gistfile1

#!/usr/bin/ruby  
 
require 'net/imap' 
 
class ExchangeCalendar 
  def initialize(servername, user, password) 
    @imap = Net::IMAP.new(servername) 
    @imap.login(user, password) 
    @imap.examine('Calendar') 
  end 
 
  def each_calendar 
    @imap.search("ALL").each do |sequence_id| 
      fetchdata = @imap.fetch(sequence_id, ["UID", "BODYSTRUCTURE"])[0] 
      # Find the calendar part. 
      uid, bodystructure = fetchdata.attr["UID"], fetchdata.attr["BODYSTRUCTURE"] 
      catch :nocalendar do 
        partno = part_number_for_calendar(bodystructure) 
        yield @imap.uid_fetch(uid, "BODY.PEEK[#{partno}]")[0].attr["BODY[#{partno}]"] 
      end 
    end 
  end 
 
  def finish 
    @imap.logout 
    @imap.disconnect 
  end 
 
  protected 
  def part_number_for_calendar(msg) 
    if msg.media_type == "TEXT" and msg.subtype == "CALENDAR" 
      return 1 
    elsif msg.multipart? 
      i = 1 
      msg.parts.each do |part| 
        if part.media_type == "TEXT" and part.subtype == "CALENDAR" 
          return i 
        end 
        i += 1 
      end 
    else 
      throw :nocalendar 
    end 
  end 
end 

class IcalAccumulator 
  def initialize() 
    @events = [] 
    @timezones = [] 
    @tzids_seen = {}   end 
 
  def push(calendar) 
    calendar = clean_timezone(calendar) 
    calendar.scan(/^BEGIN:VEVENT.*?^END:VEVENT|^BEGIN:VTIMEZONE.*?^END:VTIMEZONE/m).each do |component| 
       
      case component 
      when /^BEGIN:VEVENT/ 
        @events << component 
      when /^BEGIN:VTIMEZONE/ 
        component =~ /^TZID:.*/ 
        if !@tzids_seen[$&] 
          @tzids_seen[$&] = true 
          @timezones << component 
        end 
      end 
    end 
  end 
 
  def to_s 
    cal = <<-EOF
      BEGIN:VCALENDAR 
      METHOD:REQUEST 
      PRODID:Exchange2Ical 
      VERSION:2.0 
      EOF
    cal << @timezones.join("\n") + "\n" 
    cal << @events.join("\n") + "\n" 
    cal << "END:VCALENDAR\n" 
    cal 
  end 
 
  protected 
  def clean_timezone(component) 
    component.gsub!(/GMT -0500 \(Standard\) \/ GMT -0400 \(Daylight\)/, "US/Eastern") 
    component.gsub!(/\(GMT-05\.00\) Eastern Time \(US & Canada\)/, "US/Eastern") 
    component 
  end 
end 

def main 
  require 'cgi' 
  cgi = CGI.new 
   
  server = cgi['server'].to_s 
  user = cgi['user'].to_s 
  password = cgi['password'].to_s 
   
  ec = ExchangeCalendar.new(server, user, password) 
  ia = IcalAccumulator.new 
   
  ec.each_calendar do |c| 
    ia.push(c) 
  end 
 
  ec.finish 
 
  cgi.out("text/calendar") {     ia.to_s 
  } end 
 
main