#!/usr/bin/perl -w

#
# Vzic - a program to convert Olson timezone database files into VZTIMEZONE
# files compatible with the iCalendar specification (RFC2445).
#
# SPDX-FileCopyrightText: 2000-2001 Ximian, Inc.
# SPDX-FileCopyrightText: 2003, Damon Chaplin <damon@ximian.com>
#
# SPDX-License-Identifier: GPL-2.0-or-later
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
#

#
# This outputs an iCalendar file containing one event in each timezone,
# as well as all the VTIMEZONEs. We use it for testing compatibility with
# other iCalendar apps like Outlook, by trying to import it there.
#
# Currently we have 377 timezones (with tzdata2001d).
#

# Set this to the toplevel directory of the VTIMEZONE files.
$ZONEINFO_DIR = "/home/damon/src/zoneinfo";

$output_file = "calendar.ics";

# Save this so we can restore it later.
$input_record_separator = $/;

chdir $ZONEINFO_DIR
  || die "Can't cd to $ZONEINFO_DIR";

# Create the output file, to contain all the VEVENTs & VTIMEZONEs.
open(OUTPUTFILE, ">$output_file")
  || die "Can't create file: $output_file";

# Output the standard header.
print OUTPUTFILE <<EOF;
BEGIN:VCALENDAR
PRODID:-//Ximian//NONSGML Vzic Test//EN
VERSION:2.0
METHOD:PUBLISH
EOF

$zone_num = 0;

# 365 days in a non-leap year.
@days_in_month = (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

foreach $file (`find -name "*.ics"`) {

  # Get rid of './' at start and whitespace at end.
  $file =~ s/^\.\///;
  $file =~ s/\s+$//;

  if ($file eq $output_file) {
    next;
  }

  #    print "File: $file\n";

  # Get the VTIMEZONE data.
  open(ZONEFILE, "$file")
    || die "Can't open file: $ZONEINFO_DIR/$file";
  undef $/;
  $vtimezone = <ZONEFILE>;
  $/         = $input_record_separator;
  close(ZONEFILE);

  # Strip the stuff before and after the VTIMEZONE component
  $vtimezone =~ s/^.*BEGIN:VTIMEZONE/BEGIN:VTIMEZONE/s;
  $vtimezone =~ s/END:VTIMEZONE.*$/END:VTIMEZONE\n/s;

  print OUTPUTFILE $vtimezone;

  # Find the TZID.
  $vtimezone =~ m/TZID:(.*)/;
  $tzid = $1;

  #    print "TZID: $tzid\n";

  # Find the location.
  $file =~ m/(.*)\.ics/;
  $location = $1;

  #    print "LOCATION: $location\n";

  # Try to find the current UTC offset that Outlook will use.
  # If there is an RRULE, we look for the first 2 TZOFFSETTO properties,
  # else we just get the first one.
  if ($vtimezone =~ m/RRULE/) {
    $vtimezone =~ m/TZOFFSETTO:([+-]?\d+)/;
    $tzoffsetto = $1;
    $vtimezone =~ m/TZOFFSETFROM:([+-]?\d+)/;
    $tzoffsetfrom = $1;
    $tzoffset     = "$tzoffsetfrom/$tzoffsetto";
  } else {
    $vtimezone =~ m/TZOFFSETTO:([+-]?\d+)/s;
    $tzoffset = $1;
  }

  #    print "TZOFFSET: $tzoffset\n";

  # We put each event on a separate day in 2001 and Jan 2002.
  $day_num = $zone_num;
  if ($day_num >= 365) {
    $year = 2002;
    $day_num -= 365;
  } else {
    $year = 2001;
  }
  $month = -1;
  for ($i = 0 ; $i < 12 ; $i++) {
    if ($day_num < $days_in_month[$i]) {
      $month = $i;
      last;
    }
    $day_num -= $days_in_month[$i];
  }
  if ($month == -1) {
    die "month = -1";
  }

  $month++;
  $day_num++;
  $date = sprintf("%i%02i%02i", $year, $month, $day_num);

  #    print "Date: $date\n";

  # Output a VEVENT using the timezone.
  print OUTPUTFILE <<EOF;
BEGIN:VEVENT
UID:vzic-test-${zone_num}
DTSTAMP:20010101T000000Z
DTSTART;TZID=${tzid}:${date}T120000
DTEND;TZID=${tzid}:${date}T130000
RRULE:FREQ=MONTHLY;BYMONTHDAY=${day_num}
SUMMARY:($tzoffset) ${location} 12:00-13:00 UTC
SEQUENCE:1
END:VEVENT
EOF

  $zone_num++;

  # Use this to stop after a certain number.
  #    last if ($zone_num == 100);
}

# Output the standard footer.
print OUTPUTFILE <<EOF;
END:VCALENDAR
EOF

close(OUTPUTFILE);
