package C4::Input; #assumes C4/Input


# Copyright 2000-2002 Katipo Communications
#
# This file is part of Koha.
#
# Koha is free software; you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# Koha is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# Koha; if not, write to the Free Software Foundation, Inc., 59 Temple Place,
# Suite 330, Boston, MA  02111-1307 USA

use strict;
require Exporter;

use vars qw($VERSION @ISA @EXPORT);

# set the version for version checking
$VERSION = 0.01;

=head1 NAME

C4::Input - Miscellaneous sanity checks

=head1 SYNOPSIS

  use C4::Input;

=head1 DESCRIPTION

This module provides functions to see whether a given library card
number or ISBN is valid.

=head1 FUNCTIONS

=over 2

=cut

@ISA = qw(Exporter);
@EXPORT = qw(
	&checkflds &checkdigit &checkvalidisbn
);

# FIXME - This is never used.
sub checkflds {
  my ($env,$reqflds,$data) = @_;
  my $numrflds = @$reqflds;
  my @probarr;
  my $i = 0;
  while ($i < $numrflds) {
    if ($data->{@$reqflds[$i]} eq "") {
      push(@probarr, @$reqflds[$i]);
    }
    $i++
  }
  return (\@probarr);
}

=item checkdigit

  $valid = &checkdigit($env, $cardnumber);

Takes a card number, computes its check digit, and compares it to the
checkdigit at the end of C<$cardnumber>. Returns a true value iff
C<$cardnumber> has a valid check digit.

C<$env> is ignored.

=cut
#'
sub checkdigit {
  my ($env,$infl) =  @_;
  $infl = uc $infl;
  my @weightings = (8,4,6,3,5,2,1);
  my $sum;
  my $i = 1;
  my $valid = 0;
  #  print $infl."<br>";
  # FIXME - for ($i = 1; $i < 8; $i++)
  # or      foreach $i (1..7)
  while ($i <8) {
    my $temp1 = $weightings[$i-1];
    my $temp2 = substr($infl,$i,1);
    $sum += $temp1 * $temp2;
#    print "$sum $temp1 $temp2<br>";
    $i++;
  }
  my $rem = ($sum%11);
  if ($rem == 10) {
    $rem = "X";
  }
  #print $rem."<br>";
  if ($rem eq substr($infl,8,1)) {
    $valid = 1;
  }
  return $valid;
} # sub checkdigit

=item checkvalidisbn

  $valid = &checkvalidisbn($isbn);

Returns a true value iff C<$isbn> is a valid ISBN: it must be ten
digits long (counting "X" as a digit), and must have a valid check
digit at the end.

=cut
#'
#--------------------------------------
# Determine if a number is a valid ISBN number, according to length
#   of 10 digits and valid checksum
sub checkvalidisbn {
        use strict;
        my ($q)=@_ ;	# Input: ISBN number

        my $isbngood = 0; # Return: true or false

        $q=~s/x$/X/g;           # upshift lower case X
        $q=~s/[^X\d]//g;
        $q=~s/X.//g;
        if (length($q)==10) {
            my $checksum=substr($q,9,1);
            my $isbn=substr($q,0,9);
            my $i;
            my $c=0;
            for ($i=0; $i<9; $i++) {
                my $digit=substr($q,$i,1);
                $c+=$digit*(10-$i);
            }
	    $c=$c%11;  # % is the modulus function
            ($c==10) && ($c='X');
            # FIXME - $isbngood = $c eq $checksum;
            if ($c eq $checksum) {
                $isbngood=1;
            } else {
                $isbngood=0;
            }
        } else {
            # FIXME - Put "return 0 if $length($q) != 10" near the
            # top, so we don't have to indent the rest of the function
            # as much.
            $isbngood=0;
        } # if length good

        return $isbngood;

} # sub checkvalidisbn

END { }       # module clean-up code here (global destructor)

1;
__END__

=back

=head1 AUTHOR

Koha Developement team <info@koha.org>

=head1 SEE ALSO

L<perl>.

=cut