Late-pulling

Client/src/main/java/dev/wiing/gossip/client/Connection.java

@@ -2,7 +2,9 @@ package dev.wiing.gossip.client;
 
 import dev.wiing.gossip.lib.PacketHandler;
 import dev.wiing.gossip.lib.PacketManager;
+import dev.wiing.gossip.lib.data.LongData;
 import dev.wiing.gossip.lib.models.SecretUser;
+import dev.wiing.gossip.lib.models.Topic;
 import dev.wiing.gossip.lib.models.User;
 import dev.wiing.gossip.lib.packets.*;
 
@@ -103,9 +105,11 @@ public class Connection {
     }
 
     public Packet nextPacket(boolean useQueue) throws SocketException {
+        synchronized (queuedPackets) {
             if (useQueue && !queuedPackets.isEmpty()) {
                 return queuedPackets.remove(0);
             }
+        }
 
         try {
             return getPacketManager().readPacket(getSocket().getInputStream());
@@ -137,6 +141,7 @@ public class Connection {
     public Packet findPacketOfTypes(List<Short> types) {
         Packet packet = null;
 
+        synchronized (queuedPackets) {
             int i;
             for (i = 0; i < queuedPackets.size(); i++) {
                 Packet queuedPacket = queuedPackets.get(i);
@@ -154,6 +159,7 @@ public class Connection {
 
             return null;
         }
+    }
 
     public boolean findAck(short acknowledgement) throws IOException {
 
@@ -162,6 +168,7 @@ public class Connection {
 
             AckPacket ack = null;
 
+            synchronized (queuedPackets) {
                 int i;
                 for (i = 0; i < queuedPackets.size(); i++) {
                     Packet queuedPacket = queuedPackets.get(i);
@@ -183,6 +190,7 @@ public class Connection {
                 }
             }
         }
+    }
 
     public SecretUser getSelf() {
         return self;
@@ -198,17 +206,9 @@ public class Connection {
         ));
     }
 
-    private final Map<Long, User> userCache = new ConcurrentHashMap<>();
+    private final DataCache<User> userCache = new DataCache<>(id -> {
-
-    public User getUser(long userID) {
-        User result;
-
-        if ((result = userCache.getOrDefault(userID, null)) != null) {
-            return result;
-        }
-
         UserFetchPacket fetch = new UserFetchPacket();
-        fetch.setUserID(userID);
+        fetch.setUserID(id);
         Connection.getInstance().sendPacket(fetch);
 
         Packet resp;
@@ -219,14 +219,50 @@ public class Connection {
         }
         if (resp.getType() == UserDataPacket.TYPE) {
             UserDataPacket userData = (UserDataPacket)resp;
-            result = new User(
+            return new User(
                     userData.getUsername(),
                     userData.getAvatarID(),
                     userData.getUserID()
             );
-            userCache.put(result.getUserID(), result);
         }
 
+        return null;
+    });
+
+    public User getUser(long userID) {
+        return userCache.get(userID);
+    }
+
+    private final DataCache<Topic> topicCache = new DataCache<>(id -> {
+        TopicFetchPacket fetch = new TopicFetchPacket();
+        fetch.setTopicID(id);
+        Connection.getInstance().sendPacket(fetch);
+
+        Packet resp;
+        try {
+            resp = Connection.getInstance().nextPacket(TopicDataPacket.TYPE);
+        } catch (SocketException e) {
+            throw new RuntimeException(e);
+        }
+        if (resp.getType() == TopicDataPacket.TYPE) {
+            TopicDataPacket topicData = (TopicDataPacket)resp;
+            Topic result = new Topic(
+                    topicData.getTopicID(),
+                    topicData.getTopicName(),
+                    topicData.getTopicDescription(),
+                    getUser(topicData.getHostID()),
+                    topicData.getTopicColor()
+            );
+            for (LongData userID : topicData.getUserIDs()) {
+                result.addUser(getUser(userID.getValue()));
+            }
             return result;
         }
+
+        return null;
+    });
+
+    public Topic getTopic(long topicID) {
+        return topicCache.get(topicID);
+    }
 }

Client/src/main/java/dev/wiing/gossip/client/DataCache.java

@@ -0,0 +1,48 @@
+package dev.wiing.gossip.client;
+
+import dev.wiing.gossip.lib.data.LongData;
+import dev.wiing.gossip.lib.models.Topic;
+import dev.wiing.gossip.lib.packets.Packet;
+import dev.wiing.gossip.lib.packets.TopicDataPacket;
+import dev.wiing.gossip.lib.packets.TopicFetchPacket;
+
+import java.net.SocketException;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class DataCache<T> {
+
+    private final DataFetchFunction<T> fetchFunction;
+
+    public DataCache(DataFetchFunction<T> fetchFunction) {
+        this.fetchFunction = fetchFunction;
+    }
+
+    @FunctionalInterface
+    public interface DataFetchFunction<U> {
+        U fetch(long id);
+    }
+
+    private final Map<Long, T> cache = new ConcurrentHashMap<>();
+
+    public T get(long id) {
+        if (id == 0) return null;
+
+        T result;
+
+        if ((result = cache.getOrDefault(id, null)) != null) {
+            return result;
+        }
+
+        result = fetchFunction.fetch(id);
+        if (result != null) {
+            cache.put(id, result);
+        }
+
+        return result;
+    }
+
+    public void put(long id, T val) {
+        cache.put(id, val);
+    }
+}

