Allow to customize ping events priority via handle-motd-order (#108)

Currently, the bungee implementation is using NORMAL priority for the
ping event handler, while the velocity implementation is using LAST.
Regardless of which choice may be the better one, this is an
inconsistency that this patch addresses by using NORMAL as the default
for both platforms.

Additionally to addressing the inconsistency, this patch adds a new
config option `handle-motd-order` which uses velocity's event priority
nomenclature to allow configuring the behavior of the MOTD handling on
both platforms.

In cases where there is a MOTD plugin that incorrectly overrides a
player count using the local player count, one may choose to use order
LAST to override the value back to the global player count.

In cases where there is a MOTD plugin that relies on a player count
value from the ping response, one may choose to use order FIRST to make
sure the response will have the correct global player count.

Fixes #107

api/src/main/java/com/imaginarycode/minecraft/redisbungee/api/config/HandleMotdOrder.java

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2013-present RedisBungee contributors
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ *
+ *  http://www.eclipse.org/legal/epl-v10.html
+ */
+
+package com.imaginarycode.minecraft.redisbungee.api.config;
+
+public enum HandleMotdOrder {
+    FIRST,
+    NORMAL,
+    LAST
+}

api/src/main/java/com/imaginarycode/minecraft/redisbungee/api/config/RedisBungeeConfiguration.java

@@ -25,12 +25,13 @@ public class RedisBungeeConfiguration {
 
     private final boolean handleReconnectToLastServer;
     private final boolean handleMotd;
+    private final HandleMotdOrder handleMotdOrder;
 
     private final CommandsConfiguration commandsConfiguration;
     private final String networkId;
 
 
-    public RedisBungeeConfiguration(String networkId, String proxyId, List<String> exemptAddresses, boolean kickWhenOnline, boolean handleReconnectToLastServer, boolean handleMotd, CommandsConfiguration commandsConfiguration) {
+    public RedisBungeeConfiguration(String networkId, String proxyId, List<String> exemptAddresses, boolean kickWhenOnline, boolean handleReconnectToLastServer, boolean handleMotd, HandleMotdOrder handleMotdOrder, CommandsConfiguration commandsConfiguration) {
         this.proxyId = proxyId;
         ImmutableList.Builder<InetAddress> addressBuilder = ImmutableList.builder();
         for (String s : exemptAddresses) {
@@ -40,6 +41,7 @@ public RedisBungeeConfiguration(String networkId, String proxyId, List<String> e
         this.kickWhenOnline = kickWhenOnline;
         this.handleReconnectToLastServer = handleReconnectToLastServer;
         this.handleMotd = handleMotd;
+        this.handleMotdOrder = handleMotdOrder;
         this.commandsConfiguration = commandsConfiguration;
         this.networkId = networkId;
     }
@@ -60,6 +62,10 @@ public boolean handleMotd() {
         return this.handleMotd;
     }
 
+    public HandleMotdOrder handleMotdOrder() {
+        return handleMotdOrder;
+    }
+
     public boolean handleReconnectToLastServer() {
         return this.handleReconnectToLastServer;
     }

api/src/main/java/com/imaginarycode/minecraft/redisbungee/api/config/loaders/ConfigLoader.java

@@ -14,6 +14,7 @@
 import com.google.common.reflect.TypeToken;
 import com.imaginarycode.minecraft.redisbungee.api.RedisBungeeMode;
 import com.imaginarycode.minecraft.redisbungee.api.RedisBungeePlugin;
+import com.imaginarycode.minecraft.redisbungee.api.config.HandleMotdOrder;
 import com.imaginarycode.minecraft.redisbungee.api.config.RedisBungeeConfiguration;
 import com.imaginarycode.minecraft.redisbungee.api.summoners.JedisClusterSummoner;
 import com.imaginarycode.minecraft.redisbungee.api.summoners.JedisPooledSummoner;
@@ -104,6 +105,16 @@ default void loadConfig(RedisBungeePlugin<?> plugin, Path dataFolder) throws IOE
         plugin.logInfo("handle reconnect to last server: {}", reconnectToLastServer);
         plugin.logInfo("handle motd: {}", handleMotd);
 
+        HandleMotdOrder handleMotdOrder = HandleMotdOrder.NORMAL;
+        String handleMotdOrderName = node.getNode("handle-motd-priority").getString();
+        if (handleMotdOrderName != null) {
+            try {
+                handleMotdOrder = HandleMotdOrder.valueOf(handleMotdOrderName.toUpperCase(Locale.ROOT));
+            } catch (IllegalArgumentException e) {
+                plugin.logWarn("handle motd order value '{}' is unsupported (allowed: {})", handleMotdOrderName, HandleMotdOrder.values());
+            }
+        }
+        plugin.logInfo("handle motd order: {}", handleMotdOrder);
 
