Added option to delete messages - for now only for the client locally

server/src/main/java/envoy/server/Startup.java

@@ -56,7 +56,8 @@ public final class Startup {
 						new NameChangeProcessor(),
 						new ProfilePicChangeProcessor(),
 						new PasswordChangeRequestProcessor(),
-						new IssueProposalProcessor())));
+						new IssueProposalProcessor(),
+						new MessageDeletionProcessor())));
 
 		// Initialize the current message ID
 		final var persistenceManager = PersistenceManager.getInstance();

server/src/main/java/envoy/server/data/Contact.java

@@ -1,7 +1,7 @@
 package envoy.server.data;
 
 import java.time.Instant;
-import java.util.Set;
+import java.util.*;
 
 import javax.persistence.*;
 
@@ -98,6 +98,34 @@ public abstract class Contact {
 	 */
 	public void setCreationDate(Instant creationDate) { this.creationDate = creationDate; }
 
+	/**
+	 * Shortcut to convert a {@code Contact} into a {@code User}.
+	 *
+	 * @param contact the contact to convert
+	 * @return the casted contact
+	 * @throws IllegalStateException if the given contact is not a User
+	 * @since Envoy Server v0.3-beta
+	 */
+	public static User toUser(Contact contact) {
+		if (!(contact instanceof User)) throw new IllegalStateException("Cannot cast a non user to a user");
+		return (User) contact;
+	}
+
+	/**
+	 * Shortcut to convert a set of {@code Contact}s into a set of {@code User}s.
+	 *
+	 * @param contacts the contacts to convert
+	 * @return the casted contacts
+	 * @throws IllegalStateException if one of the given contacts is not a User
+	 * @since Envoy Server v0.3-beta
+	 */
+	public static Set<User> toUser(Set<Contact> contacts) {
+		final var newSet = new HashSet<User>();
+		for (final var contact : contacts)
+			newSet.add(toUser(contact));
+		return newSet;
+	}
+
 	@Override
 	public String toString() { return String.format("%s[id=%d,name=%s,%d contact(s)]", getClass().getSimpleName(), id, name, contacts.size()); }
 }

server/src/main/java/envoy/server/data/MessageDeletion.java

@@ -0,0 +1,81 @@
+package envoy.server.data;
+
+import java.util.*;
+
+import javax.persistence.*;
+
+/**
+ * Defines a message that has been deleted.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Server v0.3-beta
+ */
+@Entity
+@Table(name = "deletionEvents")
+@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
+public final class MessageDeletion {
+
+	@Id
+	@GeneratedValue
+	protected long messageID;
+
+	@ManyToOne(targetEntity = User.class)
+	protected Set<User> recipientsToInform;
+
+	/**
+	 * Creates an instance of {@code DeletionEvent}.
+	 *
+	 * @since Envoy Server v0.3-beta
+	 */
+	public MessageDeletion() {}
+
+	/**
+	 * Creates an instance of {@code MessageDeletion}.
+	 *
+	 * @param messageID          the ID of the message
+	 * @param recipientsToInform the recipientsToInform of the message<br>
+	 *                           <strong>that have not yet been notified of its
+	 *                           deletion</strong>
+	 * @since Envoy Server v0.3-beta
+	 */
+	public MessageDeletion(long messageID, Set<User> recipientsToInform) {
+		this.messageID			= messageID;
+		this.recipientsToInform	= recipientsToInform;
+	}
+
+	/**
+	 * @return the messageID
+	 * @since Envoy Server v0.3-beta
+	 */
+	public long getMessageID() { return messageID; }
+
+	/**
+	 * @param messageID the messageID to set
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void setMessageID(long messageID) { this.messageID = messageID; }
+
+	/**
+	 * @return the recipients that have yet to be informed
+	 * @since Envoy Server v0.3-beta
+	 */
+	public Set<User> getRecipientsToInform() { return recipientsToInform; }
+
+	/**
+	 * @param recipientsToInform the recipients that have yet to be informed
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void setRecipientsToInform(Set<User> recipientsToInform) { this.recipientsToInform = recipientsToInform; }
+
+	/**
+	 * @param user the user who has been informed of the message deletion
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void recipientInformed(User user) { recipientsToInform.remove(user); }
+
+	/**
+	 * @param users the users that have been informed of the message deletion
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void recipientInformed(Collection<User> users) { recipientsToInform.removeAll(users); }
+}

server/src/main/java/envoy/server/data/PersistenceManager.java

@@ -1,7 +1,7 @@
 package envoy.server.data;
 
 import java.time.Instant;
-import java.util.List;
+import java.util.*;
 
 import javax.persistence.*;
 
@@ -100,12 +100,35 @@ public final class PersistenceManager {
 	public void deleteContact(Contact contact) { remove(contact); }
 
 	/**
-	 * Deletes a {@link Message} in the database.
+	 * Deletes a {@link Message} in the database and creates a new
+	 * {@link MessageDeletion} object for <strong>all</strong> recipients of the
+	 * message.
 	 *
 	 * @param message the {@link Message} to delete
-	 * @since Envoy Server Standalone v0.1-alpha
+	 * @return the created {@link MessageDeletion} object
+	 * @since Envoy Server v0.3-beta
 	 */
-	public void deleteMessage(Message message) { remove(message); }
+	public MessageDeletion deleteMessage(Message message) {
+		final var recipient = message.getRecipient();
+		return deleteMessage(message,
+				recipient instanceof Group ? Contact.toUser(getGroupByID(recipient.id).getContacts()) : Set.of(Contact.toUser(recipient)));
+	}
+
+	/**
+	 * Deletes a {@link Message} in the database and creates a new
+	 * {@link MessageDeletion} object for the given recipients of the message.
+	 *
+	 * @param message               the {@link Message} to delete
+	 * @param recipientsYetToInform the (sub)set of all recipients of that message
+	 * @return the created {@link MessageDeletion} object
+	 * @since Envoy Server v0.3-beta
+	 */
+	public MessageDeletion deleteMessage(Message message, Set<User> recipientsYetToInform) {
+		final MessageDeletion deletion = new MessageDeletion(message.id, recipientsYetToInform);
+		persist(deletion);
+		remove(message);
+		return deletion;
+	}
 
 	/**
 	 * Searches for a {@link User} with a specific ID.
@@ -172,6 +195,16 @@ public final class PersistenceManager {
 	 */
 	public ConfigItem getConfigItemByID(String key) { return entityManager.find(ConfigItem.class, key); }
 
+	/**
+	 * Searches for a {@link MessageDeletion} with the given message id.
+	 *
+	 * @param id the id of the message to search for
+	 * @return the message deletion object with the specified ID or {@code null} if
+	 *         none is found
+	 * @since Envoy Server v0.3-beta
+	 */
+	public MessageDeletion getMessageDeletionByID(long id) { return entityManager.find(MessageDeletion.class, id); }
+
 	/**
 	 * Returns all messages received while being offline or the ones that have
 	 * changed.

server/src/main/java/envoy/server/processors/MessageDeletionProcessor.java

@@ -0,0 +1,18 @@
+package envoy.server.processors;
+
+import java.io.IOException;
+
+import envoy.event.MessageDeletion;
+import envoy.server.net.ObjectWriteProxy;
+
+/**
+ * Listens for and handles incoming {@link MessageDeletion}s.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Server v0.3-beta
+ */
+public class MessageDeletionProcessor implements ObjectProcessor<MessageDeletion> {
+
+	@Override
+	public void process(MessageDeletion message, long socketID, ObjectWriteProxy writeProxy) throws IOException {}
+}