Rewrite the SkinManager to avoid race conditions & Mojang ratelimit

src/main/java/pw/kaboom/extras/Main.java

@@ -13,16 +13,23 @@
 import pw.kaboom.extras.modules.entity.EntityKnockback;
 import pw.kaboom.extras.modules.entity.EntitySpawn;
 import pw.kaboom.extras.modules.player.*;
+import pw.kaboom.extras.modules.player.skin.SkinManager;
 import pw.kaboom.extras.modules.server.ServerCommand;
 import pw.kaboom.extras.modules.server.ServerGameRule;
 import pw.kaboom.extras.modules.server.ServerTabComplete;
 
 import java.io.File;
 
 public final class Main extends JavaPlugin {
+    public static Main PLUGIN;
+
     private File prefixConfigFile;
     private FileConfiguration prefixConfig;
 
+    public Main() {
+        PLUGIN = this;
+    }
+
     @Override
     public void onLoad() {
         /* Load missing config.yml defaults */
@@ -79,6 +86,10 @@ public void onEnable() {
         this.getServer().getPluginManager().registerEvents(new PlayerTeleport(), this);
         this.getServer().getPluginManager().registerEvents(new PlayerPrefix(), this);
 
+        final var skinManager = new SkinManager();
+        this.getServer().getPluginManager().registerEvents(skinManager, this);
+        skinManager.start();
+
         /* Server-related modules */
         ServerGameRule.init(this);
 

src/main/java/pw/kaboom/extras/commands/CommandSkin.java

@@ -9,12 +9,8 @@
 import pw.kaboom.extras.modules.player.skin.SkinManager;
 
 import javax.annotation.Nonnull;
-import java.util.HashMap;
-import java.util.Map;
 
 public final class CommandSkin implements CommandExecutor {
-    private final Map<Player, Long> lastUsedMillis = new HashMap<>();
-
     @Override
     public boolean onCommand(final @Nonnull CommandSender sender,
                              final @Nonnull Command command,
@@ -26,41 +22,28 @@ public boolean onCommand(final @Nonnull CommandSender sender,
             return true;
         }
 
-        final long millis = lastUsedMillis.getOrDefault(player, 0L);
-        final long millisDifference = System.currentTimeMillis() - millis;
-
         if (args.length == 0) {
             player.sendMessage(Component
                     .text("Usage: /" + label + " <username>\n/" + label + " off",
                             NamedTextColor.RED));
             return true;
         }
 
-        if (millisDifference <= 2000) {
-            player.sendMessage(Component
-                    .text("Please wait a few seconds before changing your skin"));
-            return true;
-        }
-
-        lastUsedMillis.put(player, System.currentTimeMillis());
-
         final String name = args[0];
 
         if (name.equalsIgnoreCase("off") || name.equalsIgnoreCase("remove")
          || name.equalsIgnoreCase("disable")) {
-            SkinManager.resetSkin(player, true);
+            SkinManager.removeSkin(player, true);
             return true;
         }
 
         if (name.equalsIgnoreCase("auto") || name.equalsIgnoreCase("default")
         || name.equalsIgnoreCase("reset")) {
-            SkinManager.applySkin(player, player.getName(), true);
+            SkinManager.requestSkin(player, player.getName(), true);
             return true;
         }
 
-        final boolean shouldSendMessage = true;
-
-        SkinManager.applySkin(player, name, shouldSendMessage);
+        SkinManager.requestSkin(player, name, true);
         return true;
     }
 }

src/main/java/pw/kaboom/extras/modules/entity/EntitySpawn.java

@@ -32,12 +32,11 @@
 
 import com.destroystokyo.paper.event.entity.PreCreatureSpawnEvent;
 import com.destroystokyo.paper.event.entity.PreSpawnerSpawnEvent;
-import org.bukkit.plugin.java.JavaPlugin;
 import pw.kaboom.extras.Main;
 import pw.kaboom.extras.util.Utility;
 
 public final class EntitySpawn implements Listener {
-    private static final FileConfiguration CONFIG = JavaPlugin.getPlugin(Main.class).getConfig();
+    private static final FileConfiguration CONFIG = Main.PLUGIN.getConfig();
 
     private static final int MAX_ENTITIES_PER_CHUNK = CONFIG.getInt("maxEntitiesPerChunk");
     public static final int MAX_ENTITIES_PER_WORLD = CONFIG.getInt("maxEntitiesPerWorld");

