NAME
    Business::Barcode::EAN13 - Perform simple validation of an EAN-13
    barcode

SYNOPSIS
      use Business::Barcode::EAN13 qw/valid_barcode check_digit issuer_ccode best_barcode/;

      my $is_valid     = valid_barcode("5023965006028");
      my $check_digit  = check_digit("502396500602"); 
      my $country_code = issuer_ccode("5023965006028");
      my $best_code    = best_barcode(\@barcodes, \@prefs);

DESCRIPTION
    These subroutines will tell you whether or not an EAN-13 barcode is
    self-consistent: i.e. whether or not it checksums correctly. If provided
    with the 12 digit stem of a barcode it will also return the correct
    check digit.

    We can also return the country in which the manufacturer's identifcation
    code was registered, and a method for picking a "most preferred" barcode
    from a list, given a preferred country list.

FUNCTIONS
  check_digit
    my $check_digit = check_digit("502396500602"); # 8

    Given the first 12 digits of a barcode, this will tell you what the last
    digit should be. This will return undef if the barcode stem is not
    properly formed.

  valid_barcode
    my $is_valid = valid_barcode("5023965006028");

    Tell whether or not the given barcode is valid. This obviously does not
    check if it a real barcode; only if it is of correct length, and has a
    valid check-digit.

  issuer_ccode
    my $country_code = issuer_ccode("5023965006028"); # "uk"

    Returns the ISO 2 digit country code (you could use Locale::Country, or
    equivalent, to convert to the country name, if required) of the barcode
    issuer. (Note: This is not necessarily the same as the country of
    manufacture of the goods).

    This does not test the validity of the barcode.

  best_barcode
    my $best_barcode = best_barcode(\@list_of_barcodes, \@optional_prefs);

    Given an arrayref of barcodes, this will return the "most preferred"
    barcode from the list.

    If you don't pass any preferences, this will be the first valid barcode
    in the list. With a list of "preferred prefixes", this will return the
    best match from your list in order of preference of your prefix. A
    prefix can either be a numeric barcode stem, or a 2 letter country code,
    which will be expanded into the list of current barcode stems available
    to that country.

    e.g. if you have a list of 10 barcodes for the same product
    internationally, and would prefer the UK barcode if it exists, otherwise
    the Irish one, otherwise any valid barcode, you would call:

      my $best_barcode = best_barcode(\@barcodes, ["uk", "ie"]);

    If there are no valid barcodes in your list this will return the first
    barcode which would be valid if it was zero-padded, or null if none meet
    this final criterion.

BUGS
    When zero-filling the barcodes in "best_barcode" we should re-apply the
    preferences again, rather than just taking the first valid barcode.

TODO
    Allow other barcode families than EAN-13

AUTHOR
    Colm Dougan, Tony Bowden and Jan Willamowius (http://www.ean-search.org/)

BUGS and QUERIES
    Please direct all correspondence regarding this module to:
    bug-Business-Barcode-EAN13@rt.cpan.org

LICENSE
    This program may be distributed under the same license as Perl itself.

SEE ALSO
    EAN barcode specification: http://www.mecsw.com/specs/ean_13.html