package DateTime::Format::W3CDTF;

use strict;

use vars qw ($VERSION);

$VERSION = '0.04';

use DateTime;

sub new
{
    my $class = shift;

    return bless {}, $class;
}

# key is string length
my %valid_formats =
    ( 19 =>
      { params => [ qw( year month day hour minute second) ],
        regex  => qr/^(\d{4})-(\d\d)-(\d\d)T(\d\d):(\d\d):(\d\d)$/,
        zero   => {},
      },
      16 =>
      { params => [ qw( year month day hour minute) ],
        regex  => qr/^(\d{4})-(\d\d)-(\d\d)T(\d\d):(\d\d)$/,
        zero   => { second => 0 },
      },
      10 =>
      { params => [ qw( year month day ) ],
        regex  => qr/^(\d{4})-(\d\d)-(\d\d)$/,
        zero   => { hour => 0, minute => 0, second => 0 },
      },
      7 =>
      { params => [ qw( year month ) ],
        regex  => qr/^(\d{4})-(\d\d)$/,
        zero   => { day => 1, hour => 0, minute => 0, second => 0 },
      },
	  4 =>
      { params => [ qw( year ) ],
        regex  => qr/^(\d\d\d\d)$/,
        zero   => { month => 1, day => 1, hour => 0, minute => 0, second => 0 }
      }
    );

sub parse_datetime
{
    my ( $self, $date ) = @_;

    # save for error messages
    my $original = $date;

	my %p;
    if ( $date =~ s/([+-]\d\d:\d\d)$// )
    {
        $p{time_zone} = $1;
    }
    # Z at end means UTC
    elsif ( $date =~ s/Z$// )
    {
        $p{time_zone} = 'UTC';
    }
    else
    {
        $p{time_zone} = 'floating';
    }

    my $format = $valid_formats{ length $date }
        or die "Invalid W3CDTF datetime string ($original)";

    @p{ @{ $format->{params} } } = $date =~ /$format->{regex}/;

    return DateTime->new( %p, %{ $format->{zero} } );
}

sub format_datetime
{
    my ( $self, $dt ) = @_;

    # removed in 0.4 as it behaved improperly at midnight - kellan 2003/11/23
    #my $base =
    #    ( $dt->hour || $dt->min || $dt->sec ?
    #      sprintf( '%04d-%02d-%02dT%02d:%02d:%02d',
    #               $dt->year, $dt->month, $dt->day,
    #               $dt->hour, $dt->minute, $dt->second ) :
    #      sprintf( '%04d-%02d-%02d', $dt->year, $dt->month, $dt->day )
    #    );
    
	my $base = sprintf( '%04d-%02d-%02dT%02d:%02d:%02d',
		$dt->year, $dt->month, $dt->day,
        $dt->hour, $dt->minute, $dt->second );


    my $tz = $dt->time_zone;

    return $base if $tz->is_floating;

	return $base . 'Z' if $tz->is_utc;

	if (my $offset = $dt->offset()) {
		return $base . offset_as_string($offset );
	}
}

sub format_date
{
    my ( $self, $dt ) = @_;

    my $base = sprintf( '%04d-%02d-%02d', $dt->year, $dt->month, $dt->day );
	return $base; 
}

# minor offset_as_string variant w/ :
#
sub offset_as_string
{
    my $offset = shift;

    return undef unless defined $offset;

    my $sign = $offset < 0 ? '-' : '+';

    my $hours = $offset / ( 60 * 60 );
    $hours = abs($hours) % 24;

    my $mins = ( $offset % ( 60 * 60 ) ) / 60;

    my $secs = $offset % 60;

    return ( $secs ?
             sprintf( '%s%02d:%02d:%02d', $sign, $hours, $mins, $secs ) :
             sprintf( '%s%02d:%02d', $sign, $hours, $mins )
           );
}

1;

__END__

=head1 NAME

DateTime::Format::W3CDTF - Parse and format W3CDTF datetime strings

=head1 SYNOPSIS

  use DateTime::Format::W3CDTF;

  my $f = DateTime::Format::W3CDTF->new;
  my $dt = $f->parse_datetime( '2003-02-15T13:50:05-05:00' );

  # 2003-02-15T13:50:05-05:00
  $f->format_datetime($dt);

=head1 DESCRIPTION

This module understands the W3CDTF date/time format, an ISO 8601 profile,
defined at http://www.w3.org/TR/NOTE-datetime.  This format as the native
date format of RSS 1.0.

It can be used to parse these formats in order to create the appropriate 
objects.

=head1 METHODS

This API is currently experimental and may change in the future.

=over 4

=item * parse_datetime($string)

Given a W3CDTF datetime string, this method will return a new
C<DateTime> object.

If given an improperly formatted string, this method may die.

=item * format_datetime($datetime)

Given a C<DateTime> object, this methods returns a W3CDTF datetime
string.

NOTE: As of version 0.4, format_datetime no longer attempts to truncate
datetimes without a time component.  This is due to the fact that C<DateTime>
doesn't distinguish between a date with no time component, and midnight.

=item * format_date($datetime)

Given a C<DateTime> object, return a W3CDTF datetime string without the time component.

=back

=head1 SUPPORT

Support for this module is provided via the datetime@perl.org email
list.  See http://lists.perl.org/ for more details.

=head1 AUTHOR

Kellan Elliott-McCrea <kellan@protest.net>

This module was inspired by C<DateTime::Format::ICal>

=head1 COPYRIGHT

Copyright (c) 2003 Kellan Elliott-McCrea.  All rights reserved.  This program
is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.

The full text of the license can be found in the LICENSE file included
with this module.

=head1 SEE ALSO

datetime@perl.org mailing list

http://datetime.perl.org/

=cut