File Coverage

lib/Data/Identifier.pm

Criterion	Covered	Total	%
statement	241	433	55.6
branch	133	320	41.5
condition	75	195	38.4
subroutine	26	37	70.2
pod	23	23	100.0
total	498	1008	49.4

#!/usr/bin/perl -w

# Copyright (c) 2023-2026 Philipp Schafft

# licensed under Artistic License 2.0 (see LICENSE file)

# ABSTRACT: format independent identifier object


package Data::Identifier;

use v5.20;
use strict;
use warnings;

use parent qw(Data::Identifier::Interface::Known Data::Identifier::Interface::Userdata);

use Carp;
use Math::BigInt lib => 'GMP';
use URI;

our $VERSION = v0.30;

use constant {
    RE_UUID         => qr/^[0-9a-f]{8}-(?:[0-9a-f]{4}-){3}[0-9a-f]{12}\z/,
    RE_OID          => qr/^[0-2](?:\.(?:0|[1-9][0-9]*))+\z/,
    RE_URI          => qr/^[a-zA-Z][a-zA-Z0-9\+\.\-]+:/,
    RE_UINT         => qr/^(?:0|[1-9][0-9]*)\z/,
    RE_SINT         => qr/^(?:0|-?[1-9][0-9]*)\z/,
    RE_QID          => qr/^[QPL][1-9][0-9]*\z/,
    RE_DOI          => qr/^10\.[1-9][0-9]+(?:\.[0-9]+)*\/./,
    RE_GTIN         => qr/^[0-9]{8}(?:[0-9]{4,6})?\z/,
    RE_UNICODE      => qr/^U\+([0-9A-F]{4,7})\z/,
    RE_SIMPLE_TAG   => qr/^[^\p{upper case}\s]+\z/,
};

use constant {
    WK_NULL         => '00000000-0000-0000-0000-000000000000', # NULL, undef, ...
    WK_UUID         => '8be115d2-dc2f-4a98-91e1-a6e3075cbc31', # uuid
    WK_OID          => 'd08dc905-bbf6-4183-b219-67723c3c8374', # oid
    WK_URI          => 'a8d1637d-af19-49e9-9ef8-6bc1fbcf6439', # uri
    WK_SID          => 'f87a38cb-fd13-4e15-866c-e49901adbec5', # small-identifier
    WK_WD           => 'ce7aae1e-a210-4214-926a-0ebca56d77e3', # wikidata-identifier
    WK_GTIN         => '82d529be-0f00-4b4f-a43f-4a22de5f5312', # gtin
    WK_IBAN         => 'b1418262-6bc9-459c-b4b0-a054d77db0ea', # iban
    WK_BIC          => 'c8a3a132-f160-473c-b5f3-26a748f37e62', # bic
    WK_DOI          => '931f155e-5a24-499b-9fbb-ed4efefe27fe', # doi
    WK_FC           => 'd576b9d1-47d4-43ae-b7ec-bbea1fe009ba', # factgrid-identifier
    WK_UNICODE_CP   => '5f167223-cc9c-4b2f-9928-9fe1b253b560', # unicode-code-point
    WK_SNI          => '039e0bb7-5dd3-40ee-a98c-596ff6cce405', # sirtx-numerical-identifier
    WK_HDI          => 'f8eb04ef-3b8a-402c-ad7c-1e6814cb1998', # host-defined-identifier
    WK_UDI          => '05af99f9-4578-4b79-aabe-946d8e6f5888', # user-defined-identifier
    WK_CHAT0W       => '2c7e15ed-aa2f-4e2f-9a1d-64df0c85875a', # chat-0-word-identifier

    NS_WD           => '9e10aca7-4a99-43ac-9368-6cbfa43636df', # Wikidata-namespace
    NS_FC           => '6491f7a9-0b29-4ef1-992c-3681cea18182', # factgrid-namespace
    NS_INT          => '5dd8ddbb-13a8-4d6c-9264-36e6dd6f9c99', # integer-namespace
    NS_DATE         => 'fc43fbba-b959-4882-b4c8-90a288b7d416', # gregorian-date-namespace
    NS_GTIN         => 'd95d8b1f-5091-4642-a6b0-a585313915f1', # gtin-namespace
    NS_UNICODE_CP   => '132aa723-a373-48bf-a88d-69f1e00f00cf', # unicode-character-namespace
};

# Features:
my $enabled_oid = 1;

my %uuid_to_uriid_org = (
    WK_UUID()       => 'uuid',
    WK_OID()        => 'oid',
    WK_URI()        => 'uri',
    WK_SID()        => 'sid',
    WK_GTIN()       => 'gtin',
    WK_WD()         => 'wikidata-identifier',
);

my %uuid_org_to_uuid = map {$uuid_to_uriid_org{$_} => $_} keys %uuid_to_uriid_org;

my $well_known_uuid = __PACKAGE__->new(ise => WK_UUID, validate => RE_UUID);

my %well_known = (
    uuid => $well_known_uuid,
    oid  => __PACKAGE__->new($well_known_uuid => WK_OID,    validate => RE_OID),
    uri  => __PACKAGE__->new($well_known_uuid => WK_URI,    validate => RE_URI),
    sid  => __PACKAGE__->new($well_known_uuid => WK_SID,    validate => RE_UINT),
    sni  => __PACKAGE__->new($well_known_uuid => WK_SNI,    validate => RE_UINT),
    wd   => __PACKAGE__->new($well_known_uuid => WK_WD,     validate => RE_QID,  generate => 'id-based'),
    fc   => __PACKAGE__->new($well_known_uuid => WK_FC,     validate => RE_QID,  generate => 'id-based'),
    gtin => __PACKAGE__->new($well_known_uuid => WK_GTIN,   validate => RE_GTIN, generate => 'id-based'),
    iban => __PACKAGE__->new($well_known_uuid => WK_IBAN),
    bic  => __PACKAGE__->new($well_known_uuid => WK_BIC),
    doi  => __PACKAGE__->new($well_known_uuid => WK_DOI,    validate => RE_DOI),

