package C4::Barcodes;

# Copyright 2008 LibLime
#
# 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 3 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, see <http://www.gnu.org/licenses>.

use strict;
use warnings;

use Carp qw( carp );

use C4::Context;
use C4::Barcodes::hbyymmincr;
use C4::Barcodes::annual;
use C4::Barcodes::incremental;
use C4::Barcodes::EAN13;

use vars qw($max $prefformat);

sub _prefformat {
	unless (defined $prefformat) {
		unless ($prefformat = C4::Context->preference('autoBarcode')) {
			carp "The autoBarcode syspref is missing/undefined.  Assuming 'incremental'.";
			$prefformat = 'incremental';
		}
	}
	return $prefformat;
}

sub initial {
	return '0000001';
}
sub width {
	return;
}
sub process_head {	# (self,head,whole,specific)
	my $self = shift;
	return shift;			# Default: just return the head unchanged.
}
sub process_tail {	# (self,tail,whole,specific)
	my $self = shift;
	return shift;			# Default: just return the tail unchanged.
}
sub is_max {
	my $self = shift;
	ref($self) or carp "Called is_max on a non-object: '$self'";
	(@_) and $self->{is_max} = shift;
	return $self->{is_max} || 0;
}
sub value {
	my $self = shift;
	if (@_) {
		my $value = shift;
        warn "Error: UNDEF argument to value"
            unless defined $value;
		$self->{value} = $value;
	}
	return $self->{value};
}
sub autoBarcode {
	(@_) or return _prefformat;
	my $self = shift;
	my $value = $self->{autoBarcode} or return _prefformat;
	$value =~ s/^.*:://;	# in case we get C4::Barcodes::incremental, we just want 'incremental'
	return $value;
}
sub parse {	# return 3 parts of barcode: non-incrementing, incrementing, non-incrementing
	my $self = shift;
	my $barcode = (@_) ? shift : $self->value;
	unless ($barcode =~ /(.*?)(\d+)$/) {	# non-greedy match in first part
		carp "Barcode '$barcode' has no incrementing part!";
		return ($barcode,undef,undef);
	}
	return ($1,$2,'');	# the third part is in anticipation of barcodes that include checkdigits
}
sub max {
	my $self = shift;
	if ($self->{is_max}) {
		return $self->value;
	}
	return $self->db_max;
}
sub db_max {
	my $self = shift;
	my $query = "SELECT max(abs(barcode)) FROM items LIMIT 1"; # Possible problem if multiple barcode types populated
	my $sth = C4::Context->dbh->prepare($query);
	$sth->execute();
	return $sth->fetchrow_array || $self->initial;
}
sub next_value {
	my $self = shift;
	my $specific = (scalar @_) ? 1 : 0;
	my $max = $specific ? shift : $self->max;		# optional argument, i.e. next_value after X
	unless ($max) {
		warn "No max barcode ($self->autoBarcode format) found.  Using initial value.";
		return $self->initial;
	}
	my ($head,$incr,$tail) = $self->parse($max);	# for incremental, you'd get ('',the_whole_barcode,'')
	unless (defined $incr) {
		warn "No incrementing part of barcode ($max) returned by parse.";
		return;
	}
	my $x = length($incr);		# number of digits
	$incr =~ /^9+$/ and $x++;	# if they're all 9's, we need an extra.
        # Note, this enlargement might be undesirable for some barcode formats.
		# Those should override next_value() to work accordingly.
	$incr++;

	$head = $self->process_head($head,$max,$specific);
    $tail = $self->process_tail($tail,$incr,$specific); # XXX use $incr and not $max!
	my $next_value = $head . $incr . $tail;
	return $next_value;
}
sub next {
	my $self = shift or return;
	(@_) and $self->{next} = shift;
	return $self->{next};
}
sub previous {
	my $self = shift or return;
	(@_) and $self->{previous} = shift;
	return $self->{previous};
}
sub serial {
	my $self = shift or return;
	(@_) and $self->{serial} = shift;
	return $self->{serial};
}
sub default_self {
	(@_) or carp "default_self called with no argument.  Reverting to _prefformat.";
	my $autoBarcode = (@_) ? shift : _prefformat;
	$autoBarcode =~ s/^.*:://;  # in case we get C4::Barcodes::incremental, we just want 'incremental'
	return {
		is_max => 0,
		autoBarcode => $autoBarcode,
		   value => undef,
		previous => undef,
		  'next' => undef,
		serial => 1
	};
}

