package Travel::Status::DE::DBWagenreihung;

use strict;
use warnings;
use 5.020;
use utf8;

use parent 'Class::Accessor';

use Carp qw(cluck confess);
use JSON;
use List::Util qw(uniq);
use LWP::UserAgent;
use Travel::Status::DE::DBWagenreihung::Group;
use Travel::Status::DE::DBWagenreihung::Section;
use Travel::Status::DE::DBWagenreihung::Wagon;

our $VERSION = '0.13';

Travel::Status::DE::DBWagenreihung->mk_ro_accessors(
	qw(direction platform station train_no train_type));

# {{{ Rolling Stock Models

my %is_redesign = (
	"02" => 1,
	"03" => 1,
	"06" => 1,
	"09" => 1,
	"10" => 1,
	"13" => 1,
	"14" => 1,
	"15" => 1,
	"16" => 1,
	"18" => 1,
	"19" => 1,
	"20" => 1,
	"23" => 1,
	"24" => 1,
	"27" => 1,
	"28" => 1,
	"29" => 1,
	"31" => 1,
	"32" => 1,
	"33" => 1,
	"34" => 1,
	"35" => 1,
	"36" => 1,
	"37" => 1,
	"53" => 1
);

my %model_name = (
	'011'      => [ 'ICE T', 'ÖBB 4011' ],
	'401'      => ['ICE 1'],
	'402'      => ['ICE 2'],
	'403.S1'   => [ 'ICE 3',        'BR 403, 1. Serie' ],
	'403.S2'   => [ 'ICE 3',        'BR 403, 2. Serie' ],
	'403.R'    => [ 'ICE 3',        'BR 403 Redesign' ],
	'406'      => [ 'ICE 3',        'BR 406' ],
	'406.R'    => [ 'ICE 3',        'BR 406 Redesign' ],
	'407'      => [ 'ICE 3 Velaro', 'BR 407' ],
	'408'      => [ 'ICE 3neo',     'BR 408' ],
	'411.S1'   => [ 'ICE T',        'BR 411, 1. Serie' ],
	'411.S2'   => [ 'ICE T',        'BR 411, 2. Serie' ],
	'412'      => ['ICE 4'],
	'415'      => [ 'ICE T', 'BR 415' ],
	'420'      => ['BR 420'],
	'422'      => ['BR 422'],
	'423'      => ['BR 423'],
	'425'      => ['BR 425'],
	'427'      => [ 'FLIRT', 'BR 427' ],
	'428'      => [ 'FLIRT', 'BR 428' ],
	'429'      => [ 'FLIRT', 'BR 429' ],
	'430'      => ['BR 430'],
	'440'      => [ 'Coradia Continental', 'BR 440' ],
	'442'      => [ 'Talent 2',            'BR 442' ],
	'445'      => [ 'Twindexx Vario',      'BR 445' ],
	'446'      => [ 'Twindexx Vario',      'BR 446' ],
	'462'      => [ 'Desiro HC',           'BR 462' ],
	'463'      => [ 'Mireo',               'BR 463' ],
	'475'      => [ 'TGV',                 'BR 475' ],
	'612'      => [ 'RegioSwinger',        'BR 612' ],
	'620'      => [ 'LINT 81',             'BR 620' ],
	'622'      => [ 'LINT 54',             'BR 622' ],
	'631'      => [ 'Link I',              'BR 631' ],
	'632'      => [ 'Link II',             'BR 632' ],
	'633'      => [ 'Link III',            'BR 633' ],
	'640'      => [ 'LINT 27',             'BR 640' ],
	'642'      => [ 'Desiro Classic',      'BR 642' ],
	'643'      => [ 'TALENT',              'BR 643' ],
	'648'      => [ 'LINT 41',             'BR 648' ],
	'IC2.TWIN' => ['IC 2 Twindexx'],
	'IC2.KISS' => ['IC 2 KISS'],
);

my %power_desc = (
	90 => 'mit sonstigem Antrieb',
	91 => 'mit elektrischer Lokomotive',
	92 => 'mit Diesellokomotive',
	93 => 'Hochgeschwindigkeitszug',
	94 => 'Elektrischer Triebzug',
	95 => 'Diesel-Triebzug',
	96 => 'mit speziellen Beiwagen',
	97 => 'mit elektrischer Rangierlok',
	98 => 'mit Diesel-Rangierlok',
	99 => 'Sonderfahrzeug',
);

