From 6a2e1a8114df760228a6fc28fbdf977a7cfde5d0 Mon Sep 17 00:00:00 2001
From: creeper123123321 <creeper123123321@gmail.com>
Date: Fri, 15 Feb 2019 13:51:54 -0200
Subject: [PATCH] Support ViaBackwards 1.13 with Velocity modern forwarding

---
 .../platform/VelocityViaInjector.java         | 20 +++++++++++++
 .../providers/VelocityVersionProvider.java    | 29 ++++++++++++-------
 2 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaInjector.java b/velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaInjector.java
index daa63940d..64c7c4f6e 100644
--- a/velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaInjector.java
+++ b/velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaInjector.java
@@ -4,11 +4,25 @@ import io.netty.channel.ChannelInitializer;
 import us.myles.ViaVersion.VelocityPlugin;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.ViaInjector;
+import us.myles.ViaVersion.api.protocol.ProtocolVersion;
 import us.myles.ViaVersion.util.ReflectionUtil;
 import us.myles.ViaVersion.velocity.handlers.VelocityChannelInitializer;
 
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
 
 public class VelocityViaInjector implements ViaInjector {
+    public static Method getPlayerInfoForwardingMode;
+
+    static {
+        try {
+            getPlayerInfoForwardingMode = Class.forName("com.velocitypowered.proxy.config.VelocityConfiguration").getMethod("getPlayerInfoForwardingMode");
+        } catch (NoSuchMethodException | ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
     @Override
     public void inject() throws Exception {
         Object connectionManager = ReflectionUtil.get(VelocityPlugin.PROXY, "cm", Object.class);
@@ -30,6 +44,12 @@ public class VelocityViaInjector implements ViaInjector {
     }
 
     public static int getLowestSupportedProtocolVersion() {
+        try {
+            if (getPlayerInfoForwardingMode != null
+                    && ((Enum<?>) getPlayerInfoForwardingMode.invoke(VelocityPlugin.PROXY.getConfiguration()))
+                    .name().equals("MODERN")) return ProtocolVersion.v1_13.getId();
+        } catch (IllegalAccessException | InvocationTargetException ignored) {
+        }
         return com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION.getProtocol();
     }
 
diff --git a/velocity/src/main/java/us/myles/ViaVersion/velocity/providers/VelocityVersionProvider.java b/velocity/src/main/java/us/myles/ViaVersion/velocity/providers/VelocityVersionProvider.java
index 04939df8b..7f7f786c9 100644
--- a/velocity/src/main/java/us/myles/ViaVersion/velocity/providers/VelocityVersionProvider.java
+++ b/velocity/src/main/java/us/myles/ViaVersion/velocity/providers/VelocityVersionProvider.java
@@ -1,6 +1,6 @@
 package us.myles.ViaVersion.velocity.providers;
 
-import com.google.common.collect.Lists;
+import us.myles.ViaVersion.VelocityPlugin;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.data.UserConnection;
 import us.myles.ViaVersion.api.protocol.ProtocolVersion;
@@ -8,32 +8,41 @@ import us.myles.ViaVersion.protocols.base.ProtocolInfo;
 import us.myles.ViaVersion.protocols.base.VersionProvider;
 import us.myles.ViaVersion.velocity.platform.VelocityViaInjector;
 
-import java.util.*;
-import java.util.stream.Collectors;
+import java.util.Arrays;
+import java.util.stream.IntStream;
 
 public class VelocityVersionProvider extends VersionProvider {
-    private static final List<Integer> VELOCITY_PROTOCOLS = com.velocitypowered.api.network.ProtocolVersion.SUPPORTED_VERSIONS.stream()
-            .map(com.velocitypowered.api.network.ProtocolVersion::getProtocol)
-            .collect(Collectors.toList());
 
     @Override
     public int getServerProtocol(UserConnection user) throws Exception {
         int playerVersion = user.get(ProtocolInfo.class).getProtocolVersion();
 
+        IntStream versions = com.velocitypowered.api.network.ProtocolVersion.SUPPORTED_VERSIONS.stream()
+                .mapToInt(com.velocitypowered.api.network.ProtocolVersion::getProtocol);
+
+        // Modern forwarding mode needs 1.13 Login plugin message
+        if (VelocityViaInjector.getPlayerInfoForwardingMode != null
+                && ((Enum<?>) VelocityViaInjector.getPlayerInfoForwardingMode.invoke(VelocityPlugin.PROXY.getConfiguration()))
+                .name().equals("MODERN")) {
+            versions = versions.filter(ver -> ver >= ProtocolVersion.v1_13.getId());
+        }
+        int[] compatibleProtocols = versions.toArray();
+
         // Bungee supports it
-        if (Collections.binarySearch(VELOCITY_PROTOCOLS, playerVersion) >= 0)
+        if (Arrays.binarySearch(compatibleProtocols, playerVersion) >= 0)
             return playerVersion;
 
         // Older than bungee supports, get the lowest version
-        if (playerVersion < VELOCITY_PROTOCOLS.get(0)) {
-            return VelocityViaInjector.getLowestSupportedProtocolVersion();
+        if (playerVersion < compatibleProtocols[0]) {
+            return compatibleProtocols[0];
         }
 
         // Loop through all protocols to get the closest protocol id that bungee supports (and that viaversion does too)
 
         // TODO: This needs a better fix, i.e checking ProtocolRegistry to see if it would work.
         // This is more of a workaround for snapshot support by bungee.
-        for (Integer protocol : Lists.reverse(VELOCITY_PROTOCOLS)) {
+        for (int i = compatibleProtocols.length - 1; i >= 0; i--) {
+            int protocol = compatibleProtocols[i];
             if (playerVersion > protocol && ProtocolVersion.isRegistered(protocol))
                 return protocol;
         }