Add /reset to start over from scratch and hint at it in the endless stage

src/main/java/eu/mhsl/minecraft/endlessjumper/EndlessJumper.java

@@ -3,6 +3,8 @@ package eu.mhsl.minecraft.endlessjumper;
 import eu.mhsl.minecraft.endlessjumper.generator.JumpGenerator;
 import net.minestom.server.Auth;
 import net.minestom.server.MinecraftServer;
+import net.minestom.server.command.builder.Command;
+import net.minestom.server.coordinate.Vec;
 import net.minestom.server.coordinate.Pos;
 import net.minestom.server.entity.Player;
 import net.minestom.server.entity.PlayerSkin;
@@ -20,7 +22,6 @@ import net.minestom.server.event.player.PlayerUseItemEvent;
 import net.minestom.server.event.player.PlayerUseItemOnBlockEvent;
 import net.minestom.server.instance.Instance;
 import net.minestom.server.instance.InstanceContainer;
-import net.minestom.server.instance.InstanceManager;
 import net.minestom.server.instance.block.Block;
 import net.minestom.server.item.ItemStack;
 
@@ -32,26 +33,20 @@ import java.util.concurrent.ConcurrentHashMap;
 
 public class EndlessJumper {
     private static final Pos START = new Pos(0, 100, 0);
+    private static final Pos SPAWN = START.add(0.5, 1, 0.5);
     private static final Map<Player, JumpGenerator> games = new ConcurrentHashMap<>();
 
     public static void main(String[] args) throws IOException {
         MinecraftServer server = MinecraftServer.init(new Auth.Velocity(readForwardingSecret()));
         Progress.load();
-        InstanceManager instanceManager = MinecraftServer.getInstanceManager();
         GlobalEventHandler eventHandler = MinecraftServer.getGlobalEventHandler();
         PlayerSkin skin = PlayerSkin.fromUsername("Notch");
 
         eventHandler.addListener(AsyncPlayerConfigurationEvent.class, event -> {
             final Player p = event.getPlayer();
-            p.setRespawnPoint(START.add(0.5, 1.5, 0.5));
-
-            final InstanceContainer world = instanceManager.createInstanceContainer();
-            world.setBlock(START, Block.DIAMOND_BLOCK);
-            // Tageszeit steuert der jeweilige Abschnitt
-            world.defaultClock().pause();
-
+            p.setRespawnPoint(SPAWN);
             p.setSkin(skin);
-            event.setSpawningInstance(world);
+            event.setSpawningInstance(createWorld());
         });
 
         eventHandler.addListener(PlayerSpawnEvent.class, event -> {
@@ -94,13 +89,46 @@ public class EndlessJumper {
             games.remove(p);
             ScoreTab.leave(p);
             // jede Partie hat eine eigene Welt: nach dem Verlassen freigeben
-            Instance world = p.getInstance();
-            if(world != null) MinecraftServer.getSchedulerManager().scheduleNextTick(() -> instanceManager.unregisterInstance(world));
+            releaseLater(p.getInstance());
         });
 
+        Command reset = new Command("reset");
+        reset.setDefaultExecutor((sender, context) -> {
+            if(sender instanceof Player player) resetGame(player);
+        });
+        MinecraftServer.getCommandManager().register(reset);
+
         server.start("0.0.0.0", 25501);
     }
 
+    private static InstanceContainer createWorld() {
+        InstanceContainer world = MinecraftServer.getInstanceManager().createInstanceContainer();
+        world.setBlock(START, Block.DIAMOND_BLOCK);
+        // Tageszeit steuert der jeweilige Abschnitt
+        world.defaultClock().pause();
+        return world;
+    }
+
+    private static void releaseLater(Instance world) {
+        if(world != null) MinecraftServer.getSchedulerManager().scheduleNextTick(() -> MinecraftServer.getInstanceManager().unregisterInstance(world));
+    }
+
+    /** /reset: Fortschritt, Strecke, Score und Joker zurücksetzen und in einer frischen Welt bei 0 beginnen. */
+    private static void resetGame(Player player) {
+        JumpGenerator old = games.remove(player);
+        if(old != null) old.close();
+        Progress.reset(player.getUuid());
+
+        Instance oldWorld = player.getInstance();
+        InstanceContainer world = createWorld();
+        player.setVelocity(Vec.ZERO);
+        player.setInstance(world, SPAWN).thenRun(() -> {
+            Jokers.giveStart(player);
+            games.put(player, new JumpGenerator(START, 0, player, world));
+            releaseLater(oldWorld);
+        });
+    }
+
     private static void useJoker(Player player, ItemStack item) {
         JumpGenerator generator = games.get(player);
         if(generator != null && Jokers.BRIDGE.matches(item) && generator.useBridge()) Jokers.BRIDGE.take(player);