Notify users mentioned in chat messages

lib/Chat/ChatManager.php

@@ -23,6 +23,7 @@
 
 namespace OCA\Spreed\Chat;
 
+use OCP\Comments\IComment;
 use OCP\Comments\ICommentsManager;
 
 /**
@@ -31,17 +32,26 @@
  * sendMessage() saves a comment using the ICommentsManager, while
  * receiveMessages() tries to read comments from ICommentsManager (with a little
  * wait between reads) until comments are found or until the timeout expires.
+ *
+ * When a message is saved the mentioned users are notified as needed, and
+ * pending notifications are removed if the messages are deleted.
  */
 class ChatManager {
 
 	/** @var ICommentsManager */
 	private $commentsManager;
 
+	/** @var Notifier */
+	private $notifier;
+
 	/**
 	 * @param ICommentsManager $commentsManager
+	 * @param Notifier $notifier
 	 */
-	public function __construct(ICommentsManager $commentsManager) {
+	public function __construct(ICommentsManager $commentsManager,
+								Notifier $notifier) {
 		$this->commentsManager = $commentsManager;
+		$this->notifier = $notifier;
 	}
 
 	/**
@@ -62,6 +72,8 @@ public function sendMessage($chatId, $actorType, $actorId, $message, \DateTime $
 		$comment->setVerb('comment');
 
 		$this->commentsManager->save($comment);
+
+		$this->notifier->notifyMentionedUsers($comment);
 	}
 
 	/**
@@ -78,6 +90,7 @@ public function sendMessage($chatId, $actorType, $actorId, $message, \DateTime $
 	 * maximum time to wait must be set using the $timeout parameter.
 	 *
 	 * @param string $chatId
+	 * @param string $userId
 	 * @param int $timeout the maximum number of seconds to wait for messages
 	 * @param int $offset optional, starting point
 	 * @param \DateTime|null $notOlderThan optional, the date and time of the
@@ -86,7 +99,7 @@ public function sendMessage($chatId, $actorType, $actorId, $message, \DateTime $
 	 *         creation date and message are relevant), or an empty array if the
 	 *         timeout expired.
 	 */
-	public function receiveMessages($chatId, $timeout, $offset = 0, \DateTime $notOlderThan = null) {
+	public function receiveMessages($chatId, $userId, $timeout, $offset = 0, \DateTime $notOlderThan = null) {
 		$comments = [];
 
 		$commentsFound = false;
@@ -102,6 +115,8 @@ public function receiveMessages($chatId, $timeout, $offset = 0, \DateTime $notOl
 			}
 		}
 
+		$this->notifier->markMentionNotificationsRead($chatId, $userId);
+
 		if ($commentsFound) {
 			// The limit and offset of getForObject can not be based on the
 			// number of comments, as more comments may have been added between
@@ -127,6 +142,8 @@ public function receiveMessages($chatId, $timeout, $offset = 0, \DateTime $notOl
 	 */
 	public function deleteMessages($chatId) {
 		$this->commentsManager->deleteCommentsAtObject('chat', $chatId);
+
+		$this->notifier->removePendingNotificationsForRoom($chatId);
 	}
 
