}</a></p>"
end

# lalala
def same_day(date1, date2)
  (date1 != nil && date2 != nil) &&
  (date1.year == date2.year) && 
  (date1.month == date2.month) && 
  (date1.day == date2.day)
end


# ========
# = main =
# ========

# parse
events = parse_schedule(ical_data)
version = ical_data.match(/22C3 Schedule Release (\d+.\d+)/i)[1]


# group events by starting time
start_times = Hash.new  # maps DateTime to an array of event-indexes
events.each_index do |event_idx|
  event = events[event_idx]
  if (start_times[event['DTSTART']] == nil)
    start_times[event['DTSTART']] = Array.new
  end
  start_times[event['DTSTART']] << event_idx
end

# get a list of all locations
locations = events.collect { |event| event['LOCATION'] }.uniq.sort

# get a list of all days
days = events.collect { |event| event['DTSTART'].strftime('%Y-%m-%d') }.uniq.sort

# ==========
# = output =
# ==========

puts "<html>
<head>
  <title>22C3 Fahrplan version #{version}</title>
	<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">
  <link rel=\"stylesheet\" href=\"schedule.css\">
</head>
<body>
<a name=\"top\"></a>
<h1>22C3 Fahrplan version #{version}</h1>
"

# links to indiv. days
link_days = days.map { |day| "<a href=\"##{day}\">#{day}</a>"}
puts "<p class=\"url\"> #{ link_days.join(' &middot; ') } &middot; <a href=\"https://events.ccc.de/congress/2005/fahrplan/\">official schedule</a></p>"

# day counter, stores Dates
cur_day = nil

# to keep the current rowspan state for each column
rowspan_counter = Hash.new # maps a column's name to an int
locations.each { |location| rowspan_counter[location] = 0 }

# for each start time == row
start_times.keys.sort.each do |start_time|
  
  # see if we are at the start of a new day -> print table header  
  next_day = start_time
  if (same_day(next_day, cur_day) == false)
    
    if (cur_day != nil)
      # we're not on the first day -> close previous day's table
      puts "</table>"
      puts "<p class=\"url\"><a href=\"#top\">top</a></p>"
    end
    
    cur_day = next_day
    
    puts "<a name=\"#{cur_day.strftime('%Y-%m-%d')}\"></a>"
    puts "<h2>#{cur_day.strftime('%A, %Y-%m-%d')}</h2>"
    
    puts "<table>"
    puts "<tr>"
    puts "  <th class=\"topleft\"></th>"
    locations.each { |location| puts "  <th><p class=\"location\">#{location}</p></th>" }
    puts "</tr>"
    
  end

  # table row
  puts "<tr>"
  puts "  <td><p class=\"time\">#{start_time.strftime("%H:%M")}</p></td>"

  cur_events = start_times[start_time]

  # for each column
  locations.each do |location|
    
    # check if t
    if (rowspan_counter[location] != 0) 
      # overhanging rowspan -> no new cell
      rowspan_counter[location] -= 1

    else
      # new cell

      # select event for this cell
      cell_event_idx = nil
      cur_events.each do |event_idx|
        event = events[event_idx]
        if (event['LOCATION'] == location)
          cell_event_idx = event_idx
        end
      end
          
      # print cell
      if cell_event_idx
        
        event = events[cell_event_idx]
        
        # does this event take more than an hour? -> rowspan
        duration = event['DTEND'].hour - event['DTSTART'].hour
        if (duration > 1)
          puts "  <td class=\"event\" rowspan=\"#{duration}\">#{format_event(event)}</td>"
          rowspan_counter[location] = duration - 1
        else
          puts "  <td class=\"event\">#{format_event(event)}</td>"
        end
          
      else
        # no event here -> empty cell
        puts "  <td></td>"
      end
    
    end
  end
  puts "</tr>"

end

puts "</table>"

# eof
puts "</body>"
puts "</html>"