    # Unofficial, not part of public API:
    # Also used by Data::Identifier::Util!
    unicodecp => __PACKAGE__->new($well_known_uuid => WK_UNICODE_CP, validate => RE_UNICODE, generate => 'id-based'),

    hdi  => __PACKAGE__->new($well_known_uuid => WK_HDI, validate => RE_UINT),
    udi  => __PACKAGE__->new($well_known_uuid => WK_UDI, validate => RE_UINT),
    null => __PACKAGE__->new($well_known_uuid => WK_NULL),
);

my %registered;

$_->register foreach values %well_known;

# Refill with namespaces:
{
    my %ns = (
        wd   => NS_WD,
        fc   => NS_FC,
        gtin => NS_GTIN,
        unicodecp => NS_UNICODE_CP,
    );

    foreach my $wk (keys %ns) {
        $well_known{$wk}->{namespace} //= Data::Identifier->new(ise => $ns{$wk})->register;
    }
}

# Refill with sids:
{
    my %wk_sids = (
        WK_NULL()                               =>   0, # NULL
        'ddd60c5c-2934-404f-8f2d-fcb4da88b633'  =>   1, # also-shares-identifier
        WK_UUID()                               =>   2,
        'bfae7574-3dae-425d-89b1-9c087c140c23'  =>   3, # tagname
        '7f265548-81dc-4280-9550-1bd0aa4bf748'  =>   4, # has-type
        WK_URI()                                =>   5,
        WK_OID()                                =>   6,
        # Unassigned: 7
        'd0a4c6e2-ce2f-4d4c-b079-60065ac681f1'  =>   8, # language-tag-identifier
        WK_WD()                                 =>   9,
        '923b43ae-a50e-4db3-8655-ed931d0dd6d4'  =>  10, # specialises
        'eacbf914-52cf-4192-a42c-8ecd27c85ee1'  =>  11, # unicode-string
        '928d02b0-7143-4ec9-b5ac-9554f02d3fb1'  =>  12, # integer
        'dea3782c-6bcb-4ce9-8a39-f8dab399d75d'  =>  13, # unsigned-integer
        # Unassigned: 14, 15
        '6ba648c2-3657-47c2-8541-9b73c3a9b2b4'  =>  16, # default-context
        '52a516d0-25d8-47c7-a6ba-80983e576c54'  =>  17, # proto-file
        '1cd4a6c6-0d7c-48d1-81e7-4e8d41fdb45d'  =>  18, # final-file-size
        '6085f87e-4797-4bb2-b23d-85ff7edc1da0'  =>  19, # text-fragment
        '4c9656eb-c130-42b7-9348-a1fee3f42050'  =>  20, # also-list-contains-also
        '298ef373-9731-491d-824d-b2836250e865'  =>  21, # proto-message
        '7be4d8c7-6a75-44cc-94f7-c87433307b26'  =>  22, # proto-entity
        '65bb36f2-b558-48af-8512-bca9150cca85'  =>  23, # proxy-type
        'a1c478b5-0a85-4b5b-96da-d250db14a67c'  =>  24, # flagged-as
        '59cfe520-ba32-48cc-b654-74f7a05779db'  =>  25, # marked-as
        '2bffc55d-7380-454e-bd53-c5acd525d692'  =>  26, # roaraudio-error-number
        WK_SID()                                =>  27,
        'd2750351-aed7-4ade-aa80-c32436cc6030'  =>  28, # also-has-role
        '11d8962c-0a71-4d00-95ed-fa69182788a8'  =>  29, # also-has-comment
        '30710bdb-6418-42fb-96db-2278f3bfa17f'  =>  30, # also-has-description
        # Unassigned: 31
        '448c50a8-c847-4bc7-856e-0db5fea8f23b'  =>  32, # final-file-encoding
        '79385945-0963-44aa-880a-bca4a42e9002'  =>  33, # final-file-hash
        '3fde5688-6e34-45e9-8f33-68f079b152c8'  =>  34, # SEEK_SET
        'bc598c52-642e-465b-b079-e9253cd6f190'  =>  35, # SEEK_CUR
        '06aff30f-70e8-48b4-8b20-9194d22fc460'  =>  36, # SEEK_END
        '59a5691a-6a19-4051-bc26-8db82c019df3'  =>  37, # inode
        WK_CHAT0W()                             => 112, # chat-0-word-identifier
        WK_SNI()                                => 113, # sirtx-numerical-identifier
        WK_GTIN()                               => 160,
    );

    foreach my $ise (keys %wk_sids) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{id_cache} //= {};
        $identifier->{id_cache}->{WK_SID()} //= $wk_sids{$ise};
        $identifier->register; # re-register
    }
}

