package DateTime::TimeZone;

use strict;

use vars qw( $VERSION );
$VERSION = '0.75';

use DateTime::TimeZoneCatalog;
use DateTime::TimeZone::Floating;
use DateTime::TimeZone::Local;
use DateTime::TimeZone::OffsetOnly;
use DateTime::TimeZone::UTC;
use Params::Validate qw( validate validate_pos SCALAR ARRAYREF BOOLEAN );

use constant INFINITY     =>       100 ** 1000 ;
use constant NEG_INFINITY => -1 * (100 ** 1000);

# the offsets for each span element
use constant UTC_START   => 0;
use constant UTC_END     => 1;
use constant LOCAL_START => 2;
use constant LOCAL_END   => 3;
use constant OFFSET      => 4;
use constant IS_DST      => 5;
use constant SHORT_NAME  => 6;

my %SpecialName = map { $_ => 1 } qw( EST MST HST EST5EDT CST6CDT MST7MDT PST8PDT );

sub new
{
    my $class = shift;
    my %p = validate( @_,
                      { name => { type => SCALAR } },
                    );

    if ( exists $DateTime::TimeZone::LINKS{ $p{name} } )
    {
        $p{name} = $DateTime::TimeZone::LINKS{ $p{name} };
    }
    elsif ( exists $DateTime::TimeZone::LINKS{ uc $p{name} } )
    {
        $p{name} = $DateTime::TimeZone::LINKS{ uc $p{name} };
    }

    unless ( $p{name} =~ m,/,
             || $SpecialName{ $p{name} }
           )
    {
        if ( $p{name} eq 'floating' )
        {
            return DateTime::TimeZone::Floating->new;
        }

        if ( $p{name} eq 'local' )
        {
            return DateTime::TimeZone::Local->TimeZone();
        }

        if ( $p{name} eq 'UTC' || $p{name} eq 'Z' )
        {
            return DateTime::TimeZone::UTC->new;
        }

        return DateTime::TimeZone::OffsetOnly->new( offset => $p{name} );
    }

    my $subclass = $p{name};
    $subclass =~ s/-/_/g;
    $subclass =~ s{/}{::}g;
    my $real_class = "DateTime::TimeZone::$subclass";

    die "The timezone '$p{name}' in an invalid name.\n"
        unless $real_class =~ /^\w+(::\w+)*$/;

    unless ( $real_class->can('instance') )
    {
        eval "require $real_class";

        if ($@)
        {
            my $regex = join '.', split /::/, $real_class;
            $regex .= '\\.pm';

            if ( $@ =~ /^Can't locate $regex/i )
            {
                die "The timezone '$p{name}' could not be loaded, or is an invalid name.\n";
            }
            else
            {
                die $@;
            }
        }
    }

    my $zone = $real_class->instance( name => $p{name}, is_olson => 1 );

    if ( $zone->is_olson() )
    {
        my $object_version =
            $zone->can('olson_version')