Client/src/main/java/dev/wiing/gossip/client/GossipApp.java

@@ -13,7 +13,7 @@ public class GossipApp extends Application {
         System.setProperty("prism.lcdtext", "false");
 
         FXMLLoader fxmlLoader = new FXMLLoader(Program.class.getResource("views/login-view.fxml"));
-        Scene scene = new Scene(fxmlLoader.load(), 320, 240);
+        Scene scene = new Scene(fxmlLoader.load(), 500, 400);
 
         stage.setTitle("GossipApp");
         stage.setScene(scene);

Client/src/main/java/dev/wiing/gossip/client/controllers/MainChatController.java

@@ -2,9 +2,11 @@ package dev.wiing.gossip.client.controllers;
 
 import dev.wiing.gossip.client.Connection;
 import dev.wiing.gossip.client.controllers.item.MessageItemController;
+import dev.wiing.gossip.client.controllers.item.SystemMessageItemController;
 import dev.wiing.gossip.client.generic.Pair;
 import dev.wiing.gossip.client.utils.Utils;
-import dev.wiing.gossip.lib.models.Message;
+import dev.wiing.gossip.lib.models.SystemMessage;
+import dev.wiing.gossip.lib.models.UserMessage;
 import dev.wiing.gossip.lib.models.Topic;
 import dev.wiing.gossip.lib.packets.MessagePushPacket;
 import dev.wiing.gossip.lib.packets.TopicJoinPacket;
@@ -17,6 +19,7 @@ import javafx.scene.control.TextArea;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.layout.VBox;
 
+import java.beans.PropertyChangeEvent;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -81,7 +84,13 @@ public class MainChatController {
 
             if (evt.getPropertyName().equals("messageAdd")) {
                 Platform.runLater(() -> {
-                    addMessage((Message)evt.getNewValue());
+                    if (evt.getNewValue() instanceof UserMessage) {
+                        addMessage((UserMessage)evt.getNewValue());
+                    }
+
+                    else if (evt.getNewValue() instanceof SystemMessage) {
+                        addSystemMessage((SystemMessage)evt.getNewValue());
+                    }
                 });
             }
         });
@@ -113,18 +122,28 @@ public class MainChatController {
         vboxVisitPage.setVisible(!participating);
     }
 
-    private void addMessage(Message message) {
+    private void addMessage(UserMessage userMessage) {
-        if (latestMessageItem == null || latestMessageItem.getAuthor().getUserID() != message.getAuthor().getUserID()) {
+        if (latestMessageItem == null || latestMessageItem.getAuthor().getUserID() != userMessage.getAuthor().getUserID()) {
             var newPair = MessageItemController.createInstance();
 
-            newPair.second().setAuthor(message.getAuthor());
+            newPair.second().setAuthor(userMessage.getAuthor());
 
             vboxMessages.getChildren().add(newPair.first());
 
             latestMessageItem = newPair.second();
         }
 
-        latestMessageItem.addMessage(message);
+        latestMessageItem.addMessage(userMessage);
+    }
+
+    private void addSystemMessage(SystemMessage systemMessage) {
+        latestMessageItem = null;
+
+        var pair = SystemMessageItemController.createInstance();
+
+        pair.second().setSystemMessage(systemMessage);
+
+        vboxMessages.getChildren().add(pair.first());
     }
 
     @FXML

Client/src/main/java/dev/wiing/gossip/client/controllers/MainController.java

@@ -6,9 +6,7 @@ import dev.wiing.gossip.client.data.UserAvatar;
 import dev.wiing.gossip.client.generic.Pair;
 import dev.wiing.gossip.client.utils.Utils;
 import dev.wiing.gossip.lib.data.LongData;
-import dev.wiing.gossip.lib.models.Message;
+import dev.wiing.gossip.lib.models.*;
-import dev.wiing.gossip.lib.models.Topic;
-import dev.wiing.gossip.lib.models.User;
 import dev.wiing.gossip.lib.packets.*;
 import javafx.application.Platform;
 import javafx.event.ActionEvent;
@@ -20,6 +18,7 @@ import javafx.scene.layout.AnchorPane;
 import javafx.scene.layout.Pane;
 import javafx.scene.layout.VBox;
 