# Refill with snis:
{
    my %wk_snis = (
        WK_NULL()                               =>   0, # NULL
        '039e0bb7-5dd3-40ee-a98c-596ff6cce405'  =>  10, # sirtx-numerical-identifier
        'f87a38cb-fd13-4e15-866c-e49901adbec5'  => 115, # small-identifier
        '2bffc55d-7380-454e-bd53-c5acd525d692'  => 116, # roaraudio-error-number
        WK_CHAT0W()                             => 118, # chat-0-word-identifier
        WK_UUID()                               => 119,
        WK_OID()                                => 120,
        WK_URI()                                => 121,
        WK_WD()                                 => 123,
    );

    foreach my $ise (keys %wk_snis) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{id_cache} //= {};
        $identifier->{id_cache}->{WK_SNI()} //= $wk_snis{$ise};
        $identifier->register; # re-register
    }
}

# Update NULL:
{
    my $identifier = __PACKAGE__->new(uuid => WK_NULL);
    $identifier->{id_cache} //= {};
    foreach my $type (WK_HDI, WK_CHAT0W) {
        $identifier->{id_cache}->{$type} //= 0;
    }
    $identifier->register;
}

# Some extra tags such as namespaces:
foreach my $ise (NS_WD, NS_INT, NS_DATE) {
    my $identifier = __PACKAGE__->new(ise => $ise);
    $identifier->register; # re-register
}

# Refill with tagnames
{
    my %tagnames = (
        WK_NULL()                               => 'null',
        WK_UUID()                               => 'uuid',
        WK_OID()                                => 'oid',
        WK_URI()                                => 'uri',
        WK_SID()                                => 'small-identifier',
        WK_WD()                                 => 'wikidata-identifier',
        WK_GTIN()                               => 'gtin',
        WK_IBAN()                               => 'iban',
        WK_BIC()                                => 'bic',
        WK_DOI()                                => 'doi',
        WK_FC()                                 => 'factgrid-identifier',
        WK_UNICODE_CP()                         => 'unicode-code-point',
        WK_SNI()                                => 'sirtx-numerical-identifier',
        WK_HDI()                                => 'host-defined-identifier',
        WK_UDI()                                => 'user-defined-identifier',
        WK_CHAT0W()                             => 'chat-0-word-identifier',
        NS_WD()                                 => 'Wikidata-namespace',
        NS_FC()                                 => 'factgrid-namespace',
        NS_INT()                                => 'integer-namespace',
        NS_DATE()                               => 'gregorian-date-namespace',
        NS_UNICODE_CP()                         => 'unicode-character-namespace',

        'ddd60c5c-2934-404f-8f2d-fcb4da88b633'  => 'also-shares-identifier',
        'bfae7574-3dae-425d-89b1-9c087c140c23'  => 'tagname',
        '7f265548-81dc-4280-9550-1bd0aa4bf748'  => 'has-type',
        'd0a4c6e2-ce2f-4d4c-b079-60065ac681f1'  => 'language-tag-identifier',
        '923b43ae-a50e-4db3-8655-ed931d0dd6d4'  => 'specialises',
        'eacbf914-52cf-4192-a42c-8ecd27c85ee1'  => 'unicode-string',
        '928d02b0-7143-4ec9-b5ac-9554f02d3fb1'  => 'integer',
        'dea3782c-6bcb-4ce9-8a39-f8dab399d75d'  => 'unsigned-integer',
        '6ba648c2-3657-47c2-8541-9b73c3a9b2b4'  => 'default-context',
        '52a516d0-25d8-47c7-a6ba-80983e576c54'  => 'proto-file',
        '1cd4a6c6-0d7c-48d1-81e7-4e8d41fdb45d'  => 'final-file-size',
        '6085f87e-4797-4bb2-b23d-85ff7edc1da0'  => 'text-fragment',
        '4c9656eb-c130-42b7-9348-a1fee3f42050'  => 'also-list-contains-also',
        '298ef373-9731-491d-824d-b2836250e865'  => 'proto-message',
        '7be4d8c7-6a75-44cc-94f7-c87433307b26'  => 'proto-entity',
        '65bb36f2-b558-48af-8512-bca9150cca85'  => 'proxy-type',
        'a1c478b5-0a85-4b5b-96da-d250db14a67c'  => 'flagged-as',
        '59cfe520-ba32-48cc-b654-74f7a05779db'  => 'marked-as',
        '2bffc55d-7380-454e-bd53-c5acd525d692'  => 'roaraudio-error-number',
        'd2750351-aed7-4ade-aa80-c32436cc6030'  => 'also-has-role',
        '11d8962c-0a71-4d00-95ed-fa69182788a8'  => 'also-has-comment',
        '30710bdb-6418-42fb-96db-2278f3bfa17f'  => 'also-has-description',
        '448c50a8-c847-4bc7-856e-0db5fea8f23b'  => 'final-file-encoding',
        '79385945-0963-44aa-880a-bca4a42e9002'  => 'final-file-hash',
        '3fde5688-6e34-45e9-8f33-68f079b152c8'  => 'SEEK_SET',
        'bc598c52-642e-465b-b079-e9253cd6f190'  => 'SEEK_CUR',
        '06aff30f-70e8-48b4-8b20-9194d22fc460'  => 'SEEK_END',
        '59a5691a-6a19-4051-bc26-8db82c019df3'  => 'inode',
        '53863a15-68d4-448d-bd69-a9b19289a191'  => 'unsigned-integer-generator',
        'e8aa9e01-8d37-4b4b-8899-42ca0a2a906f'  => 'signed-integer-generator',
        'd74f8c35-bcb8-465c-9a77-01010e8ed25c'  => 'unicode-character-generator',
        '55febcc4-6655-4397-ae3d-2353b5856b34'  => 'rgb-colour-generator',
        '97b7f241-e1c5-4f02-ae3c-8e31e501e1dc'  => 'date-generator',
        '19659233-0a22-412c-bdf1-8ee9f8fc4086'  => 'multiplicity-generator',
        '5ec197c3-1406-467c-96c7-4b1a6ec2c5c9'  => 'minimum-multiplicity-generator',
    );

