could this be the worst possible way to copy a chunk array

src/launch/java/baritone/launch/mixins/MixinChunkArray.java

@@ -0,0 +1,92 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package baritone.launch.mixins;
+
+import baritone.utils.accessor.IChunkArray;
+import net.minecraft.util.math.ChunkPos;
+import net.minecraft.world.chunk.Chunk;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.concurrent.atomic.AtomicReferenceArray;
+
+@Mixin(targets = "net.minecraft.client.multiplayer.ClientChunkProvider$ChunkArray")
+public abstract class MixinChunkArray implements IChunkArray {
+    @Shadow
+    private AtomicReferenceArray<Chunk> chunks;
+    @Shadow
+    private int viewDistance;
+    @Shadow
+    private int sideLength;
+    @Shadow
+    private int centerX;
+    @Shadow
+    private int centerZ;
+    @Shadow
+    private int loaded;
+
+    @Shadow
+    protected abstract boolean inView(int x, int z);
+
+    @Shadow
+    protected abstract int getIndex(int x, int z);
+
+    @Shadow
+    protected abstract void replace(int index, Chunk chunk);
+
+    @Override
+    public int centerX() {
+        return centerX;
+    }
+
+    @Override
+    public int centerZ() {
+        return centerZ;
+    }
+
+    @Override
+    public int viewDistance() {
+        return viewDistance;
+    }
+
+    @Override
+    public AtomicReferenceArray<Chunk> getChunks() {
+        return chunks;
+    }
+
+    @Override
+    public void copyFrom(IChunkArray other) {
+        centerX = other.centerX();
+        centerZ = other.centerZ();
+
+        AtomicReferenceArray<Chunk> copyingFrom = other.getChunks();
+        for (int k = 0; k < copyingFrom.length(); ++k) {
+            Chunk chunk = copyingFrom.get(k);
+            if (chunk != null) {
+                ChunkPos chunkpos = chunk.getPos();
+                if (inView(chunkpos.x, chunkpos.z)) {
+                    int index = getIndex(chunkpos.x, chunkpos.z);
+                    if (chunks.get(index) != null) {
+                        throw new IllegalStateException("Doing this would mutate the client's REAL loaded chunks?!");
+                    }
+                    replace(index, chunk);
+                }
+            }
+        }
+    }
+}

src/launch/java/baritone/launch/mixins/MixinClientChunkProvider.java

@@ -0,0 +1,61 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package baritone.launch.mixins;
+
+import baritone.utils.accessor.IChunkArray;
+import baritone.utils.accessor.IClientChunkProvider;
+import net.minecraft.client.multiplayer.ClientChunkProvider;
+import net.minecraft.client.world.ClientWorld;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.lang.reflect.Field;
+import java.util.Arrays;
+
+@Mixin(ClientChunkProvider.class)
+public class MixinClientChunkProvider implements IClientChunkProvider {
+
+    @Shadow
+    private ClientWorld world;
+
+    @Override
+    public ClientChunkProvider createThreadSafeCopy() {
+        IChunkArray arr = extractReferenceArray();
+        ClientChunkProvider result = new ClientChunkProvider(world, arr.viewDistance() - 3); // -3 because its adds 3 for no reason lmao
+        IChunkArray copyArr = ((IClientChunkProvider) result).extractReferenceArray();
+        copyArr.copyFrom(arr);
+        if (copyArr.viewDistance() != arr.viewDistance()) {
+            throw new IllegalStateException(copyArr.viewDistance() + " " + arr.viewDistance());
+        }
+        return result;
+    }
+
+    @Override
+    public IChunkArray extractReferenceArray() {
+        for (Field f : ClientChunkProvider.class.getDeclaredFields()) {
+            if (IChunkArray.class.isAssignableFrom(f.getType())) {
+                try {
+                    return (IChunkArray) f.get(this);
+                } catch (IllegalAccessException e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        }
+        throw new RuntimeException(Arrays.toString(ClientChunkProvider.class.getDeclaredFields()));
+    }
+}

src/launch/resources/mixins.baritone.json

@@ -9,6 +9,8 @@
   },
   "client": [
     "MixinBlockPos",
+    "MixinChunkArray",
+    "MixinClientChunkProvider",
     "MixinClientPlayerEntity",
     "MixinClientPlayNetHandler",
     "MixinEntity",

src/main/java/baritone/event/GameEventHandler.java

@@ -51,6 +51,7 @@ public final class GameEventHandler implements IEventBus, Helper {
             try {
                 baritone.bsi = new BlockStateInterface(baritone.getPlayerContext(), true);
             } catch (Exception ex) {
+                ex.printStackTrace();
                 baritone.bsi = null;
             }
         } else {

src/main/java/baritone/utils/BlockStateInterface.java

@@ -21,6 +21,7 @@ import baritone.Baritone;
 import baritone.api.utils.IPlayerContext;
 import baritone.cache.CachedRegion;
 import baritone.cache.WorldData;
+import baritone.utils.accessor.IClientChunkProvider;
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockState;
 import net.minecraft.block.Blocks;
@@ -59,9 +60,10 @@ public class BlockStateInterface {
 
     public BlockStateInterface(World world, WorldData worldData, boolean copyLoadedChunks) {
         this.worldData = worldData;
-        this.provider = (ClientChunkProvider) world.getChunkProvider();
-        if (copyLoadedChunks) { // todo
-            System.out.println("Really gotta do this");
+        if (copyLoadedChunks) {
+            this.provider = ((IClientChunkProvider) world.getChunkProvider()).createThreadSafeCopy();
+        } else {
+            this.provider = (ClientChunkProvider) world.getChunkProvider();
         }
         this.useTheRealWorld = !Baritone.settings().pathThroughCachedOnly.value;
         if (!Minecraft.getInstance().isOnExecutionThread()) {

src/main/java/baritone/utils/accessor/IChunkArray.java

@@ -0,0 +1,34 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package baritone.utils.accessor;
+
+import net.minecraft.world.chunk.Chunk;
+
+import java.util.concurrent.atomic.AtomicReferenceArray;
+
+public interface IChunkArray {
+    void copyFrom(IChunkArray other);
+
+    AtomicReferenceArray<Chunk> getChunks();
+
+    int centerX();
+
+    int centerZ();
+
+    int viewDistance();
+}

src/main/java/baritone/utils/accessor/IClientChunkProvider.java

@@ -0,0 +1,26 @@
+/*
+ * This file is part of Baritone.
+ *
+ * Baritone is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Baritone 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Baritone.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package baritone.utils.accessor;
+
+import net.minecraft.client.multiplayer.ClientChunkProvider;
+
+public interface IClientChunkProvider {
+    ClientChunkProvider createThreadSafeCopy();
+
+    IChunkArray extractReferenceArray();
+}