 }

lib/Chat/Notifier.php

@@ -0,0 +1,261 @@
+<?php
+
+/**
+ *
+ * @copyright Copyright (c) 2017, Daniel Calviño Sánchez (danxuliu@gmail.com)
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * 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
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OCA\Spreed\Chat;
+
+use OCA\Spreed\Exceptions\ParticipantNotFoundException;
+use OCA\Spreed\Exceptions\RoomNotFoundException;
+use OCA\Spreed\Manager;
+use OCA\Spreed\Room;
+use OCP\Comments\IComment;
+use OCP\Notification\IManager as INotificationManager;
+use OCP\Notification\INotification;
+use OCP\IUserManager;
+
+/**
+ * Helper class for notifications related to user mentions in chat messages.
+ *
+ * This class uses the NotificationManager to create and remove the
+ * notifications as needed; OCA\Spreed\Notification\Notifier is the one that
+ * prepares the notifications for display.
+ */
+class Notifier {
+
+	/** @var INotificationManager */
+	private $notificationManager;
+
+	/** @var IUserManager */
+	private $userManager;
+
+	/** @var Manager */
+	private $manager;
+
+	/**
+	 * @param INotificationManager $notificationManager
+	 * @param IUserManager $userManager
+	 * @param Manager $manager
+	 */
+	public function __construct(INotificationManager $notificationManager,
+								IUserManager $userManager,
+								Manager $manager) {
+		$this->notificationManager = $notificationManager;
+		$this->userManager = $userManager;
+		$this->manager = $manager;
+	}
+
+	/**
+	 * Notifies the user mentioned in the comment.
+	 *
+	 * The comment must be a chat message comment. That is, its "objectId" must
+	 * be the room ID.
+	 *
+	 * Not every user mentioned in the message is notified, but only those that
+	 * are able to participate in the room.
+	 *
+	 * @param IComment $comment
+	 */
+	public function notifyMentionedUsers(IComment $comment) {
+		$mentionedUserIds = $this->getMentionedUserIds($comment);
+		if (empty($mentionedUserIds)) {
+			return;
+		}
+
+		foreach ($mentionedUserIds as $mentionedUserId) {
+			if ($this->shouldUserBeNotified($mentionedUserId, $comment)) {
+				$notification = $this->createNotification($comment, $mentionedUserId);
+
+				$this->notificationManager->notify($notification);
+			}
+		}
+	}
+
+	/**
+	 * Removes all the pending notifications for the room with the given ID.
+	 *
+	 * @param string $roomId
+	 */
+	public function removePendingNotificationsForRoom($roomId) {
+		$notification = $this->notificationManager->createNotification();
+
+		$notification
+			->setApp('spreed')
+			->setObject('room', $roomId);
+
+		$this->notificationManager->markProcessed($notification);
+	}
+
+	/**
+	 * Removes all the pending mention notifications for the room
+	 *
+	 * @param string $roomId
+	 * @param string $userId
+	 */
+	public function markMentionNotificationsRead($roomId, $userId) {
+
+		if ($userId === null || $userId === '') {
+			return;
+		}
+
+		$notification = $this->notificationManager->createNotification();
+
+		$notification
+			->setApp('spreed')
+			->setObject('room', $roomId)
+			->setSubject('mention')
+			->setUser($userId);
+
+		$this->notificationManager->markProcessed($notification);
+	}
+
+	/**
+	 * Returns the IDs of the users mentioned in the given comment.
+	 *
+	 * @param IComment $comment
+	 * @return string[] the mentioned user IDs
+	 */
+	private function getMentionedUserIds(IComment $comment) {
+		$mentions = $comment->getMentions();
+
+		if (empty($mentions)) {
+			return [];
+		}
+
+		$userIds = [];
+		foreach ($mentions as $mention) {
+			if ($mention['type'] === 'user') {
+				$userIds[] = $mention['id'];
+			}
+		}
+
+		return $userIds;
+	}
+
+	/**
+	 * Creates a notification for the given chat message comment and mentioned
+	 * user ID.
+	 *
+	 * @param IComment $comment
+	 * @param string $mentionedUserId
+	 * @return INotification
+	 */
+	private function createNotification(IComment $comment, $mentionedUserId) {
+		$notification = $this->notificationManager->createNotification();
+		$notification
+			->setApp('spreed')
+			->setObject('room', $comment->getObjectId())
+			->setUser($mentionedUserId)
+			->setSubject('mention', [
+				'userType' => $comment->getActorType(),
+				'userId' => $comment->getActorId(),
+				])
+			->setDateTime($comment->getCreationDateTime());
+
+		$notificationMessage = $this->getNotificationMessage($comment, $mentionedUserId);
+		if (count($notificationMessage) === 1) {
+			$notification->setMessage($notificationMessage[0]);
+		} else {
+			$notification->setMessage($notificationMessage[0], $notificationMessage[1]);
+		}
+
+		return $notification;
+	}
+
+	/**
+	 * Returns the message for a notification from the message of the comment.
+	 *
+	 * The message is returned as an array; the first element is the message
+	 * itself, and the second element is another array that contains the
+	 * parameters for the message. If no parameters are needed then the returned
+	 * array has a single element.
+	 *
+	 * The message of a comment can be much longer than the maximum allowed
+	 * length for the message of a notification so, if needed, the comment
+	 * message is trimmed around the first mention to the user. In that case
+	 * the "ellipsisStart" and/or "ellipsisEnd" (depending on the case) are
+	 * returned as the parameters.
+	 *
+	 * @param IComment $comment
+	 * @param string $mentionedUserId
+	 * @return array the first element is a message suitable to be stored in a
+	 *         notification, and the second are the parameters, if any.
+	 */
+	private function getNotificationMessage(IComment $comment, $mentionedUserId) {
+		$maximumLength = 64;
+
+		$message = $comment->getMessage();
+
+		$messageLength = strlen($message);
+		if ($messageLength <= $maximumLength) {
+			return [$message];
+		}
+
+		$mention = '@' . $mentionedUserId;
+		$mentionLength = strlen($mention);
+		// Only the first mention is taken into account
+		$mentionMiddleIndex = strpos($message, $mention) + $mentionLength / 2;
+
+		if ($mentionMiddleIndex <= $maximumLength / 2) {
+			return [substr($message, 0, $maximumLength), ['ellipsisEnd']];
+		}
+
+		if ($mentionMiddleIndex >= ($messageLength - $maximumLength / 2)) {
+			return [substr($message, -$maximumLength), ['ellipsisStart']];
+		}
+
+		return [substr($message, $mentionMiddleIndex - ($maximumLength / 2), $maximumLength), ['ellipsisStart', 'ellipsisEnd']];
+	}
+
+	/**
+	 * Determinates whether a user should be notified about the mention:
+	 *
+	 * 1. The user did not mention themself
+	 * 2. The user must exist
+	 * 3. The user must be a participant of the room
+	 * 4. The user must not be active in the room
+	 *
+	 * @param string $userId
+	 * @param IComment $comment
+	 * @return bool
+	 */
+	private function shouldUserBeNotified($userId, IComment $comment) {
+		if ($userId === $comment->getActorId()) {
+			// Do not notify the user if they mentioned themself
+			return false;
+		}
+
+		if (!$this->userManager->userExists($userId)) {
+			return false;
+		}
+
+		try {
+			$room = $this->manager->getRoomById($comment->getObjectId());
+			$room->getParticipant($userId);
+		} catch (RoomNotFoundException $e) {
+			return false;
+		} catch (ParticipantNotFoundException $e) {
+			return false;
+		}
+
+		return true;
+	}
+}