MVP for anvil

worldedit-bukkit/adapters/adapter-1_20_2/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_20_R2/PaperweightAdapter.java

@@ -630,6 +630,16 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
         return CraftItemStack.asCraftMirror(stack);
     }
 
+    @Override
+    public char[] getIbdToStateOrdinal() {
+        return new char[0];
+    }
+
+    @Override
+    public int[] getOrdinalToIbdID() {
+        return new int[0];
+    }
+
     @Override
     public BaseItemStack adapt(org.bukkit.inventory.ItemStack itemStack) {
         final ItemStack nmsStack = CraftItemStack.asNMSCopy(itemStack);

worldedit-bukkit/adapters/adapter-1_20_4/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R3/PaperweightAdapter.java

@@ -629,6 +629,16 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
         return CraftItemStack.asCraftMirror(stack);
     }
 
+    @Override
+    public char[] getIbdToStateOrdinal() {
+        return new char[0];
+    }
+
+    @Override
+    public int[] getOrdinalToIbdID() {
+        return new int[0];
+    }
+
     @Override
     public BaseItemStack adapt(org.bukkit.inventory.ItemStack itemStack) {
         final ItemStack nmsStack = CraftItemStack.asNMSCopy(itemStack);

worldedit-bukkit/adapters/adapter-1_20_5/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext.fawe/v1_20_R4/PaperweightAdapter.java

@@ -644,6 +644,16 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
         return CraftItemStack.asCraftMirror(stack);
     }
 
+    @Override
+    public char[] getIbdToStateOrdinal() {
+        return new char[0];
+    }
+
+    @Override
+    public int[] getOrdinalToIbdID() {
+        return new int[0];
+    }
+
     @Override
     public BaseItemStack adapt(org.bukkit.inventory.ItemStack itemStack) {
         var registryAccess = DedicatedServer.getServer().registryAccess();

worldedit-bukkit/adapters/adapter-1_21/src/main/java/com/sk89q/worldedit/bukkit/adapter/ext/fawe/v1_21_R1/PaperweightAdapter.java

@@ -654,6 +654,16 @@ public final class PaperweightAdapter implements BukkitImplAdapter<net.minecraft
         return CraftItemStack.asCraftMirror(stack);
     }
 
+    @Override
+    public char[] getIbdToStateOrdinal() {
+        return new char[0];
+    }
+
+    @Override
+    public int[] getOrdinalToIbdID() {
+        return new int[0];
+    }
+
     @Override
     public BaseItemStack adapt(org.bukkit.inventory.ItemStack itemStack) {
         var registryAccess = DedicatedServer.getServer().registryAccess();

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/FaweBukkit.java

@@ -45,6 +45,7 @@ import org.bukkit.plugin.Plugin;
 import org.bukkit.plugin.PluginManager;
 
 import java.io.File;
+import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -312,6 +313,16 @@ public class FaweBukkit implements IFawe, Listener {
         return platformAdapter;
     }
 
+    @Override
+    public Path getWorldsFolder() {
+        return Bukkit.getWorldContainer().toPath();
+    }
+
+    @Override
+    public boolean isWorldLoaded(String world) {
+        return Bukkit.getWorld(world) != null;
+    }
+
     private void setupPlotSquared() {
         Plugin plotSquared = this.plugin.getServer().getPluginManager().getPlugin("PlotSquared");
         if (plotSquared == null) {

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/adapter/CachedBukkitAdapter.java

@@ -100,8 +100,4 @@ public abstract class CachedBukkitAdapter implements IBukkitAdapter {
         }
     }
 
-    protected abstract char[] getIbdToStateOrdinal();
-
-    protected abstract int[] getOrdinalToIbdID();
-
 }

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/adapter/IBukkitAdapter.java

@@ -396,4 +396,14 @@ public interface IBukkitAdapter {
         return TaskManager.taskManager().sync(world::getEntities);
     }
 
+    /**
+     * Get a char array of minecraft internal IDs against FAWE char IDs
+     */
+    char[] getIbdToStateOrdinal();
+
+    /**
+     * Get an int array of FAWE char IDs against minecraft internal IDs
+     */
+    int[] getOrdinalToIbdID();
+
 }

worldedit-bukkit/src/main/java/com/fastasyncworldedit/bukkit/adapter/SimpleBukkitAdapter.java

@@ -23,12 +23,12 @@ public class SimpleBukkitAdapter extends CachedBukkitAdapter {
     }
 
     @Override
-    protected char[] getIbdToStateOrdinal() {
+    public char[] getIbdToStateOrdinal() {
         return new char[Character.MAX_VALUE + 1];
     }
 
     @Override
-    protected int[] getOrdinalToIbdID() {
+    public int[] getOrdinalToIbdID() {
         return new int[Character.MAX_VALUE + 1];
     }
 

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitAdapter.java

@@ -495,4 +495,20 @@ public enum BukkitAdapter {
         return getAdapter().adapt(item);
         //FAWE end
     }
+
+    //FAWE start
+    /**
+     * Get a char array of minecraft internal IDs against FAWE char IDs
+     */
+    public static char[] getIbdToStateOrdinal() {
+        return getAdapter().getIbdToStateOrdinal();
+    }
+
+    /**
+     * Get an int array of FAWE char IDs against minecraft internal IDs
+     */
+    public static int[] getOrdinalToIbdID() {
+        return getAdapter().getOrdinalToIbdID();
+    }
+    //FAWE end
 }

worldedit-bukkit/src/main/java/com/sk89q/worldedit/bukkit/BukkitServerInterface.java

@@ -309,5 +309,17 @@ public class BukkitServerInterface extends AbstractPlatform implements MultiUser
         }
         return this.plugin.getBukkitImplAdapter().getTickingPostProcessor();
     }
+
+    @Nullable
+    @Override
+    public char[] getIbdToStateOrdinal() {
+        return BukkitAdapter.getIbdToStateOrdinal();
+    }
+
+    @Nullable
+    @Override
+    public int[] getOrdinalToIbdID() {
+        return BukkitAdapter.getOrdinalToIbdID();
+    }
     //FAWE end
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/IFawe.java

@@ -8,6 +8,7 @@ import com.fastasyncworldedit.core.util.image.ImageViewer;
 import com.sk89q.worldedit.entity.Player;
 
 import java.io.File;
+import java.nio.file.Path;
 import java.util.Collection;
 import java.util.UUID;
 
@@ -49,4 +50,8 @@ public interface IFawe {
 
     FAWEPlatformAdapterImpl getPlatformAdapter();
 
+    Path getWorldsFolder();
+
+    boolean isWorldLoaded(String world);
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/anvil/MCAFile.java

