Late-pulling

Lib/src/main/java/dev/wiing/gossip/lib/PacketHandler.java

@@ -1,9 +1,6 @@
 package dev.wiing.gossip.lib;
 
-import dev.wiing.gossip.lib.packets.MessageCreatedPacket;
-import dev.wiing.gossip.lib.packets.Packet;
-import dev.wiing.gossip.lib.packets.TopicCreatedPacket;
-import dev.wiing.gossip.lib.packets.TopicUpdatePacket;
+import dev.wiing.gossip.lib.packets.*;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
@@ -42,17 +39,14 @@ public class PacketHandler {
     }
 
     public boolean runPacket(Packet packet) {
-        switch (packet.getType()) {
-            case TopicCreatedPacket.TYPE:
-                return runPacket(TopicCreatedPacket.class, (TopicCreatedPacket)packet);
-
-            case TopicUpdatePacket.TYPE:
-                return runPacket(TopicUpdatePacket.class, (TopicUpdatePacket)packet);
-
-            case MessageCreatedPacket.TYPE:
-                return runPacket(MessageCreatedPacket.class, (MessageCreatedPacket)packet);
-        }
-        return false;
+        return switch (packet.getType()) {
+            case TopicCreatedPacket.TYPE -> runPacket(TopicCreatedPacket.class, (TopicCreatedPacket) packet);
+            case TopicUpdatePacket.TYPE -> runPacket(TopicUpdatePacket.class, (TopicUpdatePacket) packet);
+            case TopicListDataPacket.TYPE -> runPacket(TopicListDataPacket.class, (TopicListDataPacket) packet);
+            case MessageCreatedPacket.TYPE -> runPacket(MessageCreatedPacket.class, (MessageCreatedPacket) packet);
+            case MessageSystemPacket.TYPE -> runPacket(MessageSystemPacket.class, (MessageSystemPacket) packet);
+            default -> false;
+        };
     }
 
     public <T extends Packet> Set<PacketListener<T>> getListeners(Class<T> packetClass) {
@@ -69,7 +63,9 @@ public class PacketHandler {
             {
                 add(TopicCreatedPacket.TYPE);
                 add(TopicUpdatePacket.TYPE);
+                add(TopicListDataPacket.TYPE);
                 add(MessageCreatedPacket.TYPE);
+                add(MessageSystemPacket.TYPE);
             }
         };
     }

Lib/src/main/java/dev/wiing/gossip/lib/PacketManager.java

@@ -23,12 +23,21 @@ public class PacketManager {
             add(new TopicCreatedPacket());
             add(new TopicJoinPacket());
             add(new TopicUpdatePacket());
+            add(new TopicListFetchPacket());
+            add(new TopicListDataPacket());
+            add(new TopicFetchPacket());
+            add(new TopicDataPacket());
 
             add(new UserFetchPacket());
             add(new UserDataPacket());
 
             add(new MessagePushPacket());
             add(new MessageCreatedPacket());
+            add(new MessageSystemPacket());
+            add(new MessageListFetchPacket());
+            add(new MessageListDataPacket());
+            add(new MessageFetchPacket());
+            add(new MessageDataPacket());
         }
     };
 
@@ -49,7 +58,7 @@ public class PacketManager {
         }
     }
 
-    public Packet readPacket(BufferedInputStream stream) throws IOException {
+    public Packet readPacket(InputStream stream) throws IOException {
         ByteBuffer buffer = ByteBuffer.wrap(stream.readNBytes(6));
 
         if (buffer.capacity() < 6) return null;
@@ -64,10 +73,6 @@ public class PacketManager {
         return packet.readBytes(ByteBuffer.wrap(stream.readNBytes(size)), size);
     }
 
-    public Packet readPacket(InputStream stream) throws IOException {
-        return readPacket(new BufferedInputStream(stream));
-    }
-
     public void writePacket(BufferedOutputStream stream, Packet packet) throws IOException {
         ByteBuffer buffer = ByteBuffer.allocate(packet.getTotalLength());
 
@@ -77,7 +82,6 @@ public class PacketManager {
         packet.writeBytes(buffer);
 
         stream.write(buffer.array());
-        stream.flush();
     }
 
     public void writePacket(OutputStream stream, Packet packet) throws IOException {
@@ -86,6 +90,14 @@ public class PacketManager {
         outputStream.flush();
     }
 
