package MARC::File;


# 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

=head1 NAME

MARC::File - Base class for files of MARC records

=cut

use 5.6.0;
use strict;
use integer;
use vars qw( $VERSION $ERROR );

# FIXME - Fix the POD to conform to Perl style. In particular,
# functions get an =item, not a =head2.

=head1 VERSION

Version 0.93

    $Id$

=cut

our $VERSION = '0.93';

=head1 SYNOPSIS

    use MARC::File::USMARC;

    my $file = MARC::File::USMARC->in( $filename );
    
    while ( my $marc = $file->next() ) {
	# Do something
    }
    $file->close();
    undef $file;

=head1 EXPORT

None.  

=head1 METHODS

=head2 in()

Opens a file for input.

=cut

sub in {
    my $class = shift;
    my $filename = shift;

    my $self = {
	filename => $filename,
    };

    bless $self, $class;

    if ( !open( $self->{fh}, "<", $filename ) ) {
	undef $self;
	$MARC::File::ERROR = "Couldn't open $filename: $!";
    }

    return $self;
} # new()

sub indata {
    my $class = shift;
    my $data = shift;

    my $self = {
	fh => '',
	data => $data,
	pointer => 0,
    };

    bless $self, $class;

#    if ( !open( $self->{fh}, "<", $filename ) ) {
#	undef $self;
#	$MARC::File::ERROR = "Couldn't open $filename: $!";
#    }

    return $self;
} # new()

sub out {
    die "Not yet written";
}

=head2 next()

Reads the next record from the file handle passed in.

=cut

sub next {
    my $self = shift;

    my $rec = $self->_next();

    return $rec ? $self->decode($rec) : undef;
}

=head2 skip

Skips over the next record in the file.  Same as C<next()>,
without the overhead of parsing a record you're going to throw away
anyway.

Returns 1 or undef.

=cut

sub skip {
    my $self = shift;

    my $rec = $self->_next();

    return $rec ? 1 : undef;
}

sub close {
    my $self = shift;

    close( $self->{fh} );
    delete $self->{fh};

    return;
}

sub _unimplemented() {
    my $self = shift;
    my $method = shift;

    warn "Method $method must be overridden";
}

sub write   { $_[0]->_unimplemented("write"); }
sub decode  { $_[0]->_unimplemented("decode"); }

# NOTE: _gripe can be called as an object method, or not.  Your choice.
sub _gripe(@) {
    if ( @_ ) {
	shift if ref($_[0]) =~ /^MARC::File/;	# Skip first parm if it's a $self
	$ERROR = join( "", @_ );
    }

    return undef;
}

1;

__END__

=head1 RELATED MODULES

L<MARC::Record>

=head1 TODO

=over 4

=item * C<out()> method

We only handle files for input right now.

=back

=cut

=head1 LICENSE

This code may be distributed under the same terms as Perl itself. 

Please note that these modules are not products of or supported by the
employers of the various contributors to the code.

=head1 AUTHOR

Andy Lester, E<lt>marc@petdance.comE<gt> or E<lt>alester@flr.follett.comE<gt>

=cut