@@ -0,0 +1,594 @@
+package com.fastasyncworldedit.core.anvil;
+
+import com.fastasyncworldedit.core.math.FastBitSet;
+import com.fastasyncworldedit.core.util.task.RunnableVal4;
+import com.plotsquared.core.util.task.RunnableVal;
+import com.sk89q.jnbt.NBTInputStream;
+import com.sk89q.worldedit.MissingWorldException;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import it.unimi.dsi.fastutil.io.FastByteArrayInputStream;
+import org.apache.logging.log4j.Logger;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.io.BufferedInputStream;
+import java.io.Closeable;
+import java.io.Flushable;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.zip.GZIPInputStream;
+import java.util.zip.InflaterInputStream;
+
+@SuppressWarnings({"removal"})
+public class MCAFile implements Closeable, Flushable {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    private static final int CHUNK_HEADER_SIZE = 5;
+    private static final byte VERSION_GZIP = 1;
+    private static final byte VERSION_DEFLATE = 2;
+    private static final byte VERSION_UNCOMPRESSED = 3;
+    private static final int SECTOR_BYTES = 4096;
+    private static final int SECTOR_INTS = SECTOR_BYTES / 4;
+
+    private final Int2IntOpenHashMap offsetMap;
+    private final Path file;
+    private RandomAccessFile raf;
+    private int[] offsets;
+    private boolean deleted;
+    private final int X, Z;
+    private final Int2ObjectOpenHashMap<MCAChunk> chunks = new Int2ObjectOpenHashMap<>();
+    private FastBitSet sectorFree;
+    private boolean closed = false;
+    private volatile boolean init = false;
+
+    public MCAFile(Path file) {
+        this.file = file;
+        if (!Files.exists(file)) {
+            throw new MissingWorldException();
+        }
+        String[] split = file.getFileName().toString().split("\\.");
+        X = Integer.parseInt(split[1]);
+        Z = Integer.parseInt(split[2]);
+        offsetMap = new Int2IntOpenHashMap();
+        offsetMap.defaultReturnValue(Integer.MAX_VALUE);
+        init();
+    }
+
+    public MCAFile(int mcrX, int mcrZ, Path file) {
+        this.file = file;
+        X = mcrX;
+        Z = mcrZ;
+        offsetMap = new Int2IntOpenHashMap();
+        offsetMap.defaultReturnValue(Integer.MAX_VALUE);
+        init();
+    }
+
+    public void clear() {
+        if (raf != null) {
+            try {
+                raf.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        synchronized (chunks) {
+            chunks.clear();
+        }
+        offsetMap.clear();
+        offsets = null;
+    }
+
+    /**
+     * Set if the file should be delete
+     */
+    public void setDeleted(boolean deleted) {
+        if (!init) {
+            init();
+        }
+        this.deleted = deleted;
+    }
+
+    /**
+     * Get if the file has been set to be deleted
+     */
+    public boolean isDeleted() {
+        return deleted;
+    }
+
+    /**
+     * Initialises the RandomAccessFile and loads the location header from disk if not done yet
+     */
+    public synchronized void init() {
+        try {
+            if (raf == null) {
+                this.offsets = new int[SECTOR_INTS];
+                if (file != null) {
+                    this.raf = new RandomAccessFile(file.toFile(), "rw");
+                    final int nSectors = (int) Math.round(Math.ceil((double) raf.length() / SECTOR_BYTES));
+                    sectorFree = new FastBitSet(nSectors);
+                    sectorFree.setAll();
+                    sectorFree.set(0, false);
+                    sectorFree.set(1, false);
+                    if (raf.length() < 8192) {
+                        raf.setLength(8192);
+                    } else {
+                        if ((raf.length() & 0xFFF) != 0) {
+                            raf.setLength(((raf.length() + 0xFFF) >> 12) << 12);
+                        }
+                        raf.seek(0);
+                        for (int i = 0; i < SECTOR_INTS; i++) {
+                            final int offset = raf.readInt();
+                            offsets[i] = offset;
+                            int sectorStart = offset >> 8;
+                            int numSectors = offset & 0xFF;
+                            if (offset != 0 && sectorStart + numSectors <= sectorFree.size()) {
+                                offsetMap.put(offset, i);
+                                for (int sectorNum = 0; sectorNum < (offset & 0xFF); sectorNum++) {
+                                    sectorFree.set((offset >> 8) + sectorNum, false);
+                                }
+                            }
+                        }
+                    }
+                }
+                init = true;
+                closed = false;
+            }
+        } catch (Throwable e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Get the region file X
+     */
+    public int getX() {
+        return X;
+    }
+
+    /**
+     * Get the region file Z
+     */
+    public int getZ() {
+        return Z;
+    }
+
+    /**
+     * Get the RandomAccessFile of the MCA region file
+     */
+    public RandomAccessFile getRandomAccessFile() {
+        return raf;
+    }
+
+    /**
+     * Get the MCA region file
+     */
+    public Path getFile() {
+        return file;
+    }
+
+    /**
+     * Gets a cached {@link MCAChunk} if present else returns null
+     */
+    @Nullable
+    public MCAChunk getCachedChunk(int cx, int cz) {
+        if (!init) {
+            init();
+        }
+        short pair = (short) ((cx & 31) + ((cz & 31) << 5));
+        synchronized (chunks) {
+            return chunks.get(pair);
+        }
+    }
+
+    /**
+     * Create a new empty {@link MCAChunk}.
+     */
+    public MCAChunk newChunk(int cx, int cz) {
+        if (!init) {
+            init();
+        }
+        short pair = (short) ((cx & 31) + ((cz & 31) << 5));
+        MCAChunk chunk;
+        synchronized (chunks) {
+            chunks.put(pair, chunk = new MCAChunk(this, cx, cx));
+        }
+        return chunk;
+    }
+
+    /**
+     * Insert a {@link MCAChunk} into the cache.
+     */
+    public void setChunk(MCAChunk chunk) {
+        if (!init) {
+            init();
+        }
+        int cx = chunk.getX();
+        int cz = chunk.getZ();
+        short pair = (short) ((cx & 31) + ((cz & 31) << 5));
+        synchronized (chunks) {
+            chunks.put(pair, chunk);
+        }
+    }
+
+    /**
+     * Load data from the mca region into the given {@link MCAChunk}.
+     */
+    public void loadIntoChunkFromFile(MCAChunk chunk) throws IOException {
+        if (!init) {
+            init();
+        }
+        int cx = chunk.getX();
+        int cz = chunk.getZ();
+        int i = (cx & 31) + ((cz & 31) << 5);
+        int offset = offsets[i];
+        synchronized (this) {
+            if (offset == 0) {
+                chunk.setEmpty(true);
+                return;
+            }
+            chunk.loadFromNIS(getChunkIS(offset >> 8), false);
+            if (offset == 0) {
+                return;
+            }
+            if (i < 2) {
+                int length;
+                byte version;
+                byte[] data;
+                synchronized (this) {
+                    raf.seek((long) (offset >> 8) << 12);
+                    length = raf.readInt();
+                    version = raf.readByte();
+                    data = new byte[length - 1];
+                    raf.read(data);
+                }
+                FastByteArrayInputStream bais = new FastByteArrayInputStream(data);
+                BufferedInputStream bis = switch (version) {
+                    case VERSION_GZIP -> new BufferedInputStream(new GZIPInputStream(bais));
+                    case VERSION_DEFLATE -> new BufferedInputStream(new InflaterInputStream(bais));
+                    case VERSION_UNCOMPRESSED -> new BufferedInputStream(bais);
+                    default -> throw new IllegalStateException("Unexpected compression version: " + version);
+                };
+            }
+        }
+    }
+
+    @Nonnull
+    public MCAChunk getChunk(int cx, int cz) throws IOException {
+        if (!init) {
+            init();
+        }
+        MCAChunk cached = getCachedChunk(cx, cz);
+        if (cached != null) {
+            return cached;
+        } else {
+            return readChunk(cx, cz);
+        }
+    }
+
+    public MCAChunk readChunk(int cx, int cz) throws IOException {
+        if (!init) {
+            init();
+        }
+        int i = (cx & 31) + ((cz & 31) << 5);
+        int offset = offsets[i];
+        if (offset == 0) {
+            return newChunk(cx, cz);
+        }
+        try {
+            MCAChunk chunk;
+            synchronized (this) {
+                chunk = getChunkIS(offset >> 8, cx, cz);
+            }
+            if (i < 2) {
+                int length;
+                byte version;
+                byte[] data;
+                synchronized (this) {
+                    raf.seek((long) (offset >> 8) << 12);
+                    length = raf.readInt();
+                    version = raf.readByte();
+                    data = new byte[length - 1];
+                    raf.read(data);
+                }
+                FastByteArrayInputStream bais = new FastByteArrayInputStream(data);
+                BufferedInputStream bis = switch (version) {
+                    case VERSION_GZIP -> new BufferedInputStream(new GZIPInputStream(bais));
+                    case VERSION_DEFLATE -> new BufferedInputStream(new InflaterInputStream(bais));
+                    case VERSION_UNCOMPRESSED -> new BufferedInputStream(bais);
+                    default -> throw new IllegalStateException("Unexpected compression version: " + version);
+                };
+            }
+            short pair = (short) ((cx & 31) + ((cz & 31) << 5));
+            synchronized (chunks) {
+                chunks.put(pair, chunk);
+            }
+            return chunk;
+        } catch (Exception e) {
+            throw new RuntimeException("Error attempting to read chunk locally located at `" + (cx & 31) + "," + (cz & 31) + "`" +
+                    " in file `" + file.getFileName() + "` at offset: `" + (offset >> 8) + "`", e);
+        }
+    }
+
+    /**
+     * @param onEach cx, cz, offset, size (in kB)
+     */
+    public void forEachChunk(RunnableVal4<Integer, Integer, Integer, Integer> onEach) {
+        if (!init) {
+            init();
+        }
+        int i = 0;
+        for (int z = 0; z < 32; z++) {
+            for (int x = 0; x < 32; x++, i += 4) {
+                int offset = offsets[x + (z << 5)];
+                if (offset != 0) {
+                    int size = offset & 0xFF;
+                    onEach.run(x, z, offset >> 8, size);
+                }
+            }
+        }
+    }
+
+    public void forEachChunk(RunnableVal<MCAChunk> onEach) {
+        if (!init) {
+            init();
+        }
+        int rx = X << 5;
+        int rz = Z << 5;
+        for (int z = 0; z < 32; z++) {
+            for (int x = 0; x < 32; x++) {
+                int offset = offsets[x + (z << 5)];
+                if (offset != 0) {
+                    try {
+                        onEach.run(getChunk(rx + x, rz + z));
+                    } catch (Throwable ignore) {
+                    }
+                }
+            }
+        }
+    }
+
+    private NBTInputStream getChunkIS(int offset) throws IOException {
+        int length = -1;
+        byte version = -1;
+        byte[] data;
+        try {
+            if (offset == 0) {
+                return null;
+            }
+            synchronized (this) {
+                raf.seek((long) offset << 12);
+                length = raf.readInt();
+                version = raf.readByte();
+                data = new byte[length - 1];
+                raf.read(data);
+            }
+            FastByteArrayInputStream bais = new FastByteArrayInputStream(data);
+            BufferedInputStream bis = switch (version) {
+                case VERSION_GZIP -> new BufferedInputStream(new GZIPInputStream(bais));
+                case VERSION_DEFLATE -> new BufferedInputStream(new InflaterInputStream(bais));
+                case VERSION_UNCOMPRESSED -> new BufferedInputStream(bais);
+                default -> throw new IllegalStateException("Unexpected compression version: " + version);
+            };
+            return new NBTInputStream(bis);
+        } catch (IOException e) {
+            throw new IOException("Length: " + length + ", version: " + version + ", offset: " + offset, e);
+        }
+    }
+
+    private MCAChunk getChunkIS(int offset, int cx, int cz) throws IOException {
+        int length = -1;
+        byte version = -1;
+        byte[] data;
+        try {
+            if (offset == 0) {
+                return null;
+            }
+            synchronized (this) {
+                raf.seek((long) offset << 12);
+                length = raf.readInt();
+                version = raf.readByte();
+                data = new byte[length - 1];
+                raf.read(data);
+            }
+            FastByteArrayInputStream bais = new FastByteArrayInputStream(data);
+            BufferedInputStream bis = switch (version) {
+                case VERSION_GZIP -> new BufferedInputStream(new GZIPInputStream(bais));
+                case VERSION_DEFLATE -> new BufferedInputStream(new InflaterInputStream(bais));
+                case VERSION_UNCOMPRESSED -> new BufferedInputStream(bais);
+                default -> throw new IllegalStateException("Unexpected compression version: " + version);
+            };
+            return new MCAChunk(this, new NBTInputStream(bis), cx, cz, false);
+        } catch (Exception e) {
+            throw new IOException("Length: " + length + ", version: " + version + ", offset: " + offset, e);
+        }
+    }
+
+    public List<MCAChunk> getCachedChunks() {
+        synchronized (chunks) {
+            return new ArrayList<>(chunks.values());
+        }
+    }
+
+    public void uncache(int cx, int cz) {
+        int pair = (cx & 31) + ((cz & 31) << 5);
+        synchronized (chunks) {
+            chunks.remove(pair);
+        }
+    }
+
+    @Override
+    public synchronized void close() throws IOException {
+        if (raf == null || closed) {
+            return;
+        }
+        flush();
+        try {
+            raf.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        raf = null;
+        offsets = null;
+        offsetMap.clear();
+        closed = true;
+        init = false;
+    }
+
+    public boolean isModified() {
+        if (isDeleted()) {
+            return true;
+        }
+        synchronized (chunks) {
+            for (Int2ObjectMap.Entry<MCAChunk> entry : chunks.int2ObjectEntrySet()) {
+                MCAChunk chunk = entry.getValue();
+                if (chunk.isModified() || chunk.isDeleted()) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    public synchronized void setOffset(final int x, final int z, final int offset)
+            throws IOException {
+        int i = (x & 31) + ((z & 31) << 5);
+        if (offset == 0) {
+            offsetMap.remove(offsets[i]);
+        } else {
+            offsetMap.put(offset, i);
+        }
+        offsets[x + (z << 5)] = offset;
+        raf.seek((long) i << 2);
+        raf.writeInt(offset);
+    }
+
+    /**
+     * Write the chunk to the file
+     */
+    @Override
+    public synchronized void flush() throws IOException {
+        boolean delete = true;
+        int currentSector = 2;
+        Queue<Integer> offsets =
+                new LinkedBlockingDeque<>(Arrays.stream(this.offsets).boxed().sorted(Comparator.comparingInt(i -> (i >> 8))).toList());
+        int offset;
+        int count = 0;
+        while (offsets.peek() != null) {
+            count++;
+            offset = offsets.poll();
+            if (offset == 0) {
+                continue;
+            }
+            delete = false;
+            int pair = offsetMap.get(offset);
+            int sectorNumber = offset >> 8;
+            int sectorsAllocated = offset & 0xFF;
+            if (sectorNumber < 2) {
+                throw new IllegalStateException("Sector number cannot be < 2!");
+            }
+            if (pair == Integer.MAX_VALUE) {
+                sectorFree.setRange(sectorNumber, sectorNumber + sectorsAllocated);
+                continue;
+            }
+            MCAChunk chunk = chunks.remove(pair);
+
+            byte[] data;
+            int sectorsNeeded;
+            boolean writeChunkHeader;
+
+            if (currentSector <= sectorNumber) { // Only set free if we definitely won't be overwriting
+                sectorFree.setRange(sectorNumber, sectorNumber + sectorsAllocated);
+            } else {
+                throw new IllegalStateException("Current sector number being written to cannot exceed sector number of chunk to" +
+                        " be written!");
+            }
+            if (chunk == null) {
+                if (currentSector != sectorNumber) {
+                    writeChunkHeader = false;
+                    data = new byte[sectorsAllocated << 12];
+                    sectorsNeeded = sectorsAllocated;
+                    raf.seek((long) sectorNumber << 12);
+                    raf.read(data);
+                } else {
+                    sectorFree.clearRange(currentSector, currentSector + sectorsAllocated);
+                    currentSector += sectorsAllocated;
+                    continue;
+                }
+            } else if (chunk.isDeleted()) {
+                int x = pair & 31;
+                int z = (pair >> 5) & 31;
+                setOffset(x, z, 0);
+                continue;
+            } else {
+                data = chunk.toBytes(null);
+                writeChunkHeader = true;
+                sectorsNeeded = ((data.length + CHUNK_HEADER_SIZE) >> 12) + 1;
+            }
+
+            boolean hasSpace = sectorsNeeded <= sectorsAllocated;
+            long position = (long) currentSector << 12;
+            if (!hasSpace) {
+                hasSpace = true;
+                for (int i = currentSector; i < currentSector + sectorsNeeded; i++) {
+                    if (!sectorFree.get(i) || i > sectorFree.size()) {
+                        hasSpace = false;
+                        break;
+                    }
+                }
+                if (!hasSpace) {
+                    if (sectorNumber > 2500 || count > 30000) {
+                        throw new RuntimeException();
+                    }
+                    sectorNumber = sectorFree.size() + 1;
+                    offset = (sectorNumber << 8) | (sectorsNeeded & 0xFF);
+                    setOffset(pair & 31, (pair >> 5) & 31, offset);
+                    position = (long) sectorNumber << 12;
+                    raf.setLength((long) (sectorNumber + sectorsNeeded + 1) << 12);
+                    sectorFree.expandTo(sectorNumber + sectorsNeeded, true);
+                    sectorFree.clearRange(sectorNumber, sectorNumber + sectorsNeeded);
+                    offsets.add(offset); // Come back later to clean up.
+                }
+            }
+            raf.seek(position);
+            if (writeChunkHeader) {
+                raf.writeInt(data.length + 1);
+                raf.writeByte(VERSION_DEFLATE);
+            }
+            raf.write(data);
+            if (hasSpace) {
+                offset = (currentSector << 8) | (sectorsNeeded & 0xFF);
+                setOffset(pair & 31, (pair >> 5) & 31, offset);
+                sectorFree.clearRange(currentSector, currentSector + sectorsNeeded);
+                currentSector += sectorsNeeded;
+            }
+        }
+        int size = 0;
+        for (int i = sectorFree.size(); i > 0; i--) {
+            if (!sectorFree.get(i)) {
+                size = i + 1;
+                break;
+            }
+        }
+        raf.setLength((long) (size + 1) * SECTOR_BYTES);
+        if (delete || size < 3) {
+            clear();
+            Files.delete(file);
+        }
+        synchronized (chunks) {
+            chunks.clear();
+        }
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/anvil/MCAWorld.java

@@ -0,0 +1,202 @@
+package com.fastasyncworldedit.core.anvil;
+
+import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.queue.IChunkGet;
+import com.fastasyncworldedit.core.queue.implementation.packet.ChunkPacket;
+import com.fastasyncworldedit.core.util.MathMan;
+import com.sk89q.jnbt.CompoundTag;
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.blocks.BaseItemStack;
+import com.sk89q.worldedit.entity.Player;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.math.Vector3;
+import com.sk89q.worldedit.util.SideEffect;
+import com.sk89q.worldedit.util.SideEffectSet;
+import com.sk89q.worldedit.util.TreeGenerator;
+import com.sk89q.worldedit.world.AbstractWorld;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockStateHolder;
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import org.apache.logging.log4j.Logger;
+import org.jetbrains.annotations.Nullable;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.Set;
+
+public class MCAWorld extends AbstractWorld {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    private static final Int2ObjectOpenHashMap<MCAWorld> worldMap = new Int2ObjectOpenHashMap<>();
+    private final String name;
+    private final Path folder;
+    private final Path regionFolder;
+    private final Int2ObjectOpenHashMap<MCAFile> mcaFileCache = new Int2ObjectOpenHashMap<>();
+
+    private MCAWorld(String name, Path folder) {
+        this.name = name;
+        this.folder = folder;
+        this.regionFolder = folder.resolve("region");
+    }
+
+    /**
+     * New MCAWorld instance.
+     *
+     * @param name World name
+     */
+    public static synchronized MCAWorld of(String name) {
+        return of(name, Fawe.platform().getWorldsFolder().resolve(name));
+    }
+
+    /**
+     * New MCAWorld instance.
+     *
+     * @param name   World name
+     * @param folder World file/folder
+     */
+    public static synchronized MCAWorld of(String name, Path folder) {
+        if (Fawe.platform().isWorldLoaded(name)) {
+            throw new IllegalStateException("World " + name + " is loaded. Anvil operations cannot be completed on a loaded world.");
+        }
+        // World could be the same name but in a different folder
+        int combinedHash = Objects.hash(name, folder);
+        return worldMap.computeIfAbsent(combinedHash, (i) -> new MCAWorld(name, folder));
+    }
+
+    public Collection<MCAFile> getMCAs() {
+        getRegionFileFiles().forEach(file -> {
+            String[] split = file.getFileName().toString().split("\\.");
+            short regionX = Short.parseShort(split[1]);
+            short regionZ = Short.parseShort(split[2]);
+            int paired = MathMan.pair(regionX, regionZ);
+            mcaFileCache.computeIfAbsent(
+                    paired,
+                    (i) -> new MCAFile(regionX, regionZ, regionFolder.resolve("r." + regionX + "." + regionZ + ".mca"))
+            );
+        });
+        return mcaFileCache.values();
+    }
+
+    public List<Path> getRegionFileFiles() {
+        try {
+            return Files.list(regionFolder).filter(p -> p.toString().endsWith(".mca")).toList();
+        } catch (IOException e) {
+            LOGGER.error("Error listing region files", e);
+            return Collections.emptyList();
+        }
+    }
+
+    @Override
+    public boolean setTile(final int x, final int y, final int z, final CompoundTag tile) throws WorldEditException {
+        return false;
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String getNameUnsafe() {
+        return name;
+    }
+
+    public Path getFolder() {
+        return folder;
+    }
+
+    @Override
+    public <B extends BlockStateHolder<B>> boolean setBlock(
+            final BlockVector3 position,
+            final B block,
+            final SideEffectSet sideEffects
+    ) throws WorldEditException {
+        return false;
+    }
+
+    @Override
+    public Set<SideEffect> applySideEffects(
+            final BlockVector3 position,
+            final BlockState previousType,
+            final SideEffectSet sideEffectSet
+    ) throws WorldEditException {
+        return null;
+    }
+
+    @Override
+    public boolean clearContainerBlockContents(final BlockVector3 position) {
+        return false;
+    }
+
+    @Override
+    public void dropItem(final Vector3 position, final BaseItemStack item) {
+
+    }
+
+    @Override
+    public void simulateBlockMine(final BlockVector3 position) {
+
+    }
+
+    @Override
+    public boolean generateTree(
+            final TreeGenerator.TreeType type,
+            final EditSession editSession,
+            final BlockVector3 position
+    ) throws MaxChangedBlocksException {
+        return false;
+    }
+
+    @Override
+    public BlockVector3 getSpawnPosition() {
+        return null;
+    }
+
+    @Override
+    public void refreshChunk(final int chunkX, final int chunkZ) {
+        throw new UnsupportedOperationException("Not supported in anvil operations.");
+    }
+
+    @Override
+    public IChunkGet get(final int chunkX, final int chunkZ) {
+        short regionX = (short) (chunkX >> 5);
+        short regionZ = (short) (chunkZ >> 5);
+        int paired = MathMan.pair(regionX, regionZ);
+        MCAFile mca = mcaFileCache.computeIfAbsent(
+                paired,
+                (i) -> new MCAFile(regionX, regionZ, regionFolder.resolve("r." + regionX + "." + regionZ + ".mca"))
+        );
+        try {
+            return mca.getChunk(chunkX, chunkZ);
+        } catch (IOException e) {
+            LOGGER.error("Error loading chunk. Creating empty chunk.", e);
+            return mca.newChunk(chunkX, chunkZ);
+        }
+    }
+
+    @Override
+    public void sendFakeChunk(@Nullable final Player player, final ChunkPacket packet) {
+        throw new UnsupportedOperationException("Not supported in anvil operations.");
+    }
+
+    @Override
+    public synchronized void flush() {
+        for (MCAFile mca : mcaFileCache.values()) {
+            try {
+                mca.close();
+            } catch (IOException e) {
+                LOGGER.error("Could not flush MCAFile {}", mca.getFile().getFileName(), e);
+            }
+        }
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/internal/io/BufferedRandomAccessFile.java