    foreach my $ise (keys %tagnames) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{tagname} //= [$tagnames{$ise}];
        $identifier->register; # re-register
    }
}

{
    # ISE -> namespace
    my %namespaces_uint = (
        '4a7fc2e2-854b-42ec-b24f-c7fece371865' => 'ac59062c-6ba2-44de-9f54-09e28f2c0b5c', # e621-post-identifier: e621-post-namespace
        'a0a4fae2-be6f-4a51-8326-6110ba845a16' => '69b7ff38-ca78-43a8-b9ea-66cb02312eef', # e621-pool-identifier: e621-pool-namespace
        '6e3590b6-2a0c-4850-a71f-8ba196a52280' => 'b96e5d94-0767-40fa-9864-5977eb507ae0', # danbooru2chanjp-post-identifier: danbooru2chanjp-post-namespace
    );
    my %namespaces_sint = (
        '2bffc55d-7380-454e-bd53-c5acd525d692' => '744eaf4e-ae93-44d8-9ab5-744105222da6', # roaraudio-error-number: roaraudio-error-namespace
    );
    my %namespaces_simple_tag = (
        '6fe0dbf0-624b-48b3-b558-0394c14bad6a' => '3623de4d-0dd4-4236-946a-2613467d50f1', # e621tag: e621tag-namespace
        'c5632c60-5da2-41af-8b60-75810b622756' => '93f2c36b-8cb6-4f2c-924b-98188f224235', # danbooru2chanjp-tag: danbooru2chanjp-tag-namespace
    );

    foreach my $ise (keys %namespaces_uint) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{namespace}    //= __PACKAGE__->new(ise => $namespaces_uint{$ise});
        $identifier->{validate}     //= RE_UINT;
        $identifier->{generate}     //= 'id-based';
        $identifier->register; # re-register
    }

    foreach my $ise (keys %namespaces_sint) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{namespace}    //= __PACKAGE__->new(ise => $namespaces_sint{$ise});
        $identifier->{validate}     //= RE_SINT;
        $identifier->{generate}     //= 'id-based';
        $identifier->register; # re-register
    }

    foreach my $ise (keys %namespaces_simple_tag) {
        my $identifier = __PACKAGE__->new(ise => $ise);
        $identifier->{namespace}    //= __PACKAGE__->new(ise => $namespaces_simple_tag{$ise});
        $identifier->{validate}     //= RE_SIMPLE_TAG;
        $identifier->{generate}     //= 'id-based';
        $identifier->register; # re-register
    }

    # validate => RE_QID, namespace => NS_FC, generate => 'id-based'
}

# Call this after after we loaded all our stuff and before anyone else will register stuff:
__PACKAGE__->_known_provider('wellknown');


sub new {
    my ($pkg, $type, $id, %opts) = @_;
    my $self = bless {};

    croak 'No type given' unless defined $type;
    croak 'No id given'   unless defined $id;

    if (!ref($type) && $type eq 'from') {
        if (ref($id)) {
            my $from = $id;
            if ($id->isa('Data::Identifier')) {
                if (scalar(keys %opts)) {
                    $type = $id->type;
                    $id   = $id->id;
                } else {
                    return $id;
                }
            } elsif ($id->isa('URI')) {
                $type = 'uri';
            } elsif ($id->isa('Mojo::URL')) {
                $type = 'uri';
                $id = $id->to_string;
            } elsif ($id->isa('Data::URIID::Result')) {
                $opts{displayname} //= sub { return $from->attribute('displayname', default => undef) };
                $type = $id->id_type;
                $id   = $id->id;
            } elsif ($id->isa('Data::URIID::Base') || $id->isa('Data::URIID::Colour') || $id->isa('Data::URIID::Service')) {
                #$opts{displayname} //= $id->name if $id->isa('Data::URIID::Service');
                $opts{displayname} //= $id->displayname(default => undef, no_defaults => 1);
                $type = 'ise';
                $id   = $id->ise;
            } elsif ($id->isa('Data::TagDB::Tag')) {
                $opts{displayname} //= sub { $from->displayname };
                $type = 'ise';
                $id   = $id->ise;
            } elsif ($id->isa('File::FStore::File') || $id->isa('File::FStore::Adder') || $id->isa('File::FStore::Base')) {
                $type = 'ise';
                $id = $id->contentise;
            } elsif ($id->isa('SIRTX::Datecode')) {
                $id = $id->as('Data::Identifier');
                unless (scalar(keys %opts)) {
                    return $id->as('Data::Identifier');
                }
                $type = $id->type;
                $id   = $id->id;
            } elsif ($id->isa('Business::ISBN')) {
                $type = $well_known{gtin};
                $id   = $id->as_isbn13->as_string([]);
            } elsif ($id->isa('Data::Identifier::Interface::Simple')) {
                # TODO: We cannot call $id->as('Data::Identifier') here as much as that would be fun,
                #       as this might in turn call exactly this code again resulting in a deep recursion.
                #       A future version might come up with some trick here.
                $type = 'ise';
                $id   = $id->ise;
            } elsif ($id->isa('JSON::PP::Boolean') || $id->isa('JSON::XS::Boolean')) {
                require Data::Identifier::Util;
                return Data::Identifier::Util->from_bool($id);
            } else {
                croak 'Unsupported input data';
            }
        } else {
            # If it's not a ref, try as ise.
            $type = 'ise';
        }
    }

