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;