@@ -0,0 +1,434 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.fastasyncworldedit.core.internal.io;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.Arrays;
+
+
+/**
+ * A <code>BufferedRandomAccessFile</code> is like a
+ * <code>RandomAccessFile</code>, but it uses a private buffer so that most
+ * operations do not require a disk access.
+ * <P>
+ *
+ * Note: The operations on this class are unmonitored. Also, the correct
+ * functioning of the <code>RandomAccessFile</code> methods that are not
+ * overridden here relies on the implementation of those methods in the
+ * superclass.
+ * Author : Avinash Lakshman ( alakshman@facebook.com) & Prashant Malik ( pmalik@facebook.com )
+ */
+
+public class BufferedRandomAccessFile extends RandomAccessFile {
+    static final int LogBuffSz_ = 16; // 64K buffer
+    public static final int BuffSz_ = (1 << LogBuffSz_);
+    static final long BuffMask_ = ~(((long) BuffSz_) - 1L);
+
+    /*
+     * This implementation is based on the buffer implementation in Modula-3's
+     * "Rd", "Wr", "RdClass", and "WrClass" interfaces.
+     */
+    private boolean dirty_; // true iff unflushed bytes exist
+    private boolean closed_; // true iff the file is closed
+    private long curr_; // current position in file
+    private long lo_, hi_; // bounds on characters in "buff"
+    private byte[] buff_; // local buffer
+    private long maxHi_; // this.lo + this.buff.length
+    private boolean hitEOF_; // buffer contains last file block?
+    private long diskPos_; // disk position
+
+    /*
+     * To describe the above fields, we introduce the following abstractions for
+     * the file "f":
+     *
+     * len(f) the length of the file curr(f) the current position in the file
+     * c(f) the abstract contents of the file disk(f) the contents of f's
+     * backing disk file closed(f) true iff the file is closed
+     *
+     * "curr(f)" is an index in the closed interval [0, len(f)]. "c(f)" is a
+     * character sequence of length "len(f)". "c(f)" and "disk(f)" may differ if
+     * "c(f)" contains unflushed writes not reflected in "disk(f)". The flush
+     * operation has the effect of making "disk(f)" identical to "c(f)".
+     *
+     * A file is said to be *valid* if the following conditions hold:
+     *
+     * V1. The "closed" and "curr" fields are correct:
+     *
+     * f.closed == closed(f) f.curr == curr(f)
+     *
+     * V2. The current position is either contained in the buffer, or just past
+     * the buffer:
+     *
+     * f.lo <= f.curr <= f.hi
+     *
+     * V3. Any (possibly) unflushed characters are stored in "f.buff":
+     *
+     * (forall i in [f.lo, f.curr): c(f)[i] == f.buff[i - f.lo])
+     *
+     * V4. For all characters not covered by V3, c(f) and disk(f) agree:
+     *
+     * (forall i in [f.lo, len(f)): i not in [f.lo, f.curr) => c(f)[i] ==
+     * disk(f)[i])
+     *
+     * V5. "f.dirty" is true iff the buffer contains bytes that should be
+     * flushed to the file; by V3 and V4, only part of the buffer can be dirty.
+     *
+     * f.dirty == (exists i in [f.lo, f.curr): c(f)[i] != f.buff[i - f.lo])
+     *
+     * V6. this.maxHi == this.lo + this.buff.length
+     *
+     * Note that "f.buff" can be "null" in a valid file, since the range of
+     * characters in V3 is empty when "f.lo == f.curr".
+     *
+     * A file is said to be *ready* if the buffer contains the current position,
+     * i.e., when:
+     *
+     * R1. !f.closed && f.buff != null && f.lo <= f.curr && f.curr < f.hi
+     *
+     * When a file is ready, reading or writing a single byte can be performed
+     * by reading or writing the in-memory buffer without performing a disk
+     * operation.
+     */
+
+    /**
+     * Open a new <code>BufferedRandomAccessFile</code> on <code>file</code>
+     * in mode <code>mode</code>, which should be "r" for reading only, or
+     * "rw" for reading and writing.
+     */
+    public BufferedRandomAccessFile(File file, String mode) throws IOException {
+        super(file, mode);
+        this.init(0);
+    }
+
+    public BufferedRandomAccessFile(File file, String mode, int size) throws IOException {
+        super(file, mode);
+        this.init(size);
+    }
+
+    /**
+     * Open a new <code>BufferedRandomAccessFile</code> on the file named
+     * <code>name</code> in mode <code>mode</code>, which should be "r" for
+     * reading only, or "rw" for reading and writing.
+     */
+    public BufferedRandomAccessFile(String name, String mode) throws IOException {
+        super(name, mode);
+        this.init(0);
+    }
+
+    public BufferedRandomAccessFile(String name, String mode, int size) throws FileNotFoundException {
+        super(name, mode);
+        this.init(size);
+    }
+
+    public BufferedRandomAccessFile(File file, String mode, byte[] buf) throws FileNotFoundException {
+        super(file, mode);
+        this.dirty_ = this.closed_ = false;
+        this.lo_ = this.curr_ = this.hi_ = 0;
+        this.buff_ = buf;
+        this.maxHi_ = (long) BuffSz_;
+        this.hitEOF_ = false;
+        this.diskPos_ = 0L;
+    }
+
+    private void init(int size) {
+        this.dirty_ = this.closed_ = false;
+        this.lo_ = this.curr_ = this.hi_ = 0;
+        this.buff_ = (size > BuffSz_) ? new byte[size] : new byte[BuffSz_];
+        this.maxHi_ = (long) BuffSz_;
+        this.hitEOF_ = false;
+        this.diskPos_ = 0L;
+    }
+
+    @Override
+    public void close() throws IOException {
+        this.flush();
+        this.closed_ = true;
+        super.close();
+    }
+
+    /**
+     * Flush any bytes in the file's buffer that have not yet been written to
+     * disk. If the file was created read-only, this method is a no-op.
+     */
+    public void flush() throws IOException {
+        this.flushBuffer();
+    }
+
+    /* Flush any dirty bytes in the buffer to disk. */
+    private void flushBuffer() throws IOException {
+        if (this.dirty_) {
+            if (this.diskPos_ != this.lo_)
+                super.seek(this.lo_);
+            int len = (int) (this.curr_ - this.lo_);
+            super.write(this.buff_, 0, len);
+            this.diskPos_ = this.curr_;
+            this.dirty_ = false;
+        }
+    }
+
+    /*
+     * Read at most "this.buff.length" bytes into "this.buff", returning the
+     * number of bytes read. If the return result is less than
+     * "this.buff.length", then EOF was read.
+     */
+    private int fillBuffer() throws IOException {
+        int cnt = 0;
+        int rem = this.buff_.length;
+        while (rem > 0) {
+            int n = super.read(this.buff_, cnt, rem);
+            if (n < 0)
+                break;
+            cnt += n;
+            rem -= n;
+        }
+        if ((cnt < 0) && (this.hitEOF_ = (cnt < this.buff_.length))) {
+            // make sure buffer that wasn't read is initialized with -1
+            Arrays.fill(this.buff_, cnt, this.buff_.length, (byte) 0xff);
+        }
+        this.diskPos_ += cnt;
+        return cnt;
+    }
+
+    /*
+     * This method positions <code>this.curr</code> at position <code>pos</code>.
+     * If <code>pos</code> does not fall in the current buffer, it flushes the
+     * current buffer and loads the correct one.<p>
+     *
+     * On exit from this routine <code>this.curr == this.hi</code> iff <code>pos</code>
+     * is at or past the end-of-file, which can only happen if the file was
+     * opened in read-only mode.
+     */
+    @Override
+    public void seek(long pos) throws IOException {
+        if (pos >= this.hi_ || pos < this.lo_) {
+            // seeking outside of current buffer -- flush and read
+            this.flushBuffer();
+            this.lo_ = pos & BuffMask_; // start at BuffSz boundary
+            this.maxHi_ = this.lo_ + (long) this.buff_.length;
+            if (this.diskPos_ != this.lo_) {
+                super.seek(this.lo_);
+                this.diskPos_ = this.lo_;
+            }
+            int n = this.fillBuffer();
+            this.hi_ = this.lo_ + (long) n;
+        } else {
+            // seeking inside current buffer -- no read required
+            if (pos < this.curr_) {
+                // if seeking backwards, we must flush to maintain V4
+                this.flushBuffer();
+            }
+        }
+        this.curr_ = pos;
+    }
+
+    /*
+     * Does not maintain V4 (i.e. buffer differs from disk contents if previously written to)
+     *  - Assumes no writes were made
+     * @param pos
+     * @throws IOException
+     */
+    public void seekUnsafe(long pos) throws IOException {
+        if (pos >= this.hi_ || pos < this.lo_) {
+            // seeking outside of current buffer -- flush and read
+            this.flushBuffer();
+            this.lo_ = pos & BuffMask_; // start at BuffSz boundary
+            this.maxHi_ = this.lo_ + (long) this.buff_.length;
+            if (this.diskPos_ != this.lo_) {
+                super.seek(this.lo_);
+                this.diskPos_ = this.lo_;
+            }
+            int n = this.fillBuffer();
+            this.hi_ = this.lo_ + (long) n;
+        }
+        this.curr_ = pos;
+    }
+
+    @Override
+    public long getFilePointer() {
+        return this.curr_;
+    }
+
+    @Override
+    public long length() throws IOException {
+        return Math.max(this.curr_, super.length());
+    }
+
+    @Override
+    public int read() throws IOException {
+        if (this.curr_ >= this.hi_) {
+            // test for EOF
+            // if (this.hi < this.maxHi) return -1;
+            if (this.hitEOF_)
+                return -1;
+
+            // slow path -- read another buffer
+            this.seek(this.curr_);
+            if (this.curr_ == this.hi_)
+                return -1;
+        }
+        byte res = this.buff_[(int) (this.curr_ - this.lo_)];
+        this.curr_++;
+        return ((int) res) & 0xFF; // convert byte -> int
+    }
+
+    public byte read1() throws IOException {
+        if (this.curr_ >= this.hi_) {
+            // test for EOF
+            // if (this.hi < this.maxHi) return -1;
+            if (this.hitEOF_)
+                return -1;
+
+            // slow path -- read another buffer
+            this.seek(this.curr_);
+            if (this.curr_ == this.hi_)
+                return -1;
+        }
+        byte res = this.buff_[(int) (this.curr_ - this.lo_)];
+        this.curr_++;
+        return res;
+    }
+
+    @Override
+    public int read(byte[] b) throws IOException {
+        return this.read(b, 0, b.length);
+    }
+
+    @Override
+    public int read(byte[] b, int off, int len) throws IOException {
+        if (this.curr_ >= this.hi_) {
+            // test for EOF
+            // if (this.hi < this.maxHi) return -1;
+            if (this.hitEOF_)
+                return -1;
+
+            // slow path -- read another buffer
+            this.seek(this.curr_);
+            if (this.curr_ == this.hi_)
+                return -1;
+        }
+        len = Math.min(len, (int) (this.hi_ - this.curr_));
+        int buffOff = (int) (this.curr_ - this.lo_);
+        System.arraycopy(this.buff_, buffOff, b, off, len);
+        this.curr_ += len;
+        return len;
+    }
+
+    public byte readCurrent() throws IOException {
+        if (this.curr_ >= this.hi_) {
+            // test for EOF
+            // if (this.hi < this.maxHi) return -1;
+            if (this.hitEOF_)
+                return -1;
+
+            // slow path -- read another buffer
+            this.seek(this.curr_);
+            if (this.curr_ == this.hi_)
+                return -1;
+        }
+        byte res = this.buff_[(int) (this.curr_ - this.lo_)];
+        return res;
+    }
+
+    public void writeCurrent(byte b) throws IOException {
+        if (this.curr_ >= this.hi_) {
+            if (this.hitEOF_ && this.hi_ < this.maxHi_) {
+                // at EOF -- bump "hi"
+                this.hi_++;
+            } else {
+                // slow path -- write current buffer; read next one
+                this.seek(this.curr_);
+                if (this.curr_ == this.hi_) {
+                    // appending to EOF -- bump "hi"
+                    this.hi_++;
+                }
+            }
+        }
+        this.buff_[(int) (this.curr_ - this.lo_)] = (byte) b;
+        this.dirty_ = true;
+    }
+
+    public void writeUnsafe(int b) throws IOException {
+        this.buff_[(int) (this.curr_ - this.lo_)] = (byte) b;
+        this.curr_++;
+        this.dirty_ = true;
+    }
+
+    @Override
+    public void write(int b) throws IOException {
+        if (this.curr_ >= this.hi_) {
+            if (this.hitEOF_ && this.hi_ < this.maxHi_) {
+                // at EOF -- bump "hi"
+                this.hi_++;
+            } else {
+                // slow path -- write current buffer; read next one
+                this.seek(this.curr_);
+                if (this.curr_ == this.hi_) {
+                    // appending to EOF -- bump "hi"
+                    this.hi_++;
+                }
+            }
+        }
+        this.buff_[(int) (this.curr_ - this.lo_)] = (byte) b;
+        this.curr_++;
+        this.dirty_ = true;
+    }
+
+    @Override
+    public void write(byte[] b) throws IOException {
+        this.write(b, 0, b.length);
+    }
+
+    @Override
+    public void write(byte[] b, int off, int len) throws IOException {
+        while (len > 0) {
+            int n = this.writeAtMost(b, off, len);
+            off += n;
+            len -= n;
+            this.dirty_ = true;
+        }
+    }
+
+    /*
+     * Write at most "len" bytes to "b" starting at position "off", and return
+     * the number of bytes written.
+     */
+    private int writeAtMost(byte[] b, int off, int len) throws IOException {
+        if (this.curr_ >= this.hi_) {
+            if (this.hitEOF_ && this.hi_ < this.maxHi_) {
+                // at EOF -- bump "hi"
+                this.hi_ = this.maxHi_;
+            } else {
+                // slow path -- write current buffer; read next one
+                this.seek(this.curr_);
+                if (this.curr_ == this.hi_) {
+                    // appending to EOF -- bump "hi"
+                    this.hi_ = this.maxHi_;
+                }
+            }
+        }
+        len = Math.min(len, (int) (this.hi_ - this.curr_));
+        int buffOff = (int) (this.curr_ - this.lo_);
+        System.arraycopy(b, off, this.buff_, buffOff, len);
+        this.curr_ += len;
+        return len;
+    }
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/jnbt/streamer/StreamDelegate.java