+import java.net.SocketException;
 import java.net.URL;
 import java.util.Map;
 import java.util.ResourceBundle;
@@ -56,6 +55,25 @@ public class MainController implements Initializable {
 
         UserAvatar.getAvatar(user.getAvatarID()).applyToRegionBackground(paneIcon, true);
 
+        TopicListFetchPacket topicListFetchPacket = new TopicListFetchPacket();
+        Connection.getInstance().sendPacket(topicListFetchPacket);
+
+        try {
+            Packet topicListFetchResult = Connection.getInstance().nextPacket(TopicListDataPacket.TYPE);
+            if (topicListFetchResult != null) {
+                TopicListDataPacket topicListData = (TopicListDataPacket) topicListFetchResult;
+                for (LongData topicID : topicListData.getTopicIDs()) {
+                    Topic topic = Connection.getInstance().getTopic(topicID.getValue());
+
+                    if (topic == null) continue;
+
+                    addTopic(topic);
+                }
+            }
+        } catch (SocketException e) {
+            throw new RuntimeException(e);
+        }
+
         Connection.getInstance().getPacketHandler().addListener(TopicCreatedPacket.class, packet -> {
             User host = Connection.getInstance().getUser(packet.getHostID());
 
@@ -67,29 +85,7 @@ public class MainController implements Initializable {
                     packet.getTopicColor()
             );
 
-            var pair = TopicItemController.createInstance();
+            addTopic(topic);
-            pair.second().setTopic(topic);
-
-            var contentPair = MainChatController.createInstance();
-            contentPair.second().setTopic(topic);
-
-            topicMap.put(topic.getId(), contentPair);
-
-            AnchorPane.setLeftAnchor(contentPair.first(), 0.0);
-            AnchorPane.setBottomAnchor(contentPair.first(), 0.0);
-            AnchorPane.setTopAnchor(contentPair.first(), 0.0);
-            AnchorPane.setRightAnchor(contentPair.first(), 0.0);
-            contentPair.first().setVisible(false);
-
-            Platform.runLater(() -> {
-                paneContent.getChildren().add(contentPair.first());
-
-                vboxTopics.getChildren().add(pair.first());
-            });
-
-            pair.second().setOnMouseClicked(event -> {
-                setActiveTopic(topic, pair.first());
-            });
         });
 
         Connection.getInstance().getPacketHandler().addListener(TopicUpdatePacket.class, packet -> {
@@ -122,9 +118,24 @@ public class MainController implements Initializable {
 
             User author = Connection.getInstance().getUser(packet.getAuthorID());
 
-            Message message = new Message(author, topic, packet.getContents());
+            UserMessage userMessage = new UserMessage(packet.getMessageID(), author, topic, packet.getContents());
 
-            topic.addMessage(message);
+            topic.addMessage(userMessage);
+        });
+
+        Connection.getInstance().getPacketHandler().addListener(MessageSystemPacket.class, packet -> {
+            if (!topicMap.containsKey(packet.getTopicID())) return;
+
+            Topic topic = topicMap.get(packet.getTopicID()).second().getTopic();
+
+            User targetUser = null;
+            if (packet.getUserID() != 0) {
+                targetUser = Connection.getInstance().getUser(packet.getUserID());
+            }
+
+            SystemMessage systemMessage = new SystemMessage(packet.getMessageID(), topic, packet.getSystemType(), targetUser, packet.getContent());
+
+            topic.addMessage(systemMessage);
         });
 
         Connection.getInstance().beginHandlingPackets();
@@ -132,6 +143,90 @@ public class MainController implements Initializable {
         vboxTopics.getChildren().clear();
     }
 