# }}}
# {{{ Constructors

sub new {
	my ( $class, %opt ) = @_;

	if ( not $opt{train_number} and not $opt{from_json} ) {
		confess('train_number option must be set');
	}

	if ( not $opt{departure} and not $opt{from_json} ) {
		confess('departure option must be set');
	}

	my $self = {
		api_base => $opt{api_base}
		  // 'https://ist-wr.noncd.db.de/wagenreihung/1.0',
		developer_mode => $opt{developer_mode},
		cache          => $opt{cache},
		departure      => $opt{departure},
		from_json      => $opt{from_json},
		json           => JSON->new,
		train_number   => $opt{train_number},
		user_agent     => $opt{user_agent},
	};

	bless( $self, $class );

	if ( not $self->{user_agent} ) {
		my %lwp_options = %{ $opt{lwp_options} // { timeout => 10 } };
		$self->{user_agent} = LWP::UserAgent->new(%lwp_options);
		$self->{user_agent}->env_proxy;
	}

	$self->get_wagonorder;

	return $self;
}

sub get_wagonorder {
	my ($self) = @_;

	my $api_base     = $self->{api_base};
	my $cache        = $self->{cache};
	my $train_number = $self->{train_number};

	my $datetime = $self->{departure};

	if ( ref($datetime) eq 'DateTime' ) {
		$datetime = $datetime->strftime('%Y%m%d%H%M');
	}

	my $json = $self->{from_json};

	if ( not $json ) {
		my ( $content, $err )
		  = $self->get_with_cache( $cache,
			"${api_base}/${train_number}/${datetime}" );

		if ($err) {
			$self->{errstr} = "Failed to fetch station data: $err";
			return;
		}
		$json = $self->{json}->utf8->decode($content);
	}

	if ( exists $json->{error} ) {
		$self->{errstr} = 'Backend error: ' . $json->{error}{msg};
		return;
	}

	if (    @{ $json->{data}{istformation}{allFahrzeuggruppe} // [] } == 0
		and @{ $json->{data}{istformation}{halt} // [] } == 0 )
	{
		$self->{errstr} = 'No wagon order available';
		return;
	}

	$self->{data} = $json->{data};
	$self->{meta} = $json->{meta};

	return $self->parse_wagonorder;
}

# }}}
# {{{ Internal Helpers

sub get_with_cache {
	my ( $self, $cache, $url ) = @_;

	if ( $self->{developer_mode} ) {
		say "GET $url";
	}

	if ($cache) {
		my $content = $cache->thaw($url);
		if ($content) {
			if ( $self->{developer_mode} ) {
				say '  cache hit';
			}
			return ( ${$content}, undef );
		}
	}

	if ( $self->{developer_mode} ) {
		say '  cache miss';
	}

	my $ua  = $self->{user_agent};
	my $res = $ua->get($url);

	if ( $res->is_error ) {
		return ( undef, $res->status_line );
	}
	my $content = $res->decoded_content;

	if ($cache) {
		$cache->freeze( $url, \$content );
	}

	return ( $content, undef );
}

sub wagongroup_powertype {
	my ( $self, @wagons ) = @_;

	if ( not @wagons ) {
		@wagons = $self->wagons;
	}

	my %ml = map { $_ => 0 } ( 90 .. 99 );

	for my $wagon (@wagons) {

		if ( not $wagon->uic_id or length( $wagon->uic_id ) != 12 ) {
			next;
		}

		my $wagon_type = substr( $wagon->uic_id, 0, 2 );
		if ( $wagon_type < 90 ) {
			next;
		}

		$ml{$wagon_type}++;
	}

	my @likelihood = reverse sort { $ml{$a} <=> $ml{$b} } keys %ml;

	if ( $ml{ $likelihood[0] } == 0 ) {
		return undef;
	}

	return $likelihood[0];
}

sub parse_wagonorder {
	my ($self) = @_;

	$self->{platform} = $self->{data}{istformation}{halt}{gleisbezeichnung};

	$self->{station} = {
		ds100 => $self->{data}{istformation}{halt}{rl100},
		eva   => $self->{data}{istformation}{halt}{evanummer},
		name  => $self->{data}{istformation}{halt}{bahnhofsname},
	};

	$self->{train_type} = $self->{data}{istformation}{zuggattung};
	$self->{train_no}   = $self->{data}{istformation}{zugnummer};