@@ -2,13 +2,18 @@ package com.fastasyncworldedit.core.jnbt.streamer;
 
 import com.sk89q.jnbt.NBTConstants;
 import com.sk89q.jnbt.NBTInputStream;
+import com.sk89q.jnbt.Tag;
 import com.sk89q.worldedit.internal.util.LogManagerCompat;
 import org.apache.logging.log4j.Logger;
 
+import javax.annotation.Nullable;
 import java.io.DataInputStream;
 import java.io.IOException;
+import java.util.Arrays;
+import java.util.LinkedHashMap;
+import java.util.Map;
 
-@SuppressWarnings({"unchecked", "rawtypes"})
+@SuppressWarnings({"unchecked", "rawtypes", "removal"})
 public class StreamDelegate {
 
     private static final Logger LOGGER = LogManagerCompat.getLogger();
@@ -16,6 +21,8 @@ public class StreamDelegate {
     private static final byte[][] ZERO_KEYS = new byte[0][];
     private static final StreamDelegate[] ZERO_VALUES = new StreamDelegate[0];
 
+    private Map<String, Tag> retained = null;
+
     private byte[] buffer;
     private byte[][] keys;
     private StreamDelegate[] values;
@@ -25,25 +32,36 @@ public class StreamDelegate {
     private InfoReader infoReader;
     private ValueReader valueReader;
 
+    private String retainedName = null;
+    private String currentName = null;
+
+    /**
+     * Used to read a streamed {@link NBTInputStream}
+     */
     public StreamDelegate() {
         keys = ZERO_KEYS;
         values = ZERO_VALUES;
     }
 
+    /**
+     * Set that keys not added to this StreamDelegate instance should still be retained alongside their value retained. They can
+     * be accessed via {@link StreamDelegate#getRetained}
+     */
+    public StreamDelegate retainOthers() {
+        retained = new LinkedHashMap<>();
+        return this;
+    }
+
     public StreamDelegate addAndGetParent(String name) {
         add(name);
         return this;
     }
 
-    public StreamDelegate add() {
-        return add("");
-    }
-
-    public StreamDelegate add(String name) {
+    public StreamDelegate add(@Nullable String name) {
         return add(name, new StreamDelegate());
     }
 
-    private StreamDelegate add(String name, StreamDelegate scope) {
+    private StreamDelegate add(@Nullable String name, StreamDelegate scope) {
         if (valueReader != null) {
             LOGGER.warn(
                     "Scope {} | {} may not run, as the stream is only read once, and a value reader is already set",
@@ -51,7 +69,7 @@ public class StreamDelegate {
                     scope
             );
         }
-        byte[] bytes = name.getBytes(NBTConstants.CHARSET);
+        byte[] bytes = name == null ? new byte[0] : name.getBytes(NBTConstants.CHARSET);
         int maxSize = bytes.length;
 
         byte[][] tmpKeys = new byte[keys.length + 1][];
@@ -96,10 +114,12 @@ public class StreamDelegate {
     public StreamDelegate get(DataInputStream is) throws IOException {
         int nameLength = is.readShort() & 0xFFFF;
         if (nameLength == 0 && keys.length > 0 && keys[0].length == 0) {
+            currentName = "";
+            retainedName = null;
             return values[0];
         }
         if (nameLength > buffer.length) {
-            is.skipBytes(nameLength);
+            setRetained(is, nameLength);
             return null;
         }
         int index = 0;
@@ -139,34 +159,59 @@ public class StreamDelegate {
                                     continue middle;
                                 }
                             }
+                            currentName = new String(key);
+                            retainedName = null;
                             return values[i];
                         }
+                        currentName = null;
+                        retainedName = new String(Arrays.copyOf(buffer, nameLength), NBTConstants.CHARSET);
                         return null;
                     }
                 }
+                // fall through
             }
             case 1: {
                 byte[] key = keys[index];
                 if (key.length == nameLength) {
                     int i = 0;
+                    boolean retain = false;
                     for (; nameLength > 0; nameLength--, i++) {
                         byte b = is.readByte();
                         buffer[i] = b;
-                        if (b != key[i]) {
-                            nameLength--;
-                            break outer;
+                        if (!retain && b != key[i]) {
+                            if (retained == null) {
+                                nameLength--;
+                                break outer;
+                            }
+                            retain = true;
                         }
-
                     }
-                    return values[index];
+                    if (!retain) {
+                        currentName = new String(key);
+                        retainedName = null;
+                        return values[index];
+                    }
+                    retainedName = new String(Arrays.copyOf(buffer, i), NBTConstants.CHARSET);
+                    return null;
                 }
                 break;
             }
         }
-        is.skipBytes(nameLength);
+        setRetained(is, nameLength);
         return null;
     }
 
+    private void setRetained(DataInputStream is, int nameLength) throws IOException {
+        if (retained == null) {
+            is.skipBytes(nameLength);
+        } else {
+            byte[] nameBytes = new byte[nameLength];
+            is.readFully(nameBytes);
+            retainedName = new String(nameBytes, NBTConstants.CHARSET);
+        }
+        currentName = null;
+    }
+
     public StreamDelegate withLong(LongValueReader valueReader) {
         return withElem(valueReader);
     }
@@ -220,6 +265,19 @@ public class StreamDelegate {
         return elemReader;
     }
 
+    @Nullable
+    public Map<String, Tag> getRetained() {
+        return retained;
+    }
+
+    public void retain(Tag tag) {
+        if (retainedName == null) {
+            throw new IllegalStateException("Retained name null?!");
+        }
+        retained.put(retainedName, tag);
+        retainedName = null;
+    }
+
     public void acceptInfo(int length, int type) throws IOException {
         if (infoReader != null) {
             infoReader.apply(length, type);
@@ -234,4 +292,12 @@ public class StreamDelegate {
         return false;
     }
 
+    public String getCurrentName() {
+        return currentName;
+    }
+
+    public String getRetainedName() {
+        return retainedName;
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/math/FastBitSet.java

@@ -1,11 +1,12 @@
 package com.fastasyncworldedit.core.math;
 
+import java.math.BigInteger;
 import java.util.Arrays;
 
 public class FastBitSet {
 
-    private final int size;
-    private final long[] bits;
+    private int size;
+    private long[] bits;
 
     public FastBitSet(int size) {
         this.size = size;
@@ -93,6 +94,28 @@ public class FastBitSet {
         }
     }
 
+    public void expandTo(int newSize, boolean value) {
+        //System.out.println(newSize);
+        int newLength = (newSize + 64) >> 6;
+        if (newLength <= this.bits.length) {
+            if (this.size > newSize) {
+                this.size = newSize;
+            }
+            return;
+        }
+        long[] tmp = new long[newLength];
+        if (value) {
+            Arrays.fill(tmp, -1L);
+        }
+        System.arraycopy(bits, 0, tmp, 0, bits.length);
+        this.bits = tmp;
+        this.size = newSize;
+    }
+
+    public void setAll() {
+        setAll(bits);
+    }
+
     public boolean get(final int i) {
         return (bits[i >> 6] & (1L << (i & 0x3F))) != 0;
     }
@@ -197,4 +220,16 @@ public class FastBitSet {
 
     }
 
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        for (int i = 0; i < this.bits.length; i++) {
+            String bits = new StringBuilder(String.format("%064d", new BigInteger(Long.toBinaryString(this.bits[i]))))
+                    .reverse()
+                    .toString();
+            builder.append(i * 64).append(":").append(bits).append(" ");
+        }
+        return builder.toString();
+    }
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IChunkGet.java

@@ -8,6 +8,7 @@ import com.sk89q.worldedit.math.BlockVector3;
 import com.sk89q.worldedit.world.biome.BiomeType;
 import com.sk89q.worldedit.world.block.BaseBlock;
 import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.storage.InvalidFormatException;
 
 import javax.annotation.Nullable;
 import java.util.UUID;

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/IQueueExtent.java

@@ -173,4 +173,6 @@ public interface IQueueExtent<T extends IChunk> extends Flushable, Trimable, ICh
         return filter;
     }
 
+    void addFlushTask(Runnable task);
+
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/ParallelAnvilQueueExtent.java