+    private void fetchTopicMessage(Topic topic, long messageID) {
+        MessageFetchPacket messageFetchPacket = new MessageFetchPacket();
+        messageFetchPacket.setMessageID(messageID);
+        messageFetchPacket.setTopicID(topic.getId());
+        Connection.getInstance().sendPacket(messageFetchPacket);
+
+        try {
+            Packet messageFetchResult = Connection.getInstance().nextPacket(MessageDataPacket.TYPE);
+            if (messageFetchResult == null) return;
+
+            MessageDataPacket messageData = (MessageDataPacket) messageFetchResult;
+
+            Message message = null;
+            if (messageData.isUserMessage()) {
+                message = new UserMessage(
+                        messageData.getMessageID(),
+                        Connection.getInstance().getUser(messageData.getUserAuthorID()),
+                        Connection.getInstance().getTopic(messageData.getTopicID()),
+                        messageData.getUserContents()
+                );
+            }
+            else if (messageData.isSystemMessage()) {
+                message = new SystemMessage(
+                        messageData.getMessageID(),
+                        Connection.getInstance().getTopic(messageData.getTopicID()),
+                        messageData.getSystemType(),
+                        Connection.getInstance().getUser(messageData.getSystemUserID()),
+                        messageData.getSystemContents()
+                );
+            }
+
+            if (message != null) {
+                message.getTopic().addMessage(message);
+            }
+
+        } catch (SocketException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public void addTopic(Topic topic) {
+        var pair = TopicItemController.createInstance();
+        pair.second().setTopic(topic);
+
+        var contentPair = MainChatController.createInstance();
+        contentPair.second().setTopic(topic);
+
+        topicMap.put(topic.getId(), contentPair);
+
+        AnchorPane.setLeftAnchor(contentPair.first(), 0.0);
+        AnchorPane.setBottomAnchor(contentPair.first(), 0.0);
+        AnchorPane.setTopAnchor(contentPair.first(), 0.0);
+        AnchorPane.setRightAnchor(contentPair.first(), 0.0);
+        contentPair.first().setVisible(false);
+
+        MessageListFetchPacket messageListFetchPacket = new MessageListFetchPacket();
+        messageListFetchPacket.setTopicID(topic.getId());
+        Connection.getInstance().sendPacket(messageListFetchPacket);
+
+        Platform.runLater(() -> {
+            paneContent.getChildren().add(contentPair.first());
+
+            vboxTopics.getChildren().add(pair.first());
+        });
+
+        pair.second().setOnMouseClicked(event -> {
+            setActiveTopic(topic, pair.first());
+        });
+
+        try {
+            Packet messageListFetchResult = Connection.getInstance().nextPacket(MessageListDataPacket.TYPE);
+            if (messageListFetchResult == null) return;
+
+            MessageListDataPacket messageListDataPacket = (MessageListDataPacket) messageListFetchResult;
+
+            for (LongData messageID : messageListDataPacket.getMessageIDs()) {
+                fetchTopicMessage(topic, messageID.getValue());
+            }
+
+        } catch (SocketException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     public void setActiveTopic(Topic topic, Parent element) {
         if (activeTopic != null) {
             activeTopicElement.getStyleClass().remove("tag-min");

Client/src/main/java/dev/wiing/gossip/client/controllers/item/MessageItemController.java

@@ -4,7 +4,7 @@ import dev.wiing.gossip.client.Connection;
 import dev.wiing.gossip.client.data.UserAvatar;
 import dev.wiing.gossip.client.generic.Pair;
 import dev.wiing.gossip.client.utils.Utils;
-import dev.wiing.gossip.lib.models.Message;
+import dev.wiing.gossip.lib.models.UserMessage;
 import dev.wiing.gossip.lib.models.User;
 import javafx.fxml.FXML;
 import javafx.fxml.Initializable;
@@ -22,7 +22,7 @@ import java.util.ResourceBundle;
 public class MessageItemController implements Initializable {
 
     private User author;
-    private final List<Message> messages = Collections.synchronizedList(new ArrayList<>());
+    private final List<UserMessage> userMessages = Collections.synchronizedList(new ArrayList<>());
 
     @FXML
     private Label lblAuthor;
@@ -61,24 +61,24 @@ public class MessageItemController implements Initializable {
         UserAvatar.getAvatar(this.author.getAvatarID()).applyToRegionBackground(paneIcon, true);
     }
 
-    public void addMessage(Message message) {
+    public void addMessage(UserMessage userMessage) {
-        if (message.getAuthor() != author) return;
+        if (userMessage.getAuthor() != author) return;
 
-        if (!this.lblTag.isVisible() && messages.isEmpty() && message.getTopic().getHost().getUserID() == message.getAuthor().getUserID()) {
+        if (!this.lblTag.isVisible() && userMessages.isEmpty() && userMessage.getTopic().getHost().getUserID() == userMessage.getAuthor().getUserID()) {
             this.lblTag.setVisible(true);
             this.lblTag.setText("Host");
             this.lblTag.getStyleClass().add("secondary");
         }
 
-        messages.add(message);
+        userMessages.add(userMessage);
 
-        Label label = new Label(message.getContents());
+        Label label = new Label(userMessage.getContents());
 
         vboxMessages.getChildren().add(label);
     }
 
-    public List<Message> getMessageReadOnly() {
+    public List<UserMessage> getMessageReadOnly() {
-        return Collections.unmodifiableList(messages);
+        return Collections.unmodifiableList(userMessages);
     }
 
     public static Pair<Parent, MessageItemController> createInstance() {

Client/src/main/java/dev/wiing/gossip/client/controllers/item/SystemMessageItemController.java

