#!/usr/bin/perl
use strict;
use warnings;

use XML::Twig;
use YAML::Tiny;
use JSON;

my $marcxml = shift || help();
my $htag     = shift || help();

open HOLDINGS, '>', "holdings";
open X, '>', "holdings.x";
open Z, '>', "holdings.z";
my $holdings = {};
my %all852 = ( x => {}, z => {} ); # hash of all subfields in all 852s
my $copyid = 0;


$| = 1;
my $count = 0;
my $total = `grep -c '<record' $marcxml`;
my $percent = 0;
my $prevper = -1;

my $yaml = YAML::Tiny->new;
my $t = XML::Twig->new( twig_handlers => { record => \&record } );
$t->parsefile($marcxml);
$yaml->[0] = \%all852;
$yaml->write('holdings.sample');
print "\n\n";

sub record {
    my($t, $r)= @_;
    $holdings = { copies => [] };

    my @dfields = $r->children('datafield');
    for my $d (@dfields) 
      { process_datafields($d) }

    for my $copy (@{$holdings->{copies}})
      { print_reports($copy) }
    $r->purge;

    $count++;
    $percent = int(($count / $total) * 100);
    print "\r$percent% done ($count)" if ($percent != $prevper);
    $prevper = $percent;
}

sub process_datafields {
    my ($d) = @_;
    # get 903
    if ($d->{'att'}->{'tag'} == 903) {
        my $s = $d->first_child('subfield');
        $holdings->{id} = $s->text;;
    }

    # and holdings data
    if ($d->{'att'}->{'tag'} == $htag) {
        push @{$holdings->{copies}}, { x =>[], z => [] };
        $holdings->{copies}[-1]{copyid} = $copyid;
        my @subs = $d->children('subfield');
        for my $s (@subs)
          { process_subs($s) }
        $copyid++;
    }
}

sub process_subs {
    my ($s) = @_;
    my $copy = $holdings->{copies}[-1];

    my $code = $s->{'att'}->{'code'};
    my $value = $s->text;

    if ($code eq 'x' or $code eq 'z') {
        push @{$copy->{$code}}, $value;
        my ($k,$v) = split /:/, $value;
        $all852{$code}{$k} = $v;
    } else {
        $copy->{$code} = $value;
        $all852{$code} = $value;
    }
}

sub print_reports {
    return unless defined $holdings->{id};
    my ($copy) = @_;
    my $note = 0;
    for (@{$copy->{x}}) {
        print X join("\t", $holdings->{id}, $copy->{copyid}, $note, $_), "\n";
        $note++;
    }
    $note = 0;
    for (@{$copy->{z}}) {
        print Z join("\t", $holdings->{id}, $copy->{copyid}, $note, $_), "\n";
        $note++;
    }
    for (qw( copyid b p h 9 ))
      { $copy->{$_} = '' unless defined $copy->{$_} }
    print HOLDINGS join("\t", $holdings->{id}, $copy->{copyid},
                        $copy->{b}, $copy->{p}, $copy->{h}, $copy->{9}), "\n";
}


sub help {
    print <<HELP;
Usage is: extract_holdings MARCXML_FILE HOLDINGS_TAG
HELP
    exit;
}