our $types = {
	annual      => sub {C4::Barcodes::annual->new_object(@_);     },
	incremental => sub {C4::Barcodes::incremental->new_object(@_);},
	hbyymmincr  => sub {C4::Barcodes::hbyymmincr->new_object(@_); },
	OFF         => sub {C4::Barcodes::OFF->new_object(@_);        },
    EAN13       => sub {C4::Barcodes::EAN13->new_object(@_);      },
};

sub new {
	my $class_or_object = shift;
	my $type = ref($class_or_object) || $class_or_object;
	my $from_obj = ref($class_or_object) ? 1 : 0;	# are we building off another Barcodes object?
	my $autoBarcodeType = (@_) ? shift : $from_obj ? $class_or_object->autoBarcode : _prefformat;
	$autoBarcodeType =~ s/^.*:://;	# in case we get C4::Barcodes::incremental, we just want 'incremental'
	unless ($autoBarcodeType) {
		carp "No autoBarcode format found.";
		return;
	}
	unless (defined $types->{$autoBarcodeType}) {
		carp "The autoBarcode format '$autoBarcodeType' is unrecognized.";
		return;
	}
	my $self;
	if ($autoBarcodeType eq 'OFF') {
 		$self = $class_or_object->default_self($autoBarcodeType);
		return bless $self, $class_or_object;
	} elsif ($from_obj) {
		$class_or_object->autoBarcode eq $autoBarcodeType
			or carp "Cannot create Barcodes object (type '$autoBarcodeType') from " . $class_or_object->autoBarcode . " object!";
		$self = $class_or_object->new_object(@_);
		$self->serial($class_or_object->serial + 1);
		if ($class_or_object->is_max) {
			$self->previous($class_or_object);
			$class_or_object->next($self);
			$self->value($self->next_value($class_or_object->value));
			$self->is_max(1) and $class_or_object->is_max(0);  # new object is max, old object is no longer max
		} else {
			$self->value($self->next_value);
		}
	} else {
		$self = &{$types->{$autoBarcodeType}} (@_);
		$self->value($self->next_value) and $self->is_max(1);
		$self->serial(1);
	}
	if ($self) {
		return $self;
	}
	carp "Failed new C4::Barcodes::$autoBarcodeType";
	return;
}

sub new_object {
	my $class_or_object = shift;
	my $type = ref($class_or_object) || $class_or_object;
	my $from_obj = ref($class_or_object) ? 1 : 0;   # are we building off another Barcodes object?
	my $self = $class_or_object->default_self($from_obj ? $class_or_object->autoBarcode : 'incremental');
	bless $self, $type;
	return $self;
}
1;
__END__

=head1 Barcodes

Note that the object returned by new is actually of the type requested (or set by syspref).
For example, C4::Barcodes::annual

The specific C4::Barcodes::* modules correspond to the autoBarcode syspref values.

The default behavior here in Barcodes should be essentially a more flexible version of "incremental".

=head1 Adding New Barcode Types

To add a new barcode format, a developer should:

	create a module in C4/Barcodes/, like C4/Barcodes/my_new_format.pm;
	add to the $types hashref in this file; 
	add tests under the "t" directory; and
	edit autoBarcode syspref to include new type.

=head2 Adding a new module

Each new module that needs differing behavior must override these subs:

	new_object
	initial
	db_max
	parse

Or else the CLASS subs will be used.

=head2 $types hashref

The hash referenced can be thought of as the constructor farm for all the C4::Barcodes types.  
Each value should be a reference to a sub that calls the module constructor.

=head1 Notes

You would think it might be easy to handle incremental barcodes, but in practice even commonly used values,
like the IBM "Boulder" format can cause problems for sprintf.  Basically, the value is too large for the 
%d version of an integer, and we cannot count on perl having been compiled with support for quads 
(64-bit integers).  So we have to use floats or increment a piece of it and return the rejoined fragments.

=cut