Silence relog messages.

Prevents a player from logging out and then immediately back in from
adding low value messages to chat.

src/me/ryanhamshire/GriefPrevention/BroadcastMessageTask.java

@@ -0,0 +1,39 @@
+/*
+    GriefPrevention Server Plugin for Minecraft
+    Copyright (C) 2016 Ryan Hamshire
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+package me.ryanhamshire.GriefPrevention;
+
+import org.bukkit.Bukkit;
+
+//sends a message to all online players
+//used to send delayed messages, for example a quit message after the player has been gone a while 
+class BroadcastMessageTask implements Runnable 
+{
+	private String message;
+	
+	public BroadcastMessageTask(String message)
+	{
+        this.message = message;
+    }
+
+    @Override
+	public void run()
+	{
+		Bukkit.getServer().broadcastMessage(this.message);
+	}	
+}

src/me/ryanhamshire/GriefPrevention/GriefPrevention.java

@@ -139,6 +139,7 @@ public class GriefPrevention extends JavaPlugin
 	public String config_spam_warningMessage;						//message to show a player who is close to spam level
 	public String config_spam_allowedIpAddresses;					//IP addresses which will not be censored
 	public int config_spam_deathMessageCooldownSeconds;				//cooldown period for death messages (per player) in seconds
+	public int config_spam_logoutMessageDelaySeconds;               //delay before a logout message will be shown (only if the player stays offline that long)
 	
 	HashMap<World, Boolean> config_pvp_specifiedWorlds;				//list of worlds where pvp anti-grief rules apply, according to the config file
 	public boolean config_pvp_protectFreshSpawns;					//whether to make newly spawned players immune until they pick up an item
@@ -567,7 +568,8 @@ public class GriefPrevention extends JavaPlugin
         this.config_spam_banMessage = config.getString("GriefPrevention.Spam.BanMessage", "Banned for spam.");
         String slashCommandsToMonitor = config.getString("GriefPrevention.Spam.MonitorSlashCommands", "/me;/global;/local");
         slashCommandsToMonitor = config.getString("GriefPrevention.Spam.ChatSlashCommands", slashCommandsToMonitor);
-        this.config_spam_deathMessageCooldownSeconds = config.getInt("GriefPrevention.Spam.DeathMessageCooldownSeconds", 120);       
+        this.config_spam_deathMessageCooldownSeconds = config.getInt("GriefPrevention.Spam.DeathMessageCooldownSeconds", 120);
+        this.config_spam_logoutMessageDelaySeconds = config.getInt("GriefPrevention.Spam.Logout Message Delay In Seconds", 10);
         
         this.config_pvp_protectFreshSpawns = config.getBoolean("GriefPrevention.PvP.ProtectFreshSpawns", true);
         this.config_pvp_punishLogout = config.getBoolean("GriefPrevention.PvP.PunishLogout", true);
@@ -809,6 +811,7 @@ public class GriefPrevention extends JavaPlugin
         outConfig.set("GriefPrevention.Spam.BanMessage", this.config_spam_banMessage);
         outConfig.set("GriefPrevention.Spam.AllowedIpAddresses", this.config_spam_allowedIpAddresses);
         outConfig.set("GriefPrevention.Spam.DeathMessageCooldownSeconds", this.config_spam_deathMessageCooldownSeconds);
+        outConfig.set("GriefPrevention.Spam.Logout Message Delay In Seconds", this.config_spam_logoutMessageDelaySeconds);
         
         for(World world : worlds)
         {

src/me/ryanhamshire/GriefPrevention/PlayerEventHandler.java

@@ -910,6 +910,22 @@ class PlayerEventHandler implements Listener
                 player.teleport(returnLocation);
             }
         }
+        
+        //if we're holding a logout message for this player, don't send that or this event's join message
+        if(GriefPrevention.instance.config_spam_logoutMessageDelaySeconds > 0)
+        {
+            String joinMessage = event.getJoinMessage();
+            if(joinMessage != null && !joinMessage.isEmpty())
+            {
+                Integer taskID = this.heldLogoutMessages.get(player.getUniqueId());
+                if(taskID != null && Bukkit.getScheduler().isQueued(taskID))
+                {
+                    Bukkit.getScheduler().cancelTask(taskID);
+                    player.sendMessage(event.getJoinMessage());
+                    event.setJoinMessage("");
+                }
+            }
+        }
 	}
 	
 	//when a player spawns, conditionally apply temporary pvp protection 
@@ -964,6 +980,7 @@ class PlayerEventHandler implements Listener
     }
 	
 	//when a player quits...
+	private HashMap<UUID, Integer> heldLogoutMessages = new HashMap<UUID, Integer>();
 	@EventHandler(priority = EventPriority.HIGHEST)
 	void onPlayerQuit(PlayerQuitEvent event)
 	{
@@ -1034,6 +1051,19 @@ class PlayerEventHandler implements Listener
         
         //drop data about this player
         this.dataStore.clearCachedPlayerData(playerID);
+        
+        //send quit message later, but only if the player stays offline
+        if(GriefPrevention.instance.config_spam_logoutMessageDelaySeconds > 0)
+        {
+            String quitMessage = event.getQuitMessage();
+            if(quitMessage != null && !quitMessage.isEmpty())
+            {
+                BroadcastMessageTask task = new BroadcastMessageTask(quitMessage);
+                int taskID = Bukkit.getScheduler().scheduleSyncDelayedTask(GriefPrevention.instance, task, 20L * GriefPrevention.instance.config_spam_logoutMessageDelaySeconds);
+                this.heldLogoutMessages.put(playerID, taskID);
+                event.setQuitMessage("");
+            }
+        }
 	}
 	
 	//determines whether or not a login or logout notification should be silenced, depending on how many there have been in the last minute