	$self->parse_wagons;
	$self->{origins}      = $self->parse_wings('startbetriebsstellename');
	$self->{destinations} = $self->parse_wings('zielbetriebsstellename');
}

sub parse_wings {
	my ( $self, $attr ) = @_;

	my @names;
	my %section;

	for my $group ( @{ $self->{data}{istformation}{allFahrzeuggruppe} } ) {
		my $name     = $group->{$attr};
		my @sections = map { $_->{fahrzeugsektor} } @{ $group->{allFahrzeug} };
		push( @{ $section{$name} }, @sections );
		push( @names,               $name );
	}

	@names = uniq @names;

	@names
	  = map { { name => $_, sections => [ uniq @{ $section{$_} } ] } } @names;

	return \@names;
}

sub parse_wagons {
	my ($self) = @_;

	my @wagon_groups;

	for my $group ( @{ $self->{data}{istformation}{allFahrzeuggruppe} } ) {
		my @group_wagons;
		for my $wagon ( @{ $group->{allFahrzeug} } ) {
			my $wagon_object
			  = Travel::Status::DE::DBWagenreihung::Wagon->new( %{$wagon},
				train_no => $group->{verkehrlichezugnummer} );
			push( @{ $self->{wagons} }, $wagon_object );
			push( @group_wagons,        $wagon_object );
			if ( not $wagon_object->{position}{valid} ) {
				$self->{has_bad_wagons} = 1;
			}
		}
		my $group_obj = Travel::Status::DE::DBWagenreihung::Group->new(
			id          => $group->{fahrzeuggruppebezeichnung},
			train_no    => $group->{verkehrlichezugnummer},
			origin      => $group->{startbetriebsstellename},
			destination => $group->{zielbetriebsstellename},
			wagons      => \@group_wagons,
		);
		push( @wagon_groups, $group_obj );

		my ( $short, $desc ) = $self->wagongroup_description( $group_obj->wagons );
		my @sections = uniq map { $_->section } $group_obj->wagons;

		if ( @sections and length( join( q{}, @sections ) ) ) {
			$group_obj->set_sections(@sections);
		}
		$group_obj->set_description( $desc, $short );
	}
	if ( @{ $self->{wagons} // [] } > 1 and not $self->has_bad_wagons ) {
		if ( $self->{wagons}[0]->{position}{start_percent}
			> $self->{wagons}[-1]->{position}{start_percent} )
		{
			$self->{direction} = 100;
		}
		else {
			$self->{direction} = 0;
		}
	}
	if ( not $self->has_bad_wagons ) {
		@{ $self->{wagons} } = sort {
			$a->{position}->{start_percent} <=> $b->{position}->{start_percent}
		} @{ $self->{wagons} };
		for my $group (@wagon_groups) {
			$group->sort_wagons;
		}
	}

	for my $i ( 0 .. $#wagon_groups ) {
		my $group = $wagon_groups[$i];
		my $tt    = $self->wagongroup_subtype( $group->wagons );
		$group->set_traintype( $i, $tt );
		$group->{type} = $tt;
	}

	$self->{wagongroups} = [@wagon_groups];
}

# }}}
# {{{ Public Functions

sub errstr {
	my ($self) = @_;

	return $self->{errstr};
}

sub destinations {
	my ($self) = @_;

	return @{ $self->{destinations} // [] };
}

sub origins {
	my ($self) = @_;

	return @{ $self->{origins} // [] };
}

sub sections {
	my ($self) = @_;

	if ( exists $self->{sections} ) {
		return @{ $self->{sections} };
	}

	for my $section ( @{ $self->{data}{istformation}{halt}{allSektor} } ) {
		my $pos = $section->{positionamgleis};
		if ( $pos->{startprozent} eq '' or $pos->{endeprozent} eq '' ) {
			next;
		}
		push(
			@{ $self->{sections} },
			Travel::Status::DE::DBWagenreihung::Section->new(
				name          => $section->{sektorbezeichnung},
				start_percent => $pos->{startprozent},
				end_percent   => $pos->{endeprozent},
				start_meters  => $pos->{startmeter},
				end_meters    => $pos->{endemeter},
			)
		);
	}

	return @{ $self->{sections} // [] };
}

sub train_numbers {
	my ($self) = @_;

	if ( exists $self->{train_numbers} ) {
		return @{ $self->{train_numbers} };
	}

	my @numbers;

	for my $group ( @{ $self->{data}{istformation}{allFahrzeuggruppe} } ) {
		push( @numbers, $group->{verkehrlichezugnummer} );
	}

	@numbers = uniq @numbers;

