From 0257c59b0e9f7685d85d17609f91b957b22fd95c Mon Sep 17 00:00:00 2001
From: David Cook <dcook@prosentient.com.au>
Date: Fri, 24 May 2024 04:26:41 +0000
Subject: [PATCH] Bug 36947: Remove diacritics from decomposed strings in ES
 search
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This patch removes the diacritics from strings decomposed using
Unicode::Normalize's NFKD function. It's necessary to provide
equivalent sorting of accented and unaccented characters.

Test plan:
0. Apply patch
1. koha-plack --restart kohadev
2. Switch to using Elasticsearch and reindex
koha-elasticsearch -b -v --rebuild kohadev
3. Setup some test records with authors with accented and unaccented names,
and different cases for the lead letter
e.g. Aa author, Åa author2, aa author3
4 Do a test search
e.g. http://localhost:8081/cgi-bin/koha/catalogue/search.pl?q=test
5. Confirm the facet names are sorted in ascending order regardless
of accent or case
e.g.
Aa author
Åa author2
aa author3
Farley, David
Humble, Jez
---
 Koha/SearchEngine/Elasticsearch/Search.pm | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/Koha/SearchEngine/Elasticsearch/Search.pm b/Koha/SearchEngine/Elasticsearch/Search.pm
index 40ec4ceeb7..f9c2066b20 100644
--- a/Koha/SearchEngine/Elasticsearch/Search.pm
+++ b/Koha/SearchEngine/Elasticsearch/Search.pm
@@ -513,7 +513,7 @@ sub _convert_facets {
         }
         if( C4::Context->preference('FacetOrder') eq 'Alphabetical' ){
             @{ $facet->{facets} } =
-                sort { NFKD(uc($a->{facet_label_value})) cmp NFKD(uc($b->{facet_label_value})) } @{ $facet->{facets} };
+                sort { _normalize_str($a->{facet_label_value}) cmp _normalize_str($b->{facet_label_value}) } @{ $facet->{facets} };
         }
         push @facets, $facet if exists $facet->{facets};
     }
@@ -586,4 +586,11 @@ sub _aggregation_scan {
     return (undef, \%result, undef);
 }
 
+sub _normalize_str {
+    my ($str) = @_;
+    my $text = NFKD(uc($str));
+    $text =~ s/\p{M}//g;
+    return $text;
+}
+
 1;
-- 
2.39.2