@@ -0,0 +1,279 @@
+package com.fastasyncworldedit.core.queue.implementation;
+
+import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.FaweCache;
+import com.fastasyncworldedit.core.anvil.MCAWorld;
+import com.fastasyncworldedit.core.configuration.Settings;
+import com.fastasyncworldedit.core.extent.NullExtent;
+import com.fastasyncworldedit.core.extent.PassthroughExtent;
+import com.fastasyncworldedit.core.extent.clipboard.WorldCopyClipboard;
+import com.fastasyncworldedit.core.extent.filter.CountFilter;
+import com.fastasyncworldedit.core.extent.filter.DistrFilter;
+import com.fastasyncworldedit.core.extent.filter.LinkedFilter;
+import com.fastasyncworldedit.core.extent.filter.block.ChunkFilterBlock;
+import com.fastasyncworldedit.core.extent.processor.BatchProcessorHolder;
+import com.fastasyncworldedit.core.extent.processor.MultiBatchProcessor;
+import com.fastasyncworldedit.core.function.mask.BlockMaskBuilder;
+import com.fastasyncworldedit.core.internal.exception.FaweException;
+import com.fastasyncworldedit.core.queue.Filter;
+import com.fastasyncworldedit.core.queue.IQueueChunk;
+import com.fastasyncworldedit.core.queue.IQueueExtent;
+import com.sk89q.worldedit.MaxChangedBlocksException;
+import com.sk89q.worldedit.extent.clipboard.Clipboard;
+import com.sk89q.worldedit.function.mask.BlockMask;
+import com.sk89q.worldedit.function.mask.ExistingBlockMask;
+import com.sk89q.worldedit.function.mask.Mask;
+import com.sk89q.worldedit.function.pattern.BlockPattern;
+import com.sk89q.worldedit.function.pattern.Pattern;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.math.BlockVector2;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.util.Countable;
+import com.sk89q.worldedit.world.block.BaseBlock;
+import com.sk89q.worldedit.world.block.BlockState;
+import com.sk89q.worldedit.world.block.BlockStateHolder;
+import com.sk89q.worldedit.world.block.BlockType;
+import org.apache.logging.log4j.Logger;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.ForkJoinTask;
+import java.util.stream.IntStream;
+
+public class ParallelAnvilQueueExtent extends PassthroughExtent {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    private final MCAWorld world;
+    private final QueueHandler handler;
+    private final BatchProcessorHolder processor;
+    private final BatchProcessorHolder postProcessor;
+    // Array for lazy avoidance of concurrent modification exceptions and needless overcomplication of code (synchronisation is
+    // not very important)
+    private final boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
+    private final boolean fastmode;
+    private int changes;
+    private int lastException = Integer.MIN_VALUE;
+    private int exceptionCount = 0;
+
+    public ParallelAnvilQueueExtent(QueueHandler handler, MCAWorld world, boolean fastmode) {
+        super(handler.getQueue(world, new BatchProcessorHolder(), new BatchProcessorHolder()));
+        this.world = world;
+        this.handler = handler;
+        this.processor = (BatchProcessorHolder) getExtent().getProcessor();
+        if (this.processor.getProcessor() instanceof MultiBatchProcessor) {
+            ((MultiBatchProcessor) this.processor.getProcessor()).setFaweExceptionArray(faweExceptionReasonsUsed);
+        }
+        this.postProcessor = (BatchProcessorHolder) getExtent().getPostProcessor();
+        if (this.postProcessor.getProcessor() instanceof MultiBatchProcessor) {
+            ((MultiBatchProcessor) this.postProcessor.getProcessor()).setFaweExceptionArray(faweExceptionReasonsUsed);
+        }
+        this.fastmode = fastmode;
+    }
+
+    @Override
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    public IQueueExtent<IQueueChunk> getExtent() {
+        return (IQueueExtent<IQueueChunk>) super.getExtent();
+    }
+
+    @Override
+    public boolean cancel() {
+        if (super.cancel()) {
+            processor.setProcessor(new NullExtent(this, FaweCache.MANUAL));
+            postProcessor.setPostProcessor(new NullExtent(this, FaweCache.MANUAL));
+            return true;
+        }
+        return false;
+    }
+
+    @SuppressWarnings("rawtypes")
+    private IQueueExtent<IQueueChunk> getNewQueue() {
+        return handler.getMCAQueue(world, this.processor, this.postProcessor);
+    }
+
+    @Override
+    @SuppressWarnings("rawtypes")
+    public <T extends Filter> T apply(Region region, T filter, boolean full) {
+        // The chunks positions to iterate over
+        final Set<BlockVector2> chunks = region.getChunks();
+        final Iterator<BlockVector2> chunksIter = chunks.iterator();
+
+        // Get a pool, to operate on the chunks in parallel
+        final int size = Math.min(chunks.size(), Settings.settings().QUEUE.PARALLEL_THREADS);
+        if (size <= 1 && chunksIter.hasNext()) {
+            BlockVector2 pos = chunksIter.next();
+            getExtent().apply(null, filter, region, pos.getX(), pos.getZ(), full);
+        } else {
+            final ForkJoinTask[] tasks = IntStream.range(0, size).mapToObj(i -> handler.submit(() -> {
+                try {
+                    final Filter newFilter = filter.fork();
+                    // Create a chunk that we will reuse/reset for each operation
+                    final SingleThreadQueueExtent queue = (SingleThreadQueueExtent) getNewQueue();
+                    queue.setFastMode(fastmode);
+                    queue.setFaweExceptionArray(faweExceptionReasonsUsed);
+                    synchronized (queue) {
+                        try {
+                            ChunkFilterBlock block = null;
+
+                            while (true) {
+                                // Get the next chunk posWeakChunk
+                                final int chunkX;
+                                final int chunkZ;
+                                synchronized (chunksIter) {
+                                    if (!chunksIter.hasNext()) {
+                                        break;
+                                    }
+                                    final BlockVector2 pos = chunksIter.next();
+                                    chunkX = pos.getX();
+                                    chunkZ = pos.getZ();
+                                }
+                                block = queue.apply(block, newFilter, region, chunkX, chunkZ, full);
+                            }
+                            queue.flush();
+                        } catch (Throwable t) {
+                            if (t instanceof FaweException) {
+                                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) t, LOGGER);
+                            } else if (t.getCause() instanceof FaweException) {
+                                Fawe.handleFaweException(faweExceptionReasonsUsed, (FaweException) t.getCause(), LOGGER);
+                            } else {
+                                throw t;
+                            }
+                        }
+                    }
+                } catch (Throwable e) {
+                    String message = e.getMessage();
+                    int hash = message != null ? message.hashCode() : 0;
+                    if (lastException != hash) {
+                        lastException = hash;
+                        exceptionCount = 0;
+                        LOGGER.catching(e);
+                    } else if (exceptionCount < Settings.settings().QUEUE.PARALLEL_THREADS) {
+                        exceptionCount++;
+                        LOGGER.warn(message);
+                    }
+                }
+            })).toArray(ForkJoinTask[]::new);
+            // Join filters
+            for (ForkJoinTask task : tasks) {
+                if (task != null) {
+                    task.quietlyJoin();
+                }
+            }
+            filter.join();
+        }
+        return filter;
+    }
+
+    @Override
+    public int countBlocks(Region region, Mask searchMask) {
+        return
+                // Apply a filter over a region
+                apply(region, searchMask
+                        .toFilter(new CountFilter()), searchMask.replacesAir()) // Adapt the mask to a filter which counts
+                        .getParent() // Get the counter of this mask
+                        .getTotal(); // Get the total from the counter
+    }
+
+    @Override
+    public <B extends BlockStateHolder<B>> int setBlocks(Region region, B block) throws MaxChangedBlocksException {
+        Mask mask = new BlockMaskBuilder().add(block).build(this).inverse();
+        return this.changes = apply(region, mask.toFilter(block), mask.replacesAir())
+                .getBlocksApplied();
+    }
+
+    @Override
+    public int setBlocks(Region region, Pattern pattern) throws MaxChangedBlocksException {
+        return this.changes = apply(region, new LinkedFilter<>(pattern, new CountFilter()), true).getChild().getTotal();
+    }
+
+    @Override
+    public int setBlocks(Set<BlockVector3> vset, Pattern pattern) {
+        if (vset instanceof Region) {
+            this.changes = setBlocks((Region) vset, pattern);
+            return this.changes;
+        }
+        // TODO optimize parallel
+        for (BlockVector3 blockVector3 : vset) {
+            if (pattern.apply(this, blockVector3, blockVector3)) {
+                this.changes++;
+            }
+        }
+        return this.changes;
+    }
+
+    @Override
+    public int replaceBlocks(Region region, Mask mask, Pattern pattern)
+            throws MaxChangedBlocksException {
+        boolean full = mask.replacesAir();
+        return this.changes = apply(region, mask.toFilter(pattern), full).getBlocksApplied();
+    }
+
+    @Override
+    public List<Countable<BlockState>> getBlockDistributionWithData(Region region) {
+        return apply(region, new DistrFilter(), true).getDistribution();
+    }
+
+    @Override
+    public List<Countable<BlockType>> getBlockDistribution(Region region) {
+        return apply(region, new DistrFilter(), true).getTypeDistribution();
+    }
+
+    /**
+     * Lazily copy a region
+     */
+    @Override
+    public Clipboard lazyCopy(Region region) {
+        Clipboard clipboard = new WorldCopyClipboard(() -> this, region);
+        clipboard.setOrigin(region.getMinimumPoint());
+        return clipboard;
+    }
+
+    /**
+     * Count the number of blocks of a list of types in a region.
+     *
+     * @param region       the region
+     * @param searchBlocks the list of blocks to search
+     * @return the number of blocks that matched the block
+     */
+    @Override
+    public int countBlocks(Region region, Set<BaseBlock> searchBlocks) {
+        Mask mask = new BlockMask(this, searchBlocks);
+        return countBlocks(region, mask);
+    }
+
+    /**
+     * Replaces all the blocks matching a given filter, within a given region, to a block
+     * returned by a given pattern.
+     *
+     * @param region      the region to replace the blocks within
+     * @param filter      a list of block types to match, or null to use {@link ExistingBlockMask}
+     * @param replacement the replacement block
+     * @return number of blocks affected
+     * @throws MaxChangedBlocksException thrown if too many blocks are changed
+     */
+    @Override
+    public <B extends BlockStateHolder<B>> int replaceBlocks(Region region, Set<BaseBlock> filter, B replacement) throws
+            MaxChangedBlocksException {
+        return replaceBlocks(region, filter, new BlockPattern(replacement));
+    }
+
+    /**
+     * Replaces all the blocks matching a given filter, within a given region, to a block
+     * returned by a given pattern.
+     *
+     * @param region  the region to replace the blocks within
+     * @param filter  a list of block types to match, or null to use {@link ExistingBlockMask}
+     * @param pattern the pattern that provides the new blocks
+     * @return number of blocks affected
+     * @throws MaxChangedBlocksException thrown if too many blocks are changed
+     */
+    @Override
+    public int replaceBlocks(Region region, Set<BaseBlock> filter, Pattern pattern) throws MaxChangedBlocksException {
+        Mask mask = filter == null ? new ExistingBlockMask(this) : new BlockMask(this, filter);
+        return replaceBlocks(region, mask, pattern);
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/QueueHandler.java

@@ -10,6 +10,7 @@ import com.fastasyncworldedit.core.queue.IChunkSet;
 import com.fastasyncworldedit.core.queue.IQueueChunk;
 import com.fastasyncworldedit.core.queue.IQueueExtent;
 import com.fastasyncworldedit.core.queue.Trimable;
+import com.fastasyncworldedit.core.anvil.MCAWorld;
 import com.fastasyncworldedit.core.queue.implementation.chunk.ChunkCache;
 import com.fastasyncworldedit.core.util.MemUtil;
 import com.fastasyncworldedit.core.util.TaskManager;
@@ -400,6 +401,26 @@ public abstract class QueueHandler implements Trimable, Runnable {
         }
     }
 
+    /**
+     * Get or create the MCA WorldChunkCache for a world
+     */
+    public IChunkCache<IChunkGet> getOrCreateMCAWorldCache(World world) {
+        world = WorldWrapper.unwrap(world);
+
+        synchronized (chunkGetCache) {
+            final WeakReference<IChunkCache<IChunkGet>> ref = chunkGetCache.get(world);
+            if (ref != null) {
+                final IChunkCache<IChunkGet> cached = ref.get();
+                if (cached != null) {
+                    return cached;
+                }
+            }
+            final IChunkCache<IChunkGet> created = new ChunkCache<>(world);
+            chunkGetCache.put(world, new WeakReference<>(created));
+            return created;
+        }
+    }
+
     public IQueueExtent<IQueueChunk> create() {
         return new SingleThreadQueueExtent();
     }
@@ -456,6 +477,24 @@ public abstract class QueueHandler implements Trimable, Runnable {
      */
     public abstract void endUnsafe(boolean parallel);
 
+    public IQueueExtent<IQueueChunk> getMCAQueue(MCAWorld world) {
+        return getMCAQueue(world, null, null);
+    }
+
+    public IQueueExtent<IQueueChunk> getMCAQueue(MCAWorld world, IBatchProcessor processor, IBatchProcessor postProcessor) {
+        final IQueueExtent<IQueueChunk> queue = pool();
+        IChunkCache<IChunkGet> cache = getOrCreateMCAWorldCache(world);
+        queue.init(world, cache, null);
+        if (processor != null) {
+            queue.setProcessor(processor);
+        }
+        if (postProcessor != null) {
+            queue.setPostProcessor(postProcessor);
+        }
+        queue.addFlushTask(world::flush);
+        return queue;
+    }
+
     /**
      * Create a new queue for a given world.
      */

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/SingleThreadQueueExtent.java

@@ -31,6 +31,8 @@ import com.sk89q.worldedit.world.World;
 import it.unimi.dsi.fastutil.longs.Long2ObjectLinkedOpenHashMap;
 import org.apache.logging.log4j.Logger;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
@@ -68,6 +70,7 @@ public final class SingleThreadQueueExtent extends ExtentBatchProcessorHolder im
     private boolean[] faweExceptionReasonsUsed = new boolean[FaweException.Type.values().length];
     private int lastException = Integer.MIN_VALUE;
     private int exceptionCount = 0;
+    private List<Runnable> flushTasks = null;
 
     public SingleThreadQueueExtent() {
     }
@@ -198,6 +201,14 @@ public final class SingleThreadQueueExtent extends ExtentBatchProcessorHolder im
         return chunks.isEmpty() && submissions.isEmpty();
     }
 
+    @Override
+    public void addFlushTask(final Runnable task) {
+        if (flushTasks == null) {
+            flushTasks = new ArrayList<>();
+        }
+        flushTasks.add(task);
+    }
+
     @Override
     public <V extends Future<V>> V submit(IQueueChunk chunk) {
         if (lastChunk == chunk) {
@@ -470,6 +481,11 @@ public final class SingleThreadQueueExtent extends ExtentBatchProcessorHolder im
             getChunkLock.unlock();
         }
         pollSubmissions(0, true);
+        if (flushTasks != null) {
+            for (Runnable r : flushTasks) {
+                r.run();
+            }
+        }
     }
 
     @Override

worldedit-core/src/main/java/com/fastasyncworldedit/core/queue/implementation/blocks/ThreadUnsafeCharBlocks.java

@@ -440,7 +440,7 @@ public class ThreadUnsafeCharBlocks implements IChunkSet, IBlocks {
     @Override
     public boolean hasBiomes(int layer) {
         layer -= minSectionPosition;
-        return layer >= 0 && layer < biomes.length && biomes[layer] != null && biomes[layer].length > 0;
+        return layer >= 0 && biomes != null && layer < biomes.length && biomes[layer] != null && biomes[layer].length > 0;
     }
 
     @Override

worldedit-core/src/main/java/com/fastasyncworldedit/core/regions/WorldRegionsRegion.java

