/**
* Listens for a topic being removed from the space for either a MainMenuController or a
* ChatroomController.
*/
@Override
public void notify(RemoteEvent remoteEvent) throws UnknownEventException, RemoteException {
try {
// Get the event that triggered the notification
AvailabilityEvent availEvent = (AvailabilityEvent) remoteEvent;
JMSTopicDeleted topicDeleted = (JMSTopicDeleted) availEvent.getEntry();
if (isChatroomController) {
// If the listener is for a ChatroomController, inform the given
// chatroom that the chatroom's topic has been deleted
chatroomController.handleTopicDeleted();
} else {
// If the listener is for a MainMenuController, remove the given
// topic from the MainMenuController's topic list.
DefaultTableModel topicTableModel = mainMenuController.getTopicTableModel();
// Loop through all of the topics in the MainMenuController's
// topic list and remove the one that was deleted
for (int i = 0; i < topicTableModel.getRowCount(); i++) {
UUID topicIdInTable = (UUID) topicTableModel.getValueAt(i, 3);
JMSTopic topicRemoved = topicDeleted.getTopic();
UUID topicDeletedId = topicRemoved.getId();
if (topicIdInTable.equals(topicDeletedId)) {
topicTableModel.removeRow(i);
break;
}
}
}
} catch (Exception e) {
System.err.println("Failed to remove topic from list or send notifications to users.");
e.printStackTrace();
}
}
/**
* Checks if a topic has any null unique identifiers (base name, name, and UUID)
*
* @param topic
* @return <code>true</code> if any unique identifier is null, otherwise <code>false</code>
*/
private boolean isValidTopic(JMSTopic topic) {
if (StringUtils.isNotBlank(topic.getBaseName())
&& StringUtils.isNotBlank(topic.getName())
&& topic.getId() != null) {
return true;
}
return false;
}
/**
* Looks for a topic in the space with the same base name.
*
* @param baseName The base name to search for.
* @return If a matching topic exists, that topic is returned, otherwise <code>null</code> is
* returned.
*/
public JMSTopic getTopicByBaseName(String baseName) {
JMSTopic template = new JMSTopic();
template.setBaseName(baseName);
JMSTopic topicFound = null;
try {
topicFound = (JMSTopic) space.readIfExists(template, null, 1000);
} catch (Exception e) {
System.err.println("Failed to get topic by base name. Base name queried: '" + baseName + "'");
e.printStackTrace();
}
return topicFound;
}
/**
* Deletes a topic, including all of its messages and TopicUsers
*
* @param topic The topic to delete
* @param userRequestingDeletion The user who requested the topic be deleted
* @throws AccessDeniedException
*/
public void deleteTopic(JMSTopic topic, JMSUser userRequestingDeletion)
throws AccessDeniedException {
if (userRequestingDeletion.equals(topic.getOwner())) {
// If the topic does not contain null fields
if (isValidTopic(topic)) {
try {
Transaction transaction = TransactionHelper.getTransaction(10000l);
space.takeIfExists(topic, transaction, 3000l);
deleteAllTopicUsers(topic, transaction);
MessageService.getMessageService().deleteAllTopicMessages(topic, transaction);
// Writes a JMSTopicDeleted object so listeners know the
// topic
// has been removed
space.write(new JMSTopicDeleted(topic), transaction, 1000l * 60l);
transaction.commit();
} catch (Exception e) {
e.printStackTrace();
}
} else {
System.err.println(
"Attempted to delete topic with on or more null fields. "
+ "Due to how JavaSpaces work, this will delete one at random and is not allowed.");
}
} else {
throw new AccessDeniedException("Only the topic's owner can delete the topic");
}
}
/**
* Looks for a topic in the space with the same UUID.
*
* @param baseName The UUID to search for.
* @return If a matching topic exists, that topic is returned, otherwise <code>null</code> is
* returned.
*/
public JMSTopic getTopicById(UUID id) {
JMSTopic template = new JMSTopic();
template.setId(id);
JMSTopic topic = null;
try {
topic = (JMSTopic) space.readIfExists(template, null, 1000);
} catch (RemoteException
| UnusableEntryException
| TransactionException
| InterruptedException e) {
System.err.println("Failed to get topic by ID. Topic ID queried: '" + id.toString() + "'");
e.printStackTrace();
}
return topic;
}
/**
* Whether or not a topic already exists in the space with the same base name or UUID.
*
* @param topic The topic to check if exists
* @param transaction The transaction in which the check will take place
* @return <code>true</code> if a match by either base name or UUID, otherwise <code>false</code>
*/
private boolean topicExistsInSpace(JMSTopic topic, Transaction transaction) {
try {
JMSTopic template = new JMSTopic();
template.setBaseName(topic.getBaseName());
JMSTopic topicBaseNameMatch = (JMSTopic) space.readIfExists(template, transaction, 2000);
template = new JMSTopic();
template.setId(topic.getId());
JMSTopic topicIdMatch = (JMSTopic) space.readIfExists(template, transaction, 2000);
if (topicBaseNameMatch != null || topicIdMatch != null) {
return true;
}
} catch (Exception e) {
e.printStackTrace();
}
return false;
}
/**
* Removes all users from a given topic.
*
* @param topic A topic to remove all of the users from.
* @param transaction The transaction in which to run the delete
*/
private void deleteAllTopicUsers(JMSTopic topic, Transaction transaction) {
JMSTopicUser template = new JMSTopicUser(topic);
try {
while (space.readIfExists(template, transaction, 1000) != null) {
space.takeIfExists(template, transaction, 1000);
}
} catch (RemoteException
| UnusableEntryException
| TransactionException
| InterruptedException e) {
System.err.println(
"Failed to delete all users from Topic entitled: '"
+ topic.getName()
+ "' with ID: '"
+ topic.getId().toString()
+ "'");
e.printStackTrace();
}
}
/**
* Removes a given user from a given topic
*
* @param topic The topic to remove the user from
* @param user The user to remove from the topic
*/
public void removeTopicUser(JMSTopic topic, JMSUser user) {
try {
Transaction transaction = TransactionHelper.getTransaction();
boolean removed = false;
JMSTopicUser template = new JMSTopicUser(topic, user);
// If the space is in a bad state and has duplicate users in a
// topic, this while loop ensures they are all removed
while (space.takeIfExists(template, transaction, 1000) != null) {
removed = true;
}
// Put a JMSTopicUserRemoved object in the space so listeners can
// pick them up and remove them from other user's lists
if (removed) {
JMSTopicUserRemoved removedTopicUser =
new JMSTopicUserRemoved(template.getTopic(), template.getUser());
// Writes the JMSTopicUserRemoved with a 60 second lease, so
// listeners have 60 seconds to act on it
space.write(removedTopicUser, transaction, 1000l * 60l);
}
transaction.commit();
} catch (RemoteException
| UnusableEntryException
| TransactionException
| InterruptedException e) {
System.err.println(
"Failed to remove user from topic. "
+ "User ID: '"
+ user.getId().toString()
+ "' && Topic ID: '"
+ topic.getId().toString()
+ "'");
e.printStackTrace();
}
}