    if (!ref($type) && $type eq 'ise') {
        croak 'Undefined identifier but type is ISE' unless defined $id;

        if ($id =~ /^[0-9a-fA-F]{8}-(?:[0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}\z/) { # allow less normalised form than RE_UUID
            $type = $well_known_uuid;

            # For bootstrap only.
            if (!defined($type) && $id eq '8be115d2-dc2f-4a98-91e1-a6e3075cbc31') {
                $self->{type} = $well_known_uuid = $type = $self;
                $self->{id} = $id;
            }
        } elsif ($id =~ RE_OID) {
            $type = 'oid';
        } elsif ($id =~ RE_URI) {
            $type = 'uri';
        } else {
            croak 'Not a valid ISE identifier';
        }
    }

    unless (ref $type) {
        if ($type =~ /^[0-9a-fA-F]{8}-(?:[0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}\z/) { # allow less normalised form than RE_UUID
            $type = $pkg->new(uuid => $type);
            $type->register;
        } elsif ($type eq 'wellknown') {
            $self = $well_known{$id};
            croak 'Unknown well-known' unless defined $self;
            return $self;
        } else {
            $type = $well_known{$type};
        }
        croak 'Unknown type name' unless defined $type;
    }

    croak 'Not a valid type' unless $type->isa(__PACKAGE__);

    # we normalise URIs first as they may then normalised again
    if ($type == ($well_known{uri} // 0)) {
        my $uri = $id.''; # force stringification

        if ($uri =~ m#^urn:uuid:([0-9a-f]{8}-(?:[0-9a-f]{4}-){3}[0-9a-f]{12})\z#) {
            $id = $1;
            $type = $well_known_uuid;
        } elsif ($uri =~ m#^urn:oid:([0-2](?:\.(?:0|[1-9][0-9]*))+)\z#) {
            $id = $1;
            $type = $well_known{oid};
        } elsif ($uri =~ m#^https?://www\.wikidata\.org/entity/([QPL][1-9][0-9]*)\z#) {
            $id = $1;
            $type = $well_known{wd};
        } elsif ($uri =~ m#^https?://doi\.org/(10\..+)\z#) {
            $id = $1;
            $type = $well_known{doi};
        } elsif ($uri =~ m#^https?://uriid\.org/([^/]+)/[^/]+#) {
            my $ptype = $1;
            if (defined($uuid_org_to_uuid{$ptype}) || $ptype =~ RE_UUID) {
                my $u = URI->new($uri);
                my @path_segments = $u->path_segments;
                if (scalar(@path_segments) == 3 && $path_segments[0] eq '') {
                    $type = $pkg->new(uuid => ($uuid_org_to_uuid{$path_segments[1]} // $path_segments[1]));
                    $id = $path_segments[2];
                }
            }
        }
    }

    if ($type == ($well_known_uuid // 0)) {
        $id = lc($id); # normalise
    } elsif ($type == ($well_known{oid} // 0)) {
        if ($id =~ /^2\.25\.([1-9][0-9]*)\z/) {
            my $hex = Math::BigInt->new($1)->as_hex;
            $hex =~ s/^0x//;
            $hex = ('0' x (32 - length($hex))) . $hex;
            $hex =~ s/^(.{8})(.{4})(.{4})(.{4})(.{12})\z/$1-$2-$3-$4-$5/;
            $type = $well_known_uuid;
            $id = $hex;
        }
    }

    if (defined(my $v = $registered{$type->uuid}{$id})) {
        return $v;
    }


    if (defined $type->{validate}) {
        croak 'Identifier did not validate against type' unless $id =~ $type->{validate};
    }

    $self->{type} = $type;
    $self->{id} = $id;

    foreach my $key (qw(validate namespace generator request generate displayname)) {
        next unless defined $opts{$key};
        $self->{$key} //= $opts{$key};
    }

    foreach my $key (qw(namespace generator)) {
        if (defined(my $v = $self->{$key})) {
            unless (ref $v) {
                $self->{$key} = $pkg->new(from => $v)->register;
            }
        }
    }

    if (defined(my $tagname = $opts{tagname})) {
        my %tagnames;
        $tagname = [$tagname] unless ref $tagname;
        %tagnames = map {$_ => undef} grep {defined} @{$tagname};
        $tagname = [keys %tagnames];
        if (scalar(@{$tagname})) {
            $self->{tagname} = $tagname;
        }
    }

    return bless $self;
}


#@returns __PACKAGE__
sub random {
    my ($pkg, %opts) = @_;
    my $type = $opts{type} // 'uuid';

    if (ref $type) {
        if ($type == $well_known_uuid) {
            $type = 'uuid';
        } else {
            croak 'Invalid/Unsupported type';
        }
    }

    if ($type ne 'ise' && $type ne 'uuid') {
        croak 'Invalid/Unsupported type';
    }

    require Data::Identifier::Generate;
    my $uuid = Data::Identifier::Generate->_random(%opts{'sources'});
    return $pkg->new(uuid => $uuid, %opts{'displayname'});
}



