#!/usr/bin/perl -Tw
#
# Exchange Calendar to iCal webcal link
# David McNett <nugget@slacker.com> http://slacker.com/~nugget/
#
# $Id: exchange_calendar_dump,v 1.5 2006/03/28 01:05:28 nugget Exp $
#
# This script is suitable for use either as a directly-run CGI script or as a
# cronned dump to a static file.  It's purpose is to export a user calendar
# that's maintained within Microsoft Exchange Server to a form which is
# subscribe-able from Apple's iCal or Mozilla Sunbird.
#
# With this script, a user can manage their work calendar within MS Exchange
# but still have read-only access (with alarms) inside iCal or Sunbird.
#
# Requires fetchmail and a web server (to publish the webcal link)
#
# First, set up fetchmail with a ~/.fetchmailrc that resembles this:
#
#   set logfile /home/nugget/fetchmail.log
#   defaults proto imap
#   
#   poll imapserver.example.com
#     user "imapusername"
#     pass "imappassword"
#     folder "Calendar"
#     ssl
#     keep
#     fetchall
#     mda /bin/cat
#
#
# Then set up a crontab entry to periodically run this script and pipe the
# output to a file which is exposed on your web server:
#
# */15 * * * * $HOME/bin/exchange_calendar_dump > /tmp/calendar.tmp \
#                && mv /tmp/calendar.tmp $HOME/public_html/calendar.ics
#
# Once you've got that going, you should see the calendar.ics file 
# automatically populated with all the events in your Exchange calendar.
# You can then subscribe to it by opening up the appropriate url in
# iCal or Sunbird:
#
#  webcal://yourwebserver.example.com/~username/calendar.ics
#

use strict;
$ENV{'PATH'} = '/bin:/usr/bin:/usr/local/bin';

open DUMP, "/usr/local/bin/fetchmail|" or die "Unable to run fetchmail";

my $spititout = 0;
my $dtstart = 0;
print "BEGIN:VCALENDAR\n";
while(<DUMP>) {
  my $buf = $_;

  if($buf =~ /^BEGIN:VEVENT$/) {
    $spititout = 1;
    $dtstart = 0;
  }

  if($spititout>0)  {
    if($buf =~ /^DTSTART[^:]+:(\d\d\d\d\d\d\d\d)T000000/) {
      $buf = "DTSTART:$1\n";
      $dtstart = $1;
    } elsif($buf =~ /^DTEND[^:]+:(\d\d\d\d\d\d\d\d)T000000/) {
      my $dtend = $1;
      if($dtstart != 0) {
        my $days = $dtend - $dtstart;
	$buf = "DURATION:P" . $days . "D\n";
      }
    } elsif($buf =~ /^ACTION:DISPLAY$/) {
      $buf = "ACTION:AUDIO\nATTACH;VALUE=URI:Morse\n";
    }
    print $buf;
  }

  if($buf =~ /^END:VEVENT$/) {
    $spititout = 0;
  }
}
close DUMP;
print "END:VCALENDAR\n";

exit ($? >> 8);

# (c) Copyright 2006 David McNett <nugget@slacker.com>.  All Rights Reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 
# THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# -- 
# Yes, it's sort of silly when the license is longer than the code but
# I think it's better to be explicit so there's no confusion about how this
# stuff can be re-used.  I'd hate for people to assume it was GPL'd or 
# something.