Fix Argument.ArgumentBuilder

SpigotCore_Main/src/de/steamwar/command/Argument.java

@@ -23,10 +23,7 @@ package de.steamwar.command;
 
 import org.bukkit.Bukkit;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Optional;
+import java.util.*;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
@@ -100,9 +97,33 @@ public class Argument<T> {
             }
         }
 
+        public void generate(int n, Argument<?>[] elements) {
+            if (n == 1 || n == 0) {
+                options.add(Arrays.copyOf(elements, elements.length));
+                return;
+            }
+            for (int i = 0; i < n - 1; i++) {
+                generate(n - 1, elements);
+                if (n % 2 == 0) {
+                    swap(elements, i, n - 1);
+                } else {
+                    swap(elements, 0, n - 1);
+                }
+            }
+            generate(n - 1, elements);
+        }
+
+        private void swap(Argument<?>[] elements, int a, int b) {
+            Argument<?> tmp = elements[a];
+            elements[a] = elements[b];
+            elements[b] = tmp;
+        }
+
         private void generate(Argument<?>[] arguments, int length, int startPosition, Argument<?>[] result) {
             if (length == 0) {
-                options.add(Arrays.copyOf(result, result.length));
+                Set<Argument<?>> argumentSet = new HashSet<>(Arrays.asList(result));
+                if (argumentSet.size() != result.length) return;
+                generate(result.length, Arrays.copyOf(result, result.length));
                 return;
             }
             for (int i = startPosition; i <= arguments.length - length; i++) {
@@ -131,4 +152,11 @@ public class Argument<T> {
 
     }
 
+    @Override
+    public String toString() {
+        return "Argument{" +
+                "tabCompletes=" + Arrays.toString(tabCompletes) +
+                '}';
+    }
+
 }