1 files changed, 100 insertions, 0 deletions
diff --git a/apps/user_status/lib/Service/EmojiService.php b/apps/user_status/lib/Service/EmojiService.php
new file mode 100644
index 00000000000..bb0506d242f
--- /dev/null
+++ b/apps/user_status/lib/Service/EmojiService.php
@@ -0,0 +1,100 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2020, Georg Ehrke
+ *
+ * @author Georg Ehrke <oc.list@georgehrke.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program. If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\UserStatus\Service;
+
+use OCP\IDBConnection;
+
+/**
+ * Class EmojiService
+ *
+ * @package OCA\UserStatus\Service
+ */
+class EmojiService {
+
+	/** @var IDBConnection */
+	private $db;
+
+	/**
+	 * EmojiService constructor.
+	 *
+	 * @param IDBConnection $db
+	 */
+	public function __construct(IDBConnection $db) {
+		$this->db = $db;
+	}
+
+	/**
+	 * @return bool
+	 */
+	public function doesPlatformSupportEmoji(): bool {
+		return $this->db->supports4ByteText() &&
+			\class_exists(\IntlBreakIterator::class);
+	}
+
+	/**
+	 * @param string $emoji
+	 * @return bool
+	 */
+	public function isValidEmoji(string $emoji): bool {
+		$intlBreakIterator = \IntlBreakIterator::createCharacterInstance();
+		$intlBreakIterator->setText($emoji);
+
+		$characterCount = 0;
+		while ($intlBreakIterator->next() !== \IntlBreakIterator::DONE) {
+			$characterCount++;
+		}
+
+		if ($characterCount !== 1) {
+			return false;
+		}
+
+		$codePointIterator = \IntlBreakIterator::createCodePointInstance();
+		$codePointIterator->setText($emoji);
+
+		foreach ($codePointIterator->getPartsIterator() as $codePoint) {
+			$codePointType = \IntlChar::charType($codePoint);
+
+			// If the current code-point is an emoji or a modifier (like a skin-tone)
+			// just continue and check the next character
+			if ($codePointType === \IntlChar::CHAR_CATEGORY_MODIFIER_SYMBOL ||
+				$codePointType === \IntlChar::CHAR_CATEGORY_MODIFIER_LETTER ||
+				$codePointType === \IntlChar::CHAR_CATEGORY_OTHER_SYMBOL) {
+				continue;
+			}
+
+			// If it's neither a modifier nor an emoji, we only allow
+			// a zero-width-joiner or a variation selector 16
+			$codePointValue = \IntlChar::ord($codePoint);
+			if ($codePointValue === 8205 || $codePointValue === 65039) {
+				continue;
+			}
+
+			return false;
+		}
+
+		return true;
+	}
+}