@@ -0,0 +1,281 @@
+package com.fastasyncworldedit.core.regions;
+
+import com.fastasyncworldedit.core.anvil.MCAFile;
+import com.fastasyncworldedit.core.anvil.MCAWorld;
+import com.fastasyncworldedit.core.math.MutableBlockVector3;
+import com.fastasyncworldedit.core.util.task.RunnableVal4;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.extension.platform.Capability;
+import com.sk89q.worldedit.math.BlockVector2;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.regions.Region;
+import com.sk89q.worldedit.regions.RegionOperationException;
+import com.sk89q.worldedit.world.World;
+import org.jetbrains.annotations.Nullable;
+
+import javax.annotation.Nonnull;
+import java.nio.file.Path;
+import java.util.AbstractSet;
+import java.util.ArrayDeque;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.Queue;
+import java.util.Set;
+
+public class WorldRegionsRegion implements Region {
+
+    private final MCAWorld world;
+    private final BlockVector3 min;
+    private final BlockVector3 max;
+    private Set<BlockVector2> chunks = null;
+
+    public WorldRegionsRegion(@Nonnull final MCAWorld world) {
+        this.world = Objects.requireNonNull(world);
+        List<Path> regions = world.getRegionFileFiles();
+        int minX = Integer.MAX_VALUE;
+        int minZ = Integer.MAX_VALUE;
+        int maxX = Integer.MIN_VALUE;
+        int maxZ = Integer.MIN_VALUE;
+        for (Path p : regions) {
+            String[] split = p.getFileName().toString().split("\\.");
+            int x = Integer.parseInt(split[1]);
+            int z = Integer.parseInt(split[2]);
+            minX = Math.min(x, minX);
+            minZ = Math.min(z, minZ);
+            maxX = Math.max(x, maxX);
+            maxZ = Math.max(z, maxZ);
+        }
+        this.min = BlockVector3.at(
+                minX,
+                WorldEdit.getInstance().getPlatformManager().queryCapability(Capability.WORLD_EDITING).versionMinY(),
+                minZ
+        );
+        this.max = BlockVector3.at(
+                maxX,
+                WorldEdit.getInstance().getPlatformManager().queryCapability(Capability.WORLD_EDITING).versionMaxY(),
+                maxZ
+        );
+    }
+
+    @Override
+    public Iterator<BlockVector3> iterator() {
+        Queue<BlockVector2> queue = new ArrayDeque<>(getChunks());
+        return new Iterator<>() {
+            private final int by = min.getY();
+            private final int ty = max.getY();
+            private final MutableBlockVector3 mutable = new MutableBlockVector3();
+
+            private BlockVector2 chunk = queue.poll();
+            private int cx = chunk.getX() << 4;
+            private int cz = chunk.getZ() << 4;
+            private int x;
+            private int y;
+            private int z;
+
+            @Override
+            public boolean hasNext() {
+                return x < 15 || y < ty || z < 15 || queue.peek() != null;
+            }
+
+            @Override
+            public MutableBlockVector3 next() {
+                int curX = x;
+                int curY = y;
+                int curZ = z;
+                if (++x > 15) {
+                    if (++z > 15) {
+                        if (++y > ty) {
+                            if (!hasNext()) {
+                                throw new NoSuchElementException("End of iterator") {
+                                    @Override
+                                    public Throwable fillInStackTrace() {
+                                        return this;
+                                    }
+                                };
+                            }
+                            chunk = queue.poll();
+                            x = 0;
+                            y = by;
+                            z = 0;
+                            cx = chunk.getX() << 4;
+                            cz = chunk.getZ() << 4;
+                            return mutable.setComponents(cx + x, y, cz + z);
+                        } else {
+                            x = 0;
+                            z = 0;
+                        }
+                    } else {
+                        x = 0;
+                    }
+                }
+                return mutable.setComponents(cx + curX, curY, cz + curZ);
+            }
+        };
+    }
+
+    @Override
+    public void setWorld(final World world) {
+        throw new UnsupportedOperationException("Cannot modify WorldRegionsRegion - Immutable");
+    }
+
+    @Override
+    public Region clone() {
+        return new WorldRegionsRegion(world);
+    }
+
+    @Override
+    public List<BlockVector2> polygonize(final int maxPoints) {
+        return null;
+    }
+
+    @Override
+    public void shift(final BlockVector3 change) throws RegionOperationException {
+        throw new UnsupportedOperationException("Cannot modify WorldRegionsRegion - Immutable");
+    }
+
+    @Override
+    public BlockVector3 getMinimumPoint() {
+        return min;
+    }
+
+    @Override
+    public BlockVector3 getMaximumPoint() {
+        return max;
+    }
+
+    /**
+     * Get X-size.
+     *
+     * @return width
+     */
+    @Override
+    public int getWidth() {
+        BlockVector3 min = getMinimumPoint();
+        BlockVector3 max = getMaximumPoint();
+
+        return max.getX() - min.getX() + 1;
+    }
+
+    /**
+     * Get Y-size.
+     *
+     * @return height
+     */
+    @Override
+    public int getHeight() {
+        BlockVector3 min = getMinimumPoint();
+        BlockVector3 max = getMaximumPoint();
+
+        return max.getY() - min.getY() + 1;
+    }
+
+    /**
+     * Get Z-size.
+     *
+     * @return length
+     */
+    @Override
+    public int getLength() {
+        BlockVector3 min = getMinimumPoint();
+        BlockVector3 max = getMaximumPoint();
+
+        return max.getZ() - min.getZ() + 1;
+    }
+
+    @Override
+    public void expand(final BlockVector3... changes) throws RegionOperationException {
+        throw new UnsupportedOperationException("Cannot modify WorldRegionsRegion - Immutable");
+    }
+
+    @Override
+    public void contract(final BlockVector3... changes) throws RegionOperationException {
+        throw new UnsupportedOperationException("Cannot modify WorldRegionsRegion - Immutable");
+    }
+
+    @Override
+    public boolean contains(final BlockVector3 position) {
+        return false;
+    }
+
+    @Override
+    public Set<BlockVector2> getChunks() {
+        if (chunks == null) {
+            synchronized (this) {
+                if (chunks != null) {
+                    return chunks;
+                }
+                Set<BlockVector2> tmp = new HashSet<>();
+                for (MCAFile mca : world.getMCAs()) {
+                    mca.forEachChunk(new RunnableVal4<>() {
+                        @Override
+                        public void run(Integer x, Integer z, Integer offset, Integer size) {
+                            if (offset != 0 && size > 0) {
+                                tmp.add(BlockVector2.at(x, z));
+                            }
+                        }
+                    });
+                }
+                chunks = tmp;
+            }
+        }
+        return chunks;
+    }
+
+    @Override
+    public Set<BlockVector3> getChunkCubes() {
+        return new AbstractSet<>() {
+            @Override
+            public Iterator<BlockVector3> iterator() {
+                Queue<BlockVector2> chunks = new ArrayDeque<>(getChunks());
+
+                return new Iterator<>() {
+                    private final MutableBlockVector3 mutable = new MutableBlockVector3();
+                    private final int by = min.getY() >> 4;
+                    private final int ty = max.getY() >> 4;
+
+                    private BlockVector2 chunk = chunks.poll();
+                    private int y;
+
+                    @Override
+                    public boolean hasNext() {
+                        return y < ty || chunks.peek() != null;
+                    }
+
+                    @Override
+                    public BlockVector3 next() {
+                        int curY = y;
+                        if (++y > ty) {
+                            if (!hasNext()) {
+                                throw new NoSuchElementException("End of iterator") {
+                                    @Override
+                                    public Throwable fillInStackTrace() {
+                                        return this;
+                                    }
+                                };
+                            }
+                            y = by;
+                            chunk = chunks.poll();
+                            return mutable.setComponents(chunk.getX(), y, chunk.getZ());
+                        }
+                        return mutable.setComponents(chunk.getX(), curY, chunk.getZ());
+                    }
+                };
+            }
+
+            @Override
+            public int size() {
+                return getChunks().size() * ((max.getY() >> 4) - (min.getY() >> 4));
+            }
+        };
+    }
+
+    @Nullable
+    @Override
+    public World getWorld() {
+        return null;
+    }
+
+}

worldedit-core/src/main/java/com/sk89q/jnbt/NBTInputStream.java

@@ -63,6 +63,7 @@ public final class NBTInputStream implements Closeable {
         this.is = new DataInputStream(is);
     }
 
+    //FAWE start
     public NBTInputStream(DataInputStream dis) {
         this.is = dis;
     }
@@ -75,12 +76,14 @@ public final class NBTInputStream implements Closeable {
         is.reset();
     }
 
+    //FAWE end
     /**
      * Reads an NBT tag from the stream.
      *
      * @return The tag that was read.
      */
     public NamedTag readNamedTag() throws IOException {
+        //FAWE start
         return readNamedTag(0);
     }
 
@@ -101,7 +104,7 @@ public final class NBTInputStream implements Closeable {
         return readTagPayload(type, 0);
     }
 
-    public void readNamedTagLazy(StreamDelegate scope) throws IOException {
+    public void readNamedTagLazy(StreamDelegate scope) {
         try {
             int type = is.readByte();
             if (type == NBTConstants.TYPE_END) {
@@ -112,19 +115,30 @@ public final class NBTInputStream implements Closeable {
             if (child != null) {
                 child.acceptRoot(this, type, 0);
             } else {
-                readTagPayloadLazy(type, 0);
+                readTagPayloadLazy(type, 0, scope, scope.getRetained() != null);
             }
         } catch (Throwable e) {
             e.printStackTrace();
         }
     }
 
+    public void readNamedTagLazyExceptionally(StreamDelegate scope) throws IOException {
+        int type = is.readByte();
+        if (type == NBTConstants.TYPE_END) {
+            return;
+        }
+
+        StreamDelegate child = scope.get(is);
+        if (child != null) {
+            child.acceptRoot(this, type, 0);
+        } else {
+            readTagPayloadLazy(type, 0, scope, scope.getRetained() != null);
+        }
+    }
+
     public String readNamedTagName(int type) throws IOException {
         if (type != NBTConstants.TYPE_END) {
-            int nameLength = is.readShort() & 0xFFFF;
-            byte[] nameBytes = new byte[nameLength];
-            is.readFully(nameBytes);
-            return new String(nameBytes, NBTConstants.CHARSET);
+            return is.readUTF();
         } else {
             return "";
         }
@@ -133,72 +147,107 @@ public final class NBTInputStream implements Closeable {
     private byte[] buf;
 
     public void readTagPayloadLazy(int type, int depth) throws IOException {
+        readTagPayloadLazy(type, depth, null, false);
+    }
+
+    public void readTagPayloadLazy(int type, int depth, StreamDelegate scope, boolean retain) throws IOException {
+        int length;
         switch (type) {
-            case NBTConstants.TYPE_END:
-                return;
-            case NBTConstants.TYPE_BYTE:
-                is.skipBytes(1);
-                return;
-            case NBTConstants.TYPE_SHORT:
-                is.skipBytes(2);
-                return;
-            case NBTConstants.TYPE_INT:
-                is.skipBytes(4);
-                return;
-            case NBTConstants.TYPE_LONG:
-                is.skipBytes(8);
-                return;
-            case NBTConstants.TYPE_FLOAT:
-                is.skipBytes(4);
-                return;
-            case NBTConstants.TYPE_DOUBLE:
-                is.skipBytes(8);
-                return;
-            case NBTConstants.TYPE_STRING:
-                int length = is.readShort() & 0xFFFF;
-                is.skipBytes(length);
-                return;
-            case NBTConstants.TYPE_BYTE_ARRAY:
-                is.skipBytes(is.readInt());
-                return;
-            case NBTConstants.TYPE_LIST: {
-                int childType = is.readByte();
-                length = is.readInt();
-                for (int i = 0; i < length; ++i) {
-                    readTagPayloadLazy(childType, depth + 1);
-                }
-                return;
+            case NBTConstants.TYPE_END -> {
             }
-            case NBTConstants.TYPE_COMPOUND: {
-                // readDataPayload
-                depth++;
-                while (true) {
+            case NBTConstants.TYPE_BYTE -> {
+                if (!retain) {
+                    is.skipBytes(1);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_SHORT -> {
+                if (!retain) {
+                    is.skipBytes(2);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_INT, NBTConstants.TYPE_FLOAT -> {
+                if (!retain) {
+                    is.skipBytes(4);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_LONG, NBTConstants.TYPE_DOUBLE -> {
+                if (!retain) {
+                    is.skipBytes(8);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_STRING -> {
+                length = is.readShort() & 0xFFFF;
+                if (!retain) {
+                    is.skipBytes(length);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_BYTE_ARRAY -> {
+                if (!retain) {
+                    is.skipBytes(is.readInt());
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            case NBTConstants.TYPE_LIST -> {
+                if (!retain) {
                     int childType = is.readByte();
-                    if (childType == NBTConstants.TYPE_END) {
-                        return;
+                    length = is.readInt();
+                    for (int i = 0; i < length; ++i) {
+                        readTagPayloadLazy(childType, depth + 1, scope, retain);
                     }
-                    is.skipBytes(is.readShort() & 0xFFFF);
-                    readTagPayloadLazy(childType, depth + 1);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
                 }
             }
-            case NBTConstants.TYPE_INT_ARRAY: {
-                is.skipBytes(is.readInt() << 2);
-                return;
+            case NBTConstants.TYPE_COMPOUND -> {
+                if (!retain) {
+                    // readDataPayload
+                    depth++;
+                    while (true) {
+                        int childType = is.readByte();
+                        if (childType == NBTConstants.TYPE_END) {
+                            return;
+                        }
+                        is.skipBytes(is.readShort() & 0xFFFF);
+                        readTagPayloadLazy(childType, depth + 1, scope, retain);
+                    }
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
             }
-            case NBTConstants.TYPE_LONG_ARRAY: {
-                is.skipBytes(is.readInt() << 3);
-                return;
+            case NBTConstants.TYPE_INT_ARRAY -> {
+                if (!retain) {
+                    is.skipBytes(is.readInt() << 2);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
             }
-            default:
-                throw new IOException("Invalid tag type: " + type + ".");
+            case NBTConstants.TYPE_LONG_ARRAY -> {
+                if (!retain) {
+                    is.skipBytes(is.readInt() << 3);
+                } else {
+                    scope.retain(readTagPayload(type, depth));
+                }
+            }
+            default -> throw new IOException("Invalid tag type: " + type + ".");
         }
     }
 
