'Business::ISSN' => {

        'usage'    => 'Core',

        'required' => '1',

        'min_ver'  => '0.91',

    },

use Business::ISSN;

        &GetVariationsOfISSN

        &GetVariationsOfISSNs

        &NormalizeISSN

=head2 NormalizedISSN

  my $issns = NormalizedISSN({

          issn => $issn,

          strip_hyphen => [0,1]

          });

  Returns an issn validated by Business::ISSN.

  Optionally strips hyphen.

  If the string cannot be validated as an issn,

  it returns nothing.

=cut

sub NormalizeISSN {

    my ($params) = @_;

    my $string        = $params->{issn};

    my $strip_hyphen  = $params->{strip_hyphen};

    my $issn = Business::ISSN->new($string);

    if ( $issn && $issn->is_valid ){

        if ($strip_hyphen) {

            $string = $issn->_issn;

        }

        else {

            $string = $issn->as_string;

        }

        return $string;

    }

}

=head2 GetVariationsOfISSN

  my @issns = GetVariationsOfISSN( $issn );

  Returns a list of variations of the given issn in

  with and without a hyphen.

  In a scalar context, the issns are returned as a

  string delimited by ' | '.

=cut

sub GetVariationsOfISSN {

    my ($issn) = @_;

    return unless $issn;

    my @issns;

    push( @issns, NormalizeISSN({ issn => $issn }) );

    push( @issns, NormalizeISSN({ issn => $issn, strip_hyphen => 1 }) );

    # Strip out any "empty" strings from the array

    @issns = grep { defined($_) && $_ =~ /\S/ } @issns;

    return wantarray ? @issns : join( " | ", @issns );

}

=head2 GetVariationsOfISSNs

  my @issns = GetVariationsOfISSNs( @issns );

  Returns a list of variations of the given issns in

  with and without a hyphen.

  In a scalar context, the issns are returned as a

  string delimited by ' | '.

=cut

sub GetVariationsOfISSNs {

    my (@issns) = @_;

    @issns = map { GetVariationsOfISSN( $_ ) } @issns;

    return wantarray ? @issns : join( " | ", @issns );

}

        @source_keys = C4::Koha::GetVariationsOfISSNs(@source_keys)

          if ( $matchpoint->{index} =~ /^issn$/i

            && C4::Context->preference('AggressiveMatchOnISSN') )

            && !C4::Context->preference('UseQueryParser');

INSERT IGNORE INTO systempreferences (variable,value,explanation,options,type) VALUES ('AggressiveMatchOnISSN','0','If enabled, attempt to match aggressively by trying all variations of the ISSNs in the imported record as a phrase in the ISSN fields of already cataloged records when matching on ISSN with the record import tool','','YesNo')

        -

            - When matching on ISSN with the record import tool,

            - pref: AggressiveMatchOnISSN

              choices:

                  yes: "do"

                  no: "don't"

            - attempt to match aggressively by trying all variations of the ISSNs in the imported record as a phrase in the ISSN fields of already cataloged records.  Note that this preference has no effect if UseQueryParser is on.

is(C4::Koha::NormalizeISSN({ issn => '0024-9319', strip_hyphen => 1 }), '00249319', 'Test NormalizeISSN with all features enabled' );

is(C4::Koha::NormalizeISSN({ issn => '0024-9319', strip_hyphen => 0 }), '0024-9319', 'Test NormalizeISSN with all features enabled' );

my @issns = qw/ 0024-9319 00249319 /;

is( join('|', @issns), join('|', GetVariationsOfISSN('0024-9319')), 'GetVariationsOfISSN returns all variations' );

is( join('|', @issns), join('|', GetVariationsOfISSNs('0024-9319')), 'GetVariationsOfISSNs returns all variations' );

my $issn;

eval {

    $issn = C4::Koha::NormalizeISSN({ issn => '1234-5678', strip_hyphen => 1 });

};

ok($@ eq '', 'NormalizeISSN does not throw exception when parsing invalid ISSN');

@issns = GetVariationsOfISSNs('abc');

is(scalar(@issns), 0, 'zero variations returned of invalid ISSN');