@@ -0,0 +1,76 @@
+package dev.wiing.gossip.client.controllers.item;
+
+import dev.wiing.gossip.client.generic.Pair;
+import dev.wiing.gossip.client.utils.Utils;
+import dev.wiing.gossip.lib.models.SystemMessage;
+import javafx.fxml.FXML;
+import javafx.scene.Node;
+import javafx.scene.Parent;
+import javafx.scene.control.Label;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.Pane;
+
+public class SystemMessageItemController {
+
+    private SystemMessage systemMessage;
+
+    @FXML
+    private ImageView imgIcon;
+
+    @FXML
+    private Label lblPrefix;
+
+    @FXML
+    private Label lblSuffix;
+
+    @FXML
+    private Label lblTimeAgo;
+
+    @FXML
+    private Label lblContent;
+
+    public void setSystemMessage(SystemMessage systemMessage) {
+        this.systemMessage = systemMessage;
+
+        switch (this.systemMessage.getType()) {
+            case SystemMessage.SystemType.USER_JOIN:
+                removeNode(lblPrefix);
+                lblContent.setText(systemMessage.getUser().getUsernameDisplay());
+                lblSuffix.setText("joined the Topic");
+                break;
+
+            case SystemMessage.SystemType.USER_LEAVE:
+                removeNode(lblPrefix);
+                lblContent.setText(systemMessage.getUser().getUsernameDisplay());
+                lblSuffix.setText("left the Topic");
+                break;
+
+            case SystemMessage.SystemType.NAME_CHANGE:
+                lblPrefix.setText("Topic changed to");
+                lblContent.setText(systemMessage.getContents());
+                removeNode(lblSuffix);
+                break;
+
+            case SystemMessage.SystemType.DESCRIPTION_CHANGE:
+                lblPrefix.setText("Topic Description changed");
+                removeNode(lblContent);
+                removeNode(lblSuffix);
+                break;
+
+            case SystemMessage.SystemType.HOST_CHANGE:
+                lblPrefix.setText("Host changed to");
+                lblContent.setText(systemMessage.getUser().getUsernameDisplay());
+                removeNode(lblSuffix);
+                break;
+        }
+    }
+
+    private void removeNode(Node node) {
+        ((Pane)node.getParent()).getChildren().remove(node);
+    }
+
+    public static Pair<Parent, SystemMessageItemController> createInstance() {
+        return Utils.createInstance("views/system-message-item.fxml");
+    }
+
+}

Client/src/main/resources/dev/wiing/gossip/client/views/chat-view.fxml

@@ -12,11 +12,10 @@
 <?import javafx.scene.image.ImageView?>
 <?import javafx.scene.layout.AnchorPane?>
 <?import javafx.scene.layout.HBox?>
-<?import javafx.scene.layout.Pane?>
 <?import javafx.scene.layout.VBox?>
 <?import javafx.scene.shape.Circle?>
 
-<AnchorPane prefHeight="318.0" prefWidth="523.0" xmlns="http://javafx.com/javafx/21" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dev.wiing.gossip.client.controllers.MainChatController">
+<AnchorPane prefHeight="318.0" prefWidth="523.0" xmlns="http://javafx.com/javafx/20.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dev.wiing.gossip.client.controllers.MainChatController">
    <children>
       <VBox fx:id="vboxVisitPage" alignment="CENTER" layoutX="10.0" layoutY="10.0" spacing="8.0" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
          <children>
@@ -59,63 +58,6 @@
             <ScrollPane fitToWidth="true" hbarPolicy="NEVER" VBox.vgrow="ALWAYS">
                <content>
                   <VBox fx:id="vboxMessages" spacing="16.0">
-                     <children>
-                        <HBox spacing="8.0">
-                           <children>
-                              <Pane maxHeight="40.0" maxWidth="40.0" minHeight="40.0" minWidth="40.0" style="-fx-background-color: white;" />
-                              <VBox alignment="CENTER_LEFT" minHeight="40.0" spacing="4.0" HBox.hgrow="ALWAYS">
-                                 <children>
-                                    <HBox alignment="BOTTOM_LEFT" spacing="8.0">
-                                       <children>
-                                          <Label style="-fx-font-size: 14;" text="\@ Username">
-                                             <styleClass>
-                                                <String fx:value="axis" />
-                                                <String fx:value="accent" />
-                                             </styleClass>
-                                          </Label>
-                                          <Label text="You">
-                                             <styleClass>
-                                                <String fx:value="tag" />
-                                                <String fx:value="small" />
-                                                <String fx:value="axis" />
-                                             </styleClass>
-                                          </Label>
-                                          <Label alignment="CENTER_RIGHT" contentDisplay="RIGHT" maxWidth="1.7976931348623157E308" style="-fx-font-size: 10;" styleClass="faint" text="10 minutes ago" textAlignment="RIGHT" HBox.hgrow="ALWAYS" />
-                                       </children>
-                                    </HBox>
-                                    <VBox spacing="4.0">
-                                       <children>
-                                          <Label text="Message contents" />
-                                       </children>
-                                    </VBox>
-                                 </children>
-                              </VBox>
-                           </children>
-                        </HBox>
-                        <HBox alignment="CENTER_LEFT" layoutX="26.0" layoutY="26.0" spacing="8.0">
-                           <children>
-                              <ImageView fitHeight="20.0" fitWidth="20.0" opacity="0.5" pickOnBounds="true" preserveRatio="true">
-                                 <image>
-                                    <Image url="@../icons/door-enter.png" />
-                                 </image>
-                              </ImageView>
-                              <Label style="-fx-font-size: 14;" styleClass="axis" text="\@ Username" />
-                              <Label layoutX="46.0" layoutY="19.0" style="-fx-font-size: 12;" text="joined the Topic" />
-                              <Label alignment="CENTER_RIGHT" contentDisplay="RIGHT" maxWidth="1.7976931348623157E308" style="-fx-font-size: 10;" styleClass="faint" text="10 minutes ago" textAlignment="RIGHT" HBox.hgrow="ALWAYS">
-                                 <HBox.margin>
-                                    <Insets />
-                                 </HBox.margin>
-                              </Label>
-                           </children>
-                           <padding>
-                              <Insets bottom="8.0" left="16.0" right="16.0" top="8.0" />
-                           </padding>
-                           <styleClass>
-                              <String fx:value="elevated" />
-                              <String fx:value="border-radius-small" />
-                           </styleClass>
-                        </HBox>
-                     </children>
                      <padding>
                         <Insets bottom="16.0" left="16.0" right="16.0" top="16.0" />
                      </padding>

