Fix the arrays

src/main/java/us/myles/ViaVersion/api/type/Type.java

@@ -60,7 +60,7 @@ public abstract class Type<T> implements ByteBufReader<T>, ByteBufWriter<T> {
     public static final Type<EulerAngle> ROTATION = new EulerAngleType();
     public static final Type<Vector> VECTOR = new VectorType();
     public static final Type<CompoundTag> NBT = new NBTType();
-    public static final Type<List<CompoundTag>> NBT_ARRAY = new NBTArrayType();
+    public static final Type<CompoundTag[]> NBT_ARRAY = new ArrayType<>(Type.NBT);
 
     public static final Type<UUID> OPTIONAL_UUID = new OptUUIDType();
     public static final Type<Position> OPTIONAL_POSITION = new OptPositionType();

src/main/java/us/myles/ViaVersion/api/type/types/minecraft/NBTArrayType.java

@@ -1,33 +0,0 @@
-package us.myles.ViaVersion.api.type.types.minecraft;
-
-import io.netty.buffer.ByteBuf;
-import org.spacehq.opennbt.tag.builtin.CompoundTag;
-import us.myles.ViaVersion.api.type.Type;
-
-import java.util.ArrayList;
-import java.util.List;
-
-public class NBTArrayType extends Type<List<CompoundTag>> {
-    public NBTArrayType() {
-        super("NBT Array", List.class);
-    }
-
-    @Override
-    public List<CompoundTag> read(ByteBuf buffer) throws Exception {
-        int amount = Type.VAR_INT.read(buffer);
-
-        List<CompoundTag> nbtData = new ArrayList<>();
-        for (int i = 0; i < amount; i++)
-            nbtData.add(Type.NBT.read(buffer));
-
-        return nbtData;
-    }
-
-    @Override
-    public void write(ByteBuf buffer, List<CompoundTag> list) throws Exception {
-        Type.VAR_INT.write(buffer, list.size());
-
-        for (CompoundTag tag : list)
-            Type.NBT.write(buffer, tag);
-    }
-}

src/main/java/us/myles/ViaVersion/protocols/protocol1_9_3to1_9_1_2/ChunkSection1_9_1_2.java