     public void readTagPayloadLazy(int type, int depth, StreamDelegate scope) throws IOException {
         switch (type) {
-            case NBTConstants.TYPE_END:
-                return;
-            case NBTConstants.TYPE_BYTE: {
+            case NBTConstants.TYPE_END -> {
+            }
+            case NBTConstants.TYPE_BYTE -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -208,9 +257,8 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(1);
                 }
-                return;
             }
-            case NBTConstants.TYPE_SHORT: {
+            case NBTConstants.TYPE_SHORT -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -220,9 +268,8 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(2);
                 }
-                return;
             }
-            case NBTConstants.TYPE_INT: {
+            case NBTConstants.TYPE_INT -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -232,9 +279,8 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(4);
                 }
-                return;
             }
-            case NBTConstants.TYPE_LONG: {
+            case NBTConstants.TYPE_LONG -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -244,9 +290,8 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(8);
                 }
-                return;
             }
-            case NBTConstants.TYPE_FLOAT: {
+            case NBTConstants.TYPE_FLOAT -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -256,9 +301,8 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(4);
                 }
-                return;
             }
-            case NBTConstants.TYPE_DOUBLE: {
+            case NBTConstants.TYPE_DOUBLE -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
@@ -268,24 +312,20 @@ public final class NBTInputStream implements Closeable {
                 } else {
                     is.skipBytes(8);
                 }
-                return;
             }
-            case NBTConstants.TYPE_STRING: {
+            case NBTConstants.TYPE_STRING -> {
                 ValueReader value = scope.getValueReader();
                 if (value == null) {
                     value = scope.getElemReader();
                 }
-                int length = is.readShort() & 0xFFFF;
                 if (value != null) {
-                    byte[] bytes = new byte[length];
-                    is.readFully(bytes);
-                    value.apply(0, new String(bytes, NBTConstants.CHARSET));
+                    value.apply(0, is.readUTF());
                 } else {
+                    int length = is.readShort() & 0xFFFF;
                     is.skipBytes(length);
                 }
-                return;
             }
-            case NBTConstants.TYPE_LIST: {
+            case NBTConstants.TYPE_LIST -> {
                 int childType = is.readByte();
                 int length = is.readInt();
                 StreamDelegate child;
@@ -306,16 +346,15 @@ public final class NBTInputStream implements Closeable {
                 child = scope.get0();
                 if (child == null) {
                     for (int i = 0; i < length; ++i) {
-                        readTagPayloadLazy(childType, depth + 1);
+                        readTagPayloadLazy(childType, depth + 1, scope, scope.getRetained() != null);
                     }
                 } else {
                     for (int i = 0; i < length; ++i) {
                         readTagPayloadLazy(childType, depth + 1, child);
                     }
                 }
-                return;
             }
-            case NBTConstants.TYPE_COMPOUND: {
+            case NBTConstants.TYPE_COMPOUND -> {
                 // readDataPayload
                 scope.acceptInfo(-1, NBTConstants.TYPE_BYTE);
                 ValueReader valueReader = scope.getValueReader();
@@ -342,14 +381,23 @@ public final class NBTInputStream implements Closeable {
                         return;
                     }
                     StreamDelegate child = scope.get(is);
-                    if (child == null) {
-                        readTagPayloadLazy(childType, depth + 1);
-                    } else {
-                        readTagPayloadLazy(childType, depth + 1, child);
+                    try {
+                        if (child == null) {
+                            readTagPayloadLazy(childType, depth + 1, scope, scope.getRetained() != null);
+                        } else {
+                            readTagPayloadLazy(childType, depth + 1, child);
+                        }
+                    } catch (IOException e) {
+                        String cur = scope.getCurrentName() == null ? scope.getRetainedName() : scope.getCurrentName();
+                        if (cur != null) {
+                            throw new IOException("Error reading child scope: `" + scope.getCurrentName() + "`", e);
+                        } else {
+                            throw e;
+                        }
                     }
                 }
             }
-            case NBTConstants.TYPE_BYTE_ARRAY: {
+            case NBTConstants.TYPE_BYTE_ARRAY -> {
                 int length = is.readInt();
                 scope.acceptInfo(length, NBTConstants.TYPE_BYTE);
                 if (scope.acceptLazy(length, this)) {
@@ -384,9 +432,8 @@ public final class NBTInputStream implements Closeable {
                     return;
                 }
                 is.skipBytes(length);
-                return;
             }
-            case NBTConstants.TYPE_INT_ARRAY: {
+            case NBTConstants.TYPE_INT_ARRAY -> {
                 int length = is.readInt();
                 scope.acceptInfo(length, NBTConstants.TYPE_INT);
                 if (scope.acceptLazy(length, this)) {
@@ -405,9 +452,8 @@ public final class NBTInputStream implements Closeable {
                     return;
                 }
                 is.skipBytes(length << 2);
-                return;
             }
-            case NBTConstants.TYPE_LONG_ARRAY: {
+            case NBTConstants.TYPE_LONG_ARRAY -> {
                 int length = is.readInt();
                 scope.acceptInfo(length, NBTConstants.TYPE_LONG);
                 if (scope.acceptLazy(length, this)) {
@@ -426,11 +472,8 @@ public final class NBTInputStream implements Closeable {
                     return;
                 }
                 is.skipBytes(length << 3);
-                return;
             }
-
-            default:
-                throw new IOException("Invalid tag type: " + type + ".");
+            default -> throw new IOException("Invalid tag type: " + type + ".");
         }
     }
 
@@ -447,65 +490,60 @@ public final class NBTInputStream implements Closeable {
     }
 
     public static int getSize(int type) {
-        switch (type) {
-            default:
-            case NBTConstants.TYPE_END:
-            case NBTConstants.TYPE_BYTE:
-                return 1;
-            case NBTConstants.TYPE_BYTE_ARRAY:
-            case NBTConstants.TYPE_STRING:
-            case NBTConstants.TYPE_LIST:
-            case NBTConstants.TYPE_COMPOUND:
-            case NBTConstants.TYPE_INT_ARRAY:
-            case NBTConstants.TYPE_LONG_ARRAY:
-            case NBTConstants.TYPE_SHORT:
-                return 2;
-            case NBTConstants.TYPE_FLOAT:
-            case NBTConstants.TYPE_INT:
-                return 4;
-            case NBTConstants.TYPE_DOUBLE:
-            case NBTConstants.TYPE_LONG:
-                return 8;
-        }
+        return switch (type) {
+            default -> 1;
+            case NBTConstants.TYPE_BYTE_ARRAY, NBTConstants.TYPE_STRING, NBTConstants.TYPE_LIST, NBTConstants.TYPE_COMPOUND, NBTConstants.TYPE_INT_ARRAY, NBTConstants.TYPE_LONG_ARRAY, NBTConstants.TYPE_SHORT ->
+                    2;
+            case NBTConstants.TYPE_FLOAT, NBTConstants.TYPE_INT -> 4;
+            case NBTConstants.TYPE_DOUBLE, NBTConstants.TYPE_LONG -> 8;
+        };
     }
 
     public Object readTagPayloadRaw(int type, int depth) throws IOException {
+        int length;
+        byte[] bytes;
         switch (type) {
-            case NBTConstants.TYPE_END:
+            case NBTConstants.TYPE_END -> {
                 if (depth == 0) {
                     throw new IOException(
                             "TAG_End found without a TAG_Compound/TAG_List tag preceding it.");
                 } else {
                     return null;
                 }
-            case NBTConstants.TYPE_BYTE:
+            }
+            case NBTConstants.TYPE_BYTE -> {
                 return (is.readByte());
-            case NBTConstants.TYPE_SHORT:
+            }
+            case NBTConstants.TYPE_SHORT -> {
                 return (is.readShort());
-            case NBTConstants.TYPE_INT:
+            }
+            case NBTConstants.TYPE_INT -> {
                 return (is.readInt());
-            case NBTConstants.TYPE_LONG:
+            }
+            case NBTConstants.TYPE_LONG -> {
                 return (is.readLong());
-            case NBTConstants.TYPE_FLOAT:
+            }
+            case NBTConstants.TYPE_FLOAT -> {
                 return (is.readFloat());
-            case NBTConstants.TYPE_DOUBLE:
+            }
+            case NBTConstants.TYPE_DOUBLE -> {
                 return (is.readDouble());
-            case NBTConstants.TYPE_BYTE_ARRAY:
-                int length = is.readInt();
-                byte[] bytes = new byte[length];
-                is.readFully(bytes);
-                return (bytes);
-            case NBTConstants.TYPE_STRING:
-                length = is.readShort() & 0xFFFF;
+            }
+            case NBTConstants.TYPE_BYTE_ARRAY -> {
+                length = is.readInt();
                 bytes = new byte[length];
                 is.readFully(bytes);
-                return (new String(bytes, NBTConstants.CHARSET));
-            case NBTConstants.TYPE_LIST: {
+                return (bytes);
+            }
+            case NBTConstants.TYPE_STRING -> {
+                return is.readUTF();
+            }
+            case NBTConstants.TYPE_LIST -> {
                 int childType = is.readByte();
                 length = is.readInt();
                 return readListRaw(depth, childType, length);
             }
-            case NBTConstants.TYPE_COMPOUND: {
+            case NBTConstants.TYPE_COMPOUND -> {
                 Map<String, Object> tagMap = new HashMap<>();
                 while (true) {
                     int childType = is.readByte();
@@ -517,16 +555,15 @@ public final class NBTInputStream implements Closeable {
                     tagMap.put(name, value);
                 }
             }
-            case NBTConstants.TYPE_INT_ARRAY: {
+            case NBTConstants.TYPE_INT_ARRAY -> {
                 length = is.readInt();
                 return readIntArrayRaw(length);
             }
-            case NBTConstants.TYPE_LONG_ARRAY: {
+            case NBTConstants.TYPE_LONG_ARRAY -> {
                 length = is.readInt();
                 return readLongArrayRaw(length);
             }
-            default:
-                throw new IOException("Invalid tag type: " + type + ".");
+            default -> throw new IOException("Invalid tag type: " + type + ".");
         }
     }
 
@@ -542,7 +579,7 @@ public final class NBTInputStream implements Closeable {
             for (int i = 0; i < toRead; i += 4, index++) {
                 data[index] = ((buf[i] & 0xFF) << 24) + ((buf[i + 1] & 0xFF) << 16) + ((buf[i + 2] & 0xFF) << 8) + (buf[i + 3] & 0xFF);
             }
-            length -= toRead;
+            length -= (toRead >> 2);
         }
         return data;
     }
@@ -559,7 +596,7 @@ public final class NBTInputStream implements Closeable {
             for (int i = 0; i < toRead; i += 8, index++) {
                 data[index] = (((long) buf[i] << 56) | ((long) (buf[i + 1] & 255) << 48) | ((long) (buf[i + 2] & 255) << 40) | ((long) (buf[i + 3] & 255) << 32) | ((long) (buf[i + 4] & 255) << 24) | ((buf[i + 5] & 255) << 16) | ((buf[i + 6] & 255) << 8) | (buf[i + 7] & 255));
             }
-            length -= toRead;
+            length -= (toRead >> 3);
         }
         return (data);
     }
@@ -573,40 +610,47 @@ public final class NBTInputStream implements Closeable {
      * @throws IOException if an I/O error occurs.
      */
     public Tag readTagPayload(int type, int depth) throws IOException { //FAWE - public
+        int length;
+        byte[] bytes;
         switch (type) {
-            case NBTConstants.TYPE_END:
+            case NBTConstants.TYPE_END -> {
                 if (depth == 0) {
                     throw new IOException(
                             "TAG_End found without a TAG_Compound/TAG_List tag preceding it.");
                 } else {
                     return new EndTag();
                 }
-            case NBTConstants.TYPE_BYTE:
+            }
+            case NBTConstants.TYPE_BYTE -> {
                 return new ByteTag(is.readByte());
-            case NBTConstants.TYPE_SHORT:
+            }
+            case NBTConstants.TYPE_SHORT -> {
                 return new ShortTag(is.readShort());
-            case NBTConstants.TYPE_INT:
+            }
+            case NBTConstants.TYPE_INT -> {
                 return new IntTag(is.readInt());
-            case NBTConstants.TYPE_LONG:
+            }
+            case NBTConstants.TYPE_LONG -> {
                 return new LongTag(is.readLong());
-            case NBTConstants.TYPE_FLOAT:
+            }
+            case NBTConstants.TYPE_FLOAT -> {
                 return new FloatTag(is.readFloat());
-            case NBTConstants.TYPE_DOUBLE:
+            }
+            case NBTConstants.TYPE_DOUBLE -> {
                 return new DoubleTag(is.readDouble());
-            case NBTConstants.TYPE_BYTE_ARRAY:
-                int length = is.readInt();
-                byte[] bytes = new byte[length];
-                is.readFully(bytes);
-                return new ByteArrayTag(bytes);
-            case NBTConstants.TYPE_STRING:
-                length = is.readShort() & 0xFFFF;
+            }
+            case NBTConstants.TYPE_BYTE_ARRAY -> {
+                length = is.readInt();
                 bytes = new byte[length];
                 is.readFully(bytes);
-                return new StringTag(new String(bytes, NBTConstants.CHARSET));
-            case NBTConstants.TYPE_LIST:
+                return new ByteArrayTag(bytes);
+            }
+            case NBTConstants.TYPE_STRING -> {
+                return new StringTag(is.readUTF());
+            }
+            case NBTConstants.TYPE_LIST -> {
                 int childType = is.readByte();
                 length = is.readInt();
-
                 List<Tag> tagList = new ArrayList<>();
                 for (int i = 0; i < length; ++i) {
                     Tag tag = readTagPayload(childType, depth + 1);
@@ -615,9 +659,9 @@ public final class NBTInputStream implements Closeable {
                     }
                     tagList.add(tag);
                 }
-
                 return new ListTag(NBTUtils.getTypeClass(childType), tagList);
-            case NBTConstants.TYPE_COMPOUND:
+            }
+            case NBTConstants.TYPE_COMPOUND -> {
                 Map<String, Tag<?, ?>> tagMap = new HashMap<>();
                 while (true) {
                     NamedTag namedTag = readNamedTag(depth + 1);
@@ -628,24 +672,25 @@ public final class NBTInputStream implements Closeable {
                         tagMap.put(namedTag.getName(), tag);
                     }
                 }
-
                 return new CompoundTag(tagMap);
-            case NBTConstants.TYPE_INT_ARRAY:
+            }
+            case NBTConstants.TYPE_INT_ARRAY -> {
                 length = is.readInt();
                 int[] data = new int[length];
                 for (int i = 0; i < length; i++) {
                     data[i] = is.readInt();
                 }
                 return new IntArrayTag(data);
-            case NBTConstants.TYPE_LONG_ARRAY:
+            }
+            case NBTConstants.TYPE_LONG_ARRAY -> {
                 length = is.readInt();
                 long[] longData = new long[length];
                 for (int i = 0; i < length; i++) {
                     longData[i] = is.readLong();
                 }
                 return new LongArrayTag(longData);
-            default:
-                throw new IOException("Invalid tag type: " + type + ".");
+            }
+            default -> throw new IOException("Invalid tag type: " + type + ".");
         }
     }
 

worldedit-core/src/main/java/com/sk89q/jnbt/NBTOutputStream.java

@@ -112,9 +112,7 @@ public final class NBTOutputStream extends OutputStream implements Closeable, Da
         checkNotNull(value);
         int type = NBTConstants.TYPE_STRING;
         writeNamedTagName(name, type);
-        byte[] bytes = value.getBytes(NBTConstants.CHARSET);
-        os.writeShort(bytes.length);
-        os.write(bytes);
+        os.writeUTF(value);
     }
 
     public void writeNamedTag(String name, int value) throws IOException {
@@ -163,6 +161,16 @@ public final class NBTOutputStream extends OutputStream implements Closeable, Da
         }
     }
 
