feat: Implement help command

src/main/java/com/onarandombox/MultiverseCore/MultiverseCore.java

@@ -38,8 +38,10 @@ import com.onarandombox.MultiverseCore.commands.LoadCommand;
 import com.onarandombox.MultiverseCore.commands.RegenCommand;
 import com.onarandombox.MultiverseCore.commands.ReloadCommand;
 import com.onarandombox.MultiverseCore.commands.RemoveCommand;
+import com.onarandombox.MultiverseCore.commands.RootCommand;
 import com.onarandombox.MultiverseCore.commands.TeleportCommand;
 import com.onarandombox.MultiverseCore.commands.UnloadCommand;
+import com.onarandombox.MultiverseCore.commands.UsageCommand;
 import com.onarandombox.MultiverseCore.commandtools.MVCommandManager;
 import com.onarandombox.MultiverseCore.destination.DestinationsProvider;
 import com.onarandombox.MultiverseCore.destination.core.AnchorDestination;
@@ -164,7 +166,6 @@ public class MultiverseCore extends JavaPlugin implements MVCore {
         this.anchorManager.loadAnchors();
         this.registerEvents();
         this.registerCommands();
-        this.setUpLocales();
         this.registerDestinations();
         this.setupMetrics();
         this.saveMVConfig();
@@ -216,15 +217,6 @@ public class MultiverseCore extends JavaPlugin implements MVCore {
         this.commandManager.registerCommand(new UnloadCommand(this));
     }
 
-    /**
-     * Resgister locales
-     */
-    private void setUpLocales() {
-        this.commandManager.usePerIssuerLocale(true, true);
-        this.commandManager.getLocales().addFileResClassLoader(this);
-        this.commandManager.getLocales().addMessageBundles("multiverse-core");
-    }
-
     /**
      * Register all the destinations.
      */

src/main/java/com/onarandombox/MultiverseCore/commands/RootCommand.java

@@ -0,0 +1,21 @@
+package com.onarandombox.MultiverseCore.commands;
+
+import co.aikar.commands.CommandIssuer;
+import co.aikar.commands.annotation.CommandAlias;
+import com.onarandombox.MultiverseCore.MultiverseCore;
+import org.bukkit.ChatColor;
+import org.bukkit.plugin.PluginDescriptionFile;
+import org.jetbrains.annotations.NotNull;
+
+public class RootCommand extends MultiverseCoreCommand {
+    public RootCommand(@NotNull MultiverseCore plugin) {
+        super(plugin);
+    }
+
+    @CommandAlias("mv")
+    public void onRootCommand(CommandIssuer issuer) {
+        PluginDescriptionFile description = this.plugin.getDescription();
+        issuer.sendMessage(ChatColor.GREEN + description.getName() + " version " + description.getVersion());
+        issuer.sendMessage(ChatColor.GREEN + "See " + ChatColor.WHITE + "/mv help" + ChatColor.GREEN + " for commands available.");
+    }
+}

src/main/java/com/onarandombox/MultiverseCore/commands/UsageCommand.java

@@ -0,0 +1,33 @@
+package com.onarandombox.MultiverseCore.commands;
+
+import co.aikar.commands.CommandHelp;
+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.HelpCommand;
+import co.aikar.commands.annotation.Subcommand;
+import co.aikar.commands.annotation.Syntax;
+import com.onarandombox.MultiverseCore.MultiverseCore;
+import org.jetbrains.annotations.NotNull;
+
+@CommandAlias("mv")
+public class UsageCommand extends MultiverseCoreCommand {
+    public UsageCommand(@NotNull MultiverseCore plugin) {
+        super(plugin);
+    }
+
+    @HelpCommand
+    @Subcommand("help")
+    @CommandPermission("multiverse.core.help")
+    @CommandCompletion("@commands:mv")
+    @Syntax("[filter] [page]")
+    @Description("Show Multiverse-Core Command usage.")
+    public void onUsageCommand(CommandHelp help) {
+        if (help.getIssuer().isPlayer()) {
+            // Prevent flooding the chat
+            help.setPerPage(4);
+        }
+        this.plugin.getMVCommandManager().showUsage(help);
+    }
+}

src/main/java/com/onarandombox/MultiverseCore/commandtools/MVCommandCompletions.java