	$self->{train_numbers} = \@numbers;

	return @numbers;
}

sub has_bad_wagons {
	my ($self) = @_;

	if ( defined $self->{has_bad_wagons} ) {
		return $self->{has_bad_wagons};
	}

	for my $group ( @{ $self->{data}{istformation}{allFahrzeuggruppe} } ) {
		for my $wagon ( @{ $group->{allFahrzeug} } ) {
			my $pos = $wagon->{positionamhalt};
			if (   $pos->{startprozent} eq ''
				or $pos->{endeprozent} eq ''
				or $pos->{startmeter} eq ''
				or $pos->{endemeter} eq '' )
			{
				return $self->{has_bad_wagons} = 1;
			}
		}
	}

	return $self->{has_bad_wagons} = 0;
}

sub wagongroup_description {
	my ( $self, @wagons ) = @_;

	my $powertype = $self->wagongroup_powertype(@wagons);
	my @model     = $self->wagongroup_model(@wagons);

	my $short;
	my $ret = q{};

	if (@model) {
		$short = $model[0];
		$ret .= $model[0];
	}

	if ( $powertype and $power_desc{$powertype} ) {
		if ( not $ret and $power_desc{$powertype} =~ m{^mit} ) {
			$ret = "Zug";
		}
		$ret .= " $power_desc{$powertype}";
		$short //= $ret;
		$short =~ s{elektrischer }{E-};
		$short =~ s{[Ll]\Kokomotive}{ok};
	}

	if ( @model > 1 ) {
		$ret .= " ($model[1])";
	}

	return ( $short, $ret );
}

sub wagongroup_model {
	my ( $self, @wagons ) = @_;

	my $subtype = $self->wagongroup_subtype(@wagons);

	if ( $subtype and $model_name{$subtype} ) {
		return @{ $model_name{$subtype} };
	}
	if ($subtype) {
		return $subtype;
	}
	return;
}

sub wagongroup_subtype {
	my ( $self, @wagons ) = @_;

	if ( not @wagons ) {
		@wagons = $self->wagons;
	}

	my %ml = (
		'011'      => 0,
		'401'      => 0,
		'402'      => 0,
		'403.S1'   => 0,
		'403.S2'   => 0,
		'403.R'    => 0,
		'406'      => 0,
		'407'      => 0,
		'408'      => 0,
		'411.S1'   => 0,
		'411.S2'   => 0,
		'412'      => 0,
		'415'      => 0,
		'420'      => 0,
		'422'      => 0,
		'423'      => 0,
		'425'      => 0,
		'427'      => 0,
		'428'      => 0,
		'429'      => 0,
		'430'      => 0,
		'440'      => 0,
		'442'      => 0,
		'445'      => 0,
		'446'      => 0,
		'462'      => 0,
		'463'      => 0,
		'475'      => 0,
		'612'      => 0,
		'620'      => 0,
		'622'      => 0,
		'631'      => 0,
		'632'      => 0,
		'633'      => 0,
		'640'      => 0,
		'642'      => 0,
		'643'      => 0,
		'648'      => 0,
		'IC2.TWIN' => 0,
		'IC2.KISS' => 0,
	);

