Display usage information when using an existing command with wrong arguments.

Fixes #1.

Author: leMaik

src/main/java/de/craften/plugins/bkcommandapi/CommandHandler.java

@@ -18,8 +18,15 @@ enum Result {
         Done,
         /**
          * The command was not found.
+         *
+         * @deprecated use {@link #InvalidUsage} instead
          */
+        @Deprecated
         CommandNotFound,
+        /**
+         * The command was used incorrectly.
+         */
+        InvalidUsage,
         /**
          * The sender that invoked the command has no permission to use it.
          */

src/main/java/de/craften/plugins/bkcommandapi/SubCommandHandler.java

@@ -49,54 +49,63 @@ public final boolean onCommand(CommandSender sender, org.bukkit.command.Command
             }
         }
 
+        List<Command> possibleCommands = new ArrayList<>();
         for (CommandHandler handler : handlers) {
             for (Method method : handler.getClass().getMethods()) {
                 if (method.isAnnotationPresent(Command.class)) {
                     Command methodCommand = method.getAnnotation(Command.class);
                     if (((methodCommand.value().length == 0 && subCommand.isEmpty()) || containsAny(methodCommand.value(), subCommand))
-                            && args.length >= methodCommand.min() && args.length <= methodCommand.max()
                             && (methodCommand.allowFromConsole() || sender instanceof Player)) {
+                        possibleCommands.add(methodCommand);
 
-                        if (!methodCommand.permission().isEmpty() && !sender.hasPermission(methodCommand.permission())) {
-                            onPermissionDenied(sender, command, args);
-                            return true;
-                        }
-
-                        try {
-                            Object result;
-                            if (methodCommand.min() > 0 || methodCommand.max() > 0
-                                    || method.getParameterTypes().length == 3) { //handler may not have the third argument if there are no arguments
-                                result = method.invoke(handler, sender, args);
-                            } else {
-                                result = method.invoke(handler, sender);
+                        if (args.length >= methodCommand.min() && args.length <= methodCommand.max()) {
+                            if (!methodCommand.permission().isEmpty() && !sender.hasPermission(methodCommand.permission())) {
+                                onPermissionDenied(sender, command, args);
+                                return true;
                             }
 
-                            if (result instanceof Boolean) {
-                                return (boolean) result;
-                            } else if (result instanceof CommandHandler.Result) {
-                                switch ((CommandHandler.Result) result) {
-                                    case CommandNotFound:
-                                        onInvalidCommand(sender);
-                                        return false;
-                                    case NoPermission:
-                                        onPermissionDenied(sender, command, args);
-                                        return true;
-                                    case Done:
-                                        return true;
+                            try {
+                                Object result;
+                                if (methodCommand.min() > 0 || methodCommand.max() > 0
+                                        || method.getParameterTypes().length == 3) { //handler may not have the third argument if there are no arguments
+                                    result = method.invoke(handler, sender, args);
+                                } else {
+                                    result = method.invoke(handler, sender);
                                 }
-                            } else {
-                                return true;
+
+                                if (result instanceof Boolean) {
+                                    return (boolean) result;
+                                } else if (result instanceof CommandHandler.Result) {
+                                    switch ((CommandHandler.Result) result) {
+                                        case NoPermission:
+                                            onPermissionDenied(sender, command, args);
+                                            return true;
+                                        case Done:
+                                            return true;
+                                        case InvalidUsage: // intentionally empty
+                                        default:
+                                            break;
+                                    }
+                                } else {
+                                    return true;
+                                }
+                            } catch (IllegalAccessException | InvocationTargetException e) {
+                                Bukkit.getLogger().severe("Error invoking handler for command: " + command.toString());
+                                e.printStackTrace();
                             }
-                        } catch (IllegalAccessException | InvocationTargetException e) {
-                            Bukkit.getLogger().severe("Error invoking handler for command: " + command.toString());
-                            e.printStackTrace();
                         }
                     }
                 }
             }
         }
 
-        onInvalidCommand(sender);
+        if (possibleCommands.isEmpty()) {
+            onInvalidCommand(sender);
+        } else {
+            for (Command cmd : possibleCommands) {
+                sendUsageHelp(sender, cmd);
+            }
+        }
         return false;
     }