fix: version bump to 4 with minestom 1.20.2 nbt changes

build.gradle.kts

@@ -16,7 +16,9 @@ repositories {
 }
 
 dependencies {
-    compileOnly(libs.minestom)
+    val minestom = libs.minestomSnapshot
+
+    compileOnly(minestom)
     implementation(libs.zstd)
     // Fastutil is only included because minestom already uses it, otherwise it is a crazy dependency
     // for how it is used in this project.
@@ -27,7 +29,7 @@ dependencies {
 
     testImplementation(platform("org.junit:junit-bom:5.9.1"))
     testImplementation("org.junit.jupiter:junit-jupiter")
-    testImplementation(libs.minestom)
+    testImplementation(minestom)
 }
 
 java {

gradle/libs.versions.toml

@@ -2,13 +2,15 @@ metadata.format.version = "1.1"
 
 [versions]
 minestom = "9f3ee89506"
+minestomSnapshot = "1_20_2-909719b369"
 zstd = "1.5.5-3"
 fastutil = "8.5.12"
 
 nexuspublish = "1.3.0"
 
 [libraries]
 minestom = { group = "dev.hollowcube", name = "minestom-ce", version.ref = "minestom" }
+minestomSnapshot = { group = "dev.hollowcube", name = "minestom-ce-snapshots", version.ref = "minestomSnapshot" }
 zstd = { group = "com.github.luben", name = "zstd-jni", version.ref = "zstd" }
 fastutil = { group = "it.unimi.dsi", name = "fastutil", version.ref = "fastutil" }
 

src/main/java/net/hollowcube/polar/PolarReader.java

@@ -6,8 +6,12 @@
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
+import org.jglrxavpok.hephaistos.nbt.CompressedProcesser;
+import org.jglrxavpok.hephaistos.nbt.NBT;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
+import org.jglrxavpok.hephaistos.nbt.NBTReader;
 
+import java.io.InputStream;
 import java.nio.ByteBuffer;
 
 import static net.minestom.server.network.NetworkBuffer.*;
@@ -119,8 +123,13 @@ private PolarReader() {}
         var id = buffer.readOptional(STRING);
 
         NBTCompound nbt = null;
-        if (version <= PolarWorld.VERSION_USERDATA_OPT_BLOCK_ENT_NBT || buffer.read(BOOLEAN))
-            nbt = (NBTCompound) buffer.read(NBT);
+        if (version <= PolarWorld.VERSION_USERDATA_OPT_BLOCK_ENT_NBT || buffer.read(BOOLEAN)) {
+            if (version <= PolarWorld.VERSION_MINESTOM_NBT_READ_BREAK) {
+                nbt = (NBTCompound) legacyReadNBT(buffer);
+            } else {
+                buffer.read(NBT);
+            }
+        }
 
         return new PolarChunk.BlockEntity(
                 ChunkUtils.blockIndexToChunkPositionX(posIndex),
@@ -148,6 +157,31 @@ private static void validateVersion(int version) {
         };
     }
 
+    /**
+     * Minecraft (so Minestom) had a breaking change in NBT reading in 1.20.2. This method replicates the old
+     * behavior which we use for any Polar version less than {@link PolarWorld#VERSION_MINESTOM_NBT_READ_BREAK}.
+     *
+     * @see NetworkBuffer#NBT
+     */
+    private static org.jglrxavpok.hephaistos.nbt.NBT legacyReadNBT(@NotNull NetworkBuffer buffer) {
+        try {
+            var nbtReader = new NBTReader(new InputStream() {
+                @Override
+                public int read() {
+                    return buffer.read(BYTE) & 0xFF;
+                }
+                @Override
+                public int available() {
+                    return buffer.readableBytes();
+                }
+            }, CompressedProcesser.NONE);
+
+            return nbtReader.read();
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     @Contract("false, _ -> fail")
     private static void assertThat(boolean condition, @NotNull String message) {
         if (!condition) throw new Error(message);

src/main/java/net/hollowcube/polar/PolarWorld.java

@@ -15,10 +15,11 @@
 @SuppressWarnings("UnstableApiUsage")
 public class PolarWorld {
     public static final int MAGIC_NUMBER = 0x506F6C72; // `Polr`
-    public static final short LATEST_VERSION = 3;
+    public static final short LATEST_VERSION = 4;
 
     static final short VERSION_UNIFIED_LIGHT = 1;
     static final short VERSION_USERDATA_OPT_BLOCK_ENT_NBT = 2;
+    static final short VERSION_MINESTOM_NBT_READ_BREAK = 3;
 
     public static CompressionType DEFAULT_COMPRESSION = CompressionType.ZSTD;
 

src/test/java/net/hollowcube/polar/TestAnvilPolar.java

@@ -19,7 +19,7 @@ void testConvertAnvilWorld() throws Exception {
 
         var result = PolarWriter.write(world);
         System.out.println(result.length);
-        Files.write(Path.of("./src/test/resources/3.polar"), result);
+        Files.write(Path.of("./src/test/resources/4.polar"), result);
     }
 
 }

src/test/java/net/hollowcube/polar/TestReaderBackwardsCompatibility.java

@@ -22,6 +22,11 @@ void testVersion3() {
         runTest(3);
     }
 
+    @Test
+    void testVersion4() {
+        runTest(4);
+    }
+
     private static void runTest(int version) {
         var is = TestReaderBackwardsCompatibility.class.getResourceAsStream("/backward/" + version + ".polar");
         assertNotNull(is);

src/test/java/net/hollowcube/polar/demo/DemoServer.java

@@ -4,10 +4,9 @@
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.coordinate.Pos;
 import net.minestom.server.entity.GameMode;
+import net.minestom.server.event.player.AsyncPlayerConfigurationEvent;
 import net.minestom.server.event.player.PlayerChatEvent;
-import net.minestom.server.event.player.PlayerLoginEvent;
 import net.minestom.server.event.player.PlayerSpawnEvent;
-import net.minestom.server.instance.LightingChunk;
 
 import java.nio.file.Path;
 
@@ -22,7 +21,7 @@ public static void main(String[] args) throws Exception {
 //        instance.setChunkSupplier(LightingChunk::new);
 
         MinecraftServer.getGlobalEventHandler()
-                .addListener(PlayerLoginEvent.class, event -> {
+                .addListener(AsyncPlayerConfigurationEvent.class, event -> {
                     event.setSpawningInstance(instance);
                     event.getPlayer().setRespawnPoint(new Pos(0, 100, 0));
                 })