#! /usr/bin/perl
#
# This compares record counts from a Koha database to Elasticsearch

# Copyright 2019 ByWater Solutions
#
# 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>.

=head1 NAME

compare_es_to_db.pl - compares record counts from a Koha database to Elasticsearch

=head1 SYNOPSIS

B<compare_es_to_db.pl>

=cut

use Modern::Perl;
use Array::Utils qw( array_minus );

use C4::Context;

use Koha::Authorities;
use Koha::Biblios;
use Koha::Items;
use Koha::SearchEngine::Elasticsearch;

foreach my $index ( ('biblios','authorities') ){
    print "=================\n";
    print "Checking $index\n";
    my @db_records = $index eq 'biblios' ? Koha::Biblios->search()->get_column('biblionumber') : Koha::Authorities->search()->get_column('authid');

    my $searcher = Koha::SearchEngine::Elasticsearch->new({ index => $index });
    my $es = $searcher->get_elasticsearch();
    my $count = $es->indices->stats( index => $searcher->index_name )
        ->{_all}{primaries}{docs}{count};
    print "Count in db for $index is " . scalar @db_records . ", count in Elasticsearch is $count\n";

    # Now we get all the ids from Elasticsearch
    # The scroll lets us iterate through, it fetches chunks of 'size' as we move through
    my $scroll = $es->scroll_helper(
        index => $searcher->index_name,
        size => 5000,
        body => {
            query => {
                match_all => {}
            },
            stored_fields => []
        },
        scroll_in_qs => 1,
    );

    my @es_ids;

    # Here is where we actually iterate through
    # Fetching each record, pushing the id into the array
    my $i = 1;
    print "Fetching Elasticsearch records ids";
    while (my $doc = $scroll->next ){
        print "." if !($i % 500);
        print "\n$i records retrieved" if !($i % 5000);
        push @es_ids, $doc->{_id};
        $i++;
    }

    # Fetch values for providing record links
    my $es_params = $searcher->get_elasticsearch_params;
    my $es_base   = "$es_params->{nodes}[0]/".$searcher->index_name;
    my $opac_base = C4::Context->preference('OPACBaseURL');

    print "\nComparing arrays, this may take a while\n";

    my @koha_problems = sort { $a <=> $b } array_minus(@db_records, @es_ids);
    my @es_problems = sort { $a <=> $b } array_minus(@es_ids, @db_records);

    print "All records match\n" unless ( @koha_problems || @es_problems );

    if ( @koha_problems ){
        print "=================\n";
        print "Records that exist in Koha but not in ES\n";
        for my $problem ( @koha_problems ){
            if ( $index eq 'biblios' ) {
                print "  #$problem";
                print "  Visit here to see record: $opac_base/cgi-bin/koha/opac-detail.pl?biblionumber=$problem\n";
            } elsif ( $index eq 'authorities' ) {
                print "#$problem";
                print "  Visit here to see record: $opac_base/cgi-bin/koha/opac-authoritiesdetail.pl?authid=$problem\n";
            }
        }
    }

    if ( @es_problems ){
        print "=================\n";
        print "Records that exist in ES but not in Koha\n";
        for my $problem ( @es_problems ){
            print "  #$problem";
            print "  Enter this command to view record: curl $es_base/data/$problem?pretty=true\n";
        }
    }
}