	for my $wagon (@wagons) {
		if ( not $wagon->model ) {
			next;
		}
		if ( $wagon->model == 401
			or ( $wagon->model >= 801 and $wagon->model <= 804 ) )
		{
			$ml{'401'}++;
		}
		elsif ( $wagon->model == 402
			or ( $wagon->model >= 805 and $wagon->model <= 808 ) )
		{
			$ml{'402'}++;
		}
		elsif ( $wagon->model == 403
			and $is_redesign{ substr( $wagon->uic_id, 9, 2 ) } )
		{
			$ml{'403.R'}++;
		}
		elsif ( $wagon->model == 403 and substr( $wagon->uic_id, 9, 2 ) <= 37 )
		{
			$ml{'403.S1'}++;
		}
		elsif ( $wagon->model == 403 and substr( $wagon->uic_id, 9, 2 ) > 37 ) {
			$ml{'403.S2'}++;
		}
		elsif ( $wagon->model == 406 ) {
			$ml{'406'}++;
		}
		elsif ( $wagon->model == 407 ) {
			$ml{'407'}++;
		}
		elsif ( $wagon->model == 408 ) {
			$ml{'408'}++;
		}
		elsif ( $wagon->model == 412 or $wagon->model == 812 ) {
			$ml{'412'}++;
		}
		elsif ( $wagon->model == 411 and substr( $wagon->uic_id, 9, 2 ) <= 32 )
		{
			$ml{'411.S1'}++;
		}
		elsif ( $wagon->model == 411 and substr( $wagon->uic_id, 9, 2 ) > 32 ) {
			$ml{'411.S2'}++;
		}
		elsif ( $wagon->model == 415 ) {
			$ml{'415'}++;
		}
		elsif ( $wagon->model == 420 or $wagon->model == 421 ) {
			$ml{'420'}++;
		}
		elsif ( $wagon->model == 422 or $wagon->model == 432 ) {
			$ml{'422'}++;
		}
		elsif ( $wagon->model == 423 or $wagon->model == 433 ) {
			$ml{'423'}++;
		}
		elsif ( $wagon->model == 425 or $wagon->model == 435 ) {
			$ml{'425'}++;
		}
		elsif ( $wagon->model == 427 or $wagon->model == 827 ) {
			$ml{'427'}++;
		}
		elsif ( $wagon->model == 428 or $wagon->model == 828 ) {
			$ml{'428'}++;
		}
		elsif ( $wagon->model == 429 or $wagon->model == 829 ) {
			$ml{'429'}++;
		}
		elsif ( $wagon->model == 430 or $wagon->model == 431 ) {
			$ml{'430'}++;
		}
		elsif ($wagon->model == 440
			or $wagon->model == 441
			or $wagon->model == 841 )
		{
			$ml{'440'}++;
		}
		elsif ($wagon->model == 442
			or $wagon->model == 443 )
		{
			$ml{'442'}++;
		}
		elsif ($wagon->model == 462
			or $wagon->model == 862 )
		{
			$ml{'462'}++;
		}
		elsif ($wagon->model == 463
			or $wagon->model == 863 )
		{
			$ml{'463'}++;
		}
		elsif ( $wagon->model == 445 ) {
			$ml{'445'}++;
		}
		elsif ( $wagon->model == 446 ) {
			$ml{'446'}++;
		}
		elsif ( $wagon->model == 475 ) {
			$ml{'475'}++;
		}
		elsif ( $wagon->model == 612 ) {
			$ml{'612'}++;
		}
		elsif ( $wagon->model == 620 or $wagon->model == 621 ) {
			$ml{'620'}++;
		}
		elsif ( $wagon->model == 622 ) {
			$ml{'622'}++;
		}
		elsif ( $wagon->model == 631 ) {
			$ml{'631'}++;
		}
		elsif ( $wagon->model == 632 ) {
			$ml{'632'}++;
		}
		elsif ( $wagon->model == 633 ) {
			$ml{'633'}++;
		}
		elsif ( $wagon->model == 640 ) {
			$ml{'640'}++;
		}
		elsif ( $wagon->model == 642 ) {
			$ml{'642'}++;
		}
		elsif ( $wagon->model == 643 or $wagon->model == 943 ) {
			$ml{'643'}++;
		}
		elsif ( $wagon->model == 648 ) {
			$ml{'648'}++;
		}
		elsif ( $self->train_type eq 'IC' and $wagon->model == 110 ) {
			$ml{'IC2.KISS'}++;
		}
		elsif ( $self->train_type eq 'IC' and $wagon->is_dosto ) {
			$ml{'IC2.TWIN'}++;
		}
		elsif ( substr( $wagon->uic_id, 4, 4 ) eq '4011' ) {
			$ml{'011'}++;
		}
	}

	my @likelihood = reverse sort { $ml{$a} <=> $ml{$b} } keys %ml;

	# Less than two wagons are generally inconclusive.
	# Exception: BR 631 (Link I) only has a single wagon
	if (
		$ml{ $likelihood[0] } < 2
		and not($likelihood[0] eq '631'
			and @wagons == 1
			and substr( $wagons[0]->uic_id, 0, 2 ) eq '95' )
	  )
	{
		return undef;
	}

	return $likelihood[0];
}

sub groups {
	my ($self) = @_;
	return @{ $self->{wagongroups} // [] };
}

sub carriages {
	my ($self) = @_;
	return @{ $self->{wagons} // [] };
}

sub wagons {
	my ($self) = @_;
	return @{ $self->{wagons} // [] };
}

sub TO_JSON {
	my ($self) = @_;

	# ensure that all objects are available
	$self->train_numbers;
	$self->sections;

	my %copy = %{$self};

	delete $copy{from_json};

	return {%copy};
}

# }}}

1;

__END__

=head1 NAME

Travel::Status::DE::DBWagenreihung - Interface to Deutsche Bahn carriage formation API.

