#!/usr/bin/perl

=pod

=head1 NAME

tv_augment_tz - Convert floating time to explicit time.

=head1 SYNOPSIS

tv_augment_tz [--help] [--output FILE] [--tz TIMEZONE] [FILE...]

=head1 DESCRIPTION

Read XMLTV data and augment all times with the correct offset. Times that are
already explicit will be converted to TIMEZONE as well.

B<--output FILE> write to FILE rather than standard output

B<--tz TIMEZONE> use TIMEZONE (e.g. Europe/Berlin) rather then the default of UTC

=head1 SEE ALSO

L<xmltv(5)>.

=head1 AUTHOR

Karl Dietz, <dekarl@spaetfruehstuecken.org>

=head1 BUGS

Guessing the right time when local time is abigous doesn't work properly.

=cut

use strict;
use warnings;

use XMLTV;
use XMLTV::Version "$XMLTV::VERSION";

use Encode; # used to convert 'perl strings' into 'utf-8 strings'
use DateTime;
use Getopt::Long;
use XML::LibXML;

use XMLTV::Usage <<END
$0: Convert floating local time to explicit local time.
usage: $0 [--help] [--output FILE] [--tz TIMEZONE] [FILE...]
END
;


my ($opt_help, $opt_output, $opt_tz);
GetOptions('help' => \$opt_help,
           'output=s' => \$opt_output,
	   'tz=s' => \$opt_tz
)
  or usage(0);
usage(1) if $opt_help;
@ARGV = ('-') if not @ARGV;

if (!defined ($opt_tz)) {
  $opt_tz = 'UTC';
}

sub parse_date ( $ ) {
  my $raw = shift;
  my ($datetime, $tz) = split (/\s/, $raw);

  my ($year, $month, $day, $hour, $minute, $second) = (0, 0, 0, 0, 0, 0);

  if (length ($datetime) == 4+2+2+2+2+2) {
    ($year, $month, $day, $hour, $minute, $second) = ($datetime =~ m|(\d\d\d\d)(\d\d)(\d\d)(\d\d)(\d\d)(\d\d)|);
  } elsif (length ($datetime) == 4+2+2+2+2) {
    ($year, $month, $day, $hour, $minute) = ($datetime =~ m|(\d\d\d\d)(\d\d)(\d\d)(\d\d)(\d\d)|);
  } elsif (length ($datetime) == 4+2+2+2) {
    ($year, $month, $day, $hour, $minute) = ($datetime =~ m|(\d\d\d\d)(\d\d)(\d\d)(\d\d)|);
  } elsif (length ($datetime) == 4+2+2) {
    ($year, $month, $day, $hour, $minute) = ($datetime =~ m|(\d\d\d\d)(\d\d)(\d\d)|);
  } elsif (length ($datetime) == 4+2) {
    ($year, $month, $day, $hour, $minute) = ($datetime =~ m|(\d\d\d\d)(\d\d)|);
  } elsif (length ($datetime) == 4) {
    ($year, $month, $day, $hour, $minute) = ($datetime =~ m|(\d\d\d\d)|);
  }

  my $dt = DateTime->new (
    year      => $year,
    month     => $month,
    day       => $day,
    hour      => $hour,
    minute    => $minute,
    second    => $second
  );

  if ($tz) {
    $dt->set_time_zone ($tz);
  }

  return $dt;
}

# load XML
if ($ARGV[0]) {
  open *STDIN, '<', $ARGV[0];
}
binmode *STDIN; # drop all PerlIO layers possibly created by a use open pragma
my $doc = XML::LibXML->load_xml(IO => *STDIN);

my $starttimes = $doc->findnodes ('/tv/programme[@start]');
foreach my $node ($starttimes->get_nodelist ()) {
  my $time = $node->getAttribute ('start');
  $time = parse_date ($time)->set_time_zone ($opt_tz)->strftime ('%Y%m%d%H%M%S %z');
  $node->setAttribute('start', $time);
}

my $stoptimes = $doc->findnodes ('/tv/programme[@stop]');
foreach my $node ($stoptimes->get_nodelist ()) {
  my $time = $node->getAttribute ('stop');
  $time = parse_date ($time)->set_time_zone ($opt_tz)->strftime ('%Y%m%d%H%M%S %z');
  $node->setAttribute('stop', $time);
}

# save modified XML
if ($opt_output) {
  open *STDOUT, '>', $opt_output;
}
binmode *STDOUT; # as above
$doc->toFH(*STDOUT);