+    public void writeAllPackets(OutputStream stream, Packet ...packets) throws IOException {
+        BufferedOutputStream outputStream = new BufferedOutputStream(stream);
+        for (Packet packet : packets) {
+            writePacket(outputStream, packet);
+        }
+        outputStream.flush();
+    }
+
     public void replyPacket(Packet source, Packet reply) throws IOException {
         BufferedOutputStream outputStream = new BufferedOutputStream(source.getSource().getOutputStream());
         writePacket(outputStream, reply);

Lib/src/main/java/dev/wiing/gossip/lib/models/Message.java

@@ -3,34 +3,32 @@ package dev.wiing.gossip.lib.models;
 import java.time.LocalDateTime;
 
 public class Message {
-    private final User author;
+    private long id;
     private final Topic topic;
-    private final String contents;
     private final LocalDateTime postTime;
 
-    public Message(User author, Topic topic, String contents, LocalDateTime postTime) {
-        this.author = author;
+    public Message(long id, Topic topic, LocalDateTime postTime) {
+        this.id = id;
         this.topic = topic;
-        this.contents = contents;
         this.postTime = postTime;
     }
 
-    public Message(User author, Topic topic, String contents) {
-        this(author, topic, contents, LocalDateTime.now());
+    public Message(long id, Topic topic) {
+        this(id, topic, LocalDateTime.now());
     }
 
-    public User getAuthor() {
-        return author;
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
     }
 
     public Topic getTopic() {
         return topic;
     }
 
-    public String getContents() {
-        return contents;
-    }
-
     public LocalDateTime getPostTime() {
         return postTime;
     }

Lib/src/main/java/dev/wiing/gossip/lib/models/SystemMessage.java

@@ -0,0 +1,43 @@
+package dev.wiing.gossip.lib.models;
+
+import java.time.LocalDateTime;
+import java.util.Objects;
+
+public class SystemMessage extends Message {
+
+    public static class SystemType {
+        public static final short USER_JOIN = 1;
+        public static final short USER_LEAVE = 2;
+        public static final short NAME_CHANGE = 3;
+        public static final short DESCRIPTION_CHANGE = 4;
+        public static final short HOST_CHANGE = 5;
+        public static final short EXPIRE = 10;
+    }
+
+    private final short type;
+    private final User user;
+    private final String contents;
+
+    public SystemMessage(long id, Topic topic, short type, User user, String contents, LocalDateTime postTime) {
+        super(id, topic, postTime);
+        this.type = type;
+        this.user = user;
+        this.contents = contents;
+    }
+
+    public SystemMessage(long id, Topic topic, short type, User user, String contents) {
+        this(id, topic, type, user, contents, LocalDateTime.now());
+    }
+
+    public short getType() {
+        return type;
+    }
+
+    public User getUser() {
+        return user;
+    }
+
+    public String getContents() {
+        return contents;
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/models/Topic.java

@@ -16,6 +16,9 @@ public class Topic {
     private short color;
 
     private final List<Message> messages = Collections.synchronizedList(new ArrayList<>());
+    private final Map<Long, Message> messageByIDs = new ConcurrentHashMap<>();
+
+    private long messageTrackerID = 1;
 
     public Topic(long id, String name, String description, User host, short color) {
         this.id = id;
@@ -93,10 +96,19 @@ public class Topic {
 
     public void addMessage(Message message) {
         messages.add(message);
+        messageByIDs.put(message.getId(), message);
 
         this.changeSupport.firePropertyChange("messageAdd", null, message);
     }
 
+    public Message getMessageByID(long messageID) {
+        return messageByIDs.getOrDefault(messageID, null);
+    }
+
+    public long getNextMessageID() {
+        return messageTrackerID++;
+    }
+
     public void addChangeListener(PropertyChangeListener listener) {
         this.changeSupport.addPropertyChangeListener(listener);
     }

Lib/src/main/java/dev/wiing/gossip/lib/models/UserMessage.java

@@ -0,0 +1,26 @@
+package dev.wiing.gossip.lib.models;
+
+import java.time.LocalDateTime;
+
+public class UserMessage extends Message {
+    private final User author;
+    private final String contents;
+
+    public UserMessage(long id, User author, Topic topic, String contents, LocalDateTime postTime) {
+        super(id, topic, postTime);
+        this.author = author;
+        this.contents = contents;
+    }
+
+    public UserMessage(long id, User author, Topic topic, String contents) {
+        this(id, author, topic, contents, LocalDateTime.now());
+    }
+
+    public User getAuthor() {
+        return author;
+    }
+
+    public String getContents() {
+        return contents;
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageCreatedPacket.java

@@ -7,8 +7,9 @@ import java.nio.ByteBuffer;
 public class MessageCreatedPacket extends Packet {
 
     public static final short TYPE = 0x32;
-    public static final int LENGTH = 0x014;
+    public static final int LENGTH = 0x01C;
 