#@deprecated
sub wellknown {
    my ($pkg, @args) = @_;
    return $pkg->known('wellknown', @args);
}


#@returns __PACKAGE__
sub type {
    my ($self) = @_;
    return $self->{type};
}



sub id {
    my ($self) = @_;
    return $self->{id};
}


sub uuid {
    my ($self, %opts) = @_;

    return $self->{id_cache}{WK_UUID()} if !$opts{no_defaults} && defined($self->{id_cache}) && defined($self->{id_cache}{WK_UUID()});

    if ($self->{type} == $well_known_uuid) {
        return $self->{id};
    }

    unless ($opts{no_defaults}) {
        # Try to generate a UUID and recheck cache:
        $self->_generate;
        return $self->{id_cache}{WK_UUID()} if defined($self->{id_cache}) && defined($self->{id_cache}{WK_UUID()});
    }

    return $opts{default} if exists $opts{default};
    croak 'Identifier has no valid UUID';
}

sub oid {
    my ($self, %opts) = @_;
    my $type = $well_known{oid};

    return $self->{id_cache}{WK_OID()} if !$opts{no_defaults} && defined($self->{id_cache}) && defined($self->{id_cache}{WK_OID()});

    if ($self->{type} == $type) {
        return $self->{id};
    }

    unless ($opts{no_defaults}) {
        if (defined(my $uuid = $self->uuid(default => undef))) {
            return $self->{id_cache}{WK_OID()} = sprintf('2.25.%s', Math::BigInt->new('0x'.$uuid =~ tr/-//dr));
        }
    }

    return $opts{default} if exists $opts{default};
    croak 'Identifier has no valid OID';
}

sub uri {
    my ($self, %opts) = @_;
    my $type = $well_known{uri};

    if (!$opts{no_defaults} && !defined($opts{style}) && defined($self->{id_cache}) && defined($self->{id_cache}{WK_URI()})) {
        return $self->{id_cache}{WK_URI()};
    }

    if ($self->{type} == $type) {
        return $self->{id};
    }

    $opts{style} //= 'urn';

    unless ($opts{no_defaults}) {
        if ($self->{type} == $well_known{wd}) {
            return $self->{id_cache}{WK_URI()} = sprintf('http://www.wikidata.org/entity/%s', $self->{id});
        } elsif ($self->{type} == $well_known{doi}) {
            return $self->{id_cache}{WK_URI()} = sprintf('https://doi.org/%s', $self->{id});
        } elsif (defined(my $uuid = $self->uuid(default => undef)) && $opts{style} eq 'urn') {
            return $self->{id_cache}{WK_URI()} = sprintf('urn:uuid:%s', $uuid);
        } elsif ($enabled_oid && defined(my $oid = $self->oid(default => undef)) && $opts{style} eq 'urn') {
            return $self->{id_cache}{WK_URI()} = sprintf('urn:oid:%s', $oid);
        } else {
            my $u = URI->new("https://uriid.org/");
            my $type_uuid = $self->{type}->uuid;
            $u->path_segments('', $uuid_to_uriid_org{$type_uuid} // $type_uuid, $self->{id});
            return $self->{id_cache}{WK_URI()} = $u;
        }
    }

    return $opts{default} if exists $opts{default};
    croak 'Identifier has no valid URI';
}

sub sid {
    my ($self, %opts) = @_;
    my $type = $well_known{sid};
    return $self->{id_cache}{WK_SID()} if defined($self->{id_cache}) && defined($self->{id_cache}{WK_SID()});
    if ($self->{type} == $type) {
        return $self->{id};
    }

    return $opts{default} if exists $opts{default};
    croak 'Identifier has no valid SID';
}



sub ise {
    my ($self, %opts) = @_;
    my $type = $self->{type};
    my $have_default = exists $opts{default};
    my $default = delete $opts{default};
    my $value;

    if ($type == $well_known{uuid} || $type == $well_known{oid} || $type == $well_known{uri}) {
        $value = $self->{id};
    } else {
        $opts{default} = undef;
        $value = $self->uuid(%opts) // $self->oid(%opts) // $self->uri(%opts);
    }

    return $value if defined $value;
    return $default if $have_default;
    croak 'Identifier has no valid ISE';
}


sub as {
    my ($self, $as, %opts) = @_;

