From 744e9f456473c171fdfa48a485c896d29e7b7fb2 Mon Sep 17 00:00:00 2001
From: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Date: Mon, 16 Sep 2024 10:24:11 +0100
Subject: [PATCH] Bug 37918: Add email_header template toolkit filter

This patch adds a new email_header TT filter to properly encode strings
according to RFC2047 as per the email specification.  This allows
developers to set default subjects in mailto links with the correct
encoding.
---
 Koha/Template/Plugin/EmailHeader.pm | 59 +++++++++++++++++++++++++++++
 cpanfile                            |  2 +
 t/Koha_Template_Email_Header.t      | 54 ++++++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 Koha/Template/Plugin/EmailHeader.pm
 create mode 100644 t/Koha_Template_Email_Header.t

diff --git a/Koha/Template/Plugin/EmailHeader.pm b/Koha/Template/Plugin/EmailHeader.pm
new file mode 100644
index 00000000000..8552bd4f3e5
--- /dev/null
+++ b/Koha/Template/Plugin/EmailHeader.pm
@@ -0,0 +1,59 @@
+package Koha::Template::Plugin::EmailHeader;
+
+# Copyright PTFS Europe 2024
+
+# 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
+
+Koha::Template::Plugin::EmailHeader - Template Toolkit filter to encode email headers as per RFC2047
+
+=head1 SYNOPSIS
+
+    [% USE EmailHeader %]
+    [% header | email_header %]
+
+=head1 DESCRIPTION
+
+This plugin provides a Template Toolkit filter `email_header` that encodes
+email headers according to RFC2047 using Encode::MIME::Header.
+
+=cut
+
+use Modern::Perl;
+use Encode;
+use Encode::MIME::Header;
+
+use base qw( Template::Plugin::Filter );
+
+our $DYNAMIC = 1;
+
+=head1 FUNCTIONS
+
+=head2 filter
+
+  [% subject | email_header %]
+
+Filters the given text as per RFC2047.
+
+=cut
+
+sub filter {
+    my ( $self, $text, $args, $config ) = @_;
+    return encode('MIME-Header', $text);
+}
+
+1;
diff --git a/cpanfile b/cpanfile
index bf2db1d6523..fefd97029df 100644
--- a/cpanfile
+++ b/cpanfile
@@ -42,6 +42,7 @@ requires 'Email::Date', '1.103';
 requires 'Email::MessageID', '1.406';
 requires 'Email::Sender', '1.300030';
 requires 'Email::Stuffer', '0.014';
+requires 'Encode::MIME::Header', '2.17';
 requires 'Exception::Class', '1.38';
 requires 'File::Slurp', '9999.13';
 requires 'Font::TTF', '0.45';
@@ -113,6 +114,7 @@ requires 'Test', '1.25';
 requires 'Test::Harness', '2.56';
 requires 'Test::MockModule', '0.05';
 requires 'Test::More', '1.302073';
+requires 'Test::More::UTF8', '0.05';
 requires 'Text::Bidi', '0.03';
 requires 'Text::CSV', '0.01';
 requires 'Text::CSV::Encoded', '0.09';
diff --git a/t/Koha_Template_Email_Header.t b/t/Koha_Template_Email_Header.t
new file mode 100644
index 00000000000..3f6e21a9558
--- /dev/null
+++ b/t/Koha_Template_Email_Header.t
@@ -0,0 +1,54 @@
+#!/usr/bin/perl
+
+# 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 utf8;
+use Modern::Perl;
+
+use Test::More tests => 4;
+use Test::More::UTF8;
+
+use Encode qw(encode);
+use Encode::MIME::Header;
+
+use open qw( :std :encoding(UTF-8) );
+
+use_ok( 'Koha::Template::Plugin::EmailHeader' );
+
+my $filter = Koha::Template::Plugin::EmailHeader->new();
+
+# Test cases with plain text and non-ASCII characters
+my @tests = (
+    {
+        input    => 'Hello World',
+        expected => encode('MIME-Header', 'Hello World'), # ASCII text doesn't need encoding
+    },
+    {
+        input    => 'こんにちは', # Japanese text (Hello)
+        expected => encode('MIME-Header', 'こんにちは'),
+    },
+    {
+        input    => 'Café au lait', # Contains non-ASCII character (é)
+        expected => encode('MIME-Header', 'Café au lait'),
+    },
+);
+
+# Test each case
+for my $test (@tests) {
+     is($filter->filter($test->{input}), $test->{expected}, "Correctly encoded: '$test->{input} -> $test->{expected}'");
+}
+
+done_testing();
-- 
2.46.0