Implement DifficultyCommand

src/main/java/org/mvplugins/multiverse/core/commands/DifficultyCommand.java

@@ -0,0 +1,49 @@
+package org.mvplugins.multiverse.core.commands;
+
+import co.aikar.commands.annotation.CommandAlias;
+import co.aikar.commands.annotation.CommandCompletion;
+import co.aikar.commands.annotation.CommandPermission;
+import co.aikar.commands.annotation.Description;
+import co.aikar.commands.annotation.Flags;
+import co.aikar.commands.annotation.Subcommand;
+import co.aikar.commands.annotation.Syntax;
+import jakarta.inject.Inject;
+import org.bukkit.Difficulty;
+import org.jetbrains.annotations.NotNull;
+import org.jvnet.hk2.annotations.Service;
+
+import org.mvplugins.multiverse.core.commandtools.MVCommandIssuer;
+import org.mvplugins.multiverse.core.commandtools.MVCommandManager;
+import org.mvplugins.multiverse.core.commandtools.MultiverseCommand;
+import org.mvplugins.multiverse.core.world.LoadedMultiverseWorld;
+
+@Service
+@CommandAlias("mv")
+class DifficultyCommand extends MultiverseCommand {
+
+    @Inject
+    DifficultyCommand(@NotNull MVCommandManager commandManager) {
+        super(commandManager);
+    }
+
+    @Subcommand("difficulty")
+    @CommandPermission("multiverse.core.difficulty")
+    @CommandCompletion("@difficulty @mvworlds:scope=both")
+    @Syntax("<difficulty> [world]")
+    void onDifficultyCommand(
+            MVCommandIssuer issuer,
+
+            @Syntax("<difficulty>")
+            @Description("")
+            Difficulty difficulty,
+
+            @Flags("resolve=issuerAware")
+            @Syntax("[world]")
+            @Description("")
+            // TODO: Change to MultiverseWorld
+            LoadedMultiverseWorld world) {
+        world.setDifficulty(difficulty)
+                .onSuccess(w -> issuer.sendInfo("Difficulty set to " + difficulty + " for world " + world.getName()))
+                .onFailure(failure -> issuer.sendError(failure.getMessage()));
+    }
+}

src/main/java/org/mvplugins/multiverse/core/commandtools/MVCommandCompletions.java

@@ -18,6 +18,7 @@ import com.dumptruckman.minecraft.util.Logging;
 import com.google.common.collect.Sets;
 import io.vavr.control.Try;
 import jakarta.inject.Inject;
+import org.bukkit.Difficulty;
 import org.bukkit.GameRule;
 import org.jetbrains.annotations.NotNull;
 import org.jvnet.hk2.annotations.Service;
@@ -50,6 +51,7 @@ public class MVCommandCompletions extends PaperCommandCompletions {
 
         registerAsyncCompletion("commands", this::suggestCommands);
         registerAsyncCompletion("destinations", this::suggestDestinations);
+        registerStaticCompletion("difficulty", this::suggestDifficulty);
         registerAsyncCompletion("flags", this::suggestFlags);
         registerStaticCompletion("gamerules", this::suggestGamerules);
         registerStaticCompletion("mvconfigs", config.getNodes().getNames());
@@ -97,6 +99,10 @@ public class MVCommandCompletions extends PaperCommandCompletions {
                 .suggestDestinations((BukkitCommandIssuer)context.getIssuer(), context.getInput());
     }
 
+    private Collection<String> suggestDifficulty() {
+        return Arrays.stream(Difficulty.values()).map(Difficulty::name).toList();
+    }
+
     private Collection<String> suggestFlags(@NotNull BukkitCommandCompletionContext context) {
         String groupName = context.getConfig("groupName", "");
 
@@ -106,7 +112,7 @@ public class MVCommandCompletions extends PaperCommandCompletions {
     }
 
     private Collection<String> suggestGamerules() {
-        return Arrays.stream(GameRule.values()).map(GameRule::getName).collect(Collectors.toList());
+        return Arrays.stream(GameRule.values()).map(GameRule::getName).toList();
     }
 
     private Collection<String> suggestMVWorlds(BukkitCommandCompletionContext context) {