View file upload/library/XenForo/Model/UserTagging.php

<?php

class XenForo_Model_UserTagging extends XenForo_Model
{
	protected $_plainReplacements = null;

	public function getTaggedUsersInMessage($message, &$newMessage, $replaceStyle = 'bb')
	{
		// always set this for early returns
		$newMessage = $message;
		$filteredMessage = $message;
		$this->_plainReplacements = null;

		if ($replaceStyle == 'bb')
		{
			$this->_plainReplacements = array();
			$filteredMessage = preg_replace_callback(
				'#\[(code|php|html|plain|media|url|img|user|quote)(=[^\]]*)?](.*)\[/\\1]#siU',
				array($this, '_plainReplaceHandler'),
				$filteredMessage
			);
		}
		else if ($replaceStyle == 'text')
		{
			$this->_plainReplacements = array();
			$filteredMessage = preg_replace_callback(
				'#(?<=^|\s|[\](,]|--|@)@\[(\d+):(\'|"|&quot;|)(.*)\\2\]#iU',
				array($this, '_plainReplaceHandler'),
				$filteredMessage
			);
		}

		$matches = $this->_getPossibleTagMatches($filteredMessage);
		if (!$matches)
		{
			return array();
		}

		$usersByMatch = $this->_getTagMatchUsers($matches);
		if (!$usersByMatch)
		{
			return array();
		}

		$newMessage = '';
		$lastOffset = 0;
		$testString = utf8_strtolower($filteredMessage);
		$alertUsers = array();
		foreach ($matches AS $key => $match)
		{
			if ($match[0][1] > $lastOffset)
			{
				$newMessage .= substr($filteredMessage, $lastOffset, $match[0][1] - $lastOffset);
			}
			else if ($lastOffset > $match[0][1])
			{
				continue;
			}

			$lastOffset = $match[0][1] + strlen($match[0][0]);

			$haveMatch = false;
			if (!empty($usersByMatch[$key]))
			{
				$testName = utf8_strtolower($match[1][0]);
				$testOffset = $match[1][1];
				$endMatch = $this->_getTagEndPartialRegex(false);

				foreach ($usersByMatch[$key] AS $userId => $user)
				{
					$nameLen = strlen($user['lower']);
					$nextTestOffsetStart = $testOffset + $nameLen;
					if (
						($testName == $user['lower'] || substr($testString, $testOffset, $nameLen) == $user['lower'])
						&& (!isset($testString[$nextTestOffsetStart]) || preg_match('#' . $endMatch . '#i', $testString[$nextTestOffsetStart]))
					)
					{
						$alertUsers[$userId] = $user;
						$newMessage .= $this->_replaceTagUserMatch($user, $replaceStyle);
						$haveMatch = true;
						$lastOffset = $testOffset + strlen($user['username']);
						break;
					}
				}
			}

			if (!$haveMatch)
			{
				$newMessage .= $match[0][0];
			}
		}

		$newMessage .= substr($filteredMessage, $lastOffset);

		if ($this->_plainReplacements)
		{
			$newMessage = strtr($newMessage, $this->_plainReplacements);
			$this->_plainReplacements = null;
		}

		return $alertUsers;
	}

	protected function _plainReplaceHandler(array $match)
	{
		if (!is_array($this->_plainReplacements))
		{
			$this->_plainReplacements = array();
		}

		$placeholder = "\x1A" . count($this->_plainReplacements) . "\x1A";

		$this->_plainReplacements[$placeholder] = $match[0];

		return $placeholder;
	}

	protected function _getTagEndPartialRegex($negated)
	{
		return '[' . ($negated ? '^' : '') . ':;,.!?\s@\'"*/)\]\[-]';
	}

	protected function _getPossibleTagMatches($message)
	{
		$min = 2;

		if (!preg_match_all(
			'#(?<=^|\s|[\](,/\'"]|--)@(?!\[|\s)(([^\s@]|(?<![\s\](,-])@| ){' . $min . '}((?>[:,.!?](?=[^\s:,.!?[\]()])|' . $this->_getTagEndPartialRegex(true) . '+?))*)#iu',
			$message, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER
		))
		{
			return array();
		}

		return $matches;
	}

	protected function _getTagMatchUsers(array $matches)
	{
		$db = $this->_getDb();
		$matchKeys = array_keys($matches);
		$whereParts = array();
		$matchParts = array();
		$usersByMatch = array();

		foreach ($matches AS $key => $match)
		{
			if (utf8_strlen($match[1][0]) > 50)
			{
				// longer than max username length
				continue;
			}

			$sql = 'user.username LIKE ' . XenForo_Db::quoteLike($match[1][0], 'r', $db);
			$whereParts[] = $sql;
			$matchParts[] = 'IF(' . $sql . ', 1, 0) AS match_' . $key;
		}

		if (!$whereParts)
		{
			return array();
		}

		$userResults = $db->query("
			SELECT user.user_id, user.username,
				" . implode(', ', $matchParts) . "
			FROM xf_user AS user
			WHERE (" . implode(' OR ', $whereParts) . ")
			ORDER BY LENGTH(user.username) DESC
		");
		while ($user = $userResults->fetch())
		{
			$userInfo = array(
				'user_id' => $user['user_id'],
				'username' => $user['username'],
				'lower' => utf8_strtolower($user['username'])
			);

			foreach ($matchKeys AS $key)
			{
				if (!empty($user["match_$key"]))
				{
					$usersByMatch[$key][$user['user_id']] = $userInfo;
				}
			}
		}

		return $usersByMatch;
	}

	protected function _replaceTagUserMatch(array $user, $replaceStyle)
	{
		$prefix = XenForo_Application::getOptions()->userTagKeepAt ? '@' : '';

		if ($replaceStyle == 'bb')
		{
			return '[USER=' . $user['user_id'] . ']' . $prefix . $user['username'] . '[/USER]';
		}
		else if ($replaceStyle == 'text')
		{
			if (strpos($user['username'], ']') !== false)
			{
				if (strpos($user['username'], "'") !== false)
				{
					$username = '"' . $prefix . $user['username'] . '"';
				}
				else
				{
					$username = "'" . $prefix . $user['username'] . "'";
				}
			}
			else
			{
				$username = $prefix . $user['username'];
			}
			return '@[' . $user['user_id'] . ':' . $username . ']';
		}
		else
		{
			return $prefix . $user['username'];
		}
	}
}