Add Basic TabCompleting

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

@@ -23,9 +23,12 @@ package de.steamwar.command;
 
 import org.bukkit.Bukkit;
 
+import java.util.Arrays;
+import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 
 public class Argument<T> {
 
@@ -66,4 +69,18 @@ public class Argument<T> {
         return Optional.empty();
     }
 
+    public Optional<List<String>> tabCompleteSupplier(String s) {
+        try {
+            // Check if mappable
+            if (!s.isEmpty()) argumentType.mapper.apply(s);
+            List<String> strings = Arrays.stream(tabCompletes).filter(t -> t.startsWith(s)).collect(Collectors.toList());
+            if (strings.isEmpty()) strings.add(s);
+            return Optional.of(strings);
+        } catch (NumberFormatException e) {
+            return Optional.empty();
+        } catch (Exception e) {
+            throw new SecurityException(e);
+        }
+    }
+
 }

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

@@ -23,6 +23,8 @@ package de.steamwar.command;
 
 import org.bukkit.entity.Player;
 
+import java.util.Arrays;
+import java.util.List;
 import java.util.Optional;
 
 public class SWCommand {
@@ -59,4 +61,16 @@ public class SWCommand {
         return Optional.of(executor.execute(player, new ArgumentMap(objects)));
     }
 
+    public Optional<List<String>> tabComplete(String[] args) {
+        if (args.length > arguments.length) {
+            return Optional.empty();
+        }
+        for (int i = 0; i < args.length - 1; i++) {
+            Optional<?> optional = arguments[i].valueSupplier(args[i]);
+            if (!optional.isPresent()) return Optional.empty();
+        }
+        int index = args.length - 1;
+        return arguments[index].tabCompleteSupplier(args[index]);
+    }
+
 }