@@ -0,0 +1,197 @@
+package us.myles.ViaVersion.protocols.protocol1_9_3to1_9_1_2;
+
+import com.google.common.collect.Lists;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import us.myles.ViaVersion.api.minecraft.chunks.NibbleArray;
+import us.myles.ViaVersion.api.type.Type;
+
+import java.util.List;
+
+public class ChunkSection1_9_1_2 {
+    /**
+     * Size (dimensions) of blocks in a chunks section.
+     */
+    public static final int SIZE = 16 * 16 * 16; // width * depth * height
+    /**
+     * Length of the sky and block light nibble arrays.
+     */
+    public static final int LIGHT_LENGTH = 16 * 16 * 16 / 2; // size * size * size / 2 (nibble bit count)
+    /**
+     * Length of the block data array.
+     */
+
+    private final List<Integer> palette = Lists.newArrayList();
+    private final int[] blocks;
+    private final NibbleArray blockLight;
+    private NibbleArray skyLight;
+
+    public ChunkSection1_9_1_2() {
+        this.blocks = new int[SIZE];
+        this.blockLight = new NibbleArray(SIZE);
+        palette.add(0); // AIR
+    }
+
+    /**
+     * Set a block in the chunks
+     *
+     * @param x    Block X
+     * @param y    Block Y
+     * @param z    Block Z
+     * @param type The type of the block
+     * @param data The data value of the block
+     */
+    public void setBlock(int x, int y, int z, int type, int data) {
+        setBlock(index(x, y, z), type, data);
+    }
+
+    public int getBlockId(int x, int y, int z){
+        int index = blocks[index(x, y, z)];
+        return palette.indexOf(index) >> 4;
+    }
+
+    /**
+     * Set a block in the chunks based on the index
+     *
+     * @param idx  Index
+     * @param type The type of the block
+     * @param data The data value of the block
+     */
+    public void setBlock(int idx, int type, int data) {
+        int hash = type << 4 | (data & 0xF);
+        int index = palette.indexOf(hash);
+        if (index == -1) {
+            index = palette.size();
+            palette.add(hash);
+        }
+
+        blocks[idx] = index;
+    }
+
+    /**
+     * Set the block light array
+     *
+     * @param data The value to set the block light to
+     */
+    public void setBlockLight(byte[] data) {
+        blockLight.setHandle(data);
+    }
+
+    /**
+     * Set the sky light array
+     *
+     * @param data The value to set the sky light to
+     */
+    public void setSkyLight(byte[] data) {
+        if (data.length != LIGHT_LENGTH) throw new IllegalArgumentException("Data length != " + LIGHT_LENGTH);
+        this.skyLight = new NibbleArray(data);
+    }
+
+    private int index(int x, int y, int z) {
+        return z << 8 | y << 4 | x;
+    }
+
+    /**
+     * Write the blocks to a buffer.
+     *
+     * @param output The buffer to write to.
+     * @throws Exception Throws if it failed to write.
+     */
+    public void writeBlocks(ByteBuf output) throws Exception {
+        // Write bits per block
+        int bitsPerBlock = 4;
+        while (palette.size() > 1 << bitsPerBlock) {
+            bitsPerBlock += 1;
+        }
+        long maxEntryValue = (1L << bitsPerBlock) - 1;
+        output.writeByte(bitsPerBlock);
+
+        // Write pallet (or not)
+        Type.VAR_INT.write(output, palette.size());
+        for (int mappedId : palette) {
+            Type.VAR_INT.write(output, mappedId);
+        }
+
+        int length = (int) Math.ceil(SIZE * bitsPerBlock / 64.0);
+        Type.VAR_INT.write(output, length);
+        long[] data = new long[length];
+        for (int index = 0; index < blocks.length; index++) {
+            int value = blocks[index];
+            int bitIndex = index * bitsPerBlock;
+            int startIndex = bitIndex / 64;
+            int endIndex = ((index + 1) * bitsPerBlock - 1) / 64;
+            int startBitSubIndex = bitIndex % 64;
+            data[startIndex] = data[startIndex] & ~(maxEntryValue << startBitSubIndex) | ((long) value & maxEntryValue) << startBitSubIndex;
+            if (startIndex != endIndex) {
+                int endBitSubIndex = 64 - startBitSubIndex;
+                data[endIndex] = data[endIndex] >>> endBitSubIndex << endBitSubIndex | ((long) value & maxEntryValue) >> endBitSubIndex;
+            }
+        }
+        for (long l : data) {
+            Type.LONG.write(output, l);
+        }
+    }
+
+    /**
+     * Write the block light to a buffer
+     *
+     * @param output The buffer to write to
+     */
+    public void writeBlockLight(ByteBuf output) {
+        output.writeBytes(blockLight.getHandle());
+    }
+
+    /**
+     * Write the sky light to a buffer
+     *
+     * @param output The buffer to write to
+     */
+    public void writeSkyLight(ByteBuf output) {
+        output.writeBytes(skyLight.getHandle());
+    }
+
+    /**
+     * Check if sky light is present
+     *
+     * @return True if skylight is present
+     */
+    public boolean hasSkyLight() {
+        return skyLight != null;
+    }
+
+    /**
+     * Get expected size of this chunks section.
+     *
+     * @return Amount of bytes sent by this section
+     * @throws Exception If it failed to calculate bits properly
+     */
+    public int getExpectedSize() throws Exception {
+        int bitsPerBlock = palette.size() > 255 ? 16 : 8;
+        int bytes = 1; // bits per block
+        bytes += paletteBytes(); // palette
+        bytes += countBytes(bitsPerBlock == 16 ? SIZE * 2 : SIZE); // block data length
+        bytes += (palette.size() > 255 ? 2 : 1) * SIZE; // block data
+        bytes += LIGHT_LENGTH; // block light
+        bytes += hasSkyLight() ? LIGHT_LENGTH : 0; // sky light
+        return bytes;
+    }
+
+    private int paletteBytes() throws Exception {
+        // Count bytes used by pallet
+        int bytes = countBytes(palette.size());
+        for (int mappedId : palette) {
+            bytes += countBytes(mappedId);
+        }
+        return bytes;
+    }
+
+    private int countBytes(int value) throws Exception {
+        // Count amount of bytes that would be sent if the value were sent as a VarInt
+        ByteBuf buf = Unpooled.buffer();
+        Type.VAR_INT.write(buf, value);
+        buf.readerIndex(0);
+        int bitCount = buf.readableBytes();
+        buf.release();
+        return bitCount;
+    }
+}

src/main/java/us/myles/ViaVersion/protocols/protocol1_9to1_8/types/ChunkType.java

@@ -179,7 +179,7 @@ public class ChunkType extends PartialType<Chunk, ClientChunks> {
             output.writeBytes(chunk.getBiomeData());
         }
 
-        Type.NBT_ARRAY.write(buf, tags);
+        Type.NBT_ARRAY.write(output, tags.toArray(new CompoundTag[0]));
     }