feat: implemented PreloadedWorldModule

api/src/main/java/ru/dragonestia/msb3/api/module/PreloadedWorldModule.java

@@ -0,0 +1,63 @@
+package ru.dragonestia.msb3.api.module;
+
+import net.minestom.server.MinecraftServer;
+import net.minestom.server.coordinate.Pos;
+import net.minestom.server.entity.GameMode;
+import net.minestom.server.event.player.AsyncPlayerConfigurationEvent;
+import net.minestom.server.event.player.PlayerDisconnectEvent;
+import net.minestom.server.event.player.PlayerMoveEvent;
+import net.minestom.server.event.player.PlayerSpawnEvent;
+import ru.dragonestia.msb3.api.world.World;
+import ru.dragonestia.msb3.api.world.WorldFactory;
+
+import java.io.File;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Supplier;
+
+public class PreloadedWorldModule {
+
+    private static boolean used = false;
+
+    private PreloadedWorldModule() {}
+
+    public static void init(File worldDir, GameMode gameMode, Pos spawnPos) {
+        init(worldDir, gameMode, () -> spawnPos);
+    }
+
+    public static synchronized void init(File worldDir, GameMode gameMode, Supplier<Pos> spawnPosSupplier) {
+        if (used) return;
+        used = true;
+
+        var loadingWorld = MinecraftServer.getInstanceManager().createInstanceContainer();
+        loadingWorld.eventNode().addListener(PlayerMoveEvent.class, event -> event.setCancelled(true));
+
+        var factory = WorldFactory.anvil(worldDir);
+        var worlds = new ConcurrentHashMap<UUID, World>();
+
+        MinecraftServer.getGlobalEventHandler().addListener(AsyncPlayerConfigurationEvent.class, event -> {
+            var player = event.getPlayer();
+
+            player.setRespawnPoint(new Pos(0, 60, 0));
+            player.setGameMode(gameMode);
+
+            event.setSpawningInstance(loadingWorld);
+        }).addListener(PlayerSpawnEvent.class, event -> {
+            if (!event.isFirstSpawn()) return;
+
+            var player = event.getPlayer();
+            factory.createWorld().thenAccept(world -> {
+                worlds.put(player.getUuid(), world);
+                player.setInstance(world.getInstance(), spawnPosSupplier.get());
+            });
+        }).addListener(PlayerDisconnectEvent.class, event -> {
+            var player = event.getPlayer();
+            var world = worlds.remove(player.getUuid());
+
+            if (world == null) return;
+            if (world.getInstance().getEntityTracker().entities().stream().filter(entity -> entity != player).count() == 0) {
+                world.unload();
+            }
+        });
+    }
+}