=head1 SYNOPSIS

    use Travel::Status::DE::DBWagenreihung;

    my $wr = Travel::Status::DE::DBWagenreihung->new(
        departure => 'DateTime or YYYYMMDDhhmm',
        train_number => 1234,
    );

    for my $carriage ( $wr->carriages ) {
        printf("Wagen %s: Abschnitt %s\n", $carriage->number // '?', $carriage->section);
    }

=head1 VERSION

version 0.13

This is beta software. The API may change without notice.

=head1 DESCRIPTION

Travel:Status:DE::DBWagenreihung is an unofficial interface to the Deutsche
Bahn carriage formation API at L<https://ist-wr.noncd.db.de/wagenreihung/1.0>.
It returns station-specific carriage formations for a variety of trains in the
rail network associated with Deutsche Bahn.  Data includes carriage positions
on the platform, train type (e.g. ICE series), carriage-specific attributes
such as first/second class, and the internal type and number of each carriage.

Positions on the platform are given both in meters and percent (relative to
platform length).

Note that carriage formation data reported by the API is known to be bogus
from time to time. This module does not perform thorough sanity checking.

=head1 METHODS

=over

=item my $wr = Travel::Status::DE::DBWagenreihung->new(I<%opts>)

Requests carriage formation for a specific train at a specific scheduled
departure time and date, which implicitly encodes the requested station. Use
L<Travel::Status::DE::IRIS> or similar to map station name and train number to
scheduled departure.

Arguments:

=over

=item B<departure> => I<datetime-obj> | I<YYYYMMDDhhmm>

Scheduled departure at the station of interest. Must be either a
L<DateTime> object or a string in I<YYYYMMDDhhmm> format. Mandatory.

=item B<train_number> => I<number>

Train number. Do not include the train type: Use "8" for "EC 8" or
"100" for "ICE 100".

=back

=item $wr->destinations

Returns a list describing the destinations of this train's carriages. In most
cases, it contains one element. For trains consisting of multiple wings or
trains that switch locomotives along the way, it contains one element for each
wing or other kind of carriage group.

Each destination is a hash ref containing its B<name> and the corresponding
platform I<sections> (at the moment, this is a list of section identifiers).

This function is subject to change.

=item $wr->direction

Gives the train's direction of travel. Returns 0 if the train will depart
towards position 0 and 100 if the train will depart towards the other platform
end (mnemonic: towards the 100% position).

=item $wr->errstr

In case of a fatal HTTP or backend error, returns a string describing it.
Returns undef otherwise.

=item $wr->origins

Returns a list describing the origins of this train's carriages. In most
cases, it contains one element. For trains consisting of multiple wings or
trains that switch locomotives along the way, it contains one element for each
wing or other kind of carriage group.

Each origin is a hash ref containing its B<name> and the corresponding
platform I<sections> (at the moment, this is a list of section identifiers).

This function is subject to change.

=item $wr->platform

Returns the platform name.

=item $wr->sections

Describes the sections of the platform this train will depart from.
Returns a list of L<Travel::Status::DE::DBWagenreihung::Section> objects.

=item $wr->station

Returns a hashref describing the requested station. The hashref contains three
entries: B<ds100> (DS100 / Ril100 identifier), B<eva> (EVA ID, related to but
not necessarily identical with UIC station ID), and B<name> (station name).

=item $wr->train_numbers

Returns the list of train numbers for this departure. In most cases, this is
just one element. For trains consisting of multiple wings (which typically have
different numbers), it contains one element for each wing.

=item $wr->train_type

Returns a string describing the train type, e.g. "ICE" or "IC".

=item $wr->carriages

Describes the individual carriages the train consists of. Returns a list of
L<Travel::Status::DE::DBWagenreihung::Carriage> objects.

=back

=head1 DEPENDENCIES

=over

=item * L<JSON>

=item * L<LWP::UserAgent>

=back

=head1 BUGS AND LIMITATIONS

Many. This is beta software.

=head1 REPOSITORY

L<https://github.com/derf/Travel-Status-DE-DBWagenreihung>

=head1 AUTHOR

Copyright (C) 2018-2024 by Birte Kristina Friesel E<lt>derf@finalrewind.orgE<gt>

=head1 LICENSE

This module is licensed under the same terms as Perl itself.