+    public void writeNamedTag(String name, long[] data) throws IOException {
+        checkNotNull(name);
+        int type = NBTConstants.TYPE_LONG_ARRAY;
+        writeNamedTagName(name, type);
+        os.writeInt(data.length);
+        for (long aData : data) {
+            os.writeLong(aData);
+        }
+    }
+
     public void writeNamedEmptyList(String name) throws IOException {
         writeNamedEmptyList(name, NBTConstants.TYPE_COMPOUND);
     }
@@ -183,10 +191,13 @@ public final class NBTOutputStream extends OutputStream implements Closeable, Da
     }
 
     public void writeLazyCompoundTag(String name, LazyWrite next) throws IOException {
-        byte[] nameBytes = name.getBytes(NBTConstants.CHARSET);
         os.writeByte(NBTConstants.TYPE_COMPOUND);
-        os.writeShort(nameBytes.length);
-        os.write(nameBytes);
+        os.writeUTF(name);
+        next.write(this);
+        os.writeByte(NBTConstants.TYPE_END);
+    }
+
+    public void writeLazyListedCompoundTag(LazyWrite next) throws IOException {
         next.write(this);
         os.writeByte(NBTConstants.TYPE_END);
     }
@@ -327,9 +338,7 @@ public final class NBTOutputStream extends OutputStream implements Closeable, Da
      * @throws IOException if an I/O error occurs.
      */
     private void writeStringTagPayload(StringTag tag) throws IOException {
-        byte[] bytes = tag.getValue().getBytes(NBTConstants.CHARSET);
-        os.writeShort(bytes.length);
-        os.write(bytes);
+        os.writeUTF(tag.getValue());
     }
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/command/AnvilCommands.java

@@ -1,12 +1,24 @@
-package com.fastasyncworldedit.core.command;
+package com.sk89q.worldedit.command;
 
+import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.anvil.MCAChunk;
+import com.fastasyncworldedit.core.anvil.MCAWorld;
+import com.fastasyncworldedit.core.configuration.Caption;
+import com.fastasyncworldedit.core.queue.IQueueChunk;
+import com.fastasyncworldedit.core.queue.IQueueExtent;
+import com.fastasyncworldedit.core.regions.WorldRegionsRegion;
+import com.fastasyncworldedit.core.util.MaskTraverser;
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.EditSessionBuilder;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.WorldEditException;
 import com.sk89q.worldedit.command.util.CommandPermissions;
 import com.sk89q.worldedit.command.util.CommandPermissionsConditionGenerator;
 import com.sk89q.worldedit.entity.Player;
+import com.sk89q.worldedit.extension.platform.Actor;
+import com.sk89q.worldedit.function.mask.AbstractExtentMask;
+import com.sk89q.worldedit.function.mask.Mask;
 import com.sk89q.worldedit.function.pattern.Pattern;
 import com.sk89q.worldedit.internal.annotation.Selection;
 import com.sk89q.worldedit.regions.Region;
@@ -20,13 +32,6 @@ import java.io.IOException;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-/**
- * @deprecated Anvil classes were used on versions prior to 1.13 to trim chunks.
- *         The way how it's been done was unsafe and led to issues back the years, hence it
- *         hasn't been implemented in any modern version. Therefore the current
- *         implementation is deprecated for removal without replacement.
- */
-@Deprecated
 @CommandContainer(superTypes = CommandPermissionsConditionGenerator.Registration.class)
 public class AnvilCommands {
 
@@ -116,57 +121,22 @@ public class AnvilCommands {
     //    }
 
     @Command(
-            name = "replaceall",
-            aliases = {"rea", "repall"},
-            desc = "Replace all blocks in the selection with another"
-    )
+            name = "replaceall", aliases = {"rea", "repall"}, desc = "Replace all blocks in the selection with another")
     @CommandPermissions("worldedit.anvil.replaceall")
     public void replaceAll(
-            Player player, String folder,
-            @Arg(name = "from", desc = "String", def = "")
-                    String fromPattern,
-            String toPatternStr,
-            @Switch(name = 'd', desc = "Disable wildcard data matching")
-                    boolean useData
+            Actor actor,
+            @Arg(name = "world", desc = "Unloaded world") MCAWorld world,
+            @Arg(name = "from", desc = "Mask") Mask from,
+            @Arg(name = "to", desc = "Pattern") Pattern to
     ) throws WorldEditException {
-        //        final FaweBlockMatcher matchFrom;  TODO NOT IMPLEMENTED
-        //        if (from == null) {
-        //            matchFrom = FaweBlockMatcher.NOT_AIR;
-        //        } else {
-        //            if (from.contains(":")) {
-        //                useData = true; //override d flag, if they specified data they want it
-        //            }
-        //            matchFrom = FaweBlockMatcher.fromBlocks(worldEdit.getBlocks(player, from, true), useData);
-        //        }
-        //        final FaweBlockMatcher matchTo = FaweBlockMatcher.setBlocks(worldEdit.getBlocks(player, to, true));
-        //        ReplaceSimpleFilter filter = new ReplaceSimpleFilter(matchFrom, matchTo);
-        //        ReplaceSimpleFilter result = runWithWorld(player, folder, filter, true);
-        //        if (result != null) player.print(Caption.of("fawe.worldedit.visitor.visitor.block", (result.getTotal())));
+        IQueueExtent<IQueueChunk> queueExtent = Fawe.instance().getQueueHandler().getMCAQueue(world);
+        new MaskTraverser(from).setNewExtent(queueExtent);
+        queueExtent.replaceBlocks(new WorldRegionsRegion(world), from, to);
+        queueExtent.flush();
+        actor.print(Caption.of("fawe.worldedit.anvil.replaceall.complete"));
     }
 
-    @Command(
-            name = "remapall",
-            descFooter = "Remap the world between MCPE/PC values",
-            desc = "Remap the world between MCPE/PC values"
-    )
-    @CommandPermissions("worldedit.anvil.remapall")
-    public void remapall(Player player, String folder) throws WorldEditException {
-        //        ClipboardRemapper.RemapPlatform from; TODO NOT IMPLEMENTED
-        //        ClipboardRemapper.RemapPlatform to;
-        //        from = ClipboardRemapper.RemapPlatform.PE;
-        //        to = ClipboardRemapper.RemapPlatform.PC;
-        //        RemapFilter filter = new RemapFilter(from, to);
-        //        RemapFilter result = runWithWorld(player, folder, filter, true);
-        //        if (result != null) {
-        //            player.print(Caption.of("fawe.worldedit.visitor.visitor.block", (result.getTotal())));
-        //        }
-    }
-
-
-    @Command(
-            name = "deleteallunvisited",
-            aliases = {"delunvisited"},
-            desc = "Delete all chunks which haven't been occupied",
+    @Command(name = "deleteallunvisited", aliases = {"delunvisited"}, desc = "Delete all chunks which haven't been occupied",
             descFooter = "occupied for `age-ticks` (20t = 1s) and \n"
                     + "Have not been accessed since `file-duration` (ms) after creation and\n"
                     + "Have not been used in the past `chunk-inactivity` (ms)"

worldedit-core/src/main/java/com/sk89q/worldedit/command/argument/MCAWorldConverter.java

@@ -0,0 +1,96 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team 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 <https://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.command.argument;
+
+import com.fastasyncworldedit.core.Fawe;
+import com.fastasyncworldedit.core.anvil.MCAWorld;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.extension.platform.Capability;
+import com.sk89q.worldedit.internal.util.LogManagerCompat;
+import com.sk89q.worldedit.util.formatting.text.Component;
+import com.sk89q.worldedit.util.formatting.text.TextComponent;
+import com.sk89q.worldedit.world.World;
+import org.apache.logging.log4j.Logger;
+import org.enginehub.piston.CommandManager;
+import org.enginehub.piston.converter.ArgumentConverter;
+import org.enginehub.piston.converter.ConversionResult;
+import org.enginehub.piston.converter.FailedConversion;
+import org.enginehub.piston.converter.SuccessfulConversion;
+import org.enginehub.piston.inject.InjectedValueAccess;
+import org.enginehub.piston.inject.Key;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class MCAWorldConverter implements ArgumentConverter<MCAWorld> {
+
+    private static final Logger LOGGER = LogManagerCompat.getLogger();
+
+    public static void register(CommandManager commandManager) {
+        commandManager.registerConverter(Key.of(MCAWorld.class), WORLD_CONVERTER);
+    }
+
+    //FAWE start - Accessed by LocationConverter
+    public static final MCAWorldConverter WORLD_CONVERTER = new MCAWorldConverter();
+    //FAWE end
+
+    private final TextComponent choices;
+
+    private MCAWorldConverter() {
+        this.choices = TextComponent.of("any world");
+    }
+
+    @Override
+    public Component describeAcceptableArguments() {
+        return this.choices;
+    }
+
+    private Stream<? extends String> getWorlds() {
+        try {
+            return Files.list(Fawe.platform().getWorldsFolder()).filter(p -> Files.isDirectory(p) && Files.exists(p.resolve(
+                    "level.dat"))).map(p -> p.getFileName().toString());
+        } catch (IOException e) {
+            LOGGER.error("Error accessing worlds", e);
+            return Stream.empty();
+        }
+    }
+
+    @Override
+    public List<String> getSuggestions(String input, InjectedValueAccess context) {
+        return getWorlds()
+                .filter(world -> world.startsWith(input))
+                .collect(Collectors.toList());
+    }
+
+    @Override
+    public ConversionResult<MCAWorld> convert(String s, InjectedValueAccess injectedValueAccess) {
+        String result = getWorlds()
+                .filter(world -> world.equals(s))
+                .findAny().orElse(null);
+        return result == null
+                ? FailedConversion.from(new IllegalArgumentException(
+                "Not a valid world: " + s))
+                : SuccessfulConversion.fromSingle(MCAWorld.of(result));
+    }
+
+}

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/Platform.java

@@ -276,5 +276,21 @@ public interface Platform extends Keyed {
     default IBatchProcessor getPlatformPostProcessor(boolean fastMode) {
         return null;
     }
+
+    /**
+     * Get a char array of minecraft internal IDs against FAWE char IDs
+     */
+    @Nullable
+    default char[] getIbdToStateOrdinal() {
+        return null;
+    }
+
+    /**
+     * Get an int array of FAWE char IDs against minecraft internal IDs
+     */
+    @Nullable
+    default int[] getOrdinalToIbdID() {
+        return null;
+    }
     //FAWE end
 }

worldedit-core/src/main/java/com/sk89q/worldedit/extension/platform/PlatformCommandManager.java

@@ -42,6 +42,8 @@ import com.sk89q.worldedit.LocalConfiguration;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.MissingWorldException;
 import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.command.AnvilCommands;
+import com.sk89q.worldedit.command.AnvilCommandsRegistration;
 import com.sk89q.worldedit.command.ApplyBrushCommands;
 import com.sk89q.worldedit.command.BiomeCommands;
 import com.sk89q.worldedit.command.BiomeCommandsRegistration;
@@ -98,6 +100,7 @@ import com.sk89q.worldedit.command.argument.ExpressionConverter;
 import com.sk89q.worldedit.command.argument.FactoryConverter;
 import com.sk89q.worldedit.command.argument.HeightConverter;
 import com.sk89q.worldedit.command.argument.LocationConverter;
+import com.sk89q.worldedit.command.argument.MCAWorldConverter;
 import com.sk89q.worldedit.command.argument.OffsetConverter;
 import com.sk89q.worldedit.command.argument.RegionFactoryConverter;
 import com.sk89q.worldedit.command.argument.RegistryConverter;
@@ -275,6 +278,7 @@ public final class PlatformCommandManager {
         ClipboardFormatConverter.register(commandManager);
         ClipboardShareDestinationConverter.register(commandManager);
         //FAWE start
+        MCAWorldConverter.register(commandManager);
         commandManager.registerConverter(
                 Key.of(com.sk89q.worldedit.function.pattern.Pattern.class, Annotations.patternList()),
                 CommaSeparatedValuesConverter.wrap(commandManager.getConverter(Key.of(
@@ -536,6 +540,13 @@ public final class PlatformCommandManager {
                     HistorySubCommandsRegistration.builder(),
                     new HistorySubCommands(history)
             );
+            registerSubCommands(
+                    "/anvil",
+                    ImmutableList.of(),
+                    "Anvil commands",
+                    AnvilCommandsRegistration.builder(),
+                    new AnvilCommands(worldEdit)
+            );
             //FAWE end
             this.registration.register(
                     commandManager,

worldedit-core/src/main/resources/lang/strings.json

@@ -32,6 +32,7 @@
   "fawe.worldedit.history.command.undo.disabled": "Undo disabled, use: //fast",
   "fawe.worldedit.selection.selection.count": "Counted {0} blocks.",
   "fawe.worldedit.anvil.world.is.loaded": "The world shouldn't be in use when executing. Unload the world, or use -f to override (save first)",
+  "fawe.worldedit.anvil.replaceall.complete": "Replaceall with anvil completed.",
   "fawe.worldedit.brush.brush.reset": "Reset your brush. (SHIFT + Click)",
   "fawe.worldedit.brush.brush.none": "You aren't holding a brush!",
   "fawe.worldedit.brush.brush.scroll.action.set": "Set scroll action to {0}",