Paper dumpitem command

Let's you quickly view the item in your hands NBT data

paper-server/src/main/java/io/papermc/paper/command/PaperCommand.java

@@ -39,6 +39,7 @@ public final class PaperCommand extends Command {
         commands.put(Set.of("version"), new VersionCommand());
         commands.put(Set.of("dumpplugins"), new DumpPluginsCommand());
         commands.put(Set.of("syncloadinfo"), new SyncLoadInfoCommand());
+        commands.put(Set.of("dumpitem"), new DumpItemCommand());
 
         return commands.entrySet().stream()
             .flatMap(entry -> entry.getKey().stream().map(s -> Map.entry(s, entry.getValue())))

paper-server/src/main/java/io/papermc/paper/command/subcommands/DumpItemCommand.java

@@ -0,0 +1,133 @@
+package io.papermc.paper.command.subcommands;
+
+import io.papermc.paper.adventure.PaperAdventure;
+import io.papermc.paper.command.CommandUtil;
+import io.papermc.paper.command.PaperSubcommand;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.IdentityHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Consumer;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.ComponentLike;
+import net.kyori.adventure.text.JoinConfiguration;
+import net.kyori.adventure.text.TextComponent;
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.component.DataComponentMap;
+import net.minecraft.core.component.DataComponentPatch;
+import net.minecraft.core.component.DataComponentType;
+import net.minecraft.core.component.TypedDataComponent;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.NbtOps;
+import net.minecraft.nbt.NbtUtils;
+import net.minecraft.nbt.SnbtPrinterTagVisitor;
+import net.minecraft.nbt.Tag;
+import net.minecraft.resources.RegistryOps;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.command.CommandSender;
+import org.bukkit.craftbukkit.CraftServer;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.entity.Player;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+import static net.kyori.adventure.text.Component.join;
+import static net.kyori.adventure.text.Component.text;
+import static net.kyori.adventure.text.Component.textOfChildren;
+import static net.kyori.adventure.text.event.ClickEvent.copyToClipboard;
+import static net.kyori.adventure.text.format.NamedTextColor.AQUA;
+import static net.kyori.adventure.text.format.NamedTextColor.GRAY;
+import static net.kyori.adventure.text.format.NamedTextColor.RED;
+import static net.kyori.adventure.text.format.NamedTextColor.WHITE;
+import static net.kyori.adventure.text.format.NamedTextColor.YELLOW;
+import static net.kyori.adventure.text.format.TextColor.color;
+import static net.kyori.adventure.text.format.TextDecoration.ITALIC;
+
+@DefaultQualifier(NonNull.class)
+public final class DumpItemCommand implements PaperSubcommand {
+    @Override
+    public boolean execute(final CommandSender sender, final String subCommand, final String[] args) {
+        this.doDumpItem(sender, args.length > 0 && "all".equals(args[0]));
+        return true;
+    }
+
+    @SuppressWarnings({"unchecked", "OptionalAssignedToNull", "rawtypes"})
+    private void doDumpItem(final CommandSender sender, final boolean includeAllComponents) {
+        if (!(sender instanceof final Player player)) {
+            sender.sendMessage("Only players can use this command");
+            return;
+        }
+        final ItemStack itemStack = CraftItemStack.asNMSCopy(player.getInventory().getItemInMainHand());
+        final TextComponent.Builder visualOutput = Component.text();
+        final StringBuilder itemCommandBuilder = new StringBuilder();
+        final String itemName = itemStack.getItemHolder().unwrapKey().orElseThrow().location().toString();
+        itemCommandBuilder.append(itemName);
+        visualOutput.append(text(itemName, YELLOW)); // item type
+        final Set<DataComponentType<?>> referencedComponentTypes = Collections.newSetFromMap(new IdentityHashMap<>());
+        final DataComponentPatch patch = itemStack.getComponentsPatch();
+        referencedComponentTypes.addAll(patch.entrySet().stream().map(Map.Entry::getKey).toList());
+        final DataComponentMap prototype = itemStack.getItem().components();
+        if (includeAllComponents) {
+            referencedComponentTypes.addAll(prototype.keySet());
+        }
+
+        final RegistryAccess.Frozen access = ((CraftServer) sender.getServer()).getServer().registryAccess();
+        final RegistryOps<Tag> ops = access.createSerializationContext(NbtOps.INSTANCE);
+        final Registry<DataComponentType<?>> registry = access.lookupOrThrow(Registries.DATA_COMPONENT_TYPE);
+        final List<ComponentLike> componentComponents = new ArrayList<>();
+        final List<String> commandComponents = new ArrayList<>();
+        for (final DataComponentType<?> type : referencedComponentTypes) {
+            final String path = registry.getResourceKey(type).orElseThrow().location().getPath();
+            final @Nullable Optional<?> patchedValue = patch.get(type);
+            final @Nullable TypedDataComponent<?> prototypeValue = prototype.getTyped(type);
+            if (patchedValue != null) {
+                if (patchedValue.isEmpty()) {
+                    componentComponents.add(text().append(text('!', RED), text(path, AQUA)));
+                    commandComponents.add("!" + path);
+                } else {
+                    final Tag serialized = (Tag) ((DataComponentType) type).codecOrThrow().encodeStart(ops, patchedValue.get()).getOrThrow();
+                    writeComponentValue(componentComponents::add, commandComponents::add, path, serialized);
+                }
+            } else if (includeAllComponents && prototypeValue != null) {
+                final Tag serialized = prototypeValue.encodeValue(ops).getOrThrow();
+                writeComponentValue(componentComponents::add, commandComponents::add, path, serialized);
+            }
+        }
+        if (!componentComponents.isEmpty()) {
+            visualOutput.append(
+                text("[", color(0x8910CE)),
+                join(JoinConfiguration.separator(text(",", GRAY)), componentComponents),
+                text("]", color(0x8910CE))
+            );
+            itemCommandBuilder
+                .append("[")
+                .append(String.join(",", commandComponents))
+                .append("]");
+        }
+        player.sendMessage(visualOutput.build().compact());
+        final Component copyMsg = text("Click to copy item definition to clipboard for use with /give", GRAY, ITALIC);
+        sender.sendMessage(copyMsg.clickEvent(copyToClipboard(itemCommandBuilder.toString())));
+    }
+
+    private static void writeComponentValue(final Consumer<Component> visualOutput, final Consumer<String> commandOutput, final String path, final Tag serialized) {
+        visualOutput.accept(textOfChildren(
+            text(path, color(0xFF7FD7)),
+            text("=", WHITE),
+            PaperAdventure.asAdventure(NbtUtils.toPrettyComponent(serialized))
+        ));
+        commandOutput.accept(path + "=" + new SnbtPrinterTagVisitor("", 0, new ArrayList<>()).visit(serialized));
+    }
+
+    @Override
+    public List<String> tabComplete(final CommandSender sender, final String subCommand, final String[] args) {
+        if (args.length == 1) {
+            return CommandUtil.getListMatchingLast(sender, args, "all");
+        }
+        return Collections.emptyList();
+    }
+}