feat: add sieve utils

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

lib/Sieve/SieveUtils.php

@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Sieve;
+
+class SieveUtils {
+	/**
+	 * Escape a string for use in a Sieve script
+	 *
+	 * @see https://www.rfc-editor.org/rfc/rfc5228#section-2.4.2
+	 */
+	public static function escapeString(string $subject): string {
+		$subject = preg_replace(
+			['/\\\\/', '/"/'],
+			['\\\\\\\\', '\\"'],
+			$subject
+		);
+
+		return (string)$subject;
+	}
+
+	/**
+	 * Return a string list for use in a Sieve script
+	 *
+	 * @see https://www.rfc-editor.org/rfc/rfc5228#section-2.4.2.1
+	 */
+	public static function stringList(array $values): string {
+		$values = array_map([__CLASS__, 'escapeString'], $values);
+
+		return '["' . implode('", "', $values) . '"]';
+	}
+}

tests/Unit/Sieve/SieveUtilsTest.php

@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace Unit\Sieve;
+
+use ChristophWurst\Nextcloud\Testing\TestCase;
+use OCA\Mail\Sieve\SieveUtils;
+
+class SieveUtilsTest extends TestCase {
+	/**
+	 * @dataProvider providerEscapeString
+	 */
+	public function testEscapeString(string $subject, string $expected): void {
+		$actual = SieveUtils::escapeString($subject);
+		$this->assertSame($expected, $actual);
+	}
+
+	public static function providerEscapeString(): array {
+		return [
+			['foo"bar', 'foo\"bar'],
+			['foo\\bar', 'foo\\\\bar'],
+			['foo"\\bar', 'foo\"\\\\bar'],
+			['foobar', 'foobar'],
+			['', ''],
+		];
+	}
+
+	/**
+	 * @dataProvider providerStringList
+	 */
+	public function testStringList(array $values, string $expected): void {
+		$actual = SieveUtils::stringList($values);
+		$this->assertSame($expected, $actual);
+	}
+
+	public static function providerStringList(): array {
+		return [
+			[['Hello', 'World'], '["Hello", "World"]'],
+			[['foo"bar', 'foo\\bar'], '["foo\"bar", "foo\\\\bar"]'],
+			[['foo"bar', 'foo\\bar', 'foo"\\bar'], '["foo\"bar", "foo\\\\bar", "foo\"\\\\bar"]'],
+			[['foobar'], '["foobar"]'],
+			[[], '[""]'],
+		];
+	}
+}