Client/src/main/resources/dev/wiing/gossip/client/views/system-message-item.fxml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import java.lang.String?>
+<?import javafx.geometry.Insets?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.image.Image?>
+<?import javafx.scene.image.ImageView?>
+<?import javafx.scene.layout.HBox?>
+
+<HBox alignment="CENTER_LEFT" spacing="8.0" stylesheets="@../styling.css" xmlns="http://javafx.com/javafx/20.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="dev.wiing.gossip.client.controllers.item.SystemMessageItemController">
+   <children>
+      <ImageView fx:id="imgIcon" fitHeight="20.0" fitWidth="20.0" opacity="0.5" pickOnBounds="true" preserveRatio="true">
+         <image>
+            <Image url="@../icons/door-enter.png" />
+         </image>
+      </ImageView>
+      <Label fx:id="lblPrefix" style="-fx-font-size: 12;" text="joined the Topic" />
+      <Label fx:id="lblContent" style="-fx-font-size: 14;" styleClass="axis" text="\@ Username" />
+      <Label fx:id="lblSuffix" layoutX="46.0" layoutY="19.0" style="-fx-font-size: 12;" text="joined the Topic" />
+      <Label fx:id="lblTimeAgo" alignment="CENTER_RIGHT" contentDisplay="RIGHT" maxWidth="1.7976931348623157E308" style="-fx-font-size: 10;" styleClass="faint" text="10 minutes ago" textAlignment="RIGHT" HBox.hgrow="ALWAYS">
+         <HBox.margin>
+            <Insets />
+         </HBox.margin>
+      </Label>
+   </children>
+   <padding>
+      <Insets bottom="8.0" left="16.0" right="16.0" top="8.0" />
+   </padding>
+   <styleClass>
+      <String fx:value="elevated" />
+      <String fx:value="border-radius-small" />
+   </styleClass>
+</HBox>

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.*;
-import dev.wiing.gossip.lib.packets.Packet;
-import dev.wiing.gossip.lib.packets.TopicCreatedPacket;
-import dev.wiing.gossip.lib.packets.TopicUpdatePacket;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
@@ -42,17 +39,14 @@ public class PacketHandler {
     }
 
     public boolean runPacket(Packet packet) {
-        switch (packet.getType()) {
+        return switch (packet.getType()) {
-            case TopicCreatedPacket.TYPE:
+            case TopicCreatedPacket.TYPE -> runPacket(TopicCreatedPacket.class, (TopicCreatedPacket) packet);
-                return runPacket(TopicCreatedPacket.class, (TopicCreatedPacket)packet);
+            case TopicUpdatePacket.TYPE -> runPacket(TopicUpdatePacket.class, (TopicUpdatePacket) packet);
-
+            case TopicListDataPacket.TYPE -> runPacket(TopicListDataPacket.class, (TopicListDataPacket) packet);
-            case TopicUpdatePacket.TYPE:
+            case MessageCreatedPacket.TYPE -> runPacket(MessageCreatedPacket.class, (MessageCreatedPacket) packet);
-                return runPacket(TopicUpdatePacket.class, (TopicUpdatePacket)packet);
+            case MessageSystemPacket.TYPE -> runPacket(MessageSystemPacket.class, (MessageSystemPacket) packet);
-
+            default -> false;
-            case MessageCreatedPacket.TYPE:
+        };
-                return runPacket(MessageCreatedPacket.class, (MessageCreatedPacket)packet);
-        }
-        return 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) {
+    public Message(long id, Topic topic, LocalDateTime postTime) {
-        this.author = author;
+        this.id = id;
         this.topic = topic;
-        this.contents = contents;
         this.postTime = postTime;
     }
 