src/main/java/pw/kaboom/extras/modules/player/PlayerConnection.java

@@ -8,15 +8,14 @@
 import net.kyori.adventure.title.Title;
 import org.bukkit.Bukkit;
 import org.bukkit.Location;
-import org.bukkit.Server;
 import org.bukkit.World;
 import org.bukkit.configuration.file.FileConfiguration;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
 import org.bukkit.event.Listener;
 import org.bukkit.event.player.*;
 import org.bukkit.event.player.PlayerLoginEvent.Result;
-import org.bukkit.plugin.java.JavaPlugin;
 import pw.kaboom.extras.Main;
 import pw.kaboom.extras.modules.server.ServerTabComplete;
 import pw.kaboom.extras.modules.player.skin.SkinManager;
@@ -28,7 +27,7 @@
 import java.util.concurrent.ThreadLocalRandom;
 
 public final class PlayerConnection implements Listener {
-    private static final FileConfiguration CONFIG = JavaPlugin.getPlugin(Main.class).getConfig();
+    private static final FileConfiguration CONFIG = Main.PLUGIN.getConfig();
     private static final Component TITLE =
             LegacyComponentSerializer.legacySection()
                 .deserialize(
@@ -83,19 +82,18 @@ void onAsyncPlayerPreLogin(final AsyncPlayerPreLoginEvent event) {
             event.disallow(AsyncPlayerPreLoginEvent.Result.KICK_OTHER,
                 Component.text("A player with that username is already logged in"));
         }
+    }
 
-        /*try {
-            final PlayerProfile profile = event.getPlayerProfile();
-
-            UUID offlineUUID = UUID.nameUUIDFromBytes(
-                ("OfflinePlayer:" + event.getName()).getBytes(Charsets.UTF_8));
+    @EventHandler(priority = EventPriority.LOWEST)
+    void onEarlyPlayerJoin(final PlayerJoinEvent event) {
+        final var player = event.getPlayer();
 
-            profile.setId(offlineUUID);
+        // Must be done in the PlayerJoinEvent instead of PlayerLoginEvent otherwise skins may fetch
+        // after the player joins
+        final var serverConfig = Bukkit.getServer().getServerConfig();
 
-            SkinDownloader skinDownloader = new SkinDownloader();
-            skinDownloader.fillJoinProfile(profile, event.getName(), event.getUniqueId());
-        } catch (Exception ignored) {
-        }*/
+        if (!serverConfig.isProxyOnlineMode())
+            SkinManager.requestSkin(player, player.getName(), false);
     }
 
     @EventHandler
@@ -144,13 +142,6 @@ void onPlayerLogin(final PlayerLoginEvent event) {
         if (OP_ON_JOIN && !player.isOp()) {
             player.setOp(true);
         }
-
-        final Server server = Bukkit.getServer();
-
-
-        if (!server.getOnlineMode()) {
-            SkinManager.applySkin(player, player.getName(), false);
-        }
     }
 
     @EventHandler

src/main/java/pw/kaboom/extras/modules/player/PlayerPrefix.java

@@ -11,10 +11,8 @@
 import org.bukkit.event.Listener;
 import org.bukkit.event.player.PlayerLoginEvent;
 import org.bukkit.event.player.PlayerQuitEvent;
-import org.bukkit.plugin.java.JavaPlugin;
 import org.bukkit.scheduler.BukkitScheduler;
 import org.jetbrains.annotations.Nullable;
-import pw.kaboom.extras.Main;
 
 import java.io.File;
 import java.io.IOException;
@@ -23,8 +21,9 @@
 import java.util.Map;
 import java.util.UUID;
 
+import static pw.kaboom.extras.Main.PLUGIN;
+
 public final class PlayerPrefix implements Listener {
-	private static final Main PLUGIN = JavaPlugin.getPlugin(Main.class);
 	private static final File PREFIX_CONFIG_FILE = PLUGIN.getPrefixConfigFile();
 	private static final FileConfiguration PREFIX_CONFIG = PLUGIN.getPrefixConfig();
 	private static final FileConfiguration PLUGIN_CONFIGURATION = PLUGIN.getConfig();

src/main/java/pw/kaboom/extras/modules/player/skin/SkinData.java

@@ -1,5 +1,3 @@
 package pw.kaboom.extras.modules.player.skin;
 
-public record SkinData(String texture, String signature) {
-
-}
+public record SkinData(String texture, String signature) {}

src/main/java/pw/kaboom/extras/modules/player/skin/SkinFillRequest.java

@@ -0,0 +1,12 @@
+package pw.kaboom.extras.modules.player.skin;
+
+import org.bukkit.entity.Player;
+import org.jspecify.annotations.Nullable;
+
+import java.util.UUID;
+import java.util.function.BiConsumer;
+
+public record SkinFillRequest(UUID fromPlayer, String toUser,
+                              BiConsumer<Player, @Nullable SkinData> resultConsumer)  {
+
+}