From 85c32b9a4730eaec8509f206738009b44eb266bd Mon Sep 17 00:00:00 2001
From: ReinforceZwei <39955851+ReinforceZwei@users.noreply.github.com>
Date: Sat, 15 Aug 2020 13:11:38 +0800
Subject: [PATCH] Fix entity metadata for lower MC versions

---
 MinecraftClient/McClient.cs                   | 16 +++++++++++++--
 .../Protocol/Handlers/DataTypes.cs            | 20 +++++++++++++++++--
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/MinecraftClient/McClient.cs b/MinecraftClient/McClient.cs
index 14ae10aa..efa1580c 100644
--- a/MinecraftClient/McClient.cs
+++ b/MinecraftClient/McClient.cs
@@ -59,6 +59,7 @@ namespace MinecraftClient
         private object lastKeepAliveLock = new object();
         private int respawnTicks = 0;
         private int gamemode = 0;
+        private int protocolVersion;
 
         private int playerEntityID;
 
@@ -155,6 +156,7 @@ namespace MinecraftClient
             this.username = user;
             this.host = server_ip;
             this.port = port;
+            this.protocolVersion = protocolversion;
 
             if (!singlecommand)
             {
@@ -2122,9 +2124,19 @@ namespace MinecraftClient
             if (entities.ContainsKey(entityID))
             {
                 // Get health data for an entity
-                if (metadata.ContainsKey(8) && metadata[8].GetType() == typeof(float))
+                int key;
+                // Key for 1.10+ is 7 and 1.14+ is 8
+                if (protocolVersion >= Protocol.Handlers.Protocol18Handler.MC114Version)
                 {
-                    entities[entityID].Health = (float)metadata[8];
+                    key = 8;
+                }
+                else
+                {
+                    key = 7;
+                }
+                if (metadata.ContainsKey(key) && metadata[key].GetType() == typeof(float))
+                {
+                    entities[entityID].Health = (float)metadata[key];
                 }
             }
         }
diff --git a/MinecraftClient/Protocol/Handlers/DataTypes.cs b/MinecraftClient/Protocol/Handlers/DataTypes.cs
index 21161d36..df66bc61 100644
--- a/MinecraftClient/Protocol/Handlers/DataTypes.cs
+++ b/MinecraftClient/Protocol/Handlers/DataTypes.cs
@@ -501,11 +501,25 @@ namespace MinecraftClient.Protocol.Handlers
             while (Key != 0xff)
             {
                 int Type = ReadNextVarInt(cache);
+
+                // starting from 1.13, Optional Chat is inserted as number 5 in 1.13 and IDs after 5 got shifted.
+                // Increase type ID by 1 if
+                // - below 1.13
+                // - type ID larger than 4
+                if (protocolversion < Protocol18Handler.MC113Version)
+                {
+                    if (Type > 4)
+                    {
+                        Type += 1;
+                    }
+                }
                 // Value's data type is depended on Type
                 object Value = null;
 
-                // We need to go through every data in order to get all fields in the packet
-                // Store the value as needed
+                // This is backward compatible since new type is appended to the end
+                // Version upgrade note
+                // - Check type ID got shifted or not
+                // - Add new type if any
                 switch (Type)
                 {
                     case 0: // byte
@@ -607,6 +621,8 @@ namespace MinecraftClient.Protocol.Handlers
                     case 18: // Pose
                         Value = ReadNextVarInt(cache);
                         break;
+                    default:
+                        throw new System.IO.InvalidDataException("Unknown Metadata Type ID " + Type + ". Is this up to date for new MC Version?");
                 }
                 data.Add(Key, Value);
                 Key = ReadNextByte(cache);