@@ -5,12 +5,16 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.stream.Collectors;
 
 import co.aikar.commands.BukkitCommandCompletionContext;
 import co.aikar.commands.BukkitCommandIssuer;
+import co.aikar.commands.CommandIssuer;
 import co.aikar.commands.PaperCommandCompletions;
+import co.aikar.commands.RegisteredCommand;
+import co.aikar.commands.RootCommand;
 import com.google.common.collect.Sets;
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.MVWorld;
@@ -30,6 +34,7 @@ public class MVCommandCompletions extends PaperCommandCompletions {
         this.plugin = plugin;
         this.worldManager = plugin.getMVWorldManager();
 
+        registerAsyncCompletion("commands", this::suggestCommands);
         registerAsyncCompletion("destinations", this::suggestDestinations);
         registerAsyncCompletion("flags", this::suggestFlags);
         registerStaticCompletion("gamerules", this::suggestGamerules);
@@ -41,6 +46,33 @@ public class MVCommandCompletions extends PaperCommandCompletions {
         setDefaultCompletion("mvworlds", MVWorld.class);
     }
 
+    private Collection<String> suggestCommands(BukkitCommandCompletionContext context) {
+        String rootCmdName = context.getConfig();
+        if (rootCmdName == null) {
+            return Collections.emptyList();
+        }
+
+        RootCommand rootCommand = this.plugin.getMVCommandManager().getRegisteredRootCommands().stream()
+                .unordered()
+                .filter(c -> c.getCommandName().equals(rootCmdName))
+                .findFirst()
+                .orElse(null);
+
+        if (rootCommand == null) {
+            return Collections.emptyList();
+        }
+
+        return rootCommand.getSubCommands().entries().stream()
+                .filter(entry -> checkPerms(context.getIssuer(), entry.getValue()))
+                .map(Map.Entry::getKey)
+                .filter(cmdName -> !cmdName.startsWith("__"))
+                .collect(Collectors.toList());
+    }
+
+    private boolean checkPerms(CommandIssuer issuer, RegisteredCommand<?> command) {
+        return this.plugin.getMVCommandManager().hasPermission(issuer, command.getRequiredPermissions());
+    }
+
     private Collection<String> suggestDestinations(BukkitCommandCompletionContext context) {
         if (context.hasConfig("playerOnly") && !context.getIssuer().isPlayer()) {
             return Collections.emptyList();

src/main/java/com/onarandombox/MultiverseCore/commandtools/MVCommandManager.java

@@ -1,9 +1,13 @@
 package com.onarandombox.MultiverseCore.commandtools;
 
+import java.util.List;
+
 import co.aikar.commands.BukkitCommandCompletionContext;
 import co.aikar.commands.BukkitCommandExecutionContext;
 import co.aikar.commands.CommandCompletions;
 import co.aikar.commands.CommandContexts;
+import co.aikar.commands.CommandHelp;
+import co.aikar.commands.HelpEntry;
 import co.aikar.commands.PaperCommandManager;
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.commandtools.flags.CommandFlagsManager;
@@ -92,4 +96,18 @@ public class MVCommandManager extends PaperCommandManager {
         }
         return this.completions;
     }
+
+    /**
+     * Standardise usage command formatting for all mv modules.
+     *
+     * @param help The target {@link CommandHelp}.
+     */
+    public void showUsage(@NotNull CommandHelp help) {
+        List<HelpEntry> entries = help.getHelpEntries();
+        if (entries.size() == 1) {
+            this.plugin.getMVCommandManager().getHelpFormatter().showDetailedHelp(help, entries.get(0));
+            return;
+        }
+        help.showHelp();
+    }
 }