Use the "closest" locale from Velocity

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -55,6 +55,7 @@ import com.velocitypowered.proxy.protocol.util.GameProfileSerializer;
 import com.velocitypowered.proxy.scheduler.VelocityScheduler;
 import com.velocitypowered.proxy.server.ServerMap;
 import com.velocitypowered.proxy.util.AddressUtil;
+import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
 import com.velocitypowered.proxy.util.EncryptionUtils;
 import com.velocitypowered.proxy.util.FileSystemUtils;
 import com.velocitypowered.proxy.util.VelocityChannelRegistrar;
@@ -272,6 +273,7 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
             translationRegistry.registerAll(locale,
                 ResourceBundle.getBundle("com/velocitypowered/proxy/l10n/messages",
                     locale, UTF8ResourceBundleControl.get()), false);
+            ClosestLocaleMatcher.INSTANCE.registerKnown(locale);
           });
         } catch (IOException e) {
           logger.error("Encountered an I/O error whilst loading translations", e);

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -68,6 +68,7 @@ import com.velocitypowered.proxy.protocol.packet.title.GenericTitlePacket;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import com.velocitypowered.proxy.tablist.VelocityTabList;
 import com.velocitypowered.proxy.tablist.VelocityTabListLegacy;
+import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
 import com.velocitypowered.proxy.util.DurationUtils;
 import com.velocitypowered.proxy.util.collect.CappedSet;
 import io.netty.buffer.ByteBufUtil;
@@ -268,7 +269,8 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   }
 
   public Component translateMessage(Component message) {
-    Locale locale = this.settings == null ? Locale.getDefault() : this.settings.getLocale();
+    Locale locale = ClosestLocaleMatcher.INSTANCE
+        .lookupClosest(this.settings == null ? Locale.getDefault() : this.settings.getLocale());
     return GlobalTranslator.render(message, locale);
   }
 

proxy/src/main/java/com/velocitypowered/proxy/connection/client/InitialInboundConnection.java

@@ -23,6 +23,7 @@ import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.Handshake;
+import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
 import java.net.InetSocketAddress;
 import java.util.Locale;
 import java.util.Optional;
@@ -78,7 +79,8 @@ public final class InitialInboundConnection implements InboundConnection,
    * @param reason the reason for disconnecting
    */
   public void disconnect(Component reason) {
-    Component translated = GlobalTranslator.render(reason, Locale.getDefault());
+    Component translated = GlobalTranslator.render(reason, ClosestLocaleMatcher.INSTANCE
+        .lookupClosest(Locale.getDefault()));
 
     logger.info("{} has disconnected: {}", this,
         LegacyComponentSerializer.legacySection().serialize(translated));
@@ -90,7 +92,8 @@ public final class InitialInboundConnection implements InboundConnection,
    * @param reason the reason for disconnecting
    */
   public void disconnectQuietly(Component reason) {
-    Component translated = GlobalTranslator.render(reason, Locale.getDefault());
+    Component translated = GlobalTranslator.render(reason, ClosestLocaleMatcher.INSTANCE
+        .lookupClosest(Locale.getDefault()));
     connection.closeWith(Disconnect.create(translated, getProtocolVersion()));
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/console/VelocityConsole.java

@@ -24,6 +24,7 @@ import com.velocitypowered.api.permission.PermissionFunction;
 import com.velocitypowered.api.permission.Tristate;
 import com.velocitypowered.api.proxy.ConsoleCommandSource;
 import com.velocitypowered.proxy.VelocityServer;
+import com.velocitypowered.proxy.util.ClosestLocaleMatcher;
 import java.util.List;
 import java.util.Locale;
 import net.kyori.adventure.identity.Identity;
@@ -59,7 +60,8 @@ public final class VelocityConsole extends SimpleTerminalConsole implements Cons
 
   @Override
   public void sendMessage(@NonNull Identity identity, @NonNull Component message) {
-    Component translated = GlobalTranslator.render(message, Locale.getDefault());
+    Component translated = GlobalTranslator.render(message, ClosestLocaleMatcher.INSTANCE
+        .lookupClosest(Locale.getDefault()));
     logger.info(LegacyComponentSerializer.legacySection().serialize(translated));
   }
 

proxy/src/main/java/com/velocitypowered/proxy/util/ClosestLocaleMatcher.java

@@ -0,0 +1,35 @@
+package com.velocitypowered.proxy.util;
+
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.LoadingCache;
+import java.util.Locale;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class ClosestLocaleMatcher {
+  public static final ClosestLocaleMatcher INSTANCE = new ClosestLocaleMatcher();
+
+  private final Map<String, Locale> byLanguage;
+  private final LoadingCache<Locale, Locale> closest;
+
+  private ClosestLocaleMatcher() {
+    this.byLanguage = new ConcurrentHashMap<>();
+    this.closest = Caffeine.newBuilder()
+        .build(sublocale -> {
+          final String tag = sublocale.getLanguage();
+          return byLanguage.getOrDefault(tag, sublocale);
+        });
+  }
+
+  public void registerKnown(final Locale locale) {
+    if (locale.getLanguage().equals(new Locale("zh").getLanguage())) {
+      return;
+    }
+
+    this.byLanguage.put(locale.getLanguage(), locale);
+  }
+
+  public Locale lookupClosest(final Locale locale) {
+    return closest.get(locale);
+  }
+}