From cbdc82bd444c722be70c5140e2bd4756d7f9a0fc Mon Sep 17 00:00:00 2001
From: DmitriyMX <dimon550@gmail.com>
Date: Sun, 25 Mar 2018 19:31:14 +0300
Subject: [PATCH] base packet

---
 src/main/java/mc/core/netty/BasePacket.java   | 15 +++++++
 src/main/java/mc/core/netty/NettyServer.java  |  4 +-
 .../java/mc/core/netty/PacketDecoder.java     | 41 +++++++++++++++++++
 .../java/mc/core/netty/PacketHandler.java     | 19 +++++++++
 4 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/mc/core/netty/BasePacket.java
 create mode 100644 src/main/java/mc/core/netty/PacketDecoder.java
 create mode 100644 src/main/java/mc/core/netty/PacketHandler.java

diff --git a/src/main/java/mc/core/netty/BasePacket.java b/src/main/java/mc/core/netty/BasePacket.java
new file mode 100644
index 0000000..0c258c6
--- /dev/null
+++ b/src/main/java/mc/core/netty/BasePacket.java
@@ -0,0 +1,15 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-03-25
+ */
+package mc.core.netty;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@RequiredArgsConstructor
+@Getter
+class BasePacket {
+    private final int length;
+    private final int id;
+}
diff --git a/src/main/java/mc/core/netty/NettyServer.java b/src/main/java/mc/core/netty/NettyServer.java
index cc3f334..1681c70 100644
--- a/src/main/java/mc/core/netty/NettyServer.java
+++ b/src/main/java/mc/core/netty/NettyServer.java
@@ -22,7 +22,9 @@ public class NettyServer implements Server {
             @Override
             protected void initChannel(SocketChannel socketChannel) {
                 socketChannel.pipeline().addLast(
-                        new LoggingHandler()
+                        new LoggingHandler(),
+                        new PacketDecoder(),
+                        new PacketHandler()
                 );
             }
         };
diff --git a/src/main/java/mc/core/netty/PacketDecoder.java b/src/main/java/mc/core/netty/PacketDecoder.java
new file mode 100644
index 0000000..5a09dd8
--- /dev/null
+++ b/src/main/java/mc/core/netty/PacketDecoder.java
@@ -0,0 +1,41 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-03-25
+ */
+package mc.core.netty;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.ReplayingDecoder;
+
+import java.util.List;
+
+public class PacketDecoder extends ReplayingDecoder<BasePacket> {
+    private int readVarInt(ByteBuf byteBuf) throws Exception {
+        int result = 0;
+        byte read;
+        int numRead = 0;
+
+        do {
+            read = byteBuf.readByte();
+            int value = (read & 0b01111111);
+            result |= (value << (7 * numRead));
+
+            numRead++;
+            if (numRead > 5) {
+                throw new Exception("VarInt is too big");
+            }
+        } while ((read & 0b10000000) != 0);
+
+        return result;
+    }
+
+    @Override
+    protected void decode(ChannelHandlerContext context, ByteBuf byteBuf, List<Object> list) throws Exception {
+        int length = readVarInt(byteBuf);
+        int id = readVarInt(byteBuf);
+
+        list.add(new BasePacket(length, id));
+        byteBuf.skipBytes(length);
+    }
+}
diff --git a/src/main/java/mc/core/netty/PacketHandler.java b/src/main/java/mc/core/netty/PacketHandler.java
new file mode 100644
index 0000000..3f40d5a
--- /dev/null
+++ b/src/main/java/mc/core/netty/PacketHandler.java
@@ -0,0 +1,19 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-03-25
+ */
+package mc.core.netty;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.SimpleChannelInboundHandler;
+import lombok.extern.slf4j.Slf4j;
+
+@Slf4j
+public class PacketHandler extends SimpleChannelInboundHandler<BasePacket> {
+    @Override
+    protected void channelRead0(ChannelHandlerContext context, BasePacket packet) throws Exception {
+        log.info("Lenght: {} | Id: {}",
+                packet.getLength(),
+                packet.getId());
+    }
+}