    $as = $opts{rawtype} if $as eq 'raw' && defined($opts{rawtype});

    if (ref($as) && eval {$as->isa(__PACKAGE__)}) {
        my $type_uuid = $as->uuid;
        my $next_type;

        return $self->id if $self->type->eq($as);

        foreach my $test (qw(uuid oid uri sid)) {
            if ($as == $well_known{$test}) {
                $next_type = $test;
                last;
            }
        }

        if (defined $next_type) {
            return $self->{id_cache}{$type_uuid} if !$opts{no_defaults} && defined($self->{id_cache}) && defined($self->{id_cache}{$type_uuid});
            $as = $next_type;
        } else {
            return $self->{id_cache}{$type_uuid} if defined($self->{id_cache}) && defined($self->{id_cache}{$type_uuid});
            return $opts{default} if exists $opts{default};
            croak 'Unknown/Unsupported as: '.$as;
        }
    }

    return $self if ($as =~ /^[A-Z]/ || $as =~ /::/) && eval {$self->isa($as)};

    if ($self->isa('Data::Identifier::Interface::Subobjects')) {
        require Data::Identifier::Interface::Subobjects; # Is this required?
        $opts{$_} //= $self->so_get($_, default => undef) foreach Data::Identifier::Interface::Subobjects->KEYS;
    }

    if (defined(my $so = $opts{so})) {
        require Data::Identifier::Interface::Subobjects; # Is this required?
        $opts{$_} //= $so->so_get($_, default => undef) foreach Data::Identifier::Interface::Subobjects->KEYS;
    }

    $self = __PACKAGE__->new(from => $self) unless eval {$self->isa(__PACKAGE__)};

    if ($as eq 'uuid' || $as eq 'oid' || $as eq 'uri' || $as eq 'sid' || $as eq 'ise') {
        my $func = $self->can($as);
        return $self->$func(%opts);
    } elsif ($as eq __PACKAGE__) {
        return $self;
    } elsif ($as eq 'URI') {
        my $had_default = exists $opts{default};
        my $default = delete $opts{default};
        my $val = $self->uri(%opts, default => undef);

        return URI->new($val) if defined $val;
        if ($had_default) {
            return $default if ref $default;
            return URI->new($default);
        }
        croak 'No value for URI';
    } elsif ($as eq 'Mojo::URL') {
        my $had_default = exists $opts{default};
        my $default = delete $opts{default};
        my $val = $self->uri(%opts, default => undef);

        require Mojo::URL;

        return Mojo::URL->new($val) if defined $val;
        if ($had_default) {
            return $default if ref $default;
            return Mojo::URL->new($default);
        }
        croak 'No value for URI';
    } elsif ($as eq 'Data::URIID::Result' && defined($opts{extractor})) {
        return $opts{extractor}->lookup($self->type->uuid => $self->id);
    } elsif ($as eq 'Data::URIID::Service' && defined($opts{extractor})) {
        return $opts{extractor}->service($self->uuid);
    } elsif ($as eq 'SIRTX::Datecode' && eval {
            require SIRTX::Datecode;
            SIRTX::Datecode->VERSION(v0.03);
            1;
        }) {
        return SIRTX::Datecode->new(from => $self);
    } elsif ($as eq 'Data::URIID::Colour' && eval {
            require Data::URIID;
            require Data::URIID::Colour;
            Data::URIID::Colour->VERSION(v0.14);
            1;
        }) {
        return Data::URIID::Colour->new(from => $self, %opts{qw(extractor db fii store)});
    } elsif ($as eq 'Data::TagDB::Tag' && defined($opts{db})) {
        if ($opts{autocreate}) {
            return $opts{db}->create_tag($self);
        } else {
            return $opts{db}->tag_by_id($self);
        }
    } elsif ($as eq 'File::FStore::File' && defined($opts{store})) {
        return scalar($opts{store}->query(ise => $self));
    } elsif ($as eq 'Business::ISBN' && $self->type->eq('gtin')) {
        require Business::ISBN;
        my $val = Business::ISBN->new($self->id);
        return $val if defined($val) && $val->is_valid;
    }

    return $opts{default} if exists $opts{default};
    croak 'Unknown/Unsupported as: '.$as;
}


sub eq {
    my ($self, $other) = @_;

    foreach my $e ($self, $other) {
        if (defined($e) && !scalar(eval {$e->isa(__PACKAGE__)})) {
            if (defined $well_known{$e}) {
                $e = $well_known{$e}
            } else {
                $e = Data::Identifier->new(from => $e);
            }
        }
    }

    if (defined($self)) {
        return undef unless defined $other;
        return 1 if $self == $other;
        return undef unless $self->type->eq($other->type);
        return $self->id eq $other->id;
    } else {
        return !defined($other);
    }
}


sub cmp {
    my ($self, $other) = @_;

    foreach my $e ($self, $other) {
        if (defined($e) && !scalar(eval {$e->isa(__PACKAGE__)})) {
            if (defined $well_known{$e}) {
                $e = $well_known{$e}
            } else {
                $e = Data::Identifier->new(from => $e);
            }
        }
    }

    if (defined($self)) {
        return undef unless defined $other;
        return 0 if $self == $other;
        if ((my $r = $self->type->cmp($other->type)) != 0) {
            return $r;
        }

