Implement chat preview toggling and event

src/main/java/net/minestom/server/entity/Player.java

@@ -2057,6 +2057,10 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
         }
     }
 
+    public void toggleChatPreview(boolean on) {
+        playerConnection.sendPacket(on ? ServerDataPacket.TOGGLE_PREVIEW_ON : ServerDataPacket.TOGGLE_PREVIEW_OFF);
+    }
+
     /**
      * Represents the main or off hand of the player.
      */

src/main/java/net/minestom/server/event/player/PlayerChatPreviewEvent.java

@@ -0,0 +1,53 @@
+package net.minestom.server.event.player;
+
+import net.kyori.adventure.text.Component;
+import net.minestom.server.entity.Player;
+import net.minestom.server.event.trait.CancellableEvent;
+import net.minestom.server.event.trait.PlayerEvent;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public final class PlayerChatPreviewEvent implements PlayerEvent, CancellableEvent {
+    private final Player player;
+    private final int id;
+    private final String query;
+    private boolean cancelled;
+    private @Nullable Component result;
+
+    public PlayerChatPreviewEvent(Player player, int id, String query) {
+        this.player = player;
+        this.id = id;
+        this.query = query;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getQuery() {
+        return query;
+    }
+
+    public @Nullable Component getResult() {
+        return result;
+    }
+
+    public void setResult(@Nullable Component result) {
+        this.result = result;
+    }
+
+    @Override
+    public @NotNull Player getPlayer() {
+        return player;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return cancelled;
+    }
+
+    @Override
+    public void setCancelled(boolean cancel) {
+        cancelled = cancel;
+    }
+}

src/main/java/net/minestom/server/listener/ChatPreviewListener.java

@@ -0,0 +1,15 @@
+package net.minestom.server.listener;
+
+import net.minestom.server.MinecraftServer;
+import net.minestom.server.entity.Player;
+import net.minestom.server.event.player.PlayerChatPreviewEvent;
+import net.minestom.server.network.packet.client.play.ClientChatPreviewPacket;
+import net.minestom.server.network.packet.server.play.ChatPreviewPacket;
+
+public class ChatPreviewListener {
+    public static void listener(ClientChatPreviewPacket packet, Player player) {
+        final PlayerChatPreviewEvent event = new PlayerChatPreviewEvent(player, packet.queryId(), packet.query());
+        MinecraftServer.getGlobalEventHandler().callCancellable(event,
+                () -> player.sendPacket(new ChatPreviewPacket(event.getId(), event.getResult())));
+    }
+}

src/main/java/net/minestom/server/listener/manager/PacketListenerManager.java

@@ -57,6 +57,7 @@ public final class PacketListenerManager {
         setListener(ClientAdvancementTabPacket.class, AdvancementTabListener::listener);
         setListener(ClientSpectatePacket.class, SpectateListener::listener);
         setListener(ClientEditBookPacket.class, BookListener::listener);
+        setListener(ClientChatPreviewPacket.class, ChatPreviewListener::listener);
     }
 
     /**

src/main/java/net/minestom/server/network/packet/server/play/ChatPreviewPacket.java

@@ -15,14 +15,13 @@ import java.util.function.UnaryOperator;
 
 public record ChatPreviewPacket(int queryId, @Nullable Component preview) implements ComponentHoldingServerPacket {
     public ChatPreviewPacket(BinaryReader reader) {
-        this(reader.readInt(), reader.readBoolean() ? reader.readComponent() : null);
+        this(reader.readInt(), reader.readNullableComponent());
     }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
         writer.writeInt(queryId);
-        writer.writeBoolean(preview != null);
-        if (preview != null) writer.writeComponent(preview);
+        writer.writeNullableComponent(preview);
     }
 
     @Override

src/main/java/net/minestom/server/network/packet/server/play/ServerDataPacket.java

@@ -10,17 +10,16 @@ import org.jetbrains.annotations.Nullable;
 
 public record ServerDataPacket(@Nullable Component motd, @Nullable String iconBase64,
                                boolean previewsChat) implements ServerPacket {
+    public static final ServerDataPacket TOGGLE_PREVIEW_ON = new ServerDataPacket(null, null, true);
+    public static final ServerDataPacket TOGGLE_PREVIEW_OFF = new ServerDataPacket(null, null, false);
     public ServerDataPacket(BinaryReader reader) {
-        this(reader.readBoolean() ? reader.readComponent() : null, reader.readBoolean() ? reader.readSizedString() : null,
-                reader.readBoolean());
+        this(reader.readNullableComponent(), reader.readNullableSizedString(), reader.readBoolean());
     }
 
     @Override
     public void write(@NotNull BinaryWriter writer) {
-        writer.writeBoolean(motd != null);
-        if (motd != null) writer.writeComponent(motd);
-        writer.writeBoolean(iconBase64 != null);
-        if (iconBase64 != null) writer.writeSizedString(iconBase64);
+        writer.writeNullableComponent(motd);
+        writer.writeNullableSizedString(iconBase64);
         writer.writeBoolean(previewsChat);
     }
 

src/main/java/net/minestom/server/network/packet/server/play/SetChatPreviewPacket.java

@@ -7,6 +7,9 @@ import net.minestom.server.utils.binary.BinaryWriter;
 import org.jetbrains.annotations.NotNull;
 
 public record SetChatPreviewPacket(boolean enable) implements ServerPacket {
+    public static final SetChatPreviewPacket ENABLE = new SetChatPreviewPacket(true);
+    public static final SetChatPreviewPacket DISABLE = new SetChatPreviewPacket(true);
+
     public SetChatPreviewPacket(BinaryReader reader) {
         this(reader.readBoolean());
     }