From 64b3bedc623f9e4c500c7ae13eb8b200379576ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Albin=20Cor=C3=A9n?= <twoten@twoten.io>
Date: Thu, 22 Mar 2018 09:55:26 +0100
Subject: [PATCH] Added helper class to chunk byte arrays

---
 MLAPI/MLAPI.csproj                            |  1 +
 .../MessageChunker.cs                         | 65 +++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 MLAPI/NetworkingManagerComponents/MessageChunker.cs

diff --git a/MLAPI/MLAPI.csproj b/MLAPI/MLAPI.csproj
index 3706f5e..44c7b80 100644
--- a/MLAPI/MLAPI.csproj
+++ b/MLAPI/MLAPI.csproj
@@ -76,6 +76,7 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="NetworkingManagerComponents\ClientIdManager.cs" />
     <Compile Include="Data\ClientIdKey.cs" />
+    <Compile Include="NetworkingManagerComponents\MessageChunker.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
 </Project>
\ No newline at end of file
diff --git a/MLAPI/NetworkingManagerComponents/MessageChunker.cs b/MLAPI/NetworkingManagerComponents/MessageChunker.cs
new file mode 100644
index 0000000..ba22aca
--- /dev/null
+++ b/MLAPI/NetworkingManagerComponents/MessageChunker.cs
@@ -0,0 +1,65 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace MLAPI.NetworkingManagerComponents
+{
+    public static class MessageChunker
+    {
+        public static List<byte[]> GetChunkedMessage(ref byte[] message, int chunkSize)
+        {
+            List<byte[]> chunks = new List<byte[]>((int)Math.Ceiling((double)message.Length / chunkSize));
+            //The extra 4 bytes is the chunkIndex   
+            byte[] chunk = new byte[chunkSize + 4];
+
+            for (int i = 0; i < message.Length; i++)
+            {
+                uint currentChunkIndex = (uint)Math.Floor((double)i / (double)chunkSize);
+                int currentByteIndex = i % chunkSize;
+
+                if (currentByteIndex == 0)
+                {
+                    byte[] chunkIndexBytes = BitConverter.GetBytes(currentChunkIndex);
+                    if (BitConverter.IsLittleEndian)
+                        Array.Reverse(chunkIndexBytes);
+                    chunk[0] = chunkIndexBytes[0]; 
+                    chunk[1] = chunkIndexBytes[1];
+                    chunk[2] = chunkIndexBytes[2];
+                    chunk[3] = chunkIndexBytes[3];
+                }
+                chunk[4 + currentByteIndex] = message[i];
+                if(currentByteIndex == (chunkSize -1) || i == (message.Length -1))
+                {
+                    //This is the last byte in the chunk
+                    chunks.Add(chunk);
+                }
+            }
+            return chunks;
+        }
+
+        public static byte[] GetMessageOrdered(ref List<byte[]> chunks, int chunkSize = -1)
+        {
+            if (chunks.Count == 0)
+                return new byte[0];
+            if (chunkSize == -1)
+                chunkSize = chunks[0].Length - 4;
+
+            uint lastIndex = 0;
+            uint messageSize = 0;
+            for (int i = 0; i < chunks.Count; i++)
+            {
+                uint chunkIndex =  BitConverter.ToUInt32(chunks[i], 0);
+                if (chunkIndex <= lastIndex)
+                    throw new ArgumentException("Chunks not in order");
+                lastIndex = chunkIndex;
+                messageSize += Convert.ToUInt32(chunks[i].Length - 4);
+            }
+            byte[] message = new byte[messageSize];
+            for (int i = 0; i < chunks.Count; i++)
+            {
+                Array.Copy(chunks[i], 3, message, i * chunkSize, chunkSize);
+            }
+            return message;
+        }
+    }
+}