From 1cd7fd4eec0ff8017178a27e01e262d4c9662514 Mon Sep 17 00:00:00 2001
From: masmc05 <masmc05@gmail.com>
Date: Sun, 11 Aug 2024 03:01:52 +0300
Subject: [PATCH] Item serialization as json

---
 .../item/component/CustomData.java.patch      | 21 +++++++++++++
 .../craftbukkit/util/CraftMagicNumbers.java   | 30 +++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 paper-server/patches/sources/net/minecraft/world/item/component/CustomData.java.patch

diff --git a/paper-server/patches/sources/net/minecraft/world/item/component/CustomData.java.patch b/paper-server/patches/sources/net/minecraft/world/item/component/CustomData.java.patch
new file mode 100644
index 0000000000..73089c0170
--- /dev/null
+++ b/paper-server/patches/sources/net/minecraft/world/item/component/CustomData.java.patch
@@ -0,0 +1,21 @@
+--- a/net/minecraft/world/item/component/CustomData.java
++++ b/net/minecraft/world/item/component/CustomData.java
+@@ -34,7 +34,17 @@
+     private static final Logger LOGGER = LogUtils.getLogger();
+     public static final CustomData EMPTY = new CustomData(new CompoundTag());
+     private static final String TYPE_TAG = "id";
+-    public static final Codec<CustomData> CODEC = Codec.withAlternative(CompoundTag.CODEC, TagParser.AS_CODEC)
++    // Paper start - Item serialization as json
++    public static ThreadLocal<Boolean> SERIALIZE_CUSTOM_AS_SNBT = ThreadLocal.withInitial(() -> false);
++    public static final Codec<CustomData> CODEC = Codec.either(CompoundTag.CODEC, TagParser.AS_CODEC)
++        .xmap(com.mojang.datafixers.util.Either::unwrap, data -> { // Both will be used for deserialization, but we decide which one to use for serialization
++            if (!SERIALIZE_CUSTOM_AS_SNBT.get()) {
++                return com.mojang.datafixers.util.Either.left(data); // First codec
++            } else {
++                return com.mojang.datafixers.util.Either.right(data); // Second codec
++            }
++        })
++        // Paper end - Item serialization as json
+         .xmap(CustomData::new, component -> component.tag);
+     public static final Codec<CustomData> CODEC_WITH_ID = CODEC.validate(
+         component -> component.getUnsafe().contains("id", 8) ? DataResult.success(component) : DataResult.error(() -> "Missing id for entity in: " + component)
diff --git a/paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java b/paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
index 869b0977a4..0e8f4710c0 100644
--- a/paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
+++ b/paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java
@@ -527,6 +527,36 @@ public final class CraftMagicNumbers implements UnsafeValues {
         return CraftItemStack.asCraftMirror(net.minecraft.world.item.ItemStack.parse(MinecraftServer.getServer().registryAccess(), compound).orElseThrow());
     }
 
+    @Override
+    public com.google.gson.JsonObject serializeItemAsJson(ItemStack itemStack) {
+        Preconditions.checkNotNull(itemStack, "Cannot serialize empty ItemStack");
+        Preconditions.checkArgument(!itemStack.isEmpty(), "Cannot serialize empty ItemStack");
+
+        net.minecraft.core.RegistryAccess.Frozen reg = net.minecraft.server.MinecraftServer.getServer().registryAccess();
+        com.mojang.serialization.DynamicOps<com.google.gson.JsonElement> ops = reg.createSerializationContext(com.mojang.serialization.JsonOps.INSTANCE);
+        com.google.gson.JsonObject item;
+        // Serialize as SNBT to preserve exact NBT types; vanilla codecs already can handle such deserialization.
+        net.minecraft.world.item.component.CustomData.SERIALIZE_CUSTOM_AS_SNBT.set(true);
+        try {
+            item = net.minecraft.world.item.ItemStack.CODEC.encodeStart(ops, CraftItemStack.unwrap(itemStack)).getOrThrow().getAsJsonObject();
+        } finally {
+            net.minecraft.world.item.component.CustomData.SERIALIZE_CUSTOM_AS_SNBT.set(false);
+        }
+        item.addProperty("DataVersion", this.getDataVersion());
+        return item;
+    }
+
+    @Override
+    public ItemStack deserializeItemFromJson(com.google.gson.JsonObject data) throws IllegalArgumentException {
+        Preconditions.checkNotNull(data, "null cannot be deserialized");
+
+        final int dataVersion = data.get("DataVersion").getAsInt();
+        final int currentVersion = org.bukkit.craftbukkit.util.CraftMagicNumbers.INSTANCE.getDataVersion();
+        data = (com.google.gson.JsonObject) MinecraftServer.getServer().fixerUpper.update(References.ITEM_STACK, new Dynamic<>(com.mojang.serialization.JsonOps.INSTANCE, data), dataVersion, currentVersion).getValue();
+        com.mojang.serialization.DynamicOps<com.google.gson.JsonElement> ops = MinecraftServer.getServer().registryAccess().createSerializationContext(com.mojang.serialization.JsonOps.INSTANCE);
+        return CraftItemStack.asCraftMirror(net.minecraft.world.item.ItemStack.CODEC.parse(ops, data).getOrThrow(IllegalArgumentException::new));
+    }
+
     @Override
     public byte[] serializeEntity(org.bukkit.entity.Entity entity) {
         Preconditions.checkNotNull(entity, "null cannot be serialized");