         // commands
         boolean redisBungeeEnabled = node.getNode("commands", "redisbungee", "enabled").getBoolean(true);
@@ -130,7 +141,8 @@ default void loadConfig(RedisBungeePlugin<?> plugin, Path dataFolder) throws IOE
         boolean installPlist = node.getNode("commands", "redisbungee-legacy", "subcommands", "plist", "install").getBoolean(false);
 
 
-        RedisBungeeConfiguration configuration = new RedisBungeeConfiguration(networkId, proxyId, exemptAddresses, kickWhenOnline, reconnectToLastServer, handleMotd, new RedisBungeeConfiguration.CommandsConfiguration(
+        RedisBungeeConfiguration configuration = new RedisBungeeConfiguration(networkId, proxyId, exemptAddresses, kickWhenOnline, reconnectToLastServer, handleMotd, handleMotdOrder,
+            new RedisBungeeConfiguration.CommandsConfiguration(
                 redisBungeeEnabled, redisBungeeLegacyEnabled,
                 new RedisBungeeConfiguration.LegacySubCommandsConfiguration(
                         findEnabled, glistEnabled, ipEnabled,

api/src/main/resources/config.yml

@@ -77,6 +77,13 @@ kick-when-online: true
 # you can disable this when you want to handle motd yourself, use RedisBungee api to get total players when needed :)
 handle-motd: true
 
+# MOTD plugins compatibility setting
+# Allowed values: FIRST, NORMAL, LAST
+# This option enables RedisBungee to manage various interactions between other plugins and the online player count,
+# which is dynamically updated to a global player count in ping responses if the handle-motd option is enabled.
+# If you encounter issues with other plugins accessing or modifying the player count, try using a value of FIRST or LAST.
+handle-motd-order: NORMAL
+
 # A list of IP addresses for which RedisBungee will not modify the response for, useful for automatic
 # restart scripts.
 # Automatically disabled  if handle-motd is disabled.

proxies/bungeecord/src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeListener.java

@@ -17,7 +17,7 @@
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 import com.imaginarycode.minecraft.redisbungee.api.RedisBungeePlugin;
-import net.kyori.adventure.text.Component;
+import com.imaginarycode.minecraft.redisbungee.api.config.HandleMotdOrder;
 import net.kyori.adventure.text.serializer.bungeecord.BungeeComponentSerializer;
 import net.md_5.bungee.api.AbstractReconnectHandler;
 import net.md_5.bungee.api.ProxyServer;
@@ -29,6 +29,7 @@
 import net.md_5.bungee.api.event.ServerConnectEvent;
 import net.md_5.bungee.api.plugin.Listener;
 import net.md_5.bungee.event.EventHandler;
+import net.md_5.bungee.event.EventPriority;
 
 import java.util.*;
 
@@ -42,8 +43,31 @@ public RedisBungeeListener(RedisBungeePlugin<ProxiedPlayer> plugin) {
         this.plugin = plugin;
     }
 
-    @EventHandler
-    public void onPing(ProxyPingEvent event) {
+    @EventHandler(priority = EventPriority.LOWEST)
+    private void onPingFirst(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.FIRST) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    @EventHandler(priority = EventPriority.NORMAL)
+    private void onPingNormal(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.NORMAL) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST)
+    private void onPingLast(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.LAST) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    private void onPing0(ProxyPingEvent event) {
         if (!plugin.configuration().handleMotd()) return;
         if (plugin.configuration().getExemptAddresses().contains(event.getConnection().getAddress().getAddress())) return;
         ServerInfo forced = AbstractReconnectHandler.getForcedHost(event.getConnection());

proxies/velocity/src/main/java/com/imaginarycode/minecraft/redisbungee/RedisBungeeListener.java

@@ -17,6 +17,7 @@
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 import com.imaginarycode.minecraft.redisbungee.api.RedisBungeePlugin;
+import com.imaginarycode.minecraft.redisbungee.api.config.HandleMotdOrder;
 import com.velocitypowered.api.event.PostOrder;
 import com.velocitypowered.api.event.Subscribe;
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
@@ -41,8 +42,31 @@ public RedisBungeeListener(RedisBungeePlugin<Player> plugin) {
         this.plugin = plugin;
     }
 
-    @Subscribe(order = PostOrder.LAST) // some plugins changes it online players so we need to be executed as last
-    public void onPing(ProxyPingEvent event) {
+    @Subscribe(order = PostOrder.FIRST)
+    public void onPingFirst(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.FIRST) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    @Subscribe(order = PostOrder.NORMAL)
+    public void onPingNormal(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.NORMAL) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    @Subscribe(order = PostOrder.LAST)
+    public void onPingLast(ProxyPingEvent event) {
+        if (plugin.configuration().handleMotdOrder() != HandleMotdOrder.LAST) {
+            return;
+        }
+        onPing0(event);
+    }
+
+    private void onPing0(ProxyPingEvent event) {
         if (!plugin.configuration().handleMotd()) return;
         if (plugin.configuration().getExemptAddresses().contains(event.getConnection().getRemoteAddress().getAddress())) return;