+    private long messageID;
     private long authorID;
     private long topicID;
     private final StringData contents = new StringData();
@@ -17,6 +18,14 @@ public class MessageCreatedPacket extends Packet {
         super(TYPE, LENGTH);
     }
 
+    public long getMessageID() {
+        return messageID;
+    }
+
+    public void setMessageID(long messageID) {
+        this.messageID = messageID;
+    }
+
     public long getAuthorID() {
         return authorID;
     }
@@ -39,7 +48,7 @@ public class MessageCreatedPacket extends Packet {
 
     public void setContents(String contents) {
         this.contents.setValue(contents);
-        setLength(16 + this.contents.getLength());
+        setLength(24 + this.contents.getLength());
     }
 
     @Override
@@ -47,6 +56,7 @@ public class MessageCreatedPacket extends Packet {
         MessageCreatedPacket packet = new MessageCreatedPacket();
         packet.setLength(size);
 
+        packet.messageID = buffer.getLong();
         packet.authorID = buffer.getLong();
         packet.topicID = buffer.getLong();
         packet.contents.setBytes(buffer);
@@ -56,6 +66,7 @@ public class MessageCreatedPacket extends Packet {
 
     @Override
     public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(messageID);
         buffer.putLong(authorID);
         buffer.putLong(topicID);
         buffer.put(contents.getBytes());

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageDataPacket.java

@@ -0,0 +1,151 @@
+package dev.wiing.gossip.lib.packets;
+
+import dev.wiing.gossip.lib.data.StringData;
+
+import java.nio.ByteBuffer;
+
+public class MessageDataPacket extends Packet {
+
+    public static final short TYPE = 0x37;
+    public static final int LENGTH = 0x000;
+
+    public static class MessageType {
+        public static final byte USER = 1;
+        public static final byte SYSTEM = 2;
+    }
+
+    private long messageID;
+    private long topicID;
+
+    private byte messageType;
+
+    // USER TYPE
+    private long userAuthorID;
+    private final StringData userContents = new StringData();
+
+    // SYSTEM TYPE
+    private short systemType;
+    private long systemUserID = 0;
+    private final StringData systemContents = new StringData();
+
+    public MessageDataPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    private void updateLength() {
+        setLength(17 +
+                (isUserMessage() ? (8 + userContents.getLength()) : 0) +
+                (isSystemMessage() ? (16 + systemContents.getLength()) : 0));
+    }
+
+    public boolean isUserMessage() {
+        return messageType == MessageType.USER;
+    }
+
+    public boolean isSystemMessage() {
+        return messageType == MessageType.SYSTEM;
+    }
+
+    public long getMessageID() {
+        return messageID;
+    }
+
+    public void setMessageID(long messageID) {
+        this.messageID = messageID;
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    public byte getMessageType() {
+        return messageType;
+    }
+
+    public void setMessageType(byte messageType) {
+        this.messageType = messageType;
+    }
+
+    public long getUserAuthorID() {
+        return userAuthorID;
+    }
+
+    public void setUserAuthorID(long userAuthorID) {
+        this.userAuthorID = userAuthorID;
+    }
+
+    public String getUserContents() {
+        return userContents.getValue();
+    }
+
+    public void setUserContents(String userContents) {
+        this.userContents.setValue(userContents);
+        updateLength();
+    }
+
+    public short getSystemType() {
+        return systemType;
+    }
+
+    public void setSystemType(short systemType) {
+        this.systemType = systemType;
+    }
+
+    public long getSystemUserID() {
+        return systemUserID;
+    }
+
+    public void setSystemUserID(long systemUserID) {
+        this.systemUserID = systemUserID;
+    }
+
+    public String getSystemContents() {
+        return systemContents.getValue();
+    }
+
+    public void setSystemContents(String systemContents) {
+        this.systemContents.setValue(systemContents);
+        updateLength();
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        MessageDataPacket packet = new MessageDataPacket();
+        packet.setLength(size);
+
+        packet.messageID = buffer.getLong();
+        packet.topicID = buffer.getLong();
+        packet.messageType = buffer.get();
+
+        if (packet.isUserMessage()) {
+            packet.userAuthorID = buffer.getLong();
+            packet.userContents.setBytes(buffer);
+        } else if (packet.isSystemMessage()) {
+            packet.systemType = buffer.getShort();
+            packet.systemUserID = buffer.getLong();
+            packet.systemContents.setBytes(buffer);
+        }
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(messageID);
+        buffer.putLong(topicID);
+        buffer.put(messageType);
+
+        if (isUserMessage()) {
+            buffer.putLong(userAuthorID);
+            buffer.put(userContents.getBytes());
+        } else if (isSystemMessage()) {
+            buffer.putShort(systemType);
+            buffer.putLong(systemUserID);
+            buffer.put(systemContents.getBytes());
+        }
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageFetchPacket.java

@@ -0,0 +1,48 @@
+package dev.wiing.gossip.lib.packets;
+
+import java.nio.ByteBuffer;
+
+public class MessageFetchPacket extends Packet {
+
+    public static final short TYPE = 0x36;
+    public static final int LENGTH = 0x010;
+
+    private long topicID;
+    private long messageID;
+
+    public MessageFetchPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    public long getMessageID() {
+        return messageID;
+    }
+
+    public void setMessageID(long messageID) {
+        this.messageID = messageID;
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        MessageFetchPacket packet = new MessageFetchPacket();
+
+        packet.topicID = buffer.getLong();
+        packet.messageID = buffer.getLong();
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(topicID);
+        buffer.putLong(messageID);
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageListDataPacket.java

@@ -0,0 +1,59 @@
+package dev.wiing.gossip.lib.packets;
+
+import dev.wiing.gossip.lib.data.ListData;
+import dev.wiing.gossip.lib.data.LongData;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+public class MessageListDataPacket extends Packet {
+
+    public static final short TYPE = 0x35;
+    public static final int LENGTH = 0x00C;
+
+    private long topicID;
+    private final ListData<LongData> messageIDs = new ListData<>(LongData::new);
+
+    public MessageListDataPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    private void updateLength() {
+        setLength(8 + messageIDs.getLength());
+    }
+
+    @Override
+    public int getLength() {
+        updateLength();
+        return super.getLength();
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    public List<LongData> getMessageIDs() {
+        return messageIDs.getData();
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        MessageListDataPacket packet = new MessageListDataPacket();
+        packet.setLength(size);
+
+        packet.topicID = buffer.getLong();
+        packet.messageIDs.setBytes(buffer);
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(topicID);
+        buffer.put(messageIDs.getBytes());
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageListFetchPacket.java

@@ -0,0 +1,37 @@
+package dev.wiing.gossip.lib.packets;
+
+import java.nio.ByteBuffer;
+
+public class MessageListFetchPacket extends Packet {
+
+    public static final short TYPE = 0x34;
+    public static final int LENGTH = 0x008;
+
+    private long topicID;
+
+    public MessageListFetchPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        MessageListFetchPacket packet = new MessageListFetchPacket();
+
+        packet.topicID = buffer.getLong();
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(topicID);
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/MessageSystemPacket.java

@@ -0,0 +1,86 @@
+package dev.wiing.gossip.lib.packets;
+
+import dev.wiing.gossip.lib.data.StringData;
+
+import java.nio.ByteBuffer;
+import java.util.Objects;
+
+public class MessageSystemPacket extends Packet {
+
+    public static final short TYPE = 0x33;
+    public static final int LENGTH = 0x01E;
+
+    private long messageID;
+    private long topicID;
+    private short systemType = 0;
+    private long userID = 0;
+    private final StringData content = new StringData();
+
+    public MessageSystemPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    public long getMessageID() {
+        return messageID;
+    }
+
+    public void setMessageID(long messageID) {
+        this.messageID = messageID;
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    public short getSystemType() {
+        return systemType;
+    }
+
+    public void setSystemType(short systemType) {
+        this.systemType = systemType;
+    }
+
+    public long getUserID() {
+        return userID;
+    }
+
+    public void setUserID(long userID) {
+        this.userID = userID;
+    }
+
+    public String getContent() {
+        return content.getValue();
+    }
+
+    public void setContent(String content) {
+        this.content.setValue(content);
+        setLength(26 + this.content.getLength());
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        MessageSystemPacket packet = new MessageSystemPacket();
+        packet.setLength(size);
+
+        packet.messageID = buffer.getLong();
+        packet.topicID = buffer.getLong();
+        packet.systemType = buffer.getShort();
+        packet.userID = buffer.getLong();
+        packet.content.setBytes(buffer);
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(messageID);
+        buffer.putLong(topicID);
+        buffer.putShort(systemType);
+        buffer.putLong(userID);
+        buffer.put(content.getBytes());
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/TopicDataPacket.java

@@ -0,0 +1,109 @@
+package dev.wiing.gossip.lib.packets;
+
+import dev.wiing.gossip.lib.data.ListData;
+import dev.wiing.gossip.lib.data.LongData;
+import dev.wiing.gossip.lib.data.StringData;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+public class TopicDataPacket extends Packet {
+
+    public static final short TYPE = 0x18;
+    public static final int LENGTH = 0x01E;
+
+    private long topicID;
+    private long hostID;
+    private final StringData topicName = new StringData();
+    private final StringData topicDescription = new StringData();
+    private short topicColor;
+    private final ListData<LongData> userIDs = new ListData<>(LongData::new);
+
+    public TopicDataPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    private void updateLength() {
+        super.setLength(18 +
+                topicName.getLength() +
+                topicDescription.getLength() +
+                userIDs.getLength());
+    }
+
+    @Override
+    public int getLength() {
+        updateLength();
+        return super.getLength();
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    public long getHostID() {
+        return hostID;
+    }
+
+    public void setHostID(long hostID) {
+        this.hostID = hostID;
+    }
+
+    public String getTopicName() {
+        return topicName.getValue();
+    }
+
+    public void setTopicName(String topicName) {
+        this.topicName.setValue(topicName);
+        updateLength();
+    }
+
+    public String getTopicDescription() {
+        return topicDescription.getValue();
+    }
+
+    public void setTopicDescription(String topicDescription) {
+        this.topicDescription.setValue(topicDescription);
+        updateLength();
+    }
+
+    public short getTopicColor() {
+        return topicColor;
+    }
+
+    public void setTopicColor(short topicColor) {
+        this.topicColor = topicColor;
+    }
+
+    public List<LongData> getUserIDs() {
+        return userIDs.getData();
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        TopicDataPacket packet = new TopicDataPacket();
+        packet.setLength(size);
+
+        packet.topicID = buffer.getLong();
+        packet.hostID = buffer.getLong();
+        packet.topicName.setBytes(buffer);
+        packet.topicDescription.setBytes(buffer);
+        packet.topicColor = buffer.getShort();
+        packet.userIDs.setBytes(buffer);
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(topicID);
+        buffer.putLong(hostID);
+        buffer.put(topicName.getBytes());
+        buffer.put(topicDescription.getBytes());
+        buffer.putShort(topicColor);
+        buffer.put(userIDs.getBytes());
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/TopicFetchPacket.java

@@ -0,0 +1,37 @@
+package dev.wiing.gossip.lib.packets;
+
+import java.nio.ByteBuffer;
+
+public class TopicFetchPacket extends Packet {
+
+    public static final short TYPE = 0x17;
+    public static final int LENGTH = 8;
+
+    private long topicID;
+
+    public TopicFetchPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    public long getTopicID() {
+        return topicID;
+    }
+
+    public void setTopicID(long topicID) {
+        this.topicID = topicID;
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        TopicFetchPacket packet = new TopicFetchPacket();
+
+        packet.topicID = buffer.getLong();
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.putLong(topicID);
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/TopicListDataPacket.java

@@ -0,0 +1,48 @@
+package dev.wiing.gossip.lib.packets;
+
+import dev.wiing.gossip.lib.data.ListData;
+import dev.wiing.gossip.lib.data.LongData;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+public class TopicListDataPacket extends Packet {
+
+    public static final short TYPE = 0x16;
+    public static final int LENGTH = 0x004;
+
+    private final ListData<LongData> topicIDs = new ListData<>(LongData::new);
+
+    public TopicListDataPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    private void updateLength() {
+        setLength(this.topicIDs.getLength());
+    }
+
+    @Override
+    public int getLength() {
+        updateLength();
+        return super.getLength();
+    }
+
+    public List<LongData> getTopicIDs() {
+        return topicIDs.getData();
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        TopicListDataPacket packet = new TopicListDataPacket();
+        packet.setLength(size);
+
+        packet.topicIDs.setBytes(buffer);
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+        buffer.put(topicIDs.getBytes());
+    }
+}

Lib/src/main/java/dev/wiing/gossip/lib/packets/TopicListFetchPacket.java

@@ -0,0 +1,26 @@
+package dev.wiing.gossip.lib.packets;
+
+import java.nio.ByteBuffer;
+
+public class TopicListFetchPacket extends Packet {
+
+    public static final short TYPE = 0x15;
+    public static final int LENGTH = 0x000;
+
+    public TopicListFetchPacket() {
+        super(TYPE, LENGTH);
+    }
+
+    @Override
+    public Packet readBytes(ByteBuffer buffer, int size) {
+        TopicListFetchPacket packet = new TopicListFetchPacket();
+        packet.setLength(size);
+
+        return packet;
+    }
+
+    @Override
+    public void writeBytes(ByteBuffer buffer) {
+
+    }
+}