-    public Message(User author, Topic topic, String contents) {
+    public Message(long id, Topic topic) {
-        this(author, topic, contents, LocalDateTime.now());
+        this(id, topic, LocalDateTime.now());
     }
 
-    public User getAuthor() {
+    public long getId() {
-        return author;
+        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) {
+
+    }
+}

Server/src/main/java/dev/wiing/gossip/server/Database.java

@@ -134,4 +134,8 @@ public class Database {
 
         logger.info("Topic removed: \"{}\" (#{})", topic.getName(), topic.getId());
     }
+
+    public List<Topic> getAllTopicsReadOnly() {
+        return Collections.unmodifiableList(topics.values().stream().toList());
+    }
 }

Server/src/main/java/dev/wiing/gossip/server/UserSocket.java

@@ -1,18 +1,15 @@
 package dev.wiing.gossip.server;
 
 import dev.wiing.gossip.lib.data.LongData;
-import dev.wiing.gossip.lib.models.Message;
+import dev.wiing.gossip.lib.models.*;
-import dev.wiing.gossip.lib.models.SecretUser;
-import dev.wiing.gossip.lib.models.Topic;
-import dev.wiing.gossip.lib.models.User;
 import dev.wiing.gossip.lib.packets.*;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.net.Socket;
 import java.net.SocketException;
+import java.util.List;
 
 public record UserSocket(Socket socket) implements Runnable {
 
@@ -33,7 +30,7 @@ public record UserSocket(Socket socket) implements Runnable {
                 if (!socket.isConnected())
                     break;
 
-                Packet packet = Globals.getPacketManager().readPacket(new BufferedInputStream(socket.getInputStream()));
+                Packet packet = Globals.getPacketManager().readPacket(socket.getInputStream());
 
                 if (packet == null) continue;
 
@@ -52,6 +49,14 @@ public record UserSocket(Socket socket) implements Runnable {
                         onUserJoinTopic((TopicJoinPacket) packet);
                         break;
 
+                    case TopicListFetchPacket.TYPE:
+                        onTopicListFetch((TopicListFetchPacket) packet);
+                        break;
+
+                    case TopicFetchPacket.TYPE:
+                        onFetchTopic((TopicFetchPacket) packet);
+                        break;
+
                     case UserFetchPacket.TYPE:
                         onFetchUser((UserFetchPacket) packet);
                         break;
@@ -59,6 +64,14 @@ public record UserSocket(Socket socket) implements Runnable {
                     case MessagePushPacket.TYPE:
                         onUserMessage((MessagePushPacket) packet);
                         break;
+
+                    case MessageListFetchPacket.TYPE:
+                        onMessageListFetch((MessageListFetchPacket) packet);
+                        break;
+
+                    case MessageFetchPacket.TYPE:
+                        onFetchMessage((MessageFetchPacket) packet);
+                        break;
                 }
             } catch (SocketException e) {
                 loop = false;
@@ -120,10 +133,13 @@ public record UserSocket(Socket socket) implements Runnable {
         if (requester == null) return;
         if (topic == null) return;
 
-        if (!topic.hasUser(requester)) {
+        if (topic.hasUser(requester)) return;
+
         info("\"{}\" joined topic \"{}\" (#{})", topic.getHost().getUsername().toUpperCase(), topic.getName().toUpperCase(), topic.getId());
         topic.addUser(requester);
-        }
+
+        SystemMessage message = new SystemMessage(topic.getNextMessageID(), topic, SystemMessage.SystemType.USER_JOIN, requester, "");
+        topic.addMessage(message);
 
         AckPacket resp = new AckPacket();
         resp.setAcknowledgement(packet);
@@ -138,17 +154,62 @@ public record UserSocket(Socket socket) implements Runnable {
         updatePacket.setTopicID(topic.getId());
         updatePacket.getUsersJoined().add(new LongData().setValue(requester.getUserID()));
 
+        MessageSystemPacket systemPacket = new MessageSystemPacket();
+        systemPacket.setTopicID(topic.getId());
+        systemPacket.setSystemType(message.getType());
+        systemPacket.setUserID(message.getUser().getUserID());
+
         for (User user : Database.getInstance().getUsers()) {
             Socket socket = Database.getInstance().getUserSocket(user.getUserID());
 
             try {
-                Globals.getPacketManager().writePacket(socket.getOutputStream(), updatePacket);
+                Globals.getPacketManager().writeAllPackets(socket.getOutputStream(), updatePacket, systemPacket);
             } catch (IOException e) {
                 logger.error(e);
             }
         }
     }
 
