diff --git a/core/src/main/java/mc/core/world/Block.java b/core/src/main/java/mc/core/world/Block.java
new file mode 100644
index 0000000..ba2865a
--- /dev/null
+++ b/core/src/main/java/mc/core/world/Block.java
@@ -0,0 +1,15 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-08-02
+ */
+package mc.core.world;
+
+import mc.core.Location;
+
+public interface Block {
+    int getId();
+    int getState();
+    int getMetadata();
+    int getLight();
+    Location getLocation();
+}
diff --git a/core/src/main/java/mc/core/world/Chunk.java b/core/src/main/java/mc/core/world/Chunk.java
index 15ee0fa..db8f289 100644
--- a/core/src/main/java/mc/core/world/Chunk.java
+++ b/core/src/main/java/mc/core/world/Chunk.java
@@ -4,16 +4,15 @@
  */
 package mc.core.world;
 
+import mc.core.Location;
+
 /* 16x16x16 */
 public interface Chunk {
-    int getBlockType(int x, int y, int z);
-    void setBlockType(int x, int y, int z, int type);
-
-    int getBlockMetadata(int x, int y, int z);
-    void setBlockMetadata(int x, int y, int z, int metadata);
-
-    int getBlockLight(int x, int y, int z);
-    void setBlockLight(int x, int y, int z, int lightLevel);
+    Block getBlock(int x, int y, int z);
+    default Block getBlock(Location location) {
+        return getBlock(location.getBlockX(), location.getBlockY(), location.getBlockZ());
+    }
+    void setBlock(Block block);
 
     int getSkyLight(int x, int y, int z);
     void setSkyLight(int x, int y, int z, int lightLevel);
diff --git a/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/ByteArrayOutputNetStream.java b/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/ByteArrayOutputNetStream.java
index 15810b7..d496e05 100644
--- a/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/ByteArrayOutputNetStream.java
+++ b/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/ByteArrayOutputNetStream.java
@@ -65,6 +65,10 @@ public class ByteArrayOutputNetStream extends NetOutputStream_p340 {
         writeLong(Double.doubleToLongBits(value));
     }
 
+    public int size() {
+        return baos.size();
+    }
+
     public byte[] toByteArray() {
         return baos.toByteArray();
     }
diff --git a/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/packets/ChunkDataPacket.java b/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/packets/ChunkDataPacket.java
index c05c479..f1e9f98 100644
--- a/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/packets/ChunkDataPacket.java
+++ b/proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/packets/ChunkDataPacket.java
@@ -10,6 +10,7 @@ import lombok.Setter;
 import lombok.extern.slf4j.Slf4j;
 import mc.core.network.NetOutputStream;
 import mc.core.network.SCPacket;
+import mc.core.network.proto_1_12_2.ByteArrayOutputNetStream;
 import mc.core.world.Chunk;
 
 import java.io.ByteArrayOutputStream;
@@ -17,6 +18,55 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
+/*
+Packet structure
+
+- https://wiki.vg/Chunk_Format#Packet_structure
+
++------------------------------------------------------+
+|          Field           |           Type            |
+|--------------------------|---------------------------|
+| Chunk X                  | int                       |
+|--------------------------|---------------------------|
+| Chunk Y                  | int                       |
+|--------------------------|---------------------------|
+| Init Chunk               | boolean                   |   ("Ground-Up Continuous")
+|--------------------------|---------------------------|
+| Primary Bit Mask         | VarInt                    |
+|--------------------------|---------------------------|
+| Size of Data             | VarInt                    |
+|--------------------------|---------------------------|
+| Data                     | Byte array                | - https://wiki.vg/Chunk_Format#Data_structure
+|  +------------------------------------------------+  |
+|  | Chunk Section         | Byte array             |  | - https://wiki.vg/Chunk_Format#Chunk_Section_structure
+|  |  +------------------------------------------+  |  |
+|  |  | Bits Per Block     | Unsigned Byte       |  |  |
+|  |  |--------------------|---------------------|  |  |
+|  |  | Palette            | Byte array          |  |  | - https://wiki.vg/Chunk_Format#Palettes
+|  |  |  +------------------------------------+  |  |  |   (we use Indirect type palette)
+|  |  |  | Size of palette | VarInt           |  |  |  |
+|  |  |  |-----------------|------------------|  |  |  |
+|  |  |  | Palette         | Array of VarInt  |  |  |  |
+|  |  |  +------------------------------------+  |  |  |
+|  |  |--------------------|---------------------|  |  |
+|  |  | Size of Data Array | VarInt              |  |  |
+|  |  |--------------------|---------------------|  |  |
+|  |  | Data Array         | Array of Long       |  |  |
+|  |  |--------------------|---------------------|  |  |
+|  |  | Block Light        | Byte Array          |  |  |
+|  |  |--------------------|---------------------|  |  |
+|  |  | Sky Light          | Optional Byte Array |  |  |
+|  |  +------------------------------------------+  |  |
+|  |-----------------------|------------------------|  |
+|  | Biomes                | Optional Byte array    |  |
+|  +------------------------------------------------+  |
+|--------------------------|---------------------------|
+| Number of block entities | VarInt                    |
+|--------------------------|---------------------------|
+| Block entities           | Array of NBT              |
++------------------------------------------------------+
+ */
+
 @Slf4j
 @NoArgsConstructor
 public class ChunkDataPacket implements SCPacket {
@@ -36,19 +86,14 @@ public class ChunkDataPacket implements SCPacket {
         netStream.writeBoolean(initChunk);
         netStream.writeVarInt(0b11111111); // Primary Bit Mask
 
-        ByteArrayOutputStream baos = new ByteArrayOutputStream();
-        try {
-            for (Chunk chunk : chunks) {
-                netStream.writeByte(4); // Bits Per Block
-                // <Palette  />
-                // <Data Array Length  />
-                // <Data Array />
-                // <Block Light />
-                // <Sky Light />
-//                baos.write(ChunkSerializer.serializeBiomes(chunk));
-            }
-        } catch (IOException e) {
-            log.error("Error serialize chunk", e); // what? is it possible??
+        ByteArrayOutputNetStream baos = new ByteArrayOutputNetStream();
+        for (Chunk chunk : chunks) {
+            // <Bits Per Block />
+            // <Palette  />
+            // <Data Array Length  />
+            // <Data Array />
+            // <Block Light />
+            // <Sky Light />
         }
         netStream.writeVarInt(baos.size()); // Size of Data in bytes
         netStream.writeBytes(baos.toByteArray()); // Data chunks