        {
            my $self_id = $self->id;
            my $other_id = $other->id;

            if ((my ($sa, $sb) = $self_id =~ /^([^0-9]*)([0-9]+)\z/) && (my ($oa, $ob) = $other_id =~ /^([^0-9]*)([0-9]+)\z/)) {
                my $r = $sa cmp $oa;
                return $r if $r;
                return $sb <=> $ob;
            }

            return $self_id cmp $other_id;
        }
    } else {
        return !defined($other);
    }
}


sub null_to_undef {
    my ($self, @opts) = @_;

    croak 'Stray options passed' if scalar @opts;

    return undef unless defined $self;

    unless (eval {$self->isa(__PACKAGE__)}) {
        $self = __PACKAGE__->new(from => $self);
    }

    return undef if $self->eq('null');

    return $self;
}


#@returns __PACKAGE__
sub namespace {
    my ($self, %opts) = @_;
    my $has_default = exists $opts{default};
    my $default = delete $opts{default};

    delete $opts{no_defaults};

    croak 'Stray options passed' if scalar keys %opts;

    return $self->{namespace} if defined $self->{namespace};

    return $default if $has_default;

    croak 'No namespace';
}


#@returns __PACKAGE__
sub generator {
    my ($self, %opts) = @_;
    my $has_default = exists $opts{default};
    my $default = delete $opts{default};

    delete $opts{no_defaults};

    croak 'Stray options passed' if scalar keys %opts;

    return $self->{generator} if defined $self->{generator};

    return $default if $has_default;

    croak 'No generator';
}


sub request {
    my ($self, %opts) = @_;
    my $has_default = exists $opts{default};
    my $default = delete $opts{default};

    delete $opts{no_defaults};

    croak 'Stray options passed' if scalar keys %opts;

    return $self->{request} if defined $self->{request};

    return $default if $has_default;

    croak 'No request';
}


#@returns __PACKAGE__
sub register {
    my ($self) = @_;
    $registered{$self->{type}->uuid}{$self->{id}} = $self;

    foreach my $type_name (qw(uuid oid uri sid)) {
        my $f = $self->can($type_name) || next;
        my $v = $self->$f(default => undef) // next;
        $registered{$well_known{$type_name}->uuid}{$v} = $self;
    }

    foreach my $extra (keys %{$self->{id_cache}}) {
        my $v = $self->{id_cache}{$extra} // next;
        $registered{$extra}{$v} = $self;
    }

    return $self;
}



sub displayname {
    my ($self, %opts) = @_;

    if (defined(my $displayname = $self->{displayname})) {
        $displayname = $self->$displayname() if ref $displayname;

        # recheck and return as any of the above conversions could result in $displayname becoming invalid.
        return $displayname if defined($displayname) && length($displayname);
    }

    if (defined(my $tagname = $self->tagname(default => undef, no_defaults => 1))) {
        return $tagname;
    }

    return $self->id.'' unless $opts{no_defaults}; # force stringification.
    return $opts{default} if exists $opts{default};
    croak 'No value for displayname';
}


sub displaycolour { my ($self, %opts) = @_; return $opts{default}; }
sub icontext { my ($self, %opts) = @_; return $opts{default}; }
sub description { my ($self, %opts) = @_; return $opts{default}; }


sub tagname {
    my ($self, %opts) = @_;
    my $had_default = exists $opts{default};
    my $default = delete $opts{default};
    my $list = delete $opts{list};

    delete $opts{no_defaults}; # for compatibility.

    croak 'Stray options passed' if scalar keys %opts;

    if (defined(my $tagname = $self->{tagname})) {
        return @{$tagname} if $list;

        return $tagname->[0];
    }

    if ($had_default) {
        return @{$default} if $list;
        return $default;
    }
    croak 'No value for tagname found';
}

# ---- Private helpers ----

sub import {
    my ($pkg, $opts) = @_;
    return unless defined $opts;
    croak 'Bad options' unless ref($opts) eq 'HASH';

    if (defined(my $disable = $opts->{disable})) {
        $disable = [split /\s*,\s*/, $disable] unless ref $disable;
        foreach my $to_disable (@{$disable}) {
            if ($to_disable eq 'oid') {
                $enabled_oid = undef;
                undef *oid;
            } else {
                croak 'Unknown feature: '.$to_disable;
            }
        }
    }
}

sub _generate {
    my ($self) = @_;
    unless (exists $self->{_generate}) {
        my __PACKAGE__ $type = $self->type;

        if (defined(my $generate = $type->{generate})) {
            unless (ref $generate) {
                $self->{generate} = $generate = {style => $generate};
            }

            $self->{id_cache} //= {};

            if (defined(my __PACKAGE__ $ns = eval {$type->namespace->uuid})) {
                my $style = $generate->{style};
                my $input;

                if ($style eq 'id-based') {
                    $input = lc($self->id);
                } else {
                    croak 'Unsupported generator style';
                }

                if (defined $input) {
                    require Data::Identifier::Generate;
                    $self->{id_cache}{WK_UUID()} = Data::Identifier::Generate->_uuid_v5($ns, $input);
                }
            }
        }
    }
    $self->{_generate} = undef;
}

sub _known_provider {
    my ($pkg, $class, %opts) = @_;
    croak 'Unsupported options passed' if scalar(keys %opts);

    if ($class eq 'wellknown') {
        state $wellknown = do {
            my %hash = map{$_ => $_} values(%well_known), map {values %{$_}} values(%registered);
            [values %hash];
        };

        return ($wellknown, rawtype => __PACKAGE__);
    } elsif ($class eq 'registered' || $class eq ':all') {
        my %hash = map{$_ => $_} values(%well_known), map {values %{$_}} values(%registered);
        return ([values %hash], rawtype => __PACKAGE__);
    }

    croak 'Unsupported class';
}

1;

__END__