Implement HoverSource for ItemStack, Entity and Player

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

@@ -2,6 +2,9 @@ package net.minestom.server.entity;
 
 import com.google.common.collect.Queues;
 import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.event.HoverEvent;
+import net.kyori.adventure.text.event.HoverEvent.ShowEntity;
+import net.kyori.adventure.text.event.HoverEventSource;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.Viewable;
 import net.minestom.server.chat.JsonMessage;
@@ -47,13 +50,14 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
+import java.util.function.UnaryOperator;
 
 /**
  * Could be a player, a monster, or an object.
  * <p>
  * To create your own entity you probably want to extends {@link LivingEntity} or {@link EntityCreature} instead.
  */
-public class Entity implements Viewable, EventHandler, DataContainer, PermissionHandler {
+public class Entity implements Viewable, EventHandler, DataContainer, PermissionHandler, HoverEventSource<ShowEntity> {
 
     private static final Map<Integer, Entity> entityById = new ConcurrentHashMap<>();
     private static final Map<UUID, Entity> entityByUuid = new ConcurrentHashMap<>();
@@ -1528,6 +1532,11 @@ public class Entity implements Viewable, EventHandler, DataContainer, Permission
         this.customSynchronizationCooldown = cooldown;
     }
 
+    @Override
+    public @NotNull HoverEvent<ShowEntity> asHoverEvent(@NotNull UnaryOperator<ShowEntity> op) {
+        return HoverEvent.showEntity(ShowEntity.of(this.entityType, this.uuid));
+    }
+
     private UpdateOption getSynchronizationCooldown() {
         if (this.customSynchronizationCooldown != null) {
             return this.customSynchronizationCooldown;

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

@@ -7,6 +7,9 @@ import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.inventory.Book;
 import net.kyori.adventure.sound.SoundStop;
 import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.event.HoverEvent;
+import net.kyori.adventure.text.event.HoverEvent.ShowEntity;
+import net.kyori.adventure.text.event.HoverEventSource;
 import net.kyori.adventure.title.Title;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.advancements.AdvancementTab;
@@ -77,6 +80,7 @@ import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.UnaryOperator;
 
 /**
  * Those are the major actors of the server,
@@ -84,7 +88,7 @@ import java.util.concurrent.atomic.AtomicInteger;
  * <p>
  * You can easily create your own implementation of this and use it with {@link ConnectionManager#setPlayerProvider(PlayerProvider)}.
  */
-public class Player extends LivingEntity implements CommandSender, Localizable {
+public class Player extends LivingEntity implements CommandSender, Localizable, HoverEventSource<ShowEntity> {
 
     private long lastKeepAlive;
     private boolean answerKeepAlive;
@@ -2536,6 +2540,11 @@ public class Player extends LivingEntity implements CommandSender, Localizable {
         return lastKeepAlive;
     }
 
+    @Override
+    public @NotNull HoverEvent<ShowEntity> asHoverEvent(@NotNull UnaryOperator<ShowEntity> op) {
+        return HoverEvent.showEntity(ShowEntity.of(EntityType.PLAYER, this.uuid, this.displayName));
+    }
+
     /**
      * Gets the packet to add the player from the tab-list.
      *

src/main/java/net/minestom/server/item/ItemStack.java

@@ -3,6 +3,9 @@ package net.minestom.server.item;
 import it.unimi.dsi.fastutil.objects.Object2ShortMap;
 import it.unimi.dsi.fastutil.objects.Object2ShortOpenHashMap;
 import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.event.HoverEvent;
+import net.kyori.adventure.text.event.HoverEvent.ShowItem;
+import net.kyori.adventure.text.event.HoverEventSource;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.chat.JsonMessage;
 import net.minestom.server.data.Data;
@@ -27,6 +30,7 @@ import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
 import java.util.*;
+import java.util.function.UnaryOperator;
 import java.util.stream.Collectors;
 
 // TODO should we cache a ByteBuf of this item for faster packet write
@@ -40,7 +44,7 @@ import java.util.stream.Collectors;
  * Here a non-exhaustive list of what you can do to update the item:
  * {@link PlayerInventory#refreshSlot(short)}, {@link Inventory#refreshSlot(short)} or a raw {@link SetSlotPacket}.
  */
-public class ItemStack implements DataContainer, PublicCloneable<ItemStack> {
+public class ItemStack implements DataContainer, PublicCloneable<ItemStack>, HoverEventSource<ShowItem> {
 
     public static final OwnershipHandler<Data> DATA_OWNERSHIP = new OwnershipHandler<>();
     public static final String OWNERSHIP_DATA_KEY = "ownership_identifier";
@@ -850,6 +854,11 @@ public class ItemStack implements DataContainer, PublicCloneable<ItemStack> {
         throw new UnsupportedOperationException("Not implemented yet");
     }
 
+    @Override
+    public @NotNull HoverEvent<ShowItem> asHoverEvent(@NotNull UnaryOperator<ShowItem> op) {
+        return HoverEvent.showItem(op.apply(ShowItem.of(this.material, this.amount, NBTUtils.asBinaryTagHolder(this.toNBT().getCompound("tag")))));
+    }
+
     // Callback events
 
     /**

src/main/java/net/minestom/server/utils/NBTUtils.java

@@ -1,13 +1,12 @@
 package net.minestom.server.utils;
 
+import net.kyori.adventure.nbt.api.BinaryTagHolder;
 import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
+import net.kyori.adventure.util.Codec;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.attribute.Attribute;
 import net.minestom.server.attribute.AttributeOperation;
-import net.minestom.server.chat.ChatParser;
-import net.minestom.server.chat.ColoredText;
-import net.minestom.server.chat.JsonMessage;
 import net.minestom.server.data.Data;
 import net.minestom.server.data.DataType;
 import net.minestom.server.inventory.Inventory;
@@ -28,17 +27,36 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.io.StringReader;
 import java.util.*;
 
 // for lack of a better name
 public final class NBTUtils {
-
     private final static Logger LOGGER = LoggerFactory.getLogger(NBTUtils.class);
 
+    /**
+     * An Adventure codec to convert between NBT and SNBT.
+     */
+    public static final Codec<NBT, String, NBTException, RuntimeException> SNBT_CODEC
+            = Codec.of(encoded -> new SNBTParser(new StringReader(encoded)).parse(), NBT::toSNBT);
+
     private NBTUtils() {
 
     }
 
+    /**
+     * Turns an {@link NBTCompound} into an Adventure {@link BinaryTagHolder}.
+     * @param tag the tag, if any
+     * @return the binary tag holder, or {@code null} if the tag was null
+     */
+    public static @Nullable BinaryTagHolder asBinaryTagHolder(@Nullable NBTCompound tag) {
+        if (tag == null) {
+            return null;
+        }
+
+        return BinaryTagHolder.encode(tag, SNBT_CODEC);
+    }
+
     /**
      * Loads all the items from the 'items' list into the given inventory
      *