+    private void onTopicListFetch(TopicListFetchPacket packet) {
+        TopicListDataPacket result = new TopicListDataPacket();
+
+        info("Requested Topic list");
+
+        for (Topic topic : Database.getInstance().getAllTopicsReadOnly()) {
+            result.getTopicIDs().add(new LongData().setValue(topic.getId()));
+        }
+
+        try {
+            Globals.getPacketManager().replyPacket(packet, result);
+        } catch (IOException e) {
+            logger.error(e);
+        }
+    }
+
+    private void onFetchTopic(TopicFetchPacket packet) {
+        Topic topic = Database.getInstance().getTopic(packet.getTopicID());
+
+        if (topic == null) return;
+
+        info("Requested topic #{}", topic.getId());
+
+        TopicDataPacket resp = new TopicDataPacket();
+        resp.setTopicID(topic.getId());
+        resp.setHostID(topic.getHost().getUserID());
+        resp.setTopicName(topic.getName());
+        resp.setTopicDescription(topic.getDescription());
+        resp.setTopicColor(topic.getColor());
+        for (User value : topic.getUsersReadOnly().values()) {
+            resp.getUserIDs().add(new LongData().setValue(value.getUserID()));
+        }
+
+        try {
+            Globals.getPacketManager().replyPacket(packet, resp);
+        } catch (IOException e) {
+            logger.error(e);
+        }
+    }
+
     private void onFetchUser(UserFetchPacket packet) {
         User user = Database.getInstance().getUserByID(packet.getUserID());
 
@@ -175,9 +236,9 @@ public record UserSocket(Socket socket) implements Runnable {
         if (user == null) return;
         if (topic == null) return;
 
-        Message message = new Message(user, topic, packet.getMessage());
+        UserMessage userMessage = new UserMessage(topic.getNextMessageID(), user, topic, packet.getMessage());
 
-        topic.addMessage(message);
+        topic.addMessage(userMessage);
 
         info("\"{}\" in \"{}\" sends \"{}\"", user.getUsername().toUpperCase(), topic.getName().toUpperCase(), packet.getMessage());
 
@@ -193,7 +254,7 @@ public record UserSocket(Socket socket) implements Runnable {
         MessageCreatedPacket messageCreated = new MessageCreatedPacket();
         messageCreated.setAuthorID(user.getUserID());
         messageCreated.setTopicID(topic.getId());
-        messageCreated.setContents(message.getContents());
+        messageCreated.setContents(userMessage.getContents());
 
         for (User babbler : topic.getUsersReadOnly().values()) {
             Socket userSocket = Database.getInstance().getUserSocket(babbler.getUserID());
@@ -206,4 +267,58 @@ public record UserSocket(Socket socket) implements Runnable {
         }
     }
 
+    private void onMessageListFetch(MessageListFetchPacket packet) {
+        Topic topic = Database.getInstance().getTopic(packet.getTopicID());
+
+        if (topic == null) return;
+
+        info("Requested Message list on #{}", topic.getId());
+
+        MessageListDataPacket result = new MessageListDataPacket();
+
+        for (Message message : topic.getMessagesReadOnly()) {
+            result.getMessageIDs().add(new LongData().setValue(message.getId()));
+        }
+
+        try {
+            Globals.getPacketManager().replyPacket(packet, result);
+        } catch (IOException e) {
+            logger.error(e);
+        }
+    }
+
+    private void onFetchMessage(MessageFetchPacket packet) {
+        Topic topic = Database.getInstance().getTopic(packet.getTopicID());
+
+        if (topic == null) return;
+
+        Message message = topic.getMessageByID(packet.getMessageID());
+
+        if (message == null) return;
+
+        info("Requested message #{} on #{}", message.getId(), topic.getId());
+
+        MessageDataPacket resp = new MessageDataPacket();
+        resp.setMessageID(message.getId());
+        resp.setTopicID(message.getTopic().getId());
+
+        if (message instanceof UserMessage userMessage) {
+            resp.setMessageType(MessageDataPacket.MessageType.USER);
+            resp.setUserAuthorID(userMessage.getAuthor().getUserID());
+            resp.setUserContents(userMessage.getContents());
+        } else if (message instanceof SystemMessage systemMessage) {
+            resp.setMessageType(MessageDataPacket.MessageType.SYSTEM);
+            resp.setSystemType(systemMessage.getType());
+            if (systemMessage.getUser() != null)
+                resp.setSystemUserID(systemMessage.getUser().getUserID());
+            resp.setSystemContents(systemMessage.getContents());
+        }
+
+        try {
+            Globals.getPacketManager().replyPacket(packet, resp);
+        } catch (IOException e) {
+            logger.error(e);
+        }
+    }
+
 }