Prepare class for structured data->tag rewriting

api/src/main/java/com/viaversion/viaversion/api/type/types/item/ItemType1_20_5.java

@@ -66,14 +66,14 @@ public class ItemType1_20_5 extends Type<Item> {
         for (int i = 0; i < valuesSize; i++) {
             final StructuredData<?> value = dataType.read(buffer);
             final StructuredDataKey<?> key = dataType.key(value.id());
-            Preconditions.checkNotNull(key, "No data component serializer found for $s", value);
+            Preconditions.checkNotNull(key, "No data component serializer found for %s", value);
             map.put(key, value);
         }
 
         for (int i = 0; i < markersSize; i++) {
             final int id = Type.VAR_INT.readPrimitive(buffer);
             final StructuredDataKey<?> key = dataType.key(id);
-            Preconditions.checkNotNull(key, "No data component serializer found for empty id $s", id);
+            Preconditions.checkNotNull(key, "No data component serializer found for empty id %s", id);
             map.put(key, StructuredData.empty(key, id));
         }
         return map;

common/src/main/java/com/viaversion/viaversion/protocols/protocol1_20_5to1_20_3/rewriter/BlockItemPacketRewriter1_20_5.java

@@ -82,7 +82,6 @@ import com.viaversion.viaversion.util.Key;
 import com.viaversion.viaversion.util.UUIDUtil;
 import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -250,7 +249,9 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
             return dataItem;
         }
 
-        // TODO
+        for (final StructuredData<?> structuredData : data.data().values()) {
+            StructuredDataConverter.rewrite(structuredData, tag);
+        }
 
         return dataItem;
     }
@@ -395,14 +396,15 @@ public final class BlockItemPacketRewriter1_20_5 extends ItemRewriter<Clientboun
         // TODO
         //  StructuredDataKey.CAN_PLACE_ON
         //  StructuredDataKey.CAN_BREAK
-        //  StructuredDataKey.CREATIVE_SLOT_LOCK
-        //  StructuredDataKey.INTANGIBLE_PROJECTILE
-        //  StructuredDataKey.NOTE_BLOCK_SOUND
+        //  (remaining ones should only affect non-essential item tooltip, or not be shown/checked at all)
         //  StructuredDataKey.POT_DECORATIONS
         //  StructuredDataKey.CONTAINER
+        //  StructuredDataKey.CONTAINER_LOOT
+        //  StructuredDataKey.INTANGIBLE_PROJECTILE
+        //  StructuredDataKey.CREATIVE_SLOT_LOCK
         //  StructuredDataKey.BEES
         //  StructuredDataKey.LOCK
-        //  StructuredDataKey.CONTAINER_LOOT
+        //  StructuredDataKey.NOTE_BLOCK_SOUND
 
         data.set(StructuredDataKey.CUSTOM_DATA, tag);
         return item;

common/src/main/java/com/viaversion/viaversion/protocols/protocol1_20_5to1_20_3/rewriter/StructuredDataConverter.java

@@ -0,0 +1,57 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2024 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viaversion.protocols.protocol1_20_5to1_20_3.rewriter;
+
+import com.github.steveice10.opennbt.tag.builtin.CompoundTag;
+import com.viaversion.viaversion.api.minecraft.data.StructuredData;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import com.viaversion.viaversion.util.ComponentUtil;
+import it.unimi.dsi.fastutil.objects.Reference2ObjectOpenHashMap;
+import java.util.Map;
+
+final class StructuredDataConverter {
+
+    private static final Map<StructuredDataKey<?>, Rewriter<?>> REWRITERS = new Reference2ObjectOpenHashMap<>();
+
+    static {
+        // TODO
+        register(StructuredDataKey.CUSTOM_NAME, (data, tag) -> tag.putString("CustomName", ComponentUtil.tagToJsonString(data.value())));
+    }
+
+    public static <T> void rewrite(final StructuredData<T> data, final CompoundTag tag) {
+        if (data.isEmpty()) {
+            return;
+        }
+
+        //noinspection unchecked
+        final Rewriter<T> rewriter = (Rewriter<T>) REWRITERS.get(data.key());
+        if (rewriter != null) {
+            rewriter.rewrite(data, tag);
+        }
+    }
+
+    private static <T> void register(final StructuredDataKey<T> key, final Rewriter<T> rewriter) {
+        REWRITERS.put(key, rewriter);
+    }
+
+    @FunctionalInterface
+    interface Rewriter<T> {
+
+        void rewrite(StructuredData<T> data, CompoundTag tag);
+    }
+}