From ceb1271f1e7ecc0c82e8268b0ed1ff740160f50d Mon Sep 17 00:00:00 2001
From: Alvinn8 <42838560+Alvinn8@users.noreply.github.com>
Date: Tue, 17 Oct 2023 21:23:15 +0200
Subject: [PATCH] Support restoring worlds with old chunks

---
 .../ca/bkaw/mch/region/mc/McRegionFileWriter.java     | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mch/src/main/java/ca/bkaw/mch/region/mc/McRegionFileWriter.java b/mch/src/main/java/ca/bkaw/mch/region/mc/McRegionFileWriter.java
index bbf4698..87f0652 100644
--- a/mch/src/main/java/ca/bkaw/mch/region/mc/McRegionFileWriter.java
+++ b/mch/src/main/java/ca/bkaw/mch/region/mc/McRegionFileWriter.java
@@ -57,6 +57,17 @@ private long getNextSector(long location) {
     public void writeChunk(NbtCompound chunkNbt, int lastModified) throws IOException {
         NbtInt xPos = (NbtInt) chunkNbt.get("xPos");
         NbtInt zPos = (NbtInt) chunkNbt.get("zPos");
+        if (xPos == null || zPos == null) {
+            // Some older versions of the game store all data in a nested "Level" tag. While
+            // mch mainly targets newer versions of the game, there are still cases where a
+            // world needs to be restored that has some chunks that have not been touched in
+            // a long time and therefore have chunks in this old format, despite the world
+            // being loaded and saved in the latest version.
+            if (chunkNbt.get("Level") instanceof NbtCompound level) {
+                xPos = (NbtInt) level.get("xPos");
+                zPos = (NbtInt) level.get("zPos");
+            }
+        }
         if (xPos == null || zPos == null) {
             throw new IllegalArgumentException("The provided chunk nbt does not specify its coordinates.");
         }