[core] Add MessagingManager#getAttachment()

briar-api/src/main/java/org/briarproject/briar/api/messaging/MessagingManager.java

@@ -46,4 +46,9 @@ public interface MessagingManager extends ConversationClient {
 	 */
 	String getMessageText(MessageId m) throws DbException;
 
+	/**
+	 * Returns the attachment with the given ID.
+	 */
+	Attachment getAttachment(MessageId m) throws DbException;
+
 }

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -24,20 +24,24 @@ import org.briarproject.bramble.api.versioning.ClientVersioningManager;
 import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
 import org.briarproject.briar.api.client.MessageTracker;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent;
 import org.briarproject.briar.client.ConversationClientImpl;
 
+import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
+import java.util.Random;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static java.util.Collections.emptyList;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.briar.client.MessageTrackerConstants.MSG_KEY_READ;
 
 @Immutable
@@ -221,4 +225,13 @@ class MessagingManagerImpl extends ConversationClientImpl
 		}
 	}
 
+	@Override
+	public Attachment getAttachment(MessageId m) {
+		// TODO add real implementation
+		// TODO return actual random/fake image before real implementation is done
+		byte[] b = new byte[MAX_MESSAGE_BODY_LENGTH];
+		new Random().nextBytes(b);
+		return new Attachment(ByteBuffer.wrap(b));
+	}
+
 }