Add 1.20.5 nbt->component conversion base

Has to be implemented into ViaBackwards yet and handlers are still missing

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

@@ -0,0 +1,65 @@
+/*
+ * 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.github.steveice10.opennbt.tag.builtin.Tag;
+import com.google.common.base.Preconditions;
+import com.viaversion.viaversion.api.minecraft.data.StructuredData;
+import com.viaversion.viaversion.api.minecraft.data.StructuredDataKey;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+// 1.20.5 nbt -> 1.20.5 data component conversion, technically only needed in VB but kept here to make maintenance easier
+public final class StructuredNBTConverter {
+
+    private static final Map<String, DataConverter<?>> rewriters = new HashMap<>();
+
+    static {
+        register(StructuredDataKey.CUSTOM_DATA, tag -> (CompoundTag) tag);
+        // TODO Add missing handlers for other data types, this will probably be done after the component rework
+    }
+
+    public static List<StructuredData<?>> toData(final CompoundTag tag) {
+        final List<StructuredData<?>> data = new ArrayList<>();
+        for (final Map.Entry<String, Tag> entry : tag.entrySet()) {
+            final StructuredData<?> structuredData = readFromTag(entry.getKey(), entry.getValue());
+            data.add(structuredData);
+        }
+        return data;
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <T> StructuredData<T> readFromTag(final String identifier, final Tag tag) {
+        final DataConverter<T> converter = (DataConverter<T>) rewriters.get(identifier);
+        Preconditions.checkNotNull(converter, "No converter for %s found", identifier);
+        return (StructuredData<T>) converter.convert(tag);
+    }
+
+    private static <T> void register(final StructuredDataKey<T> key, final DataConverter<T> converter) {
+        rewriters.put(key.identifier(), converter);
+    }
+
+    @FunctionalInterface
+    interface DataConverter<T> {
+
+        T convert(final Tag tag);
+    }
+}