Custom Permission Handler (#1282)

Co-authored-by: Melledy <52122272+Melledy@users.noreply.github.com>

src/main/java/emu/grasscutter/command/DefaultPermissionHandler.java

@@ -0,0 +1,32 @@
+package emu.grasscutter.command;
+
+import emu.grasscutter.game.Account;
+import emu.grasscutter.game.player.Player;
+
+public class DefaultPermissionHandler implements PermissionHandler {
+    @Override
+    public boolean EnablePermissionCommand() {
+        return true;
+    }
+
+    @Override
+    public boolean checkPermission(Player player, Player targetPlayer, String permissionNode, String permissionNodeTargeted) {
+        if(player == null) {
+            return true;
+        }
+
+        Account account = player.getAccount();
+        if (player != targetPlayer) {  // Additional permission required for targeting another player
+            if (!permissionNodeTargeted.isEmpty() && !account.hasPermission(permissionNodeTargeted)) {
+                CommandHandler.sendTranslatedMessage(player, "commands.generic.permission_error");
+                return false;
+            }
+        }
+        if (!permissionNode.isEmpty() && !account.hasPermission(permissionNode)) {
+            CommandHandler.sendTranslatedMessage(player, "commands.generic.permission_error");
+